Epithelial to mesenchymal transition (EMT) in cancer endows tumor cells with enhanced migratory and invasive property. EMT is considered as a major event during distant tumor metastasis and is mostly regulated by chronic and sustained inflammation. Cyclooxygenase-2 (COX-2) overexpression has been shown in >70% of lung adenocarcinomas and has reciprocal relationship with E-cadherin expression, an epithelial marker. Since, lung cancer is a highly malignant cancer with a potent capacity to metastasize distantly, an approach that decreases its invasive potential or the ability of cell migration may facilitate the development of an effective strategy for its treatment and/or prevention. Dietary phytochemicals offer promising new options for the development of more effective strategies for the prevention of cancer cell invasion and metastasis, and thus can be utilized as complementary and alternative medicine. We hypothesize that reduction of basal level of COX-2, a biomarker of inflammation, in non-small cell lung cancer (NSCLC) cells by grape seed proanthocyanidins (GSPs) should lead to reversal of EMT and that will result in reduced capacity of cell migration. Here we report that treatment of NSCLC A549 cells with various concentrations of GSPs (0, 10, 20, 40 µg/ml) for 24 h resulted in a dose-dependent reduction of COX-2 expression. Using an in vitro cell migration assay, we found that treatment of cells with GSPs (0, 10, 20, 40 µg/ml) inhibited tumor cell migration from 25±5%-55±5% compared to non-treated control cells. Western blot analysis revealed that treatment of A549 cells with GSPs also resulted in upregulation of epithelial markers (E-cadherin, Keratin-8 and Keratin-18) concomitant with decrease in the levels of mesenchymal markers (Fibroncetin, N-cadherin and Vimentin). Further, treatment of cells with phorbol-12-myristate 13-acetate, an inducer of COX-2, resulted in increased cell migration (118±5%-140±8%) compared to control cells and simultaneously reduced the levels of E-cadherin. Treatment of cells with celecoxib, an inhibitor of COX-2, rescued E-cadherin expression and inhibited cell migration (21±5%-63±5%). Dietary administration of GSPs (0.2% w/w) with control AIN76A-diet to athymic nude mice resulted in reduced xenograft growth and reduced expression of COX-2 in A549 tumor xenografts, and that resulted in upregulation of epithelial markers (E-cadherin, Kertain-8 and Keratin-18) while downregulation of mesenchymal biomarkers (N-cadherin and Fibronectin) in xenograft tissues. Together these data suggest that reversal of epithelial to mesenchymal transition in human NSCLC cells by GSPs is associated with the down regulation of COX-2, and that leads to inhibition of cancer cell migration.

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 2368. doi:10.1158/1538-7445.AM2011-2368