期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2013
卷号：110
期号：4
页码：1267-1272
DOI：10.1073/pnas.1211805110
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Activation of STAT3 in cancers leads to gene expression promoting cell proliferation and resistance to apoptosis, as well as tumor angiogenesis, invasion, and migration. In the characterization of effects of ST3-H2A2, a selective inhibitor of the STAT3 N-terminal domain (ND), we observed that the compound induced apoptotic death in cancer cells associated with robust activation of proapoptotic genes. Using ChIP and tiling human promoter arrays, we found that activation of gene expression in response to ST3-H2A2 is accompanied by altered STAT3 chromatin binding. Using inhibitors of STAT3 phosphorylation and a dominant-negative STAT3 mutant, we found that the unphosphorylated form of STAT3 binds to regulatory regions of proapoptotic genes and prevents their expression in tumor cells but not normal cells. siRNA knockdown confirmed the effects of ST3-HA2A on gene expression and chromatin binding to be STAT3 dependent. The STAT3-binding region of the C/EBP-homologous protein (CHOP) promoter was found to be localized in DNaseI hypersensitive site of chromatin in cancer cells but not in nontransformed cells, suggesting that STAT3 binding and suppressive action can be chromatin structure dependent. These data demonstrate a suppressive role for the STAT3 ND in the regulation of proapoptotic gene expression in cancer cells, providing further support for targeting STAT3 ND for cancer therapy.
关键词：H3K9me3 ; peptide inhibitor ; prostate cancer ; transcription factor
