Tumor promoter phorbol-12-myristate-13-acetate induces poly(ADP)-ribosylation in fibroblasts.

The tumor promoter phorbol-12-myristate-13-acetate (PMA) causes an increase in pol(ADP)-ribosylation in mouse and human fibroblasts via the intermediate formation of active oxygen. In contrast to poly(ADP)-ribosylation induced by the methylating agent N-methyl-N'-nitro-N-nitrosoguanidine, de novo RNA and protein synthesis are required and the accumulation of the polymer occurs in the absence of detectable DNA strand breakage. Our results suggest a mechanism for PMA-induced modulation of chromatin structure and gene expression.