In the United States, lung cancer is the second most common cancer in men and women. In 2017, 222,500 new cases and 155,870 deaths from lung cancer are estimated to have occurred. A tyrosine kinase receptor, epidermal growth factor receptor (EGFR), is over expressed or mutated in non-small cell lung cancer (NSCLC) resulting in increased cell proliferation and survival. Tyrosine kinase inhibitors (TKIs) are currently being used as therapy for NSCLC patients, however, they have limited efficacy in NSCLC patients due to acquisition of resistance. This study investigates the role of epithelial-mesenchymal transition (EMT) in the development of resistance against TKIs in NSCLC. Currently, the role of p120-catenin, Kaiso factor and PRMT-1 in reversal of EMT in T790M mutated and TKI-resistant NSCLC cells is a new line of study. In this investigation we found upregulation of cytoplasmic p120-catenin, which was co-localized with Kaiso factor. In the nucleus, binding of p120-catenin to Kaiso factor initiates transcription by activating EMT-transcription factors such as Snail, Slug, Twist, and ZEB1. PRMT-1 was also found to be upregulated, which induces methylation of Twist and repression of E-cadherin activity, thus promoting EMT. We confirmed that TKI-resistant cells have mesenchymal cell type characteristics based on their cell morphology and gene or protein expression of EMT related proteins. EMT proteins, Vimentin and N-cadherin, displayed increased expression, whereas E-cadherin expression was downregulated. Finally, we found that the knockdown of p120-catenin and PRMT-1 by siRNA or use of a PRMT-1 inhibitor Furamidine increased Erlotinib sensitivity and could reverse EMT to overcome TKI resistance.
Keywords: Drug resistance; EGFR; Epithelial mesenchymal transition; Lung cancer; Stem cell; Tyrosine kinase inhibitor.
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