Xi Huang, Ph.D.

Oral contraceptive use, iron stores and vascular endothelial function in healthy women
Friedman, Julie; Cremer, Miriam; Jelani, Qurat Ul-Ain; Huang, Xi; Jian, Jinlong; Shah, Sooraj; Katz, Stuart D
2011 Sep;84(3):285-290, Contraception
BACKGROUND: Increased iron stores are associated with greater cardiovascular risk in postmenopausal women. Oral contraceptive pill (OCP) use decreases the volume of menstrual blood loss and increases iron stores, but the link between OCP use, iron stores and cardiovascular risk in premenopausal women has not been characterized. STUDY DESIGN: We conducted a cross-sectional study of 23 healthy OCP users to determine the association between type and duration of OCP exposure, iron stores, and vascular endothelial function [flow-mediated dilation (FMD) in the brachial artery]. RESULTS: Median duration of OCP use was 45 months. FMD in the brachial artery was significantly associated with progestin type used (estranes/gonanes vs. drospirenone) and duration of OCP use (both p<.05) but not iron stores. In multivariate analysis, progestin type was the only independent predictor of FMD. CONCLUSIONS: Use of OCP containing drospirenone was independently associated with greater FMD in the brachial artery and, thus, a potentially more favorable cardiovascular risk profile, when compared with use of OCP containing estranes/gonanes
— id: 136646, year: 2011, vol: 84, page: 285, stat: Journal Article,

Intakes of dietary iron and heme-iron and risk of postmenopausal breast cancer in the National Institutes of Health-AARP Diet and Health Study
Huang, Xi; Katz, Stuart
2011 Aug;94(2):613-614, American journal of clinical nutrition
— id: 135553, year: 2011, vol: 94, page: 613, stat: Journal Article,

Iron sensitizes keratinocytes and fibroblasts to UVA-mediated matrix metalloproteinase-1 through TNF-alpha and ERK activation
Jian, Jinlong; Pelle, Edward; Yang, Qing; Pernodet, Nadine; Maes, Daniel; Huang, Xi
2011 Mar;20(3):249-254, Experimental dermatology
Oestrogen deficiency is regarded as the main causative factor in postmenopausal skin ageing and photoageing. While women after menopause experience low levels of oestrogen because of cease of ovarian function, they are also exposed to high levels of iron as a result of cessation of menstruation. In this study, we investigated whether this increase in iron presents a risk to the postmenopausal skin. Because of the lack of appropriate animal models to closely mimic the low oestrogen and high iron conditions, we tested the hypothesis in a high iron and low oestrogen culture model. Here, we showed that primary human dermal fibroblasts exposed to iron did not affect the baseline levels of matrix metalloproteinase-1 (MMP-1) activity. However, the iron-exposed fibroblasts were sensitized to UVA exposure, which resulted in a synergistic increase in MMP-1. UVA activated the three members of MAPK family: ERKs, p38, and JNKs. Additional activation of ERKs by iron contributed to the synergistic increases. Primary normal human epidermal keratinocytes (NHEK) did not respond to iron or UVA exposure as measured by MMP-1, but produced tumor necrosis factor-alpha (TNF-alpha) in the media, which then stimulated MMP-1 in fibroblasts. Our results indicate that iron and UVA increase MMP-1 activity in dermal fibroblasts not only directly through ERK activation but also by an indirect paracrine loop through TNF-alpha released by NHEK. We conclude that in addition to oestrogen deficiency, increased iron as a result of menopause could be a novel risk factor by sensitizing postmenopausal skin to solar irradiation
— id: 123202, year: 2011, vol: 20, page: 249, stat: Journal Article,

Effects of iron deficiency and iron overload on angiogenesis and oxidative stress-a potential dual role for iron in breast cancer (vol 50, pg 841, 2011)
Jian, Jinlong; Yang, Qing; Dai, Jisen; Eckard, Jonathan; Axelrod, Deborah; Smith, Julia; Huang, Xi
2011 JUL 1 ;51(1):243-243, Free radical biology & medicine
— id: 134497, year: 2011, vol: 51, page: 243, stat: Journal Article,

Effects of iron deficiency and iron overload on angiogenesis and oxidative stress-a potential dual role for iron in breast cancer
Jian, Jinlong; Yang, Qing; Dai, Jisen; Eckard, Jonathan; Axelrod, Debrah; Smith, Julia; Huang, Xi
2011 Apr 1;50(7):841-847, Free radical biology & medicine
Estrogen alone cannot explain the differences in breast cancer (BC) recurrence and incidence rates in pre- and postmenopausal women. In this study, we have tested a hypothesis that, in addition to estrogen, both iron deficiency due to menstruation and iron accumulation as a result of menstrual stop play important roles in menopause-related BC outcomes. We first tested this hypothesis in cell culture models mimicking the high-estrogen and low-iron premenopausal condition or the low-estrogen and high-iron postmenopausal condition. Subsequently, we examined this hypothesis in mice that were fed iron-deficient and iron-overloaded diets. We show that estrogen only slightly up-regulates vascular endothelial growth factor (VEGF), an angiogenic factor known to be important in BC recurrence. It is, rather, iron deficiency that significantly promotes VEGF by stabilizing hypoxia-inducible factor-1alpha. Conversely, high iron levels increase oxidative stress and sustain mitogen-activated protein kinase activation, which are mechanisms of known significance in BC development. Taken together, our results suggest, for the first time, that an iron-deficiency-mediated proangiogenic environment could contribute to the high recurrence of BC in young patients, and iron-accumulation-associated pro-oxidant conditions could lead to the high incidence of BC in older women
— id: 130294, year: 2011, vol: 50, page: 841, stat: Journal Article,

SRC regulates tyr20 phosphorylation of transferrin receptor-1 and potentiates breast cancer cell survival
Jian, Jinlong; Yang, Qing; Huang, Xi
2011 Oct 14;286(41):35708-35715, Journal of biological chemistry
Transferrin receptor 1 (TfR1) is a ubiquitous type II membrane receptor with 61 amino acids in the N-terminal cytoplasmic region. TfR1 is highly expressed in cancer cells, particularly under iron deficient conditions. Overexpression of TfR1 is thought to meet the increased requirement of iron uptake necessary for cell growth. In the present study, we used transferrin (Tf), a known ligand of TfR1, and gambogic acid (GA), an apoptosis-inducing agent and newly identified TfR1 ligand to investigate the signaling role of TfR1 in breast cancer cells. We found that GA but not Tf induced apoptosis in a TfR1-dependent manner in breast cancer MDA-MB-231 cells. Estrogen receptor-positive MCF-7 cells lack caspase-3 and were not responsive to GA treatment. GA activated the three major signaling pathways of the MAPK family, as well as caspase-3, -8, and Poly(ADP-ribose)polymerase apoptotic pathway. Interestingly, only Src inhibitor PP2 greatly sensitized the cells to GA-mediated apoptosis. Further investigations by confocal fluorescence microscopy and immunoprecipitation revealed that Src and TfR1 are constitutively bound. Using TfR1-deficient CHO TRVB cells, point mutation studies showed that Tyr(20) within the (20)YTRF(23) motif of the cytoplasmic region of TfR1 is the phosphorylation site by Src. TfR1 Tyr(20) phosphomutants were more sensitive to GA-mediated apoptosis. Our results indicate that, albeit its iron uptake function, TfR1 is a signaling molecule and tyrosine phosphorylation at position 20 by Src enhances anti-apoptosis and potentiates breast cancer cell survival
— id: 138710, year: 2011, vol: 286, page: 35708, stat: Journal Article,

Protection against ultraviolet A-induced oxidative damage in normal human epidermal keratinocytes under post-menopausal conditions by an ultraviolet A-activated caged-iron chelator: a pilot study
Pelle, Edward; Jian, Jinlong; Declercq, Lieve; Dong, Kelly; Yang, Qing; Pourzand, Charareh; Maes, Daniel; Pernodet, Nadine; Yarosh, Daniel B; Huang, Xi
2011 Oct;27(5):231-235, Photodermatology, photoimmunology, & photomedicine
Background/purpose: Human skin is constantly exposed to ultraviolet A (UVA), which can generate reactive oxygen species and cause iron release from ferritin, leading to oxidative damage in biomolecules. This is particularly true in post-menopausal skin due to an increase in iron as a result of menopause. As iron is generally released through desquamation, the skin becomes a main portal for the release of excess iron in this age group. In the present study, we examined a strategy for controlling UVA- and iron-induced oxidative stress in skin using a keratinocyte post-menopausal cellular model system. Methods: Keratinocytes that had been cultured under normal or high-iron, low-estrogen conditions were treated with (2-nitrophenyl) ethyl pyridoxal isonicotinoyl hydrazone (2-PNE-PIH). 2-PNE-PIH is a caged-iron chelator that does not normally bind iron but can be activated by UVA radiation to bind iron. Following incubation with 2-PNE-PIH, the cells were exposed to 5 J/cm(2) UVA and then measured for changes in lipid peroxidation and ferritin levels. Results: 2-PNE-PIH protected keratinocytes against UVA-induced lipid peroxidation and ferritin depletion. Further, 2-PNE-PIH was neither cytotoxic nor did it alter iron metabolism. Conclusion: 2-PNE-PIH may be a useful deterrent against UVA-induced oxidative stress in post-menopausal women
— id: 137893, year: 2011, vol: 27, page: 231, stat: Journal Article,

