Abstract 3181: Connecting EGFR activation to inflammatory signaling in epithelial ovarian cancer

Abstract

Abstract Epithelial Ovarian Cancer (EOC) is the leading cause of death from gynecology cancer. EOC is initially characterized by intraperitoneal growth of tumor masses followed by an increased accumulation of ascitic fluid that contains a variable numbers of tumor cells and inflammatory leukocytes, as well as, variable levels of cytokines and chemokines. The receptor/ligand pair CXCR4/CXCL12 and the cytokines IL-1β, IL-6 and IL-8 have been found to contribute to cell proliferation of EOC. Despite our limited knowledge of initiating events of EOC, it is known that RAS oncogene mutation account for 30% of advanced EOC, activated H-RAS protein is commonly detected in EOC and activation of a receptor tyrosine kinase (RTK) could be the upstream mechanism initiating the cascade via the RAS/mitogen-activated protein kinases that lead to transcriptional activation. Indeed, in a homeostatic state EGFR, member of HER family RTK, plays a key role in normal ovarian follicle development and in the growth regulation of cells of ovarian surface epithelium (OSE) from which the EOC arises. EGFR is expressed in an estimated 35% to 70% of EOCs. Here, we wanted to assess in EOC whether the activation of the oncogene EGFR is related to an inflammation-associated signaling. Within normal and several transformed ovarian cell lines we selected IGROV-1 and OAW42 cells showing the highest EGFR expression and IL-6 release. Upon receptor activation with EGF, an up-regulation of PI3K/AKT and MEK/ERK pathways were observed. In both cell lines phosphorylation of EGFR occurred in the first 15 min of EGF treatment, followed by a concomitant phosphorylation of both AKT and MAPK. We also observed that the cited phosphorylations were completely inhibited by using the AG1478 EGFR inhibitor. In both cell lines EGF triggered NF-kB transcriptional activation as evaluated by transient transfection with a promoter-reporter gene construct. In the EOC selected cells, upon EGFR activation, an up-regulation of IL-6 mRNA was observed and immunofluorescence analysis revealed that NF-kB translocated into the nucleus. To identify the secretion of specific inflammatory molecules induced by EGFR/NFkB activation in EOC cells, a fifty-one cyto-/chemokine panel in conditioned media from EGF-treated cells have been analysed by Bioplex system. We have identified some inflammatory molecules released specifically upon EGFR activation in a time dependent way such as IL-6, PAI-1, IL-5, IL-12 and VEGF. On a limited number of ascitic fluids from EOC patients IL-6 and PAI-1 have been also analysed by ELISA assay, and the correlation with the EGFR expression on tumor cells of the same patients will be carried out. Overall the acquired information about the inflammation-related EGFR could lead to the identification of alternative approaches potentially suited for improving diagnosis and treatment of EOCs. Partially supported by Italian Health Ministry (Grant ACC1) Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3181.