Treatment of SCC13 cells with various concentrations of GSPs (0, 10, 20 and 40 g/ml) for 12 h had no significant effect on cell viability or cell death (data not shown). Open in a separate window Figure 2 Effect of GSPs on cutaneous HNSCC cell invasion. cells with gefitinib and erlotinib, inhibitors of EGFR, or transient transfection of SCC13 cells with EGFR small interfering RNA, also inhibited invasion of these cells. The inhibition of cell invasion by GSPs was associated with the inhibition of the phosphorylation of ERK1/2, a member of mitogen-activated protein kinase family. Treatment of cells with UO126, an inhibitor of MEK, also inhibited the invasion potential of SCC13 cells. Additionally, inhibition of human cutaneous HNSCC cell invasion by GSPs was associated with reversal of epithelial-to-mesenchymal transition (EMT) process, 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. Comparable effect on EMT biomarkers was also observed when cells were treated with erlotinib. Conclusion The results SB-224289 hydrochloride obtained from this study indicate that grape seed proanthocyanidins have the ability to inhibit the invasion of human cutaneous HNSCC cells by targeting the EGFR expression and reversing the process of epithelial-to-mesenchymal transition. These data suggest that GSPs can be developed as a complementary and alternative medicine for the prevention of invasion/metastasis of HNSCC cells. Background Head and neck squamous cell carcinoma (HNSCC) affects more than 40,000 people in the United States annually and is responsible for over 20, 000 deaths every year [1,2]. HNSCC often generates from crucial organs including the oral cavity, SB-224289 hydrochloride larynx, pharynx, and tongue that play indispensable roles in increased mortality rate [1]. Head and neck cutaneous SCC is also very common. Advances in surgical and medical therapies for HNSCC have only modestly improved the mortality rate, which has remained at 50% for the last three decades [3-6]. It has SB-224289 hydrochloride been exhibited that epidermal growth factor receptor (EGFR), one of the ErbB family of receptors, which is usually overexpressed in over 90% of HNSCC tumors, is usually a marker of poor prognosis in patients with HNSCC [7-9]. Mortality rate due to HNSCC is usually closely associated with its potent capacity to metastasize distantly. 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 agents, particularly bioactive dietary phytochemicals, may serve as appropriate candidates for the prevention or therapy of HNSCC metastasis. If these phytochemicals are safe and devoid of toxicities, these can be considered for the prevention of malignancy cell invasion, migration or metastasis and thus can be utilized as complementary and option medicine and/or as adjuvant therapy for conventional cytotoxic therapies. Grape seed proanthocyanidins (GSPs) are such promising bioactive phytochemicals that have shown anti-carcinogenic effects in some tumor models and exhibit no apparent toxicity in vivo animal models [10-12]. GSPs contain primarily proanthocyanidins (89%), which constitute dimers, trimers, tetramers, and oligomers of monomeric catechins and/or (-)-epicatechins, as described previously [11]. Although GSPs have been shown to have SB-224289 hydrochloride anti-tumor effects [10], their chemotherapeutic effects around the invasive potential of HNSCC cells have not been explored. In the current study, we assessed the chemotherapeutic effects of GSPs around the invasion potential of human head and neck cutaneous squamous cell carcinoma cells, as the invasion of cancer cells is usually a major event in the metastatic cascade. The invasion potential of cutaneous SCC cells was also compared with the invasion potential of human epidermoid carcinoma cells which were not found on head and neck sub-sites. For this purpose, two cutaneous SCC cells lines were selected: one is SCC13 which was generated Cd200 from the squamous cell carcinoma of the facial (head) skin. Second cell line is usually A431 which is well known human epidermoid carcinoma cell line and is not related with head.