Abstract 3978: Therapeutic evaluation of eprinomectin against advanced prostate cancer

Prostate Cancer (PCa) is the second most common cancer among men in United States after skin cancer. According to the American Cancer Society, in 2017 alone there will be 16,130 new cases of PCa and 26,730 deaths from PCa. Conventional chemotherapeutic drugs available for PCa treatment are limited due to toxicity and resistance issues. Therefore, there is an urgent need to develop more potent treatment for advanced PCa. Eprinomectin (EP) belongs to the class of avermectins which are lactone derivatives with potent anti-helminthic and anti-cancer properties. EP has been widely used to treat parasitic diseases in cattle and is found to be less toxic than the other avermectin class of drugs. The goal of our current study is to test the anti-cancer efficacy of EP on PCa cells. Initially cell viability assays were performed on PCa cell lines such as PC3, DU145, LNCaP, VCaP, and 22RV1 to assess the anti-cancer efficacy of EP. Among all the PCa cell lines tested, PC3 and DU145 showed more sensitivity to EP. Specifically, cell viability assays indicated that EP reduced the viability of PC3 and DU145 PCa cells by 50% at 25μM concentration. Next, in soft agar assay, EP effectively inhibited the anchorage independent growth of prostate cancer cells in vitro. Furthermore, wound healing assay results suggested that EP targeted the migratory property of PC3 and DU145 cell lines. In addition, apoptosis assay using Annexin-FITC and propidium iodide staining revealed that EP targets PC3 and DU145 cells by inducing apoptosis. Cell cycle analysis showed that EP arrested the PC3 and DU145 cells in G0 phase of the cell cycle. Interestingly, our results also showed that EP targets the PCa cells by inducing oxidative stress. Real time PCR analysis showed that EP effectively inhibited the expression of various cancer stem cell markers such as ALDH1, Sox-2, Nanog, Oct3/4 and CD44. In PC3 and DU145 cell lines, EP effectively inhibited the activity of Alkaline Phosphatase suggesting that EP could target pluripotent stem cells. In addition, treatment of PC3 and DU145 cells with EP resulted in the translocation of s-catenin from the nucleus to the cytoplasm indicating that EP antagonizes Wnt/s-catenin signaling pathway. Furthermore, EP also decreased the expression of the downstream target genes of s-catenin such as cyclin D1 and c-Myc in PC3 and DU145 cells. EP also downregulated the expression of other key cell cycle markers such as cyclin D3, CDK4 and anti-apoptotic markers such as Bcl-2, Bcl-XL, XIAP, c-IAP2 and survivin in PC3 and DU145 cells. On the contrary, treating PC3 and DU145 cells with EP resulted in the activation of DNA damage marker, pH2AX and upregulation of pro apoptotic marker, Bad with concomitant activation of Caspase-9 and Caspase-3. Based on our results, EP appears to potently target advanced PCa cells by inhibiting tumorigenic and metastatic properties of advanced PCa cells in vitro. Further in vivo and preclinical studies are warranted to test the efficacy of EP on PCa. Citation Format: Angela Lincy Prem Antony Samy, Syed M. Ali, Subramanyam Dasari, Gnanasekar Munirathinam. Therapeutic evaluation of eprinomectin against advanced prostate cancer [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 3978.