RESUMO
Aim To establish gefitinib resistant epidermal growth factor receptor(EGFR) mutant lung cancer cell lines and to explore the changes of downstream signaling pathway of EGFR. Methods Gefitinib concentration gradient method was used to induce the establishment of H3255 and HCC827 resistant cell lines, and CCK8 assay was used to detect the proliferation of gefitinib resistant cell lines H3255/GR and HCC827/ GR. Western blot was used to detect the changes of EGFR downstream signals in H3255, HCC827, H3255/GR and HCC827/GR cells. Results The proliferation of H3255/GR and HCC827/GR cells was significantly lower than that of non-drug resistant cells. The phosphorylation signal molecules p-AKT, p-ERK1/2 and p-STAT3 of H3255/GR and HCC827/ GR drug-resistant cell lines were no significantly changed compared with their non-drug-resistant cell lines. There was no significant change in the expression of p-STAT3 and p-ERKl/2 in H3255/GR cells treated with gefitinib, but the expression of p-AKT was significantly down-regulated, while gefitinib only slightly inhibited the expression of p-ERKl/2 in drugresistant H3255/GR cells. In HCC827/GR cells, p-AKT and p-STAT3 were not inhibited by gefitinib, while p-ERKl/2 was moderately inhibited. Conclusion There are significant differences in the signal mechanism of drug resistance between H3255/GR and HCC827/GR cell lines.