Abstract 1298: The anticancer effects of RX-5902 result from inhibition of phosphorylated p68-mediated β-catenin nuclear translocation

Phosphorylated p68 (p-p68 or phospho-DDX5) has been shown to be associated with cell transformation, epithelial mesenchymal transition (EMT) and cell migration, and furthermore play a vital role in cell proliferation and tumor/cancer progression by promoting the nuclear translocation of β-catenin. RX-5902 is an oral, small molecule inhibitor of β-catenin nuclear translocation mediated by p-p68. Previous studies have shown that RX-5902 inhibits the growth of cancer cells at low nanomolar IC50 (10 to 24nM) and disrupts the p-p68-β-catenin signaling pathway through an interaction with p-p68 on Tyr 593. By interfering with the p-p68-β-catenin signaling pathway cancer cells undergo apoptosis. In this study, we expanded our investigation to study the effect of RX-5902 on nuclear β-catenin in several types of cancer cell lines that include colon, gastric, hepatic, head and neck, melanoma, breast, pancreatic, ovarian, and prostate. Western blot data, in the cell lines tested, showed a decrease of nuclear β-catenin protein as well as p-p68 and c-myc in a concentration-dependent manner. Furthermore, an in vivo study of the MDA-MD-231 xenograft model demonstrated the ability of RX-5902 to inhibit the tumor growth by decreasing p-p68, β-catenin, cyclin D1 and c-myc proteins. Collectively our findings in both in vitro and in vivo studies support the potential therapeutic effect of RX-5902 in multiple cancer indications through the disruption of the phospho-p68/nuclear β-catenin interaction and blocking the nuclear translocation of β-catenin. Citation Format: Young B. Lee, Christina George, Deog J. Kim. The anticancer effects of RX-5902 result from inhibition of phosphorylated p68-mediated β-catenin nuclear translocation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1298.