Olmutinib Reverses Doxorubicin Resistance in ETS1-Overexpressing Leukemia Cells

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/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.