Inhibitory effects of iron on bone morphogenetic protein 2-induced osteoblastogenesis
Yang, Qing; Jian, Jinlong; Abramson, Steven B; Huang, Xi
2011 Jun;26(6):1188-1196, Journal of bone & mineral research
Postmenopausal osteoporosis is characterized by an imbalance of bone resorption exceeding bone formation, resulting in a net loss of bone mineral density (BMD). Estrogen deficiency is known to promote bone resorption. However, the causative factors that impair bone formation have not been identified. Women after menopause experience not only estrogen deficiency but also iron accumulation as a result of cessation of menstruation. In this study we investigated whether increased iron plays a role in osteoporosis. By growing primary mouse osteoclast and osteoblast progenitor cells as well as immortalized cell lines in the presence of iron, we found that increased iron had minimal effects on osteoclast cell differentiation. Interestingly, iron, particularly in its inorganic form, and to a lesser extent ferritin and transferrin all suppressed alkaline phosphatase (ALP) activities in osteoblasts. Moreover, iron downregulated mRNA levels of several other osteoblastogenic markers such as Runx2, osterix, osteopontin, and osteocalcin. To further show that this in vitro finding is relevant to the in vivo condition, we demonstrated that iron-accumulated mice with intact ovaries exhibited a significant decrease in BMD. Although iron inhibited preosteoblast cell differentiation, it did enhance preosteoblast cell proliferation, as evidenced by increased cell growth and expression of cell cycle regulator genes such as CDK4, CDK6, cyclin D1, and cyclin D3 and G(2) /M phase cell population. Taken together, our results suggest that increased iron could be a factor that slows down bone formation in postmenopausal women. (c) 2011 American Society for Bone and Mineral Research
— id: 132876, year: 2011, vol: 26, page: 1188, stat: Journal Article,

Effects of cellular iron deficiency on the formation of vascular endothelial growth factor and angiogenesis. Iron deficiency and angiogenesis
Eckard, Jonathan; Dai, Jisen; Wu, Jing; Jian, Jinlong; Yang, Qing; Chen, Haobin; Costa, Max; Frenkel, Krystyna; Huang, Xi
2010 ;10:28-28, Cancer cell international
ABSTRACT: BACKGROUND: Young women diagnosed with breast cancer are known to have a higher mortality rate from the disease than older patients. Specific risk factors leading to this poorer outcome have not been identified. In the present study, we hypothesized that iron deficiency, a common ailment in young women, contributes to the poor outcome by promoting the hypoxia inducible factor-1alpha (HIF-1alpha and vascular endothelial growth factor (VEGF) formation. This hypothesis was tested in an in vitro cell culture model system. RESULTS: Human breast cancer MDA-MB-231 cells were transfected with transferrin receptor-1 (TfR1) shRNA to constitutively impair iron uptake. Cellular iron status was determined by a set of iron proteins and angiogenesis was evaluated by levels of VEGF in cells as well as by a mouse xenograft model. Significant decreases in ferritin with concomitant increases in VEGF were observed in TfR1 knockdown MDA-MB-231 cells when compared to the parental cells. TfR1 shRNA transfectants also evoked a stronger angiogenic response after the cells were injected subcutaneously into nude mice. The molecular mechanism appears that cellular iron deficiency elevates VEGF formation by stabilizing HIF-1alpha. This mechanism is also true in human breast cancer MCF-7 and liver cancer HepG2 cells. CONCLUSIONS: Cellular iron deficiency increased HIF-1alpha, VEGF, and angiogenesis, suggesting that systemic iron deficiency might play an important part in the tumor angiogenesis and recurrence in this young age group of breast cancer patients
— id: 114147, year: 2010, vol: 10, page: 28, stat: Journal Article,

Effects of Iron Deficiency Anemia on the Formation of Vascular Endothelial Growth Factor, Angiogenesis, and Metastasis
Huang, Xi; Jian, Jinlong; Yang, Qing
2010 JAN ;49(1):S62-S62, Free radical biology & medicine
— id: 119121, year: 2010, vol: 49, page: S62, stat: Journal Article,

Targeting CDK4/CDK6 impairs osteoclast progenitor pool expansion and blocks osteolytic lesion development in multiple myeloma
Feng R.; Huang X.; Coulton L.; De Raeve H.; DiLiberto M.; Ely S.; Xiao G.; Luo M.; Menu E.; Croucher P.; Roodman G.D.; Vanderkerken K.; Chen-Kiang S.; Lentzsch S.
2009 ;114(22):?-? #298, Blood
— id: 112212, year: 2009, vol: 114, page: ?, stat: Journal Article,

Human skin fibroblasts under post-menopausal conditions are more sensitive to UVA-induced MMP-1 expression
Jian, J; Yang, Q; Huang, X; Pelle, E; Pernodet, N; Maes, D
2009 APR ;129(5):S131-S131, Journal of investigative dermatology
— id: 97877, year: 2009, vol: 129, page: S131, stat: Journal Article,

Iron and menopause: does increased iron affect the health of postmenopausal women?
Jian, Jinlong; Pelle, Edward; Huang, Xi
2009 Dec;11(12):2939-2943, Antioxidants & Redox Signaling
Estrogen deficiency has been regarded as the main causative factor in menopausal symptoms and diseases. Here, we show that although estrogen decreases by 90%, a concurrent but inverse change occurs in iron levels during menopausal transition. For example, levels of serum ferritin are increased by two- to threefold from before menopause to after menopause. This observation has led us to hypothesize that, in addition to estrogen deficiency, increased iron as a result of menopause could be a risk factor affecting the health of postmenopausal women. Further studies on iron and menopause are clinically relevant and may provide novel therapeutic treatments
— id: 105496, year: 2009, vol: 11, page: 2939, stat: Journal Article,

Roles of hormone replacement therapy and iron in proliferation of breast epithelial cells with different estrogen and progesterone receptor status
Dai, Jisen; Jian, Jinlong; Bosland, Maarten; Frenkel, Krystyna; Bernhardt, Guenther; Huang, Xi
2008 Apr;17(2):172-179, Breast
Estrogen and iron play critical roles in a female body development and were investigated in the present study in relation to in vitro cell proliferation. Prempro, a hormone replacement therapy drug, and 17beta-estradiol (E2) were shown to increase cell proliferations in estrogen receptor positive (ER+) cells independent of progesterone receptor (PR) status. For example, increased cell proliferation was observed in ER+/PR+ human breast cancer MCF-7, its matching non-cancerous human breast epithelial MCF-12A, and ER+/PR+ murine mammary cancer MXT+ cells, but not in ER-/PR- MDA-MB-231, its matching non-cancerous MCF-10A, and MXT- (ER-/PR+) cells. By mimicking post-menopausal conditions of high estrogen in local breast tissue and increased iron levels due to cessation of menstrual periods, E2 and iron were shown to exert synergistic effects on proliferation of MCF-7 cells and significantly increased Ki67 and proliferating cell nuclear antigen. Western blotting of E2-treated ER+ but not ER- cells showed that E2 also increased transferrin receptor (TfR). Further studies are needed to assess the mitogenic effects of iron and estrogen in normal post-menopausal breast
— id: 80282, year: 2008, vol: 17, page: 172, stat: Journal Article,

Does iron have a role in breast cancer?
Huang, Xi
2008 Aug;9(8):803-807, Lancet oncology
Oestrogen and family history are two of the most important risk factors for breast cancer. However, these risk factors cannot explain the differences in the incidence and recurrence of breast cancer between premenopausal and postmenopausal women. In this paper I propose that, in premenopausal women, an iron deficiency caused by menstruation stabilises hypoxia inducible factor-1alpha, which increases the formation of vascular endothelial growth factor. This mechanism results in premenopausal women being more susceptible to angiogenesis and, consequently, leads to a high recurrence of breast cancer. Conversely, increased concentrations of iron in postmenopausal women, as a result of menstrual cessation, contribute to a high incidence of breast cancer via oxidative-stress pathways. Although the focus of this Personal View is on iron, this by no means negates the roles of other known risk factors in breast-cancer development. Characterisation of the role of iron in breast cancer could potentially benefit patients by decreasing recurrence and incidence and increasing overall survival
— id: 93344, year: 2008, vol: 9, page: 803, stat: Journal Article,

Understanding the chemical properties of macerals and minerals in coal and its potential application for occupational lung disease prevention
Huang, Xi; Finkelman, Robert B
2008 Jan;11(1):45-67, Journal of toxicology & environmental health. Pt. B. Critical reviews
Recent increases in oil price further strengthen the argument that coal and coal products will play an increasingly important role in fulfilling the energy needs of our society. Coal is an aggregate of heterogeneous substances composed of organic (macerals) and inorganic (minerals) materials. The objective of this review was to assess whether some chemical parameters in coal play a role in producing environmental health problems. Basic properties of coal--such as chemical forms of the organic materials, structure, compositions of minerals--vary from one coal mine region to another as well as from coals of different ranks. Most importantly, changes in chemical properties of coals due to exposure to air and humidity after mining--a dynamic process--significantly affect toxicity attributed to coal and environmental fate. Although coal is an extremely complex and heterogeneous material, the fundamental properties of coal responsible for environmental and adverse health problems are probably related to the same inducing components of coal. For instance, oxidation of pyrite (FeS2) in the coal forms iron sulfate and sulfuric acid, which produces occupational lung diseases (e.g., pneumoconiosis) and other environmental problems (e.g., acid mine drainage and acid rain). Calcite (CaCO3) contained in certain coals alters the end products of pyrite oxidation, which may make these coals less toxic to human inhalation and less hazardous to environmental pollution. Finally, knowledge gained on understanding of the chemical properties of coals is illustrated to apply for prediction of toxicity due to coal possibly before large-scale mining and prevention of occupational lung disease during mining
— id: 75681, year: 2008, vol: 11, page: 45, stat: Journal Article,

