title: Epigenetic control of HNF-4α in colon carcinoma cells affects MUC4 expression and malignancy.
abstract: BACKGROUND
  We previously found that enhanced expression of hepatocyte nuclear factor 4α (HNF-4α) is associated with hyper-proliferation of colon carcinoma cells. Here, the effect of histone deacetylase (HDAC) inhibitors on proliferation and the expression of HNF-4α and its downstream target genes were assessed in HM7, LS174T, HT29 and Caco-2 colon carcinoma cell lines.
  
  
  RESULTS
  HNF-4α expression was found to vary in the different colon carcinoma cell lines tested, being highest in HM7. Additionally, a direct correlation with proliferation was observed. In HM7 cells, the weak HDAC inhibitor butyrate significantly inhibited the transcription of HNF-4α, its downstream target gene MUC4, and genes associated with proliferation, including the proliferating cell nuclear antigen gene PCNA. siRNA-mediated silencing of HNF-4α exerted an effect similar to butyrate on HM7 cell proliferation. The stronger HDAC inhibitor trichostatin A (TSA) exerted an effect similar to that of siRNA-mediated HNF-4α silencing and, concomitantly, inhibited the expression of the transcription factor gene SP1. Also, siRNA-mediated silencing of HDAC3 and HDAC4 reduced HNF-4α expression. Chromatin immunoprecipitation (ChIP) assays revealed that TSA induces hyperacetylation of histones H3 and H4 and, concomitantly, inhibits SP1 binding to the HNF-4α promoter. Subsequent electromobility shift assays supported these latter findings.
  
  
  CONCLUSIONS
  HNF-4α transcriptional expression and activity are tightly controlled by epigenetic mechanisms. HDAC inhibitor targeting of HNF-4α may serve as an effective treatment for advanced colon carcinomas, since downstream cancer-associated target genes such as MUC4 are significantly down-regulated by this treatment.
authors: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel.
authors: Anna
authors: A
authors: Algamas-Dimantov
authors: Einav
authors: E
authors: Yehuda-Shnaidman
authors: Irena
authors: I
authors: Peri
authors: Betty
authors: B
authors: Schwartz
mesh_terms: D000107:Acetylation / Q000187:drug effects; D015153:Blotting, Western; D002087:Butyrates / Q000494:pharmacology; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D044127:Epigenesis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D019073:HT29 Cells; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics* / Q000378:metabolism; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D055264:Mucin-4 / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D000099186:Histone Deacetylase 3
chemical_list: D002087:Butyrates; D051557:Hepatocyte Nuclear Factor 4; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases; D006657:Histones; D006877:Hydroxamic Acids; D055264:Mucin-4; D012097:Repressor Proteins; D016329:Sp1 Transcription Factor; D000099186:Histone Deacetylase 3; C496592:HNF4A protein, human; C524658:MUC4 protein, human; C012589:trichostatin A; C400300:HDAC4 protein, human