Decreased DNA Damage and Improved p53 Specificity of RITA Analogs

Reactivation of p53 tumor-suppressor function by small molecules is an attractive strategy to defeat cancer. A potent p53-reactivating molecule RITA, which triggers p53-dependent apoptosis in human tumor cells in vitro and in vivo, exhibits p53-independent cytotoxicity due to modifications by detoxification enzyme Sulfotransferase 1A1 (SULT1A1), producing a reactive carbocation. Several synthetic modifications to RITA's heterocyclic scaffold lead to higher energy barriers for carbocation formation. In this study, we addressed the question whether RITA analogs NSC777196 and NSC782846 can induce p53-dependent apoptosis without SULT1A1-dependent DNA damage. We found that RITA analog NSC782846, but not NSC777196, induced p53-regulated genes, targeted oncogene addiction, and killed cancer cells upon p53 reactivation, but without induction of DNA damage and inhibition RNA pol II. Our results might demonstrate a method for designing more specific and potent RITA analogs to accelerate translation of p53-targeting compounds from laboratory bench to clinic.