ABSTRACT
AIM:To investigate the effect of microRNA ( miR)-193b on doxorubicin therapy in breast cancer in vitro.METHODS:miR-193b level in plasma was detected by real-time PCR in the patients with breast cancer or the healthy controls.MTT assay was performed to measure the inhibitory effect of miR-193b plus doxorubicin on the growth of MDA-MB-231 cells.Bioinformatics, real-time PCR and Western blot were performed to determine whether the expression of Mcl-1 was regulated by miR-193b.Mcl-1 expression vector was constructed , and the role of Mcl-1 vector toward miR-193b plus doxorubicin-induced cytotoxicity in MDA-MB-231 cells was observed by MTT assay .RESULTS:Down-regulation of miR-193b was found in breast cancer patients .The miR-193b plus doxorubicin group showed a higher growth inhibition than cisplation group in MDA-MB-231 cells.The expression of Mcl-1 at both mRNA and protein levels was down-regulated after miR-193b transfection.The growth inhibition of MDA-MB-231 cells treated with miR-193b plus doxorubicin was sig-nificantly decreased after the transfection of Mcl-1 expression vector.CONCLUSION: miR-193b sensitizes doxorubicin-induced cytotoxicity by targeting Mcl-1 in breast cancer .