Serum prohepcidin is associated with soluble transferrin receptor-1 but not ferritin in healthy post-menopausal women
Huang, Xi; Fung, Eric T; Yip, Christine; Zeleniuch-Jacquotte, Anne
2008 Nov-Dec;41(3):265-269, Blood cells, molecules, & diseases
Hepcidin is a 25-amino-acid iron peptide hormone originated from its two precursors of prohepcidin (60-amino-acid) and preprohepcidin (84-amino-acid). Serum prohepcidin levels have been widely used to evaluate iron overload in clinical and preclinical studies. However, its usefulness is often questioned and its stepwise conversion mechanism remains largely unknown. Using New York University Women's Health Study subjects, we measured serum levels of prohepcidin with ELISA and hepcidin with mass spectrometry as well as ferritin and soluble transferrin receptor 1 (sTfR1) in 45 normal healthy post-menopausal women over a 1-year period with 2 samples per subject. We found that serum prohepcidin levels are correlated with the serum sTfR1 levels (r=0.45, p<0.01) but not to ferritin levels (r=0.08, p=0.60), suggesting that serum prohepcidin is not a biomarker of iron overload that was originally thought and designed for. Interestingly, serum hepcidin levels are associated with serum ferritin levels (r=0.64, p<0.0001) but not with sTfR1 levels (r=0.06, p=0.70), indicating that hepcidin is a measure of iron overload. Although hepcidin is a downstream product of prohepcidin, the amounts of hepcidin and prohepcidin are not related to each other (r=-0.007, p=0.90) under normal physiological conditions. The interrelationships between sTfR1 and prohepcidin or between ferritin and hepcidin suggest that ferritin- and sTfR1-sensed hepcidin conversion system exist in human body and maybe regulated at the post-translational level
— id: 93350, year: 2008, vol: 41, page: 265, stat: Journal Article,

Identification of histamine receptors and reduction of squalene levels by an antihistamine in sebocytes
Pelle, Edward; McCarthy, James; Seltmann, Holger; Huang, Xi; Mammone, Thomas; Zouboulis, Christos C; Maes, Daniel
2008 May;128(5):1280-1285, Journal of investigative dermatology
Overproduction of sebum, especially during adolescence, is causally related to acne and inflammation. As a way to reduce sebum and its interference with the process of follicular keratinization in the pilosebaceous unit leading to inflammatory acne lesions, antihistamines were investigated for their effect on sebocytes, the major cell of the sebaceous gland responsible for producing sebum. Reverse transcriptase-PCR analysis and immunofluorescence of an immortalized sebocyte cell line (SZ95) revealed the presence of histamine-1 receptor (H-1 receptor), and thus indicated that histamines and, conversely, antihistamines could potentially modulate sebocyte function directly. When sebocytes were incubated with an H-1 receptor antagonist, diphenhydramine (DPH), at non-cytotoxic doses, a significant decrease in squalene levels, a biomarker for sebum, was observed. As determined by high-performance liquid chromatography, untreated sebocytes contained 6.27 (+/-0.73) nmol squalene per 10(6) cells, whereas for DPH-treated cells, the levels were 2.37 (+/-0.24) and 2.03 (+/-0.97) nmol squalene per 10(6) cells at 50 and 100 microM, respectively. These data were further substantiated by the identification of histamine receptors in human sebaceous glands. In conclusion, our data show the presence of histamine receptors on sebocytes, demonstrate how an antagonist to these receptors modulated cellular function, and may indicate a new paradigm for acne therapy involving an H-1 receptor-mediated pathway
— id: 132261, year: 2008, vol: 128, page: 1280, stat: Journal Article,

Deferoxamine synergistically enhances iron-mediated AP-1 activation: a showcase of the interplay between extracellular-signal-regulated kinase and tyrosine phosphatase
Huang, Xi; Dai, Jisen; Huang, Chuanshu; Zhang, Qi; Bhanot, Opinder; Pelle, Edward
2007 Oct;41(10):1135-1142, Free radical research
Deferoxamine (DFO) is a drug widely used for iron overload treatment to reduce body iron burden. In the present study, it was shown in mouse epidermal JB6 cells that all iron compounds transiently induced extracellular signal-regulated kinases (ERK) phosphorylation, whereas DFO further enhanced ERK phosphorylation over long periods. The ERK phosphorylation by DFO treatment appears to be due to the inhibition of MAPK phosphatases (MKP) by DFO. The combined effects of iron-initiated MAPK activation and DFO-mediated MKP inhibition resulted in a synergistic enhancement on AP-1 activities. The results indicate that the interplay between MAPK and MKP is important in regulating the extent of AP-1 activation. It is known that administration of DFO in iron overload patients often results in allergic responses at the injection sites. The results suggest that this synergistic AP-1 activation might play a role in DFO-induced skin immune responses of iron overload patients
— id: 75378, year: 2007, vol: 41, page: 1135, stat: Journal Article,

The effects of iron in a keratinocyte-derived post-menopausal cellular model
Pelle, E; Dai, J; McCarthy, J; Mammone, T; Maes, D; Huang, X
2007 APR ;127(2):S82-S82, Journal of investigative dermatology
— id: 71620, year: 2007, vol: 127, page: S82, stat: Journal Article,

Reliability of serum assays of iron status in postmenopausal women
Zeleniuch-Jacquotte, Anne; Zhang, Qi; Dai, Jisen; Shore, Roy E; Arslan, Alan A; Koenig, Karen L; Karkoszka, Jerzy; Afanasyeva, Yelena; Frenkel, Krystyna; Toniolo, Paolo; Huang, Xi
2007 May;17(5):354-358, Annals of epidemiology
PURPOSE: The aim of the study is to determine the reliability during a 2-year period of several newly developed iron-related assays to assess their potential for use in prospective epidemiologic studies. METHODS: We assessed the temporal reliability of several iron-related assays by using three serum samples collected at yearly intervals from 50 postmenopausal participants in a large prospective study. RESULTS: We observed high reliability coefficients for ferritin (0.78; 95% confidence interval [CI], 0.67-0.86), soluble transferrin receptor (sTfR; 0.79; 95% CI, 0.69-0.87), sTfR/ferritin ratio (0.74; 95% CI, 0.62-0.83), and hepcidin (0.89; 95% CI, 0.84-0.94). In a subset of 30 women, lower reliability was observed for serum iron (0.50; 95% CI, 0.29-0.70), unsaturated iron-binding capacity (0.55; 95% CI, 0.34-0.73), total iron-binding capacity (0.60; 95% CI, 0.40-0.76), and serum transferrin saturation rate (0.44; 95% CI, 0.22-0.65). The reliability of anti-5-hydroxymethyl-2'-deoxyuridine autoantibody titers, a biomarker of oxidized DNA damage, one of the mechanisms by which iron is thought to impact disease risk, was very high (0.97, 95% CI, 0.5-0.99). CONCLUSIONS: Our results show that some newly developed iron-related assays could be useful tools to assess iron-disease associations in prospective cohorts that collect a single blood sample
— id: 73252, year: 2007, vol: 17, page: 354, stat: Journal Article,

Sensitive biomarker of polycyclic aromatic hydrocarbons (PAHs): urinary 1-hydroxyprene glucuronide in relation to smoking and low ambient levels of exposure
Hu, Y; Zhou, Z; Xue, X; Li, X; Fu, J; Cohen, B; Melikian, A A; Desai, M; Tang, M -S; Huang, X; Roy, N; Sun, J; Nan, P; Qu, Q
2006 Jul-Aug;11(4):306-318, Biomarkers
The study was conducted in a Chinese population with occupational or environmental exposures to polycyclic aromatic hydrocarbons (PAHs). A total of 106 subjects were recruited from coke-oven workers (workers), residents in a metropolitan area (residents) and suburban gardeners (gardeners). All subjects were monitored twice for their personal exposures to PAHs. The biological samples were collected for measurements of 1-hydroxypyrene (1-OHP) and cotinine in urine. The geometric means of personal exposure levels of pyrene, benz(a)anthracene (BaA) and benzo(a)pyrene (BaP) in workers were 1.470, 0.978 and 0.805 microg m-3, respectively. The corresponding levels in residents were 0.050, 0.034 and 0.025 microg m-3; and those in gardeners were 0.011, 0.020 and 0.008 microg m-3, respectively. The conjugate of 1-OHP with glucuronide (1-OHP-G) is the predominant form of pyrene metabolite in urine and it showed strong associations with exposures not only to pyrene, but also to BaA, BaP and total PAHs. Most importantly, a significant difference in 1-OHP-G was even detected between the subgroups with exposures to BaP at < 0.010 and > 0.010 but < 0.020 microg m-3, suggesting that 1-OHP-G is a good marker that can be used for the risk assessment of BaP exposure at levels currently encountered in ambient air. Furthermore, multiple regression analyses of 1-OHP-G on PAHs exposure indicated that cigarette smoke was a major confounding factor and should be considered and adjusted for while using 1-OHP to estimate PAHs exposure
— id: 68305, year: 2006, vol: 11, page: 306, stat: Journal Article,

