@article {Karpf751, author = {Adam R. Karpf and Brent C. Moore and Ted O. Ririe and David A. Jones}, title = {Activation of the p53 DNA Damage Response Pathway after Inhibition of DNA Methyltransferase by 5-Aza-2'-deoxycytidine}, volume = {59}, number = {4}, pages = {751--757}, year = {2001}, doi = {10.1124/mol.59.4.751}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {Transcriptional silencing of tumor suppressor genes by DNA methylation occurs in cancer cell lines and in human tumors. This has led to the pursuit of DNA methyltransferase inhibition as a drug target. 5-Aza-2'-deoxycytidine [5-aza-CdR (decitabine)], a potent inhibitor of DNA methyltransferase, is a drug currently in clinical trials for the treatment of solid tumors and leukemia. The efficacy of 5-aza-CdR may be related to the induction of methylation-silenced tumor suppressor genes, genomic hypomethylation, and/or enzyme-DNA adduct formation. Here, we test the hypothesis that 5-aza-CdR treatment is perceived as DNA damage, as assessed by the activation of the tumor suppressor p53. We show that 1) colon tumor cell lines expressing wild-type p53 are more sensitive to 5-aza-CdR mediated growth arrest and cytotoxicity; 2) the response to 5-aza-CdR treatment includes the induction and activation of wild-type but not mutant p53 protein; and 3) the induction of the downstream p53 target gene p21 is partially p53-dependent. The induction of p53 protein after 5-aza-CdR treatment did not correlate with an increase in p53 transcripts, indicating that hypomethylation at the p53 promoter does not account for the p53 response. It is relevant that 5-aza-CdR has shown the greatest promise in clinical trials for the treatment of chronic myelogenous leukemia, a malignancy in which functional p53 is often retained. Our data raise the hypothesis that p53 activation may contribute to the clinical efficacy and/or toxicity of 5-aza-CdR.}, issn = {0026-895X}, URL = {https://molpharm.aspetjournals.org/content/59/4/751}, eprint = {https://molpharm.aspetjournals.org/content/59/4/751.full.pdf}, journal = {Molecular Pharmacology} }