Abstract 3967: High microsomal PGE2synthase-1 levels associate with low CD8 T cells and poorer melanoma patient survival

Abstract

Abstract COX-2 and its product PGE2 are reported to enhance carcinogenesis and tumor progression and to support immunosuppression, as reported by others in melanoma and other cancers. As most COX-2 inhibitors result in cardiotoxicity, the downstream microsomal PGE2 synthase-1 (mPGES1) is now also an alternative consideration for therapeutic targeting. Our previously published results (Kim, et al., 2016) showed that mPGES1 protein increased with melanoma patient clinical stage and that its intense expression was associated with reduced patient survival. We also reported that mPGES1 inhibition attenuated cell survival and increased apoptosis in human melanoma cells and significantly suppressed tumor growth in melanoma xenografts. This current study was designed to evaluate whether expression of mPGES1 contributes to immune evasion. Tumors in a Stage III melanoma TMA analysis demonstrated that high mPGES1 expression (intensity 3) was significantly associated with low CD8 levels (lower than median CD8 percent value) (r=-0.2722, p=0.0128). Importantly, stage III melanoma patients with this high mPGES1 and low CD8 signature had significantly increased risk of death as determined by Kaplan-Meier method and Univariate Cox proportional hazards regression models, and compared with patients with low mPGES1/low CD8 and low mPGES1/high CD8. Furthermore, the differential levels of several chemokines including CXCL1 and CXCL2 to regulate T cell migration were correlated the mPGES1 expression in the TCGA melanoma data set. Collectively, our study continues to resolve the potential role of mPGES1 in regulation of immune evasion and is designed as a preclinical approach to develop a rational therapeutic strategy targeting PGE2-driven inflammatory mediators as useful adjuvants for immune-based therapy. Citation Format: Sun-Hee Kim, Jason Roszik, Weiyi Peng, Suhendan Ekmekcioglu, Elizabeth A. Grimm. High microsomal PGE2synthase-1 levels associate with low CD8 T cells and poorer melanoma patient survival [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 3967. doi:10.1158/1538-7445.AM2017-3967