EYA4 reduces chemosensitivity of osteosarcoma to doxorubicin through DNA damage repair.

Previous studies have demonstrated that Eyes Absent 4 (EYA4) influences the proliferation and migration of tumor cells. Notably, studies have established that EYA4 can also limit tumor sensitivity to chemotherapeutic agents. The objective of this study was to investigate the effect of EYA4 in conferring drug resistance in osteosarcoma (OS). Bioinformatics, histological, and cellular analyses revealed that the expression level of EYA4 was higher in OS tissues than in healthy tissues/cells and in resistant tissues/cells compared with sensitive tissues/cells. In vitro and in vivo experiments demonstrated that EYA4 knockdown increased the sensitivity of OS to doxorubicin (DOX). Conversely, overexpression of EYA4 decreased the sensitivity of OS to DOX. Exploration of the resistance mechanism exposed that EYA4 facilitates DNA double-strand break (DSB) repair, a typical mode of DNA damage repair (DDR). Subsequently, our findings indicated that EYA4 could directly interact with histone H2AX to activate the DDR pathway. Taken together, our observations indicated that EYA4 may serve as a target molecule for reversing drug resistance in OS patients.