Interaction of iron and calcium minerals in coals and their roles in coal dust-induced health and environmental problems
Huang, X; Gordon, T; Rom, WN; Finkelman, RB
2006 NOV-DEC ;64(6):153-178, Reviews in mineralogy & geochemistry
Epidemiological studies using pollutant gases (e.g., SO2) and particle characteristics (e.g., elemental carbon) indicate that products of fossil fuel combustion are important contributors to particulate matter (PM)-associated hospital admissions and mortality. Coal is one of the world's most important fossil fuels, providing 40% of electricity worldwide. Besides individuals exposed to PM in ambient air, coal mining can cause adverse health effects in workers exposed to coal dusts at the workplace. Among the respiratory diseases, coal workers' pneumoconiosis (CWP) has received the most attention because of its clear occupational association. The field of CWP research is one of the few areas in occupational health in which considerable epidemiological data are available. This offers a good opportunity to focus on the relationship between epidemiological data and physico-chemical and/or biological characteristics of coals. The objective of this review is to assess whether some physico-chemical parameters play a role in the observed regional differences in the prevalence of CWP among various coalmine regions. We mainly concentrate on the chemical interaction of two minerals, pyrite (FeS2) and calcite (CaCO3) in the coals and their role in causing occupational lung diseases (e.g., pneumoconiosis) and other environmental problems (e.g., acid mine drainage). Therefore, understanding the chemical interaction of the two minerals in the coal may lead to the identification of the causal components in coal dusts as well as in PM. Examples from U.S.A. coals are used to illustrate the chemical interaction and geological distribution of iron and calcium minerals in various coalmine regions and how the differences in levels of these types of minerals contribute to the observed regional differences in the prevalence of CWP. Molecular mechanisms leading to the CWP development are also discussed, particular in the aspects of oxidative stress and inflammation
— id: 70749, year: 2006, vol: 64, page: 153, stat: Journal Article,

Effects of 12 metal ions on iron regulatory protein 1 (IRP-1) and hypoxia-inducible factor-1 alpha (HIF-1alpha) and HIF-regulated genes
Li, Qin; Chen, Haobin; Huang, Xi; Costa, Max
2006 Jun 15;213(3):245-255, Toxicology & applied pharmacology
Several metal ions that are carcinogenic affect cellular iron homeostasis by competing with iron transporters or iron-regulated enzymes. Some metal ions can mimic a hypoxia response in cells under normal oxygen tension, and induce expression of HIF-1alpha-regulated genes. This study investigated whether 12 metal ions altered iron homeostasis in human lung carcinoma A549 cells as measured by an activation of IRP-1 and ferritin level. We also studied hypoxia signaling by measuring HIF-1alpha protein levels, hypoxia response element (HRE)-driven luciferase reporter activity, and Cap43 protein level (an HIF-1alpha responsive gene). Our results show the following: (i) Ni(II), Co(II), V(V), Mn(II), and to a lesser extent As(III) and Cu(II) activated the binding of IRP-1 to IRE after 24 h, while the other metal ions had no effect; (ii) 10 of 12 metal ions induced HIF-1alpha protein but to strikingly different degrees. Two of these metal ions, Al(III) and Cd(II), did not induce HIF-1alpha protein; however, as indicated below, only Ni(II), Co (II), and to lesser extent Mn(II) and V(V) activated HIF-1alpha-dependent transcription. The combined effects of both [Ni(II) + As(III)] and [Ni(II) + Cr(VI)] on HIF-1alpha protein were synergistic; (iii) Addition of Fe(II) with Ni(II), Co(II), and Cr(VI) attenuated the induction of HIF-1alpha after 4 h treatment; (iv) Ni(II), Co(II), and Mn(II) significantly decrease ferritin level after 24 h exposure; (v) Ni(II), Co(II), V(V), and Mn(II) activated HRE reporter gene after 20 h treatment; (vi) Ni(II), Co(II), V(V), and Mn(II) increased the HIF-1-dependent Cap43 protein level after 24 h treatment. In conclusion, only Ni (II), Co (II), and to a lesser extent Mn(II) and V(V) significantly stabilized HIF-1alpha protein, activated IRP, decreased the levels of ferritin, induced the transcription of HIF-dependent reporter, and increased the expression of Cap43 protein levels (HIF-dependent gene). The mechanism for the significant stabilization and elevation of HIF-1alpha protein which drives these other parameters was previously shown by us and others to involve a loss of cellular Fe as well as inhibition of HIF-1alpha-dependent prolyl hydroxylases which target the binding of VHL ubiquitin ligase and degrade HIF-1alpha. Even though there were small effects of some of the other metals on IRP and HIF-1alpha, downstream effects of HIF-1alpha activation and therefore robust hypoxia signaling were only observed with Ni(II), Co(II), and to much lesser extents with Mn(II) and V(V) in human A549 lung cells. It is of interest that the metal ions that were most effective in activating hypoxia signaling were the ones that were poor inducers of metallothionein protein and also decreased Ferritin levels, since both of these proteins can bind metal ions and protect the cell against toxicity in human lung cells. It is important to study effects of these metals in human lung cells since this represents a major route of human environmental and occupational exposure to these metal ions
— id: 65794, year: 2006, vol: 213, page: 245, stat: Journal Article,

ATM activation and histone H2AX phosphorylation as indicators of DNA damage by DNA topoisomerase I inhibitor topotecan and during apoptosis
Tanaka, T; Kurose, A; Huang, X; Dai, W; Darzynkiewicz, Z
2006 Feb;39(1):49-60, Cell proliferation
Damage that engenders DNA double-strand breaks (DSBs) activates ataxia telangiectasia mutated (ATM) kinase through its auto- or trans-phosphorylation on Ser1981 and activated ATM is one of the mediators of histone H2AX phosphorylation on Ser139. The present study was designed to explore: (i) whether measurement of ATM activation combined with H2AX phosphorylation provides a more sensitive indicator of DSBs than each of these events alone, and (ii) to reveal possible involvement of ATM activation in H2AX phosphorylation during apoptosis. Activation of ATM and/or H2AX phosphorylation in HL-60 or Jurkat cells treated with topotecan (Tpt) was detected immunocytochemically in relation to cell cycle phase, by multiparameter cytometry. Exposure to Tpt led to concurrent phosphorylation of ATM and H2AX in S-phase cells, whereas G1 cells were unaffected. Immunofluorescence (IF) of the S-phase cells immunostained for ATM-S1981P and gammaH2AX combined was distinctly stronger compared to that of the cells stained for each of these proteins alone. However, because of the relatively high ATM-S1981P IF of G1 cells, the ratio of IF of S to G1 cells, that is, the factor that determines competence of the assay in distinction of cells with DSBs, was 2- to 3-fold lower for ATM-S1981P alone, or for ATM-S1981P and gammaH2AX IF combined, than for gammaH2AX alone. ATM activation concurrent with H2AX phosphorylation, likely triggered by induction of DSBs during DNA fragmentation, occurred during apoptosis. The data suggest that frequency of activated ATM and phosphorylated H2AX molecules, per apoptotic cell, is comparable
— id: 76366, year: 2006, vol: 39, page: 49, stat: Journal Article,

Extent of constitutive histone H2AX phosphorylation on Ser-139 varies in cells with different TP53 status
Tanaka, T; Kurose, A; Huang, X; Traganos, F; Dai, W; Darzynkiewicz, Z
2006 Aug;39(4):313-323, Cell proliferation
In response to DNA damage by genotoxic agents, histone H2AX is phosphorylated on Ser-139. However, during the cell cycle, predominantly in S and G(2)M phase, histone H2AX is also phosphorylated in untreated normal and tumour cells. This constitutive H2AX phosphorylation is markedly reduced by exposure of cells to the reactive oxygen species scavenger N-acetyl-L-cysteine. Therefore, it appears likely that constitutive H2AX phosphorylation reflects the ongoing oxidative DNA damage induced by the reactive oxygen species during progression through the cell cycle. Because the tumour suppressor p53 (tumour protein p53) is known to induce transcription of genes associated with cell response to oxidative stress, we have compared the intensity of constitutive H2AX phosphorylation, and the effect of N-acetyl-L-cysteine on it, in cells with different tumour protein p53 status. These were human lymphoblastoid cell lines derived from WIL2 cells: TK6, a p53 wt line, NH32, a tumour protein p53 knock-out derived from TK6, and WTK1, a WIL2-derived line that expresses a homozygous mutant of tumour protein p53. Also tested were the tumour protein p53-null promyelocytic HL-60 cells. The degree of constitutive H2AX phosphorylation was distinctly lower in NH32, WTK1 and HL-60 compared to TK6 cells in all phases of the cell cycle. Also, the degree of attenuation of constitutive H2AX phosphorylation by N-acetyl-L-cysteine was less pronounced in NH32, WTK1, and HL-60, compared to TK6 cells. However, the level of reactive oxygen species detected by the cells' ability to oxidize carboxyl-dichlorodihydrofluorescein diacetate was not significantly different in the cell lines studied, which would suggest that regardless of tumour protein p53 status, the level of oxidative DNA damage was similar. The observed higher level of constitutive H2AX phosphorylation in cells harbouring wt tumour protein p53 may thus indicate that tumour protein p53 plays a role in facilitating histone H2AX phosphorylation, an important step in the mobilization of the DNA repair machinery at the site of DNA double-strand breaks
— id: 76365, year: 2006, vol: 39, page: 313, stat: Journal Article,

