Combining Thalidomide With EGFR Tyrosine Kinase Inhibitors Synergistically Inhibits NSCLC Cells In Vitro And In Vivo

Background and purpose: Epidermal growth factor receptor tyrosine kinase inhibitors(EGFR-TKIs)have been widely used for therapy of NSCLC patients carrying sensitive EGFR mutations.EGFR-TKIs reduced the spontaneous phosphorylation of NSCLC-EGFR mutants thus improved the prognos is of NSCLC patients.However,the survival benefits of patients receiving EGFR-TKI monotherapy is limited by the inevitable development of acquired drug resistance.Recently,discovery of multi-targeted drug combinations is a promising strategy to improve EGFR-TKI treatment efficacy and enable the reduction of drug resistance.This study explored the impact of thalidomide in combination with EGFR-TKI icotinib on the growth of NSCLC cells and xenograft tumor.Material and methods: Humanized NSCLC cell lines,PC9 and A549,were co-cultured with thalidomide and/or icotinib to test the anti-tumor efficiency.Cell proliferation was measured by MTT assay,cell apoptosis by flow cytometry(FCM)and cell migration by wound healing assay.Western blot was performed to determine the expression of Caspase-3,-8,-9,Bax,EGFR,VEGF-R,AKT,ERK,MMP2,MMP9 and NF-κB.The xenograft mouse model was used to explore the in vivo anti-cancer effects of thalidomide and icotinib.Immunohistochemical method was used to determine the expression of Ki-67 and TUNEL positive cel s in tumor tissue section.Results: Cell viability was significantly reduced by combined treatment of thalidomide with icotinib than single-drug intervention respectively convinced by CI index analysis,better effect in PC9 than A549.Treatments of thalidomide and/or icotinib induced apoptosis accompanied by the increases of cleaved caspase-3,-8,-9 and Bax,and suppressed migration through down-regulation of NF-κB,MMP2 and MMP9.The combination effects of thalidomide sensitizing icotinib by down-regulation of phosphorylated EGFR and VEGF-R expression were observed.Dephosphorylation of signal transduction resulted in the forming activation of ERK and AKT and rendered increased anti-proliferative response.In PC9 xenograft model,comb ined administration of thalidomide and icotinib restrained tumor growth with remarkable reduced K i-67 index and increased TUNEL positive cel s.Conclusions: Thalidomide sensitizes the curative effect of EGFR targeting drug icotinib to lung tumor cells.Thalidomide may be a potentially promising anti-tumor drug in lung cancer multimodality therapy.