Abstract 564: Resistant to Erlotinib, epidermal growth factor receptor tyrosine kinase inhibitor, is involved in epithelial to mesenchymal transition, cell migration and inflammation in A549, a non-small cell lung cancer cell line

Abstract

Abstract Background: In recent years, a number of novel agents have been investigated that target specific molecular pathways in non-small cell lung cancer (NSCLC). A great deal of effort has been focused on identifying specific markers that predict treatment response. The epidermal growth factor receptor (EGFR) pathway has emerged as a key regulator of cancer cell proliferation and invasion, and several specific EGFR inhibitors have been examined. Erlotinib, a selective EGFR tyrosine kinase inhibitor (EGFR-TKI) is clinically used to treat patients with NSCLC. In this study, we investigated the mechanisms for the drug-resistance of Erlotinib and the cytotoxic effects in NSCLC cell lines treated with Erlotinib. Methods: In this study, we established an Erlotinib resistant subline (A549/ER) from parental A549 cell line. MTT assay and western blot analysis were used to measure the cell sensitivity to drugs. A549 and A549/ER cells were grown in chamber slide and stained with H&E to observe the cell morphology. The migration ability of A549 and A549/ ER cells was evaluated by transwell experiment. In addition, cDNA microarray was used to analyze gene expression patterns in transcript level, and secretory cytokine patterns were evaluated with multiplex enzyme-linked immunosorbent assay (ELISA) from A549 and A549/ER cell lines. Results: In the EGFR-TKI-resistant cell line A549/ER, cell growth inhibition by Erlotinib was only mild, and the phosphorylation of this leading target such as EGFR was not inhibited. Phenotypic changes such as a spindle-cell shape and increased pseudopodia formation suggesting epithelial to mesenchymal transition (EMT) was found in A549/ER cells. These changes were accompanied by decreased expression of E-cadherin (ECAD) and cytokeratin-8, which are mesenchymal transition markers. Moreover, the ability of migration was increased in A549/ER cells. Different pattern of gene expression in cDNA microarray reflects changes during resistant progression in A549 cells. In experiment using multiplex ELISA, the secretory cytokines including vascular endothelial growth factor (VEGF), interleukin-6, interleukin-8 known to contribute to pathological inflammation were increased in the medium of A549/ER compared to that of A549 cells. Conclusions: These results suggest that the mechanism of upstream receptor tyrosine kinase inhibitor, Erlotinib, resistance may be related with EMT, cell migration and inflammation in NSCLC. 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 564. doi:10.1158/1538-7445.AM2011-564