Altered iron homeostasis involvement in arsenite-mediated cell transformation
Wu, Jing; Eckard, Jonathan; Chen, Haobin; Costa, Max; Frenkel, Krystyna; Huang, Xi
2006 Feb 1;40(3):444-452, Free radical biology & medicine
Chronic exposure to low doses of arsenite causes transformation of human osteogenic sarcoma (HOS) cells. Although oxidative stress is considered important in arsenite-induced cell transformation, the molecular and cellular mechanisms by which arsenite transforms human cells are still unknown. In the present study, we investigated whether altered iron homeostasis, known to affect cellular oxidative stress, can contribute to the arsenite-mediated cell transformation. Using arsenite-induced HOS cell transformation as a model, it was found that total iron levels are significantly higher in transformed HOS cells in comparison to parental control HOS cells. Under normal iron metabolism conditions, iron homeostasis is tightly controlled by inverse regulation of ferritin and transferrin receptor (TfR) through iron regulatory proteins (IRP). Increased iron levels in arsenite transformed cells should theoretically lead to higher ferritin and lower TfR in these cells than in controls. However, the results showed that both ferritin and TfR are decreased, apparently through two different mechanisms. A lower ferritin level in cytoplasm was due to the decreased mRNA in the arsenite-transformed HOS cells, while the decline in TfR was due to a lowered IRP-binding activity. By challenging cells with iron, it was further established that arsenite-transformed HOS cells are less responsive to iron treatment than control HOS cells, which allows accumulation of iron in the transformed cells, as exemplified by significantly lower ferritin induction. On the other hand, caffeic acid phenethyl ester (CAPE), an antioxidant previously shown to suppress As-mediated cell transformation, prevents As-mediated ferritin depletion. In conclusion, our results suggest that altered iron homeostasis contributes to arsenite-induced oxidative stress and, thus, may be involved in arsenite-mediated cell transformation
— id: 64134, year: 2006, vol: 40, page: 444, stat: Journal Article,

Iron sucrose augments homocysteine-induced endothelial dysfunction in normal subjects
Zheng, H; Huang, X; Zhang, Q; Katz, S D
2006 Feb;69(4):679-684, Kidney international
Intravenous iron is commonly used in conjunction with erythropoietic agents to treat anemia in patients with chronic kidney disease. Iron has been proposed to promote oxidative stress and endothelial dysfunction in vascular tissues. We studied the acute effects of intravenous iron sucrose on homocysteine-induced endothelial dysfunction in the brachial artery of normal human subjects. In all, 40 healthy subjects received intravenous iron sucrose 100 mg or placebo over 30 min immediately before ingestion of 100 mg/kg of oral methionine in a double-blind, randomized study. Flow- and nitroglycerin-mediated dilation in the brachial artery, serum markers of iron stores, and homocysteine and nitrotyrosine levels were measured before and after study drug administration. Intravenous iron significantly increased transferrin saturation and non-transferrin-bound iron (NTBI) when compared with placebo. Flow-mediated dilation significantly decreased from baseline 1 h after administration of iron sucrose when compared with placebo (from 6.66+/-0.47 to 1.93+/-0.35% after iron sucrose vs from 6.00+/-0.40 to 5.61+/-0.46% after placebo, P<0.001), but did not differ between groups at 4 h (1.10+/-0.39 vs 1.33+/-0.51%). Nitroglycerin-mediated vasodilation, and homocysteine and 3-nitrotyrosine levels did not differ after administration of iron sucrose and placebo. Intravenous administration of iron sucrose in the setting of transient hyperhomocysteinemia induced by methionine ingestion significantly increased transferrin saturation and plasma levels of NTBI and significantly attenuated flow-mediated dilation in the brachial artery when compared with placebo. This potential mechanistic link between intravenous iron and endothelial dysfunction warrants further study of cardiovascular effects of intravenous iron in anemic chronic kidney disease populations
— id: 132262, year: 2006, vol: 69, page: 679, stat: Journal Article,

Mapping and prediction of coal workers' pneumoconiosis with bioavailable iron content in the bituminous coals
Huang, Xi; Li, Weihong; Attfield, Michael D; Nadas, Arthur; Frenkel, Krystyna; Finkelman, Robert B
2005 Aug;113(8):964-968, Environmental health perspectives
Based on the first National Study of Coal Workers' Pneumoconiosis (CWP) and the U.S. Geological Survey database of coal quality, we show that the prevalence of CWP in seven coal mine regions correlates with levels of bioavailable iron (BAI) in the coals from that particular region (correlation coefficient r = 0.94, p < 0.0015). CWP prevalence is also correlated with contents of pyritic sulfur (r = 0.91, p < 0.0048) or total iron (r = 0.85, p < 0.016) but not with coal rank (r = 0.59, p < 0.16) or silica (r = 0.28, p < 0.54). BAI was calculated using our model, taking into account chemical interactions of pyrite, sulfuric acid, calcite, and total iron. That is, iron present in coals can become bioavailable by pyrite oxidation, which produces ferrous sulfate and sulfuric acid. Calcite is the major component in coals that neutralizes the available acid and inhibits iron's bioavailability. Therefore, levels of BAI in the coals are determined by the available amounts of acid after neutralization of calcite and the amount of total iron in the coals. Using the linear fit of CWP prevalence and the calculated BAI in the seven coal mine regions, we have derived and mapped the pneumoconiotic potencies of 7,000 coal samples. Our studies indicate that levels of BAI in the coals may be used to predict coal's toxicity, even before large-scale mining
— id: 62597, year: 2005, vol: 113, page: 964, stat: Journal Article,

Caffeic acid phenethyl ester (CAPE) prevents transformation of human cells by arsenite (As) and suppresses growth of As-transformed cells
Yang, Chengfeng; Wu, Jing; Zhang, Ronghe; Zhang, Ping; Eckard, Jonathan; Yusuf, Rita; Huang, Xi; Rossman, Toby G; Frenkel, Krystyna
2005 Sep 15;213(1-2):81-96, Toxicology
Recent evidence suggests that inflammatory cytokines and growth factors contribute to arsenite (As)-induced human carcinogenesis. We investigated the expression of inflammatory cytokine mRNAs during the transformation process induced by chronic As exposure in non-tumorigenic human osteogenic sarcoma (N-HOS) cells using gene arrays, and results were confirmed by RT-PCR and protein arrays. Caffeic acid phenethyl ester (CAPE), a naturally occurring immunomodulating agent, was used to evaluate the role of inflammatory factors in the process of As-mediated N-HOS cell transformation and in As-transformed HOS (AsT-HOS) cells. We found that an 8-week continuous exposure of N-HOS to 0.3 microM arsenite resulted in HOS cell transformation. That exposure also caused substantial decreases in inflammatory cytokine mRNAs, such as interleukin (IL) IL-1alpha, IL-2, IL-8, IL-18, MCP-1, TGF-beta2, and TNF-alpha, while it increased c-jun mRNA in a time-dependent manner. Co-incubation of N-HOS with As and CAPE (0.5-2.5 microM) prevented As-mediated declines in cytokine mRNAs in the co-treated cells, as well as their transformation to anchorage independence, while it caused decreases in c-jun mRNA. CAPE (up to 10 microM) had no effect on growth of N-HOS cells. However, CAPE (1-10 microM) treatment of AsT-HOS cells inhibited cell growth, induced cell cycle G2/M arrest, and triggered apoptosis, accompanied by changes in cytokine gene expression, as well as decreases in cyclin B1 and cdc2 abundance. Resveratrol (RV) and (-)(.) epigallocatechin gallate (EGCG), preventive agents present in grapes and green tea, respectively, induced similar changes in AsT-HOS cell growth but required much higher doses than CAPE to cause 50% growth arrest (<2.5 microM CAPE versus 25 microM RV or 50 microM EGCG). Overall, our findings suggest that inflammatory cytokines play an important role in the suppressive effects of CAPE on As-induced cell transformation and in the selective cytotoxicity of CAPE to As-transformed HOS cells
— id: 58743, year: 2005, vol: 213, page: 81, stat: Journal Article,

