PRIMA-1(MET)/APR-246 targets mutant forms of p53 family members p63 and p73.

The low molecular weight compound PRIMA-1 and the structural analog PRIMA-1(MET), also named APR-246, reactivate mutant p53 through covalent binding to the core domain and induce apoptosis in tumor cells. Here, we asked whether PRIMA-1(MET)/APR-246 can rescue mutant forms of the p53 family members p63 and p73 that share high sequence homology with p53. We found that PRIMA-1(MET)/APR-246 can restore the pro-apoptotic function to mutant TAp63γ and TAp73β in tumor cells but has less effect on TAp73α. Moreover, PRIMA-1(MET)/APR-246-stimulated DNA binding of mutant TAp63γ and induced expression of the p53/p63/p73 downstream targets p21 and Noxa. The reactivation of mutant p53, p63 and p73 by PRIMA-1(MET)/APR-246 indicates a common mechanism, presumably involving homologous structural elements in the p53 family proteins. Our findings may open avenues for therapeutic intervention in human developmental disorders with mutations in p63.