MiR-512-3p expression pattern and function in breast cancer / 中国肿瘤临床

ABSTRACT

Objective:This study aims to investigate the expression pattern of miR-512-3p in breast cancer and noncancerous paired specimens as well as the effects of miR-512-3p on the proliferation, apoptosis, cell cycle, and cloning of MD-MBA-231 breast cancer cells. The study also aims to identify the miR-512-3p target gene. Methods:Reverse transcription-polymerase chain reaction (RT-PCR) was conducted to quantify the miR-512-3p expression in breast cancer and noncancerous paired specimens. Methylthiazol tetrazolium (MTT) assay, flow cytometry, and clone formation assay were used to characterize the function of miR-512-3p in breast cancer. Target prediction was performed using the TargetScan, PicTar, and miRanda software. The results were validated using RT-PCR and western blot target validation. Results:The relative expression of miR-512-3p in breast cancer specimens was significantly lower than those in normal breast specimens (P<0.05). MTT assay revealed that 48 h after transfection, miR-512-3p significantly repressed the proliferation of MD-MBA-231 cells at a suppression rate of 45.38%and at a concentration of 100 nmol/L. MiR-512-3p increased the percentage of early apoptotic cells in the treatment groups (9.32 ± 0.41)%compared with those in the blank controls (3.1 ± 0.54)%and in the negative controls (2.9 ± 0.39)%(P<0.05). Significant differences were found in the percentages of the G0/G1-and G2/M-phase cells after miR-512-3p transfection compared with those in the controls (P<0.05). In the cloning assay, clone formation was inhibited in the miR-512-3p-transfected groups compared with those in the control groups. RT-PCR and western blot results indicate that miR-512-3p significantly inhibited the c-FLIP mRNA and protein expression. Conclusion:MiR-512-3p expression is relatively decreased in breast cancer specimens compared with those in the normal samples. The negative effect of miR-512-3p on cell proliferation and clone formation and its positive effect on early apoptosis through c-FLIP targeting suggest that miR-512-3p acts as a tumor suppressor gene in breast cancer. Therefore, miR-512-3p may be a new target for the diagnosis and treatment of breast cancer in the future.