Addition of calcite reduces iron's bioavailability in the Pennsylvania coals--potential use of calcite for the prevention of coal workers' lung diseases
Zhang, Qi; Huang, Xi
2005 Oct 8;68(19):1663-1679, Journal of toxicology & environmental health. Pt. A
In the present study, a hypothesis was tested that the addition of calcite into the Pennsylvania coals may reduce levels of bioavailable iron (BAI), an important component in the mixed coal dust that may contribute to coal workers' lung diseases. Predetermined proportions of calcite (0, 1, 2, 5, 10% w/w) were added into three PA coals. After suspending the mixtures in an aqueous phosphate solution (10 mM, pH 4.5), which mimics the phagolysosomal conditions of the cells, levels of pH as well as calcium ions (Ca2+) in the coals were increased in a calcite concentration-dependent manner. In contrast, levels of BAI (both Fe2+ and Fe3+) were decreased. The inhibitory effects of calcite on the bioavailability of iron in human lung epithelial A549 cells and primary rat alveolar macrophages (AMs) were also examined. It was found that levels of low-molecular-weight (LMW) iron were significantly decreased in both A549 cells and AMs treated with the 10% calcite-PA coal mixture compared to those treated with the PA coal alone, while calcite itself had no effect on intracellular LMW iron. Calcite also showed a significant inhibitory effect on PA coal-induced ferritin synthesis in A549 cells. Reverse-transcription polymerase chain reaction (RT-PCR) studies revealed that the iron-containing PA coal downregulated levels of transferrin receptor (TfR) mRNA in A549 cells, which was partially restored by the addition of calcite. Our results indicate that calcite can inhibit the bioavailability of iron in the iron-containing PA coals
— id: 58699, year: 2005, vol: 68, page: 1663, stat: Journal Article,

Calcein as a fluorescent iron chemosensor for the determination of low molecular weight iron in biological fluids
Ali, Aktar; Zhang, Qi; Dai, Jisen; Huang, Xi
2003 Jun;16(2):285-293, Biometals
The fluorescence quenching of calcein (CA) is not iron specific and results in a negative calibration curve. In the present study, deferoxamine (DFO), a strong iron chelator, was used to regenerate the fluorescence quenched by iron. Therefore, the differences in fluorescence reading of the same sample with or without addition of DFO are positively and specifically proportional to the amounts of iron. We found that the same iron species but different anions (e.g. ferric sulfate or ferric citrate) differed in CA fluorescence quenching, so did the same anions but different iron (e.g. ferrous or ferric sulfates). Excessive amounts of citrate competed with CA for iron and citrate could be removed by barium precipitation. After optimizing the experimental conditions, the sensitivity of the fluorescent CA assay is 0.02 microM of iron, at least 10 times more sensitive than the colorimetric assays. Sera from 6 healthy subjects were tested for low molecular weight (LMW) chelator bound iron in the filtrates of 10 kDa nominal molecular weight limit (NMWL). The LMW iron was marginally detectable in the normal sera. However, increased levels of LMW iron were obtained at higher transferrin (Tf) saturation (1.64-2.54 microM range at 80% Tf saturation, 2.77-3.15 microM range at 100% Tf saturation and 3.09-3.39 microM range at 120% Tf saturation). The application of the assay was further demonstrated in the filtrates of human liver HepG2 and human lung epithelial A549 cells treated with iron or iron-containing dusts
— id: 39312, year: 2003, vol: 16, page: 285, stat: Journal Article,

Reliability of serum iron, ferritin, nitrite, and association with risk of renal cancer in women
Ali, M Aktar; Akhmedkhanov, Arslan; Zeleniuch-Jaquotte, Anne; Toniolo, Paolo; Frenkel, Krystyna; Huang, Xi
2003 ;27(2):116-121, Cancer detection & prevention
Reliability of serum levels of iron, ferritin and nitrite (NO(2)(-)) over a 2-year period were evaluated in 40 healthy women (20 pre-menopausal and 20 post-menopausal), ages 39-65 years, from the New York University Women's Health Study (NYUWHS). Three blood samples per woman collected at yearly intervals were analyzed. Reliability coefficients (RCs) of serum iron, ferritin, and nitrite were 0.03 (95% confidence interval (CI), 0-0.33), 0.90 (95% CI, 0.79-0.95), and 0.72 (95% CI, 0.50-0.86), respectively, for pre-menopausal women, and 0.26 (95% CI, 0-0.56), 0.77 (95% CI, 0.59-0.89), and 0.55 (95% CI, 0.30-0.77), respectively, for post-menopausal women. In a case-control study nested within NYUWHS cohort, serum levels of nitrite, ferritin, and iron were measured in women apparently healthy at the time of blood donation but diagnosed with renal cancer 1.8-12.2 years later (n=24) and in individually matched controls (two per case). The results suggest that high serum levels of ferritin and nitrite may be associated with a decreased risk of renal cancer (odds ratio (OR), 0.55, 95% CI, 0.15-2.01 for ferritin, and OR, 0.52, 95% CI, 0.17-1.60 for nitrite in women with above median level as compared to women with below median level). The possible role of ferritin and nitrite in renal cancer is discussed
— id: 34537, year: 2003, vol: 27, page: 116, stat: Journal Article,

Gene expression of primary human bronchial epithelial cells in response to coal dusts with different prevalence of coal workers' pneumoconiosis
Hu, Wenwei; Zhang, Qi; Su, Wei Cheng; Feng, Zhaohui; Rom, William; Chen, Lung Chi; Tang, Moonshong; Huang, Xi
2003 Jul 11;66(13):1249-1265, Journal of toxicology & environmental health. Pt. A
Striking regional differences in the prevalence of coal workers' pneumoconiosis (CWP) have been observed but not fully understood. This study investigated the early biological responses of primary lung cells to treatment with coal dusts from various seams. High-density oligoarray technology (GeneChip, Affymetrix, Santa Clara, CA) was used to compile gene expression profiles of primary human bronchial epithelial cells to low concentrations (2 microg/cm(2)) of coals for 6 h or 24 h of treatment. Data showed that a total of 1050 out of 12,000 genes on the chip were altered by 2 coal dusts. The coal from the Pennsylvania (PA) coal-mine region with a high prevalence of CWP altered 908 genes, many more than the coal from Utah (UT) with a low prevalence of CWP, which affected 356 genes. Many genes decreased their expression levels in response to the PA coal at 6 h and/or 24 h of treatment. For example, transferrin receptor, a gene known to control cellular iron uptake, was downregulated in the cells treated with the iron-containing PA coal in order to protect cells from iron overload. The UT coal without bioavailable iron had no such effect. The downregulation patterns of genes were confirmed by reverse-transcription polymerase chain reaction (RT-PCR). This study is one of the first in profiling gene expressions of primary bronchial epithelial cells treated with coals from various seams, which may set stages for future studies on specific genes
— id: 39145, year: 2003, vol: 66, page: 1249, stat: Journal Article,

Coal-induced interleukin-6 gene expression is mediated through ERKs and p38 MAPK pathways
Huang, X; Zhang, Q
2003 Aug 15;191(1):40-47, Toxicology & applied pharmacology
In the present study, we have tested the ability of coal dust to stimulate kinase phosphorylation of activator protein-1 (AP-1) signal transduction pathways and production of interleukin-6 (IL-6) in both mouse epidermal JB6 and human lung epithelial A549 cells. Seven coal samples from three coalmine regions of Pennsylvania (PA), West Virginia (WV), and Utah (UT) with high, medium, and low prevalence of coal workers' pneumoconiosis (CWP), respectively, were investigated. Results from the present study indicate that three PA coals stimulated the mitogen-activated protein kinase (MAPK) family of extracellular signal-regulated kinases (ERKs) and p38 MAPK, but not c-Jun-NH2-terminal kinases (JNKs) in human lung A549 cells. The effects of three UT coals on the kinase phosphorylation were less as compared to those of the PA coals. Coal dusts from three coalmine regions induced IL-6 in a dose-dependent manner in both JB6 and A549 cells. Interestingly, levels of IL-6 in both cells treated with coals from three coalmine regions correlated well with CWP prevalence from that region. To assess the role of AP-1 pathways in coal-mediated transcriptional activation of IL-6, various inhibitors were used in cells treated with one PA coal, which induced a maximal response. It was found that the increase in IL-6 protein and mRNA by the PA coal was completely eliminated by the pretreatment of both cell types with PD98059, a specific MEK1 inhibitor, and SB202190, a p38 kinase inhibitor. Our results indicate that coal dust can stimulate IL-6 release from mouse epidermal JB6 cells and human lung epithelial A549 cells, and the coal-induced IL-6 increase may involve ERKs and p38 MAPK pathways
— id: 39109, year: 2003, vol: 191, page: 40, stat: Journal Article,

