Abstract B71: Immune mechanisms that drive early carcinogenesis in endometriosis-associated ovarian cancer
Authors: Suryawanshi Swati , Huang Xin , Budiu Raluca , Mantia Gina , Edwards Robert , Vlad Anda 
Published: August 2014

Introduction: Endometriosis is a largely benign, chronic inflammatory disease defined by the presence of endometrial-like glands surrounded by stroma. Epidemiologic studies suggest that endometriosis is an independent risk factor for endometrioid and clear cell epithelial ovarian tumors, collectively called endometriosis-associated ovarian cancers (EAOC). Although it is widely accepted that chronic inflammation drives cancer, immune deregulation in chronic precursor lesions to ovarian cancer have not been studied in a systematic way.

Hypothesis: Gene expression traits intrinsic to the premalignant endometriotic epithelium (leading to fields of atypia and eventually invasive cancer) result in highly specific quantitative and qualitative changes of the immune stroma that may differentiate benign from pre-malignant and malignant lesions.

Experimental procedure: We extracted RNA from 150 paraffin tissue blocks comprising of normal endometrium (n=32), benign endometriosis consisting of ovarian and extra ovarian endometriosis cases (n=32,) atypical endometriosis (n=15) and EAOC, (n=41). Serous tumors (n=15) were included as non-endometriosis associated controls. Using Nanostring and the nCounter® GX Human Immunology Kit, we profiled a total of 511 immune genes. Cluster analyses and differential expressions (DE) were calculated using EdgeR. ELISAs were done to measure levels of complement factors in plasma samples of healthy controls (n=18), patients with EAOC (n = 12), endometriosis (n=34) and serous ovarian cancer (n = 15). Protein expression of candidate proteins was validated with immunohistochemistry (IHC).

Results: Nanostring immune gene expression profile demonstrates that non ovarian and ovarian endometriosis develop in distinct immune microenvironments with distinct cancer risk. Based on all (unsupervised) gene expression, non-ovarian endometriosis resembles that of normal endometrium while the ovarian endometriotic lesions cluster closer to ovarian cancer. Fewer immune genes differentiate atypical from ovarian than extra-ovarian endometriosis. Several of the DE genes demonstrate decreased Th1 and NK cell cytotoxicity, increased B cell activation and antibody production, further suggesting why women with ovarian endometriosis may be at higher risk of ovarian cancer. Overall, the top 3 pathways reveal the predominant role of adaptive immunity and of the adaptive-innate immune cross-talk. The complement pathway was most prominently expressed, suggesting its roles as one of the major immune pathways involved in the transition from chronic endometriosis to atypical (premalignant) endometriosis and to EAOC. Tissue deposition of several complement components and changes in peripheral blood were confirmed by IHC and ELISA, respectively. We are currently investigating the mechanisms by which complement cascades influence the tumor microenvironment, epithelium-immune cell interactions and early development of EAOC.

Conclusions: We performed the first comprehensive gene profile of the tissue immune microenvironment in benign endometriosis, EAOC and precursor lesions and identified the previously unrecognized roles for the complement pathway. These findings have high translational potential for immune therapy and prevention in EAOC.

Citation Format: Swati Suryawanshi, Xin Huang, Raluca Budiu, Gina Mantia, Robert Edwards, Anda Vlad. Immune mechanisms that drive early carcinogenesis in endometriosis-associated ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B71.