Histone deacetylase inhibitors suppress the induction of c-Jun and its target genes including COX-2.
Cyclooxygenase-2 (COX-2) is considered to be a target for anticancer therapy. Histone deacetylase (HDAC) inhibitors exhibit antitumor activity, but the mechanisms of action are incompletely understood. We investigated whether HDAC inhibitors blocked AP-1-mediated activation of COX-2 transcription. Trichostatin A and suberoylanilide hydroxamic acid, two structurally related inhibitors of HDAC activity, ... blocked AP-1-mediated induction of COX-2 expression and prostaglandin E2 biosynthesis. Chromatin immunoprecipitation assays indicated that HDAC inhibitors suppressed c-Jun binding to the COX-2 promoter and thereby blocked transcription. The observed reduction in binding reflected reduced levels of c-Jun. HDAC inhibitors suppressed the induction of c-jun transcription by blocking the recruitment of the preinitiation complex (RNA polymerase II and TFIIB) to the c-jun promoter. HDAC3 but not HDAC1 or HDAC2 was required for AP-1-mediated stimulation of c-jun expression. Because HDAC inhibitors suppressed the induction of c-jun gene expression, resulting in reduced COX-2 transcription, it was important to determine whether other known AP-1 target genes were also modulated. Cyclin D1 and collagenase-1 are AP-1-dependent genes that have been implicated in carcinogenesis. HDAC inhibitors suppressed the induction of both cyclin D1 and collagenase-1 transcription by inhibiting the binding of c-Jun to the respective promoters. Taken together, these results suggest that HDAC inhibitors block the induction of c-jun transcription by inhibiting the recruitment of the preinitiation complex to the c-jun promoter. This led, in turn, to reduced expression of several activator protein-1-dependent genes (COX-2, cyclin D1, collagenase-1). These findings provide new insights into the mechanisms underlying the antitumor activity of HDAC inhibitors.
Mesh Terms:
Blotting, Northern, Blotting, Western, Cell Line, Tumor, Chromatin, Chromatin Immunoprecipitation, Collagenases, Cyclin D1, Dinoprostone, Dose-Response Relationship, Drug, Enzyme Inhibitors, Gene Expression Regulation, Enzymologic, Genes, jun, Histone Deacetylase Inhibitors, Histone Deacetylases, Humans, Hydroxamic Acids, Models, Genetic, Promoter Regions, Genetic, Protein Binding, Proto-Oncogene Proteins c-jun, RNA Polymerase II, Transcription Factor AP-1, Transcription Factor TFIIB, Transcription, Genetic, Transfection
Blotting, Northern, Blotting, Western, Cell Line, Tumor, Chromatin, Chromatin Immunoprecipitation, Collagenases, Cyclin D1, Dinoprostone, Dose-Response Relationship, Drug, Enzyme Inhibitors, Gene Expression Regulation, Enzymologic, Genes, jun, Histone Deacetylase Inhibitors, Histone Deacetylases, Humans, Hydroxamic Acids, Models, Genetic, Promoter Regions, Genetic, Protein Binding, Proto-Oncogene Proteins c-jun, RNA Polymerase II, Transcription Factor AP-1, Transcription Factor TFIIB, Transcription, Genetic, Transfection
J. Biol. Chem.
Date: Sep. 23, 2005
PubMed ID: 15994313
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