High-throughput RNAi screen identifies ILK as a target to overcome intrinsic EGFR-TKI resistance of lung squamous carcinoma

Abstract

Although targeted therapy has made a significant efficacy in lung adenocarcinoma, there are still no effective targeted drugs for lung squamous cell carcinoma (SqCC). Moreover, immunotherapy only prolonged the OS of lung SqCC for less than 5 months, so till now, chemotherapy and radiotherapy are still the main treatments of advanced SqCC. Lung SqCC patients express higher epithelial growth factor receptor (EGFR) than adenocarcinoma patients, but they are intrinsic resistant to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Therefore, if this resistance can been reversed, it would benefit to most of the SqCCs. Herein a high-throughput RNAi technology was used to screen the genes related with EGFR-TKI erlotinib resistance of lung SqCCs, and then Integrin-linked kinase (ILK) was found to be the most effective gene. We also studied the effects of ILK on erlotinib resistance in cell line and ILK expression in SqCC and adenocarcinoma patients. At last we analyzed the mechanism of ILK in EGFR-TKIs resistance using Pathway Analysis, GO Analysis and Ingenuity Pathway Analysis (IPA). ILK knockout could overcome erlotinib resistance via inhibited cell proliferation, induced apoptosis and blocked the cells at G2/M phase. ILK was expressed significantly higher in SqCC patients than in adenocarcinoma patients with sensitizing EGFR mutations. Moreover, the cell cycle pathway of G2/M DNA Damage and checkpoint regulation was identified significantly inhibited by ILK knockout in IPA, Pathways and GO analysis. Our results may provide further understanding of EGFR-TKIs resistance in lung SqCCs and thus aiding the development of potential targeted therapies for lung SqCCs.