title: The effect of hemin-induced oxidative stress on erythropoietin production in HepG2 cells.
abstract: Erythropoietin (EPO) and iron are both indispensable hematopoietic factors and are often studied in humans and rodents. Iron activates prolyl hydroxylases (PHDs) and promotes the degradation of the α-subunit of hypoxia inducible factor (HIF), which regulates EPO production. Iron also causes oxidative stress. Oxidative stress leads to alterations in the levels of multiple factors that regulate HIF and EPO production. It is thought that iron influences EPO production by altering two pathways, namely PHDs activity and oxidative stress. We studied the differential effect of varying concentrations of hemin, an iron-containing porphyrin, on EPO production in HepG2 cells. Hemin at 100 µM reduced EPO mRNA expression. The hemin-induced reduction of EPO mRNA levels was attenuated at concentrations greater than 200 µM and EPO production increased in the presence of 500 µM hemin. In comparison, protoporphyrin IX, iron-free hemin did not influence EPO mRNA expression. Additionally, malondialdehyde (MDA) concentrations and superoxide dismutase (SOD) activity significantly increased with 300 µM hemin. Importantly, the antioxidant tempol inhibited the hemin-induced (500 µM) increase in EPO mRNA levels. In conclusion, these results suggest that restraint of EPO production by hemin was offset by the promotion of EPO production by hemin-induced oxidative stress at hemin concentrations greater than 300 µM.
authors: Laboratory of Bioenvironmental Sciences, Course of Veterinary Science, Graduate School of Life Environmental Sciences, Osaka Prefecture University, 1-58 Rinku Ohrai-Kita, Izumisano, Osaka, 598-8531, Japan.
authors: Kazuhiko
authors: K
authors: Nishimura
authors: Masahiro
authors: M
authors: Tokida
authors: Hideaki
authors: H
authors: Katsuyama
authors: Hiroshi
authors: H
authors: Nakagawa
authors: Saburo
authors: S
authors: Matsuo
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000494:pharmacology; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D006427:Hemin / Q000494:pharmacology*; D056945:Hep G2 Cells; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D012333:RNA, Messenger / Q000378:metabolism; D013113:Spin Labels; D013482:Superoxide Dismutase / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D051793:Hypoxia-Inducible Factor 1; D012333:RNA, Messenger; D013113:Spin Labels; D004921:Erythropoietin; D008315:Malondialdehyde; D006427:Hemin; D013482:Superoxide Dismutase; C001803:tempol
keywords: erythropoietin production; iron; oxidative stress