Abstract 2580: Ceramide-rubusoside nano-micelles restores p53-mediated tumor suppression in p53R248W mutant ovarian cancer cells

Abstract

Abstract Ceramide (Cer), a sphingolipid metabolite, has crucial functions in anti-proliferation, cell differentiation and apoptosis. Cellular Cer levels highly correlates to therapeutic efficacy of anticancer drugs, however, the hydrophobicity Cer has limits to develop it as a therapeutic agent. Here, we report that Cer-rubusoside (Cer-RUB) nanomicelles enhanced Cer bioavailability and restored p53-mediated tumor suppression. These nanomicelles significantly increased the levels of NBD-C6-Cer by more than 50-fold in serum, 40-fold in tumor and 70-fold in lung of tumor-bearing mice (1 mg/kg, i.p., 24 hr), respectively. Cer-RUB (3 µM) significantly increased OVCAR-3 (p53 R248W) cell sensitivity to cisplatin, and the IC50 values decreased by 3-fold, even though these values were no significant changes in A2780 (wt p53) cells. Furthermore, Cer-RUB treatments (1 mg/kg, i.p. every 3 days for 24 days) significantly increased cisplatin efficacy in tumor growth-arrest in OVCAR-3 tumor-mice, and the tumor volumes reduced by 52% (1653 vs. 805 mm3) in combination with cisplatin, compared to cisplatin alone. We found that ovarian cancer stem cells (CD44+/CD133+) decreased by 10-fold (0.85 vs. 0.08% of total cells) in OVCAR-3 tumors treated with Cer-RUB combined with cisplatin, as compared to cisplatin alone, respectively. Western blotting showed that Cer-RUB treatments selectively increased the expression levels of phosphorylated p53 (Ser15), BAX and p21 in OVCAR-3 cancer cells and tumors, respectively. These studies indicates that the gain-of-function (GOF) of p53 R248W leads OVCAR-3 cell resistance to cisplatin and tumor growth. Cer-RUB can restore p53 and eliminates the GOF of p53 R248W in cancers. Citation Format: sachin K. khiste, Zhijun Liu, Yong-Yu Liu. Ceramide-rubusoside nano-micelles restores p53-mediated tumor suppression in p53R248W mutant ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2580. doi:10.1158/1538-7445.AM2017-2580