Modulation of p53 transcriptional activity by PRIMA-1 and Pifithrin-alpha on staurosporine-induced apoptosis of wild-type and mutated p53 epithelial cells.

We recently argued for a major role of p53 in staurosporine(ST)-induced apoptosis of immortalized epithelial cells, depending on their p53 status. Here, we studied the effects of PRIMA-1 (p53 reactivation and induction of massive apoptosis) and Pifithrin-alpha (p fifty-three inhibitor) in combination with ST to reinforce our previous results by respectively restoring or inhibiting the p53 transcriptional activity in different cell lines.PRIMA-1 does modify neither expression of apoptosis-related proteins nor the percentage of wild-type p53 HeLa and CaSki cells with [symbol: see text]delta psi m and DNA cleavage, whilst it increases by 45% Bax expression and apoptosis of mutated p53 C33A cells. Pifithrin-alpha, does modify neither Bax expression nor apoptosis level of C33A cells, but readily inhibits both [symbol: see text]delta psi m and DNA fragmentation of p53wt cells with decreasing Bax expression. These data support the evidence that PRIMA-1 could be a good candidate, as an anti-cancer drug targeting mutant p53, in order to increase ST efficiency. Moreover, Pifithrin-alpha could be used in combination with ST and PRIMA-1 to prevent side effects of anti-tumor therapies in cells expressing mutant P53.