Ultraviolet-B-induced oxidative DNA base damage in primary normal human epidermal keratinocytes and inhibition by a hydroxyl radical scavenger
Pelle, Edward; Huang, Xi; Mammone, Thomas; Marenus, Kenneth; Maes, Daniel; Frenkel, Krystyna
2003 Jul;121(1):177-183, Journal of investigative dermatology
To evaluate the effects of ultraviolet-induced environmental trauma on human skin cells, primary normal human epidermal keratinocytes were exposed to ultraviolet-B radiation (290-320 nm). We found that relatively low doses of ultraviolet-B (62.5-500 mJ per cm2) caused dose-dependent increases in 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), a biomarker of oxidative DNA damage. Unirradiated normal human epidermal keratinocytes contained 1.49 (+/- 0.11) 8-oxo-dG per 10(6) 2'-deoxyguanosine (dG) residues in cellular DNA, which increased linearly to as high as 6.24 (+/- 0.85) 8-oxo-dG per 10(6) dG after irradiation with 500 mJ per cm2. Further, this oxidative damage was reduced by 60.7% when the cells were pretreated with 1 mM mannitol. As hydrogen peroxide (H2O2) is known to be generated during oxidative stress, its accumulation in ultraviolet-B-irradiated normal human epidermal keratinocytes was also assessed and correlated to 8-oxo-dG formation. An ultraviolet-B-induced increase in H2O2 was observed in normal human epidermal keratinocytes and its production was inhibited by the addition of catalase. Based on the ability of a neutral molecule like H2O2 to permeate membranes, our data indicate that, after ultraviolet-B irradiation, H2O2 migrates from the cytosol to the nucleus where it participates in a Fenton-like reaction that results in the production of hydroxyl radicals (OH*), which may then cause 8-oxo-dG formation in cellular DNA. This conclusion is supported by our data showing that OH* scavengers, such as mannitol, are effective inhibitors of oxidative DNA base damage. Although increased levels of 8-oxo-dG were previously found in immortalized mouse keratinocytes exposed to ultraviolet-B radiation, we now report the induction of 8-oxo-dG in normal human skin keratinocytes at ultraviolet-B doses relevant to human skin exposure
— id: 38128, year: 2003, vol: 121, page: 177, stat: Journal Article,

Induction of interleukin-6 by coal containing bioavailable iron is through both hydroxyl radical and ferryl species
Zhang, Q; Huang, X
2003 Feb;28(1):95-100, Journal of biosciences
Coal mining causes health problems, such as pneumoconiosis. We have previously shown that prevalence of pneumoconiosis in workers from various coalmine regions positively correlates with levels of bioavailable iron (BAI) in the coals from that region. In the present study, the nature of reactive oxygen species formed by BAI in the coals and its mechanisms of the induction of biological responses were investigated. Human lung epithelial cell line, A549 cells, were used to examine the induction of interleukin-6 (IL-6), a pro-inflammatory cytokine, which is known to play a crucial role in the development of pneumoconiosis. We found that levels of IL-6 protein as well as its mRNA were significantly increased in the cells treated for 24 h with 20 mg/cm2 of the BAI-containing Pennsylvania (PA) coal; for example we observed 6.7-fold increase in IL-6 protein. Levels of IL-6 protein in cells treated with the Utah (UT) coal containing low-BAI were only 1.9-fold of the control levels. The enhancing effect on the IL-6 by the PA coal was similar to that caused by hydrogen peroxide. Superoxide dismutase (SOD), catalase (CAT), and N-acetyl-L-cysteine (NAC) all had inhibitory effects on the PA coal-induced IL-6 formation. However, CAT had the least protective effect as compared to SOD and NAC. Our results indicate that BAI in the PA coal may induce IL-6 through both ferryl species (via iron autoxidation) and hydroxyl radicals (via the Fenton/Haber Weiss reactions)
— id: 39248, year: 2003, vol: 28, page: 95, stat: Journal Article,

Role of bioavailable iron in coal dust-induced activation of activator protein-1 and nuclear factor of activated T cells: difference between Pennsylvania and Utah coal dusts
Huang, Chuanshu; Li, Jingxia; Zhang, Qi; Huang, Xi
2002 Nov;27(5):568-574, American journal of respiratory cell & molecular biology
Activator protein-1 (AP-1) and nuclear factor of activated T cells (NFAT) are two important transcription factors responsible for the regulation of cytokines, which are involved in cell proliferation and inflammation. Coal workers' pneumoconiosis (CWP) is an occupational lung disease that may be related to chronic inflammation caused by coal dust exposure. In the present study, we demonstrate that coal from the Pennsylvania (PA) coalmine region, which has a high prevalence of CWP, can activate both AP-1 and NFAT in JB6 mouse epidermal cells. In contrast, coal from the Utah (UT) coalmine region, which has a low prevalence of CWP, has no such effects. The PA coal stimulates mitogen-activated protein kinase (MAPK) family members of extracellular signal-regulated kinases (ERKs) and p38 MAPK but not c-Jun-NH(2)-terminal kinases, as determined by the phosphorylation assay. The increase in AP-1 by the PA coal was completely eliminated by the pretreatment of cells with PD98059, a specific MAPK kinase inhibitor, and SB202190, a p38 kinase inhibitor, further confirming that the PA coal-induced AP-1 activation is mediated through ERKs and p38 MAPK pathways. Deferoxamine (DFO), an iron chelator, synergistically enhanced the PA coal-induced AP-1 activity, but inhibited NFAT activity. For comparison, cells were treated with ferrous sulfate and/or DFO. We have found that iron transactivated both AP-1 and NFAT, and DFO further enhanced iron-induced AP-1 activation but inhibited NFAT. These results indicate that activation of AP-1 and NFAT by the PA coal is through bioavailable iron present in the coal. These data are in agreement with our previous findings that the prevalence of CWP correlates well with levels of bioavailable iron in coals from various mining regions
— id: 38471, year: 2002, vol: 27, page: 568, stat: Journal Article,

Ferrous ion autoxidation and its chelation in iron-loaded human liver HepG2 cells
Huang, Xi; Dai, Jisen; Fournier, Jeanine; Ali, Aktar M; Zhang, Qi; Frenkel, Krystyna
2002 Jan 1;32(1):84-92, Free radical biology & medicine
Ferrous ion (Fe(2+)) is long thought to be the most likely active species, producing oxidants through interaction of Fe(2+) with oxygen (O(2)). Because current iron overload therapy uses only Fe(3+) chelators, such as desferrioxamine (DFO), we have tested a hypothesis that addition of a Fe(2+) chelator, 2,2'-dipyridyl (DP), may be more efficient and effective in preventing iron-induced oxidative damage in human liver HepG2 cells than DFO alone. Using ferrozine as an assay for iron measurement, levels of cellular iron in HepG2 cells treated with iron compounds correlated well with the extent of lipid peroxidation (r = 0.99 after log transformation). DP or DFO alone decreased levels of iron and lipid peroxidation in cells treated with iron. DFO + DP together had the most significant effect in preventing cells from lipid peroxidation but not as effective in decreasing overall iron levels in the cells. Using ESR spin trapping technique, we further tested factors that can affect oxidant-producing activity of Fe(2+) with dissolved O(2) in a cell-free system. Oxidant formation enhanced with increasing Fe(2+) concentrations and reached a maximum at 5 mM of Fe(2+). When the concentration of Fe(2+) was increased to 50 mM, the oxidant-producing activity of Fe(2+) sharply decreased to zero. The initial ratio of Fe(3+):Fe(2+) did not affect the oxidant producing activity of Fe(2+). However, an acidic pH (< 3.5) significantly slowed down the rate of the reaction. Our results suggest that reaction of Fe(2+) with O(2) is an important one for oxidant formation in biological system, and therefore, drugs capable of inhibiting redox activity of Fe(2+) should be considered in combination with a Fe(3+) chelator for iron overload chelation therapy
— id: 34035, year: 2002, vol: 32, page: 84, stat: Journal Article,

Roles of bioavailable iron and calcium in coal dust-induced oxidative stress: possible implications in coal workers' lung disease
Zhang, Qi; Dai, Jisen; Ali, Aktar; Chen, Lungchi; Huang, Xi
2002 Mar;36(3):285-294, Free radical research
Marked regional differences in prevalence of pneumoconiosis are apparent in the US despite comparable dust exposure. In the present study, we examined the ability of 28 coal samples to release bioavailable iron (BAI) and calcium, as well as other metals such as Cr, Ni, Cu, and Co, from three coal mine regions in Utah (UT), West Virginia (WV), and Pennsylvania (PA), respectively. BAI is defined as iron (both Fe2+ and Fe3+) released by the coals in 10 mM phosphate solution, pH 4.5, which mimics conditions of the phagolysosomes in cells. We found that coals from the UT, WV, and PA regions released average levels of BAI of 9.6, 4658.8, and 12149 parts per million (ppm, w/w), respectively, which correlated well with the prevalence of pneumoconiosis from that region (correlation coefficient r = 0.92). The low levels of BAI in the UT coals were due to the presence of calcite (CaCO3), which was shown to be preferentially acid solubilized before iron compounds. Release of iron by two coal samples from the PA and UT regions was further examined in vitro in human lung epithelial A549 cells. We found that the coal from PA, with a high prevalence of pneumoconiosis, released BAI in a dose-dependent manner, both in tissue culture media and in A549 cells. At 2 microg/cm2, levels of lipid peroxidation induced by the PA coal were increased 112% over control cells at 24 h treatment, and were sustained at this level for 3 days. The coal from UT, with a low prevalence of pneumoconiosis, induced a marginal increase in cellular iron at 5 and 10 microg/cm2 treatments and had no effect on lipid peroxidation. Calcium levels in the cells treated with the PA and UT coals were 8.6 and 11.5 micromoles/10(6) cells, respectively, and were significantly higher than that in the controls (5.3 micromoles/10(6) cells) [corrected]. Our results suggest that the differences in the BAI content in the coals may be responsible for the observed regional differences in the prevalence of pneumoconiosis. Therefore, BAI may be a useful characteristic of coal for predicting coal's toxicity
— id: 39623, year: 2002, vol: 36, page: 285, stat: Journal Article,

