PURPOSE: Hepatocyte growth factor (HGF) induces resistance to reversible and irreversible epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) in EGFR mutant lung cancer cells by activating Met and the downstream phosphoinositide 3-kinase (PI3K)/Akt pathway. Moreover, continuous exposure to HGF accelerates the emergence of EGFR-TKI-resistant clones. We examined whether norcantharidin (NCTD), a demethylated analog of cantharidin, could reverse HGF-induced resistance to EGFR-TKIs in mutant lung cancer cells PC-9 and HCC827. METHODS: MTT assay was used to evaluate cell proliferation of NCTD on PC-9 and HCC827 cells in vitro. Western blotting assays were used to determine the expression of EGFR, p-EGFR (Thr 669), MET, p-MET, AKT, p-AKT (Ser473), PI3kp85, or p-PI3k p85. HGF concentrations were measured by ELISA. HGF-producing cells and PC-9/HGF were established by recombinant adenovirus vectors Ad-GFP-HGF. Xenograft model in SCID mice was used to test the regressive effect of tumor growth on PC-9 cells in vivo. RESULTS: NCTD could reverse resistance to EGFR-TKIs induced by exogenous and endogenous HGF in EGFR mutant lung cancer cells via inhibiting the Met/PI3K/Akt pathway. These results suggested that NCTD may be a promising candidate for developing preventive agents against EGFR-TKIs acquired resistance in NSCLC. In the in vivo model, NCTD plus gefitinib resulted in marked regression of tumor growth associated with inhibition of Akt phosphorylation in cancer cells. CONCLUSIONS: NCTD may be a promising candidate for developing preventive agents against EGFR-TKIs acquired resistance in NSCLC.
PURPOSE:Hepatocyte growth factor (HGF) induces resistance to reversible and irreversible epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) in EGFR mutant lung cancer cells by activating Met and the downstream phosphoinositide 3-kinase (PI3K)/Akt pathway. Moreover, continuous exposure to HGF accelerates the emergence of EGFR-TKI-resistant clones. We examined whether norcantharidin (NCTD), a demethylated analog of cantharidin, could reverse HGF-induced resistance to EGFR-TKIs in mutant lung cancer cells PC-9 and HCC827. METHODS:MTT assay was used to evaluate cell proliferation of NCTD on PC-9 and HCC827 cells in vitro. Western blotting assays were used to determine the expression of EGFR, p-EGFR (Thr 669), MET, p-MET, AKT, p-AKT (Ser473), PI3kp85, or p-PI3k p85. HGF concentrations were measured by ELISA. HGF-producing cells and PC-9/HGF were established by recombinant adenovirus vectors Ad-GFP-HGF. Xenograft model in SCIDmice was used to test the regressive effect of tumor growth on PC-9 cells in vivo. RESULTS: NCTD could reverse resistance to EGFR-TKIs induced by exogenous and endogenous HGF in EGFR mutant lung cancer cells via inhibiting the Met/PI3K/Akt pathway. These results suggested that NCTD may be a promising candidate for developing preventive agents against EGFR-TKIs acquired resistance in NSCLC. In the in vivo model, NCTD plus gefitinib resulted in marked regression of tumor growth associated with inhibition of Akt phosphorylation in cancer cells. CONCLUSIONS: NCTD may be a promising candidate for developing preventive agents against EGFR-TKIs acquired resistance in NSCLC.