Head and neck squamous cell carcinoma (HNSCC) is responsible for over 20,000 deaths every year in the United States, and often generates from critical organs sites including the oral cavity, larynx, pharynx, and tongue. Most of the deaths are due, in large part, to its propensity to metastasize. Therefore, an approach that decreases the metastatic ability of HNSCC cells may facilitate the development of an effective strategy for its treatment and/or prevention. Naturally occurring bioactive phytochemicals may serve as appropriate candidates for the prevention of HNSCC metastasis. We have examined the effect of bioactive component grape seed proanthocyanidins (GSPs) on the invasive potential of human HNSCC cells and determined the molecular mechanisms underlying these effects using various cell lines from multiple sub-sites, such as SCC1 (oral cavity), SCC5 (larynx), FaDu (pharynx) and OSC19 (tongue). Using in vitro cell invasion assays, we observed that OSC19 cells, which was metastasis-specific, have significantly higher (P<0.001) invasive potential than SCC1, SCC5, and FaDu cell lines. Further studies were extended with OSC19 cell line to determine the effect of GSPs on cell migration. Treatment of OSC19 cells with GSPs (10, 20 and 40 μg/ml) for 48 h resulted in a concentration-dependent inhibition of cell migration of these cells. As EGFR is overexpressed in approximately 90% of HNSCC tumors, the EGFR is considered as a promising target of HNSCC therapy. It was found that the inhibitory effect of GSPs on cell migration was associated with a reduction in the levels of EGFR. Treatment of cells with gefitinib and erlotinib, small molecule inhibitors of EGFR, also inhibited migration of these cells. EGFR pathway has been involved in epithelial-mesenchymal transition (EMT), an early event that occurs during metastasis of cancers of an epithelial origin. Therefore, we determined the effect of GSPs on EMT, and was found that the inhibition of HNSCC cell migration by GSPs was associated with reversal of EMT, which resulted in an increase in the levels of epithelial biomarker (E-cadherin) while loss of mesenchymal biomarkers (vimentin, fibronectin and N-cadherin) in cells. Similar effect on EMT biomarkers was also observed when OSC19 cells were treated with erlotinib. As activation of nuclear factor-βB (NF-κB) has been implicated in stimulation of EMT, we further checked the effect of GSPs on NF-κB activation. GSPs inhibited the activation of NF-κB/p65 in OSC19 cells, and treatment of cells with caffeic acid phenethyl ester, an inhibitor of NF-κB, also inhibited cell migration. Together these results indicate that GSPs have the ability to inhibit the invasive potential of HNSCC cells by targeting EGFR expression and reversing epithelial-to-mesenchymal transition.

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 1597. doi:1538-7445.AM2012-1597