Induction of ferritin and lipid peroxidation by coal samples with different prevalence of coal workers' pneumoconiosis: role of iron in the coals
Zhang, Qi; Huang, Xi
2002 Sep;42(3):171-179, American journal of industrial medicine
BACKGROUND: Differences in levels of bioavailable iron (BAI) in coal may be responsible for the observed regional differences in the prevalence and severity of coal workers' pneumoconiosis (CWP). METHODS: Twenty-nine coal samples from three coal mine regions were tested in human lung epithelial Type II A549 cells. They were from Utah (UT), West Virginia (WV), and Pennsylvania (PA) with a prevalence of CWP of 4, 10, and 26%, respectively. RESULTS: Low molecular weight (LMW) chelators bound iron, a fraction of BAI in the cells released from coals, ferritin, and lipid peroxidation were significantly higher in cells treated with various coals than in control cells, with an increasing order of UT < WV < PA, in parallel to the prevalence of CWP in these coal mine regions. Deferoxamine (DFO), a specific iron chelator, was used to distinguish effects of BAI from those of other transition metals. Our results indicate that BAI in the coals of WV and UT is the main metal species in inducing ferritin and lipid peroxidation. In contrast, biological effects of PA coals are not only from BAI, but from other transition metals as well. CONCLUSIONS: Based on a large number of coal samples from various seams, the findings of this study provide further evidence that metals, particularly iron, play important roles in coal dust-induced cellular damage, ultimately leading to the development of CWP and contributing to the regional differences in the prevalence of the disease
— id: 39595, year: 2002, vol: 42, page: 171, stat: Journal Article,

Importance of complete DNA digestion in minimizing variability of 8-oxo-dG analyses
Huang X; Powell J; Mooney LA; Li C; Frenkel K
2001 Dec 1;31(11):1341-1351, Free radical biology & medicine
Estimates of 8-oxo-2'-deoxyguanosine (8-oxo-dG) in DNA vary at least one order of magnitude using different quantitative methods or even the same method. Our hypothesis is that an incomplete DNA hydrolysis to nucleosides by the conventional nuclease P1 (NP1) and alkaline phosphatase (AP) digestion system plays an important role in contributing to the variability of measurements using HPLC coupled with UV and electrochemical (EC) detection. We show here that factors, such as the amount of DNA, choice of enzymes, their activities, and incubation time, can affect DNA digestion and, thus, cause variability in 8-oxo-dG levels. The addition of DNase I and phosphodiesterases I and II to the NP1 + AP system improves the DNA digestion by completely releasing normal nucleosides and 8-oxo-dG, thereby reducing the interday variations of 8-oxo-dG levels. Diethylenetriamine pentaacetic acid (DTPA), an iron chelator, prevented background increases of 8-oxo-dG during DNA digestion, as well as during the waiting period in the autosampler when a batch of DNA samples is analyzed by HPLC. After optimization of the DNA digestion conditions, the interday variability of 8-oxo-dG measurements using commercially available salmon testes DNA (ST DNA) were 26% over a period of 2 years. Under these optimal conditions, our laboratory variability may contribute as little as 13% to the overall variability as shown by assessment of oxidative DNA damage in a population of smokers. Based on our results, we believe that the modified DNA digestion conditions will provide much more accurate 8-oxo-dG determinations and, thus, more reliable estimates of cancer risk
— id: 34036, year: 2001, vol: 31, page: 1341, stat: Journal Article,

Bioavailable or potentially bioavailable iron as a biomarker of cancer risk
Huang, X; Zhang, Q; Ali, A; Dai, J S; Frenkel, K
2000 Nov 16-20;29(Supplement 1):S16-S16, Free radical biology & medicine
— id: 15768, year: 2000, vol: 29, page: S16, stat: Journal Article,

A brief history of antibiotic science
Dai, J; Zhang, G; Huang, X; Wu, T
1999 Apr;29(2):88-90, Zhonghua yi shi za zhi = Chinese journal of medical history
As the greatest achievement in the history of microbiology, the story of antibiotic is an extremely inspired chapter in its history. Like the developmental process of other sciences, antibiotic reveals a history of first accumulating experience, followed by the stage of interpretation of the phenomena as other experimental study. Meantime, there is no end to the discovery of new antibiotics. Currently, the scope and province of antibiotic research is expanding both in its profundity and coverage
— id: 138815, year: 1999, vol: 29, page: 88, stat: Journal Article,

Chemical reactivity of the carbon-centered free radicals and ferrous iron in coals: role of bioavailable Fe2+ in coal workers pneumoconiosis
Huang X; Zalma R; Pezerat H
1999 Jun;30(6):439-451, Free radical research
Striking differences in the prevalence of coal workers' pneumoconiosis (CWP) exist between different coal mine regions. The major factors responsible for the observed regional differences in CWP have not yet been identified. In the present study, chemical reactivity of the carbon-centered free radicals in coals and lung tissues, as well as ferrous iron in the coals, were studied by ESR techniques. The ESR spectra clearly demonstrated the presence of at least two types of carbon-centered free radical species, which might respectively attribute to the macromolecular phase and the molecular phase of coal. Grinding produced free radicals in coals. Exposure of freshly ground coal to air for 28 h induced a slight increase of free radicals for most of the coals, and a slight decrease after 4 months' exposure. The lung tissue samples of coal workers deceased of CWP showed similar ESR spectra as coal samples, and these radicals were highly stable in the lung. After incubation of coals with glutathione, hydrogen peroxide, sodium formate or oxygen, the coal sample from the Gardanne mine which has never induced CWP, and thus is the least hazardous coal, showed the most significant change in the carbon-centered free radical concentration. No significant changes were observed among other coals reported to induce CWP. On the other hand, we found that the coals released different amounts of Fe2+ in an acidic medium. Interestingly, the prevalence of CWP correlates positively with the released Fe2+ content in these coals and with the amount of oxygen radicals produced by the interaction of Fe2+ with O2 in the acidified coal filtrates. Our studies indicate that the carbon-centered free radicals may not be biologically relevant to coal dust-induced pneumoconiosis, whereas the acid soluble Fe2+, which may be dissolved in the phagolysosomes of macrophages, can then lead to Fe2+-induced oxidative stress and eventual CWP development
— id: 6158, year: 1999, vol: 30, page: 439, stat: Journal Article,

The integrin alpha v beta 6 binds and activates latent TGF beta 1: a mechanism for regulating pulmonary inflammation and fibrosis
Munger JS; Huang X; Kawakatsu H; Griffiths MJ; Dalton SL; Wu J; Pittet JF; Kaminski N; Garat C; Matthay MA; Rifkin DB; Sheppard D
1999 Feb 5;96(3):319-328, Cell
Transforming growth factor beta (TGF beta) family members are secreted in inactive complexes with a latency-associated peptide (LAP), a protein derived from the N-terminal region of the TGF beta gene product. Extracellular activation of these complexes is a critical but incompletely understood step in regulation of TGF beta function in vivo. We show that TGF beta 1 LAP is a ligand for the integrin alpha v beta 6 and that alpha v beta 6-expressing cells induce spatially restricted activation of TGF beta 1. This finding explains why mice lacking this integrin develop exaggerated inflammation and, as we show, are protected from pulmonary fibrosis. These data identify a novel mechanism for locally regulating TGF beta 1 function in vivo by regulating expression of the alpha v beta 6 integrin
— id: 7411, year: 1999, vol: 96, page: 319, stat: Journal Article,

Prolonged suppression of human immunodeficiency virus type 1 (HIV-1) viremia in persons with advanced disease results in enhancement of CD4 T cell reactivity to microbial antigens but not to HIV-1 antigens
Rinaldo, C R Jr; Liebmann, J M; Huang, X L; Fan, Z; Al-Shboul, Q; McMahon, D K; Day, R D; Riddler, S A; Mellors, J W
1999 Feb;179(2):329-336, Journal of infectious diseases
CD4 T cell responses were studied for >2 years in 27 zidovudine-experienced patients with advanced human immunodeficiency virus type 1 (HIV-1) infection who received triple combination drug therapy with indinavir, zidovudine and lamivudine or zidovudine plus lamivudine or zidovudine alone for 24-42 weeks before switching to the three-drug therapy. Subjects initially given the three drugs had viremia suppressed to undetectable levels and increases in T cell proliferative and cytokine responses to microbial antigens through 2 years of follow-up. Patients receiving the triple-drug therapy after either indinavir or zidovudine-lamivudine treatment had similar increases in T cell responses only if they also had suppression of virus load. CD4 T cell reactivity to HIV-1 antigens was not restored. Prolonged indinavir-zidovudine-lamivudine treatment has significant but incomplete enhancing effects on CD4 T cell reactivity, which could be important in host control of microbial and persistent HIV-1 infections
— id: 148352, year: 1999, vol: 179, page: 329, stat: Journal Article,

The role of ferrous sulfate in coal dust induced lung injury
Chen LC; Huang X; Wu CY; Zalma R; Perzerat H; Qu QS
1996 ;11:973-979, Applied occupational & environmental hygiene
— id: 72668, year: 1996, vol: 11, page: 973, stat: Journal Article,