Synergistic Inhibition of Thalidomide and Icotinib on Human Non-Small Cell Lung Carcinomas Through ERK and AKT Signaling.

Background: Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have been widely used in the treat- ment of non-small cell lung cancer (NSCLC) patients with sensitive EGFR mutations. However, the survival of patients with EGFR-TKI administration is limited by the inevitable development of acquired drug resistance. Recently, multi-targeted drugs combination has been shown to be a promising strategy to improve the efficacy of EGFR-TKI treatment and enable the reduction of drug resistance in NSCLC. Material/Methods: Humanized NSCLC cell lines PC9 and A549 were co-cultured with thalidomide and/or icotinib to test for anti- tumor efficiency. Cell proliferation was measured by MTT assay, cell apoptosis by flow cytometry 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-kappa B. The xenograft mouse model was used to explore the effects of thalidomide and icotinib in vivo. Immunohistochemical testing was used to determine the expression of Ki-67 and TUNEL staining in tumor tissues. Results: Treatments of thalidomide and/or icotinib reduced cell viability, induced apoptosis, and suppressed migration. Attenuation of pEGFR and pVEGF-R resulted in deactivation of ERK and AKT pathways, which eventually increased the anti-proliferative response. In PC9 xenograft model, combined administration of thalidomide and icotinib restrained tumor growth with remarkable reduced Ki-67 index and increased TUNEL positive cells. Conclusions: Thalidomide sensitizes icotinib to increase apoptosis and prevent migration, and it may be a potentially promising anti-tumor drug in lung cancer multi-modality therapy.