Abstract 1507: TGF-beta induced stromal versican promotes cancer invasion in advanced stage serous ovarian cancer

Abstract

Abstract Tumor microenvironment is crucial for tumor progression. Cancer associated fibroblasts (CAFs) support tumor growth and invasion by actively secrete different proteins into the extracellular matrix. Using transcriptome profiling analysis on microdissected normal and malignant ovarian tumor tissues, we obtained a CAF specific gene signature. One of the identified genes, versican, showed a 15fold increase in expression in the fibroblastic stromal component of the tumor tissue. This study seeks to evaluate the clinical significance of stromal versican over-expression, to delineate the role of versican in ovarian cancer progression and to understand the regulatory mechanism of versican. Clinical significance of stromal versican expression was evaluated by Kaplan Meier analysis (N=102). Results suggested that high versican expression in cancer stroma is significantly associated with poor overall and progression free survival in high-grade serous ovarian cancer (HGSC) patients (p<0.01). Co-culturing ovarian cancer cells with normal ovarian fibroblasts showed significantly increased in versican expression in fibroblasts. Based on this observation, we hypothesize that signaling molecules secreted by cancer cells induce versican expression in fibroblasts. To test this hypothesis, we treated ovarian fibroblasts with different cytokines. The results showed a significant increase in versican expression in TGF-beta treated cells (p<0.01). Further studies using pathway inhibitors suggested that the induction is mediated through the TGF-beta receptor type II and the subsequent Smad signaling. To delineate the function roles of versican in cancer progression, cell motility and cell invasion assays were conducted. Cancer cells demonstrated increased invasiveness and motility in the presence of extracellular versican. The results were further confirmed using a 3D cancer invasion model in which ovarian cancer cells were co-cultured with fibroblasts and supplied with high-levels of versican in the type I collagen matrix. Transcriptome profiling analysis and luciferase reporter assay were performed to evaluate the underlying molecular mechanism. The results showed that versican up-regulated CD44 and MMP9, and activated the NFκB signaling pathway. Co-localization of versican with CD44 and MMP9 proteins demonstrated that elevation of versican in stromal fibroblasts, and both CD44 and MMP9 in cancer cells particularly at the epithelial-stromal interface of the invasion front. In conclusion, stromal versican is a prognostic marker for HGSC and is associated with poor patient survival. Ovarian cancer cells induce versican production in CAFs through TGF-beta. Subsequently, stromal versican up-regulates CD44 and MMP9 expression in cancer cells, which may facilitate the degradation of ECM at the invasion front. Our result demonstrated an important role of CAFs in supporting cancer progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1507. doi:1538-7445.AM2012-1507