Study On The Mechanism Of IGF-1R/?-catenin Signaling Pathway In The Treatment Of NSCLC With Gefitinib Combined With Chemotherapy

Objective: Chemotherapy combined with gefitinib resistance is currently a hot topic in the treatment of non-small cell lung cancer.This study further explored the resistance mechanism of IGF-1R/?-catenin in chemotherapy combined with gefitinib in the treatment of non-small cell lung cancer.Methods: Four NSCLC cell lines including A549,NCI-H1299,NCI-H1437 and NCI-H2126 were selected to construct three resistant cell groups in every selected NSCLC cell lines according to the clinical treatment plans,which were resistant to cisplatin and paclitaxel,cisplatin combined with paclitaxel and gefitinib,and Gefitinib,named TC,TC+G and G resistant cell groups,respectively.The proliferation ability of all constructed resistant cells and non-resistant cells and the IC50 value of each drug were determined by CCK-8 assay.Cell cycle and apoptosis were detected by flow cytometry.Transwell assay was used to detect the invasion ability of cells.Mutations of EGFR exon 18,exon 19,exon20 and exon 21 were detected by gene sequencing.Western Blot was used to detect the expression of intracellular protein molecules.Transfection of highly expressed plasmids and small interfering RNA plasmids interfered with intracellular gene expression,demonstrating the role of IGF-1R/?-catenin signaling pathway in drug resistance.Results: Three resistant NSCLC cells was successfully constructed using A549,NCI-H1299,NCI-H1437 and NCI-H2126 NSCLC cell lines.Abnormal activation of IGF-1R/?-catenin signal pathway was found to be closely related to the enhancement of cell proliferation and invasion,increase of IC50,drug resistance,and change of cell cycle and apoptosis.In the meanwhile,the expressions of proteins in the IGF-1R/?-catenin signal pathway including P-IGF-1R,GSK-3?,P-GSK-3?,?-catenin and P-?-catenin showed an increasing trend with the increase of drug resistance,and the expression of P-EGFR proteinrelated to gefitinib was also affected.In order to further investigation,we up-regulated the expression of IGF-1R in non-resistant cell lines,which enhanced the proliferation,invasion and drug resistance of the cell lines,and also reduced the apoptosis accompanied by the increased expression of its downstream proteins including GSK-3?,P-GSK-3?,?-catenin and P-?-catenin.Proliferation rate of drug-resistant cells,and the expression of P-IGF-1R,P-GSK-3?,?-catenin and P-?-catenin proteins decreased by interferring the gene expression in the IGF-1R/?-catenin signal pathway in drug-resistant cells.Meanwhile,the drug resistance to gefitinib and cisplatin also decreased,among which cisplatin decreased more significantly.Above results showed that IGF-1R/?-catenin signaling pathway led to the failure of combination chemotherapy with gefitinib in NSCLC mainly caused by platinum resistance.Based on this phenomenon,we guessed that IGF-1R/?-catenin signaling pathway also led to resistance to other platinums.A549 cells which were resistant to cisplatin and paclitaxel were selected to be treated with other three platinum drugs commonly used in clinic with gradient concentrations,those were carboplatin,nedaplatin and oxaliplatin,showing cell survival,drug concentration-dependently increased expression of P-IGF-1R,P-GSK-3?,?-catenin and P-?-catenin proteins,which proved that the IGF-1R/?-catenin signal pathway was one of the main causes of platinum resistance.Conclusion:(1)The IGF-1R/ ?-catenin signal pathway is one of the main causes for resistance to chemotherapy combined with gefitinib in NSCLC;(2)The IGF-1R/ ?-catenin signal pathway is one of the main causes of platinum resistance.