MiR-142-3p enhances chemosensitivity of breast cancer cells and inhibits autophagy by targeting HMGB1

MiR-142-3p has been reported to act as a tumor suppressor in breast cancer.However,the regulatory effect of miR-142-3p on drug resistance of breast cancer cells and its underlying mechanism remain unknown.Here,we found that miR-142-3p was significantly downregulated in the doxorubicin(DOX)-resistant MCF-7 cell line(MCF-7/DOX).MiR-142-3p overexpression increased DOX sensitivity and enhanced DOXinduced apoptosis in breast cancer cells.High-mobility group box 1(HMGB1) is a direct functional target of miR-142-3p in breast cancer cells and miR-142-3p negatively regulated HMGB1 expression.Moreover,overexpres sion of HMGB1 dramatically reversed the promotion of apoptosis and inhibition of autophagy mediated by miR-142-3p up-regulation.In conclusion,miR-142-3p overexpression may inhibit autophagy and promote the drug sensitivity of breast cancer cells to DOX by targeting HMGB 1.The miR-142-3 p/HMGB1 axis might be a novel target to regulate the drug resistance of breast cancer patients.