Tumor promoter arsenite stimulates histone H3 phosphoacetylation of proto-oncogenes c-fos and c-jun chromatin in human diploid fibroblasts.

Ji Li, Myriam Gorospe, Janice Barnes, Yusen Liu

The Journal of biological chemistry 2003 Apr 11

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Although epidemiological studies have long established that inorganic arsenic is a potent human carcinogen, the underlying mechanisms are still poorly understood. Recent studies suggest that inorganic arsenic may act as a tumor promoter by perturbing key signaling transduction pathways. We have shown previously that arsenite can potently activate the mitogen-activated protein kinase cascades and induce the expression of proliferation-associated genes, including proto-oncogenes c-jun and c-fos. In order to elucidate further the molecular mechanisms underlying its tumor-promoting properties, we investigated the signaling events involved in arsenite-mediated induction of c-fos and c-jun. We found that induction of both c-fos and c-jun by arsenite can be substantially inhibited by the MEK- selective inhibitor U0126, suggesting that the ERK pathway is critically involved in their up-regulation. Interestingly, arsenite dramatically induced the phosphorylation and acetylation of histone H3 preceding the induction of mRNAs encoding c-fos and c-jun. Finally, chromatin immunoprecipitation assays revealed that arsenite treatment markedly induced the phosphorylation/acetylation of histone H3 associated with the c-fos and c-jun genes through an ERK-dependent pathway. Our results strongly suggest that arsenic-triggered alterations in chromatin structure perturb specific gene transcription, including that of proto-oncogenes c-jun and c-fos, and may thereby contribute to the carcinogenic process.

Citation

Ji Li, Myriam Gorospe, Janice Barnes, Yusen Liu. Tumor promoter arsenite stimulates histone H3 phosphoacetylation of proto-oncogenes c-fos and c-jun chromatin in human diploid fibroblasts. The Journal of biological chemistry. 2003 Apr 11;278(15):13183-91