Epigenetic control of HNF-4α in colon carcinoma cells affects MUC4 expression and malignancy

• Published in: Cellular oncology (Dordrecht) Vol. 36; no. 2; pp. 155 - 167
• Main Authors: Algamas-Dimantov, Anna, Yehuda-Shnaidman, Einav, Peri, Irena, Schwartz, Betty
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-04-2013
• Subjects: Acetylation - drug effects; Biomedical and Life Sciences; Biomedicine; Blotting, Western; Butyrates - pharmacology; Caco-2 Cells; Cancer Research; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms - genetics; Colonic Neoplasms - metabolism; Colonic Neoplasms - pathology; Epigenesis, Genetic; Gene Expression Regulation, Neoplastic; Hepatocyte Nuclear Factor 4 - genetics; Hepatocyte Nuclear Factor 4 - metabolism; Histone Deacetylase Inhibitors - pharmacology; Histone Deacetylases - genetics; Histone Deacetylases - metabolism; Histones - metabolism; HT29 Cells; Humans; Hydroxamic Acids - pharmacology; Mucin-4 - genetics; Mucin-4 - metabolism; Oncology; Original Paper; Pathology; Promoter Regions, Genetic - genetics; Protein Binding - drug effects; Repressor Proteins - genetics; Repressor Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Sp1 Transcription Factor - genetics; Sp1 Transcription Factor - metabolism; Transcription, Genetic - drug effects; HNF-4α; HDAC inhibitors; Colon carcinoma; MUC4
• ISSN: 2211-3428; 2211-3436
• DOI: 10.1007/s13402-012-0123-3

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.