ABSTRACT
Objective Establishment of an osimertinib-resistant PC-9/ZDOR cell line of human non-small cell lung cancer (NSCLC) , and exploration of its drug resistance mechanisms and the sensitivity of themotherapeutic drugs. Methods An osimertinib-resistant PC-9/ZDOR cell line was induced by increasing doses of osimertinib to gefitinib-resistant cells PC-9/ZD. Mutation analysis of EGFR genes was performed by NGS. Cell growth was measured by CCK-8 assay and the sensitivity of chemotherapy was determined via analysis of resistance index (RI).The expression of EGFR and its signal transduction protein was determined by western blot. Results (1) An osimertinib-resistant human NSCLC cell line PC-9/ZDOR was successfully established with resistance index of 44. (2) The evidence from NGS data showed the mutation and amplification of EGFR was eliminated in PC-9/ZDOR cells. (3) The data from Western blot showed that the expression of EGFR and its phosphorylated form protein such as P-AKT and P-ERK was significantly decreased in PC-9/ZDOR cells when compared with those in PC-9/ZD cells (P <0.05). (4) The sensitivity of PC-9/ZDOR cell lines to docetaxel, gemcitabine and paclitaxel was significantly higher than that of PC-9/ZD cell lines (P < 0.05) , while the sensitivity of PC-9/ZDOR cell lines to cisplatin and pemetrexed was similar to the one of PC-9/ZD cell lines (P> 0.05). Conclusions The PC-9/ZDOR cell lines is an osimertinibresistant human NSCLC cell line. Elimination of EGFR gene mutation and/or the decrease of protein expressions of EGFR, p-EGFR, p-ERK and p-AKT maybe serve as the mechanisms of acquired resistance to osimertinib. This osimertinib-resistant cell line, PC-9/ZDOR, showed a elevated level of sensitivity to taxanes and gemcitabine.