Abstract 2402: TGF beta-mediated epithelial to mesenchymal transition in non small cell lung cancer: effects on stemness, invasiveness and chemotherapy sensitivity

Abstract

Abstract The developmental program of epithelial to mesenchymal transition (EMT) can be activated in tumor cells and is implicated in the metastatic spread of tumor cells. EMT leads to loss of cell adhesion and increased motility of cells and can be detected by down regulation of epithelial makers such as E-cadherin and gain of mesenchymal ones such as vimentin and fibronectin. Interestingly, EMT has also been implicated in enhancing stemness properties of tumor cells and in causing chemotherapy resistance. The aim of this study is to examine the invasive, stem-ness and chemotherapy sensitive properties of mesenchymal and epithelial Non-small cell lung cancer (NSCLC) cells. In particular we use a TGF beta-inducible EMT model of A549 cells. A pannel of NSCLC cell lines, A549, H460, H322, SW1573, H1650 and H1299 were explored for epithelial (EpCAM. E-cadherin) and mesenhymal markers (N- cadherin, Vimentin and Fibronectin). Only A549 cells exhibit epithelial characteristics while remaning cell lines were either mesenchymal in nature or weekly expressing epithelial markers. Treatment of A549 cells with TGFbeta induced EMT as confirmed by loss of epithelial and gain of mesenchymal markers by FACS and WB analysis. This process was independent of Src since knockdown of Src did not effect EMT activation. Other kinases are currently evaluated for mediating EMT in this model. A549 mesenchymal cells (M) cells were somewhat more resistant to cisplatin and paclitaxel compared to parental A549 cells, whereas no marked difference in the response to proapoptotic TRAIL was found. Furthermore, using wound healing assays A549M cells showed higher rates of migration. Possible effects of EMT on stem cell properties in A549 cells were studied next. A549M cells displayed enhanced spheroid formation potential when cultured in serum free Neurobasal media (NBM) that was associated with an increase in Sox-2 expression. To further explore stemness of A549(M) cells, currently the expression of stem cell markers such as CD133, CD24, CD44 is examined. In conclusion, our results thus far suggest that in A549 NSCLC cells, induction of EMT by TGF beta results in chemoresistance, higher migratory potential and increased stem cell properties. The in-vitro results observed will be extended by in-vivo assays. For this purpose we are establishing orthotopic NSCLC mice models. 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 2402. doi:1538-7445.AM2012-2402