Abstract 3954: Anti-cancer agent P306 restores p53 pathway through PUMA

Abstract

Abstract The tumor-suppressor p53 prevents cancer development via initiating cell-cycle arrest, cell death, repair, or anti-angiogenesis processes. Over 50% of human cancers harbor cancer-causing mutations in p53. p53 mutations not only abrogate its tumor-suppressor function, but also endow mutant p53 with a gain of function (GOF), creating a proto-oncogene that contributes to tumorigenesis, tumor progression, and chemo- or radiotherapy resistance. Thus, targeting mutant p53 and/or restoring a wild-type p53 signaling pathway provides an attractive strategy for cancer therapy. We previously showed that P01, a natural product, has potent anti-cancer activity against tumors with mutated p53. Based on the structure of the pharmacophore of the P01 family, we designed and synthesized new analogues. The novel synthetic analogue, P306, is potent in reducing both short-term and long-term proliferation in a broad panel of mutant p53 cell lines, including HT29, SW480, DLD-1, MDA-MB-231, MDA-MB-468, U251, FaDu, CAL-27, PANC-1, ASPC-1 and H1975, with IC50 values in the range of 33.9 to 242 nM. In this study, we have characterized a distinct mechanism of P306 that engages the apoptosis pathway by upregulating pro-apoptotic proteins including PUMA in a time-and dose-dependent manner in colorectal cancer cell lines. PUMA is necessary for the apoptotic effects of P306 in colorectal cancer cells with PUMA-mediated caspase 8 activation mediating P306-induced apoptosis. P306 not only restores p53 pathway but also depletes mutant p53 protein in various mutant p53-expressing cancer cells regardless of what kinds of mutation. P306 treatment potently downregulates c-Myc protein level, and apoptosis induced by P306 is dependent on the c-Myc-PUMA pathway. Our results provide novel mechanistic insights into the tumor cell death promoting activity of a candidate therapeutic agent for cancer. Citation Format: Xiaobing Tian, Amriti R. Lulla, Shengling Zhang, Avital Lev, Philip Abbosh, Rahmat Sikder, David T. Dicker, Wafik S. El-Deiry. Anti-cancer agent P306 restores p53 pathway through PUMA [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3954.