Abstract 2974: Preclinical evaluation of Ozanimod for prostate cancer treatment

Abstract

Abstract Prostate cancer (PCa) is the second leading cause of cancer-related death in men of United States, after lung cancer. There are various treatment options such as surgery, radiation therapy, chemotherapy, and androgen deprivation therapy are availabale for PCa. However, invariably patients develop resistance to these therapies, resulting in the manifestation of aggressive and recurrent PCa. Hence, there is an urgent need for an effective treatment strategy for managing PCa. Previous studies have identified that the sphingosine 1-phosphate receptor (S1PR) as a potential target to treat prostate cancer. Ozanimod (OZM) is a selective sphingosine 1- phosphate receptor 1 (S1PR1) and (S1PR5) modulator, which is in phase 3 clinical trial for patients with relapsing multiple sclerosis and ulcerative colitis. The objective of this study is to determine the anticancer effects of OZM, an S1PR modulator using LNCaP, PC-3, and DU-145 as cellular models of PCa. These PCa cell lines were subjected to cell viability, colony formation and wound healing assays as endpoints to assess the anticancer effects of OZM. The cell viability assay results revealed that OZM had a differential effect on PCa cell lines with LNCaP cells being the most sensitive and DU-145, PC-3 showing similar sensitivities to OZM treatment. Furthermore, OZM treatment inhibited the colony formation characteristics of PCa cell lines in-vitro when compared with control in all the three cell lines. In wound healing assay, the migratory characteristics of PCa cell lines were inhibited by OZM in a dose dependent manner. These findings suggested that OZM has both tumor growth suppression and metastasis inhibition potential. Furthermore, Annexin V and Propidium Iodide staining assay revealed that OZM induces apoptosis in PC-3 and DU-145 cells. Following these findings, human apoptotic array study using LNCaP cells showed that anti-apoptotic protein molecules such as c-IAP1, clusterin, and livin were downregulated by OZM treatment in addition to inhibition of HIF-1α expression. The mechanistic study conducted using LNCaP cells by Western blot analysis revealed that OZM treatment upregulated BiP expression while downregulated PERK, IRE-1α which are protein markers associated with endoplasmic reticulum (ER) stress pathway. Furthermore, our results showed that c-myc was down-regulated and MAD, MAX transcription factors were upregulated when treated with OZM. Based on these findings, we suggest that OZM treatment modulates ER stress pathway and anti-apoptotic proteins leading to prostate tumor suppression. In conclusion, OZM might be a potential chemotherapeutic agent for treating both indolent and aggressive PCa. Citation Format: Reshmii Venkatesan, Somaiah Chinnapaka, John Schappert, Gnanasekar Munirathinam. Preclinical evaluation of Ozanimod for prostate cancer treatment [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 2974.