Study on microRNA-9-5p reducing sensitivity of breast cancer cells to doxorubicin through targeting HIC1

Objective To study the effect of microRNA-9-5p (miR-9-5p) which regulate hypermethylated in cancer 1 (HIC1) in reducing sensitivity of breast cancer MDA-MB-231 cells to doxorubicin (DOX) and the mechanisms. Methods ①Up-regulation or down-regulation of miR-9-5p in cells was constructed by lentivirus transfection. Cell viability and apoptosis were detected with CCK-8 and flow cytometry after adding different concentrations of DOC. ②Expression of HIC1 was detected by reverse transcription-polymerase chain reaction and Western blotting when miRNA-9-5p was overexpressed or inhibited. The interaction between miR-9-5p and HIC1 was analyzed by database and luciferase assay. ③HIC1 was down-regulated to detect cell viability and apoptosis after adding different concentrations of DOX. Results ①Up-regulation of miR-9-5p increased cell viability, and reduced apoptosis. Down-regulation of miR-9-5p reduced cell viability and increased apoptosis. ②miR-9-5p directly targeted HIC1 and negative relationship of expression was pr