Abstract 420: Up-regulation of stromal versican in advanced stage serous ovarian cancer modifies tumor microenvironment and promotes cancer invasion

Objective: The extracellular matrix (ECM) is a three-dimensional structure which regulates cell migration, differentiation and proliferation. Modification of the ECM is crucial for tumor progression. Using transcriptome profiling, we identified a number of significantly up-regulated genes in the microdissected ovarian cancer stroma. Versican, a chondroitin sulfate proteoglycan, showed a 15 fold increase in expression in the tumor stroma when compared with both tumor epithelium and normal stroma. This study seeks to further evaluate the clinical signifcance of versican up-regulation and to delineate the role of versican in modifying the tumor microenvironment and promoting caner invasion. Methods: Immunlocalization of versican was performed on paraffin tissue sections of high grade serous ovarian cancer (HGSC). The clinical significance of stromal versican expression was evaluated by Kaplan Meier analysis. To delineate the function roles of Versican in cancer progression, cell motility assay and cell invasion assays were conducted on versican treated ovarian cancer cells. For mechanistic studies, luciferase reporter assay and microarray study were performed. A three-dimensional co-culture model consisting of HeyA8 ovarian cancer cells and WI38 fibroblast in type I collagen matrix was developed. The interaction between cancer cells and fibroblasts in the three-dimensional model was evaluated using confocal microscopy. Result: Kaplan Meier analysis revealed that patients with higher versican expression (n = 30) had a median overall survival of 37.5 months, whereas those with lower versican expression (n = 72) had a value of 79.8 months (P=0.001). For progression-free survival, patients with higher versican expression (n = 24) had a median of 9.5 months, while those with lower versican expression (n = 68) had a median of 37.6 months (P=0.008). Functional studies showed that, ovarian cancer cells demonstrated increased invasiveness and motility in the presence of extracellular versican using the 2D culture system. The results were further confirmed using the three-dimensional co-culture model with cancer cells and fibroblasts expressing high-levels of versican in the collagen matrix. Luciferase reporter assay and microarray, and real-time PCR analyses on versican treated ovarian cancer cells showed that versican up-regulated CD44 and MMP9, and activated the NFκB signaling pathway. Co-localization of CD44 and MMP9 with stromal versican demonstrated that elevation of both CD44 and MMP9 in cancer cells at the epithelial-stromal interphase of the invasion front. Conclusions: Stroaml versican is a prognostic marker for advanced stage HGSC. Versican produce by cancer associated fibroblasts up-regulates MMP9 and CD44 expression in cancer cells, which may facilitate the degradation of ECM at the invasion front and subsequently ovarian cancer invasion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 420. doi:10.1158/1538-7445.AM2011-420