Molecular Analysis of Short- versus Long-Term Survivors of High-Grade Serous Ovarian Carcinoma

Simple Summary Ovarian cancer is commonly associated with poor survival; patients with a diagnosis of high-grade serous ovarian carcinoma (HGSC) have an overall survival of 39% at 5 years. For reasons not well known, about 32% of ovarian cancer patients survive 10 years or more. In this study, our goal was to determine the molecular differences that drive long-term survival (LTS) in patients with HGSC. Indeed, this study shows that patients with LTS have a distinct pattern of gene expression, with TMEM62 being related to LTS. Increased TMEM62 expression led to decreased proliferation of ovarian cancer cells in vitro and decreased tumor burden in vivo. Despite having similar histologic features, patients with high-grade serous ovarian carcinoma (HGSC) often experience highly variable outcomes. The underlying determinants for long-term survival (LTS, >= 10 years) versus short-term survival (STS, <3 years) are largely unknown. The present study sought to identify molecular predictors of LTS for women with HGSC. A cohort of 24 frozen HGSC samples was collected (12 LTS and 12 STS) and analyzed at DNA, RNA, and protein levels. OVCAR5 and OVCAR8 cell lines were used for in vitro validation studies. For in vivo studies, we injected OVCAR8 cells into the peritoneal cavity of female athymic nude mice. From RNAseq analysis, 11 genes were found to be differentially expressed between the STS and LTS groups (fold change > 2; false discovery rate < 0.01). In the subsequent validation cohort, transmembrane protein 62 (TMEM62) was found to be related to LTS. CIBERSORT analysis showed that T cells (follicular helper) were found at higher levels in tumors from LTS than STS groups. In vitro data using OVCAR5 and OVCAR8 cells showed decreased proliferation with TMEM62 overexpression and positive correlation with a longevity-regulating pathway (KEGG HSA04213) at the RNA level. In vivo analysis using the OVCAR8-TMEM62-TetON model showed decreased tumor burden in mice with high- vs. low-expressing TMEM62 tumors. Our results demonstrate that restoring TMEM62 may be a novel approach for treatment of HGSC. These findings may have implications for biomarker and intervention strategies to help improve patient outcomes