Abstract
BACKGROUND Drug resistance is a major problem in the treatment of leukemia with doxorubicin (Dox), and the erythroblastosis virus E26 oncogene homolog 1 (ETS1) gene is associated with drug resistance. Olmutinib is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) reported to play a role in reversing multidrug resistance (MDR) in cancer cells. The objective of this study was to investigate whether olmutinib could reverse Dox resistance in leukemia cells overexpressing ETS1. MATERIAL AND METHODS Human chronic myelogenous leukemia cell line K562 and its Dox-resistant cell line K562/ADR were used. Western blot and qPCR detected the expression of ETS1 and ABCB1. Cell proliferation was measured by cell counting kit-8 and methyl thiazolyl tetrazolium. Cell apoptosis was observed by western blot and flow cytometry. A nude mice K562/ADR xenograft model was used to investigate the inhibitory effects of olmutinib on tumor growth in vivo. RESULTS The mRNA and protein expressions of ETS1 and ABCB1 were up-regulated in Dox-resistant leukemia cell line K562/ADR. We overexpressed ETS1 in both cell lines, finding that olmutinib inhibited the cell viability of K562 and K562/ADR in a concentration-dependent manner. The cytotoxicity of Dox to EST1-overexpressing K562/ADR cells was enhanced by olmutinib. Olmutinib also promoted apoptosis of K562 and K562/ADR cells compared with Dox treatment alone. In vivo, olmutinib enhanced the inhibitory effects of Dox on ETS1-overexpressing K562/ADR cell xenograft growth. CONCLUSIONS Our results suggest that the novel EGFR TKI olmutinib enhances the sensitivity of ETS1-overexpressing leukemia cells to Dox.