Abstract 5261: PKC alpha is implicated in epithelial to mesenchymal transition and erlotinib resistance in non-small cell lung carcinoma cells.

Abstract

Abstract Overexpression and mutational activation of the epidermal growth factor receptor (EGFR) play important roles in the pathogenesis of non-small-cell lung cancer (NSCLC). For patients with EGFR activating mutations, EGFR tyrosine kinase inhibitors (TKIs) are given as a primary therapy. However, the majority of these patients eventually develop resistance to TKIs. To address a potential role of PKC isozymes in the resistance to TKIs, we used an isogenic model: the NSCLC H1650 cell line and its erlotinib-resistance derivative H1650-M3. H1650-M3 cells display a mesenchymal-like morphology driven by TGF-β signaling (PNAS 107:15535-15540, 2010). Comparison of the expression of PKC isozymes by Western blot between parental and erlotinib-resistant H1650 cells revealed that the M3 derivative displays remarkably high levels of PKCα and reduced levels of PKCδ. qPCR analysis established that PKCα mRNA levels in H1650-M3 cells are ∼ 40-fold higher than in parental cells. In order to investigate a potential involvement of PKCα in TKI resistance we used RNAi. Upon PKCα depletion H1650-M3 cells display a morphology that is consistent with the epithelial phenotype. Moreover, depletion of PKCα from H1650-M3 cells led to significant changes in the expression of EMT markers. Indeed, mRNA levels of vimentin, Zeb2, SNAIL and TWIST were reduced by more than 50 % in erlotinib-resistant cells when PKCα expression was silenced. Analysis of cell viability in response to erlotinib treatment showed that pretreatment with either the pan-PKC inhibitor GF 109203X or the cPKC inhibitor Gö6976 sensitized H1650-M3 to erlotinib. Furthermore, PKCα RNAi depletion markedly sensitized H1650 cells to the TKI. Therefore, PKCα up-regulation in erlotinib-resistant cells may play an important role in driving the resistance to the drug. Our results also highlight a potential role for PKCα in EMT in lung cancer cells. Citation Format: Mahlet Abera, Raffaella Sordella, Marcelo Kazanietz. PKC alpha is implicated in epithelial to mesenchymal transition and erlotinib resistance in non-small cell lung carcinoma cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5261. doi:10.1158/1538-7445.AM2013-5261