title: The small molecule, genistein, increases hepcidin expression in human hepatocytes.
abstract: Hepcidin, a peptide hormone that decreases intestinal iron absorption and macrophage iron release, is a potential drug target for patients with iron overload syndromes because its levels are inappropriately low in these individuals. Endogenous stimulants of Hepcidin transcription include bone morphogenic protein 6 (BMP6) and interleukin-6 (IL-6) by effects on mothers against decapentaplegic homolog (Smad)4 or signal transducer and activator of transcription (Stat)3, respectively. We conducted a small-scale chemical screen in zebrafish embryos to identify small molecules that modulate hepcidin expression. We found that treatment with the isoflavone, genistein, from 28-52 hours postfertilization in zebrafish embryos enhanced Hepcidin transcript levels, as assessed by whole-mount in situ hybridization and quantitative real-time reverse-transcriptase polymerase chain reaction. Genistein's stimulatory effect was conserved in human hepatocytes: Genistein treatment of HepG2 cells increased both Hepcidin transcript levels and promoter activity. We found that genistein's effect on Hepcidin expression did not depend on estrogen receptor signaling or increased cellular iron uptake, but was impaired by mutation of either BMP response elements or the Stat3-binding site in the Hepcidin promoter. RNA sequencing of transcripts from genistein-treated hepatocytes indicated that genistein up-regulated 68% of the transcripts that were up-regulated by BMP6; however, genistein raised levels of several transcripts involved in Stat3 signaling that were not up-regulated by BMP6. Chromatin immunoprecipitation and ELISA experiments revealed that genistein enhanced Stat3 binding to the Hepcidin promoter and increased phosphorylation of Stat3 in HepG2 cells.
  
  
  CONCLUSIONS
  Genistein is the first small-molecule experimental drug that stimulates Hepcidin expression in vivo and in vitro. These experiments demonstrate the feasibility of identifying and characterizing small molecules that increase Hepcidin expression. Genistein and other candidate molecules may subsequently be developed into new therapies for iron overload syndromes.
authors.affiliation: Division of Hematology/Oncology, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, MA.
authors.forename: Aileen W
authors.initials: AW
authors.lastname: Zhen
authors.forename: Nancy H
authors.initials: NH
authors.lastname: Nguyen
authors.forename: Yann
authors.initials: Y
authors.lastname: Gibert
authors.forename: Shmulik
authors.initials: S
authors.lastname: Motola
authors.forename: Peter
authors.initials: P
authors.lastname: Buckett
authors.forename: Marianne
authors.initials: M
authors.lastname: Wessling-Resnick
authors.forename: Ernest
authors.initials: E
authors.lastname: Fraenkel
authors.forename: Paula G
authors.initials: PG
authors.lastname: Fraenkel
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000378:metabolism; D047108:Embryonic Development / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism*; D064451:Hepcidins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism; D023421:Models, Animal; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D051901:Smad4 Protein / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000378:metabolism
chemical_list: D064451:Hepcidins; D050796:STAT3 Transcription Factor; D051901:Smad4 Protein; D019833:Genistein; D007501:Iron