MicroRNA‑96 promotes the proliferation and migration of breast cancer cells by inhibiting Smad7 expression

The present study aimed to investigate the effects of microRNA (miR)-96 on the proliferation and migration of breast cancer cells, and indicated that miR-96 may have a promoting role in breast cancer by inhibiting Smad7. Reverse transcription-quantitative (RT-q)PCR was used to detect the expression levels of miR-96 and Smad7 in breast cancer tissues and adjacent tissues. Western blotting and immunohistochemistry were conducted to determine the expression levels of SMAD7 in breast cancer and adjacent tissues. A dual luciferase assay was performed to verify the targeted binding between miR-96 and Smad7. Furthermore, the different expression patterns of miR-96 and Smad7 were compared in various breast cancer cell lines using RT-qPCR and western blotting. Among these cell lines, MDA-MB-231, which exhibited the highest expression of miR-96, was chosen for subsequent functional verification. The expression levels of miR-96 were significantly higher in breast cancer tissues compared with those in adjacent tissues. By contrast, the expression levels of Smad7 were significantly lower in breast cancer tissues compared with those in adjacent tissues. The dual luciferase assay revealed a targeted binding effect between miR-96 and Smad7. Notably, transfection with miR-96-5p mimics and short hairpin RNA-Smad7 markedly promoted the proliferation, adhesion, invasion and migration of breast cancer cells. Conversely, transfection with a miR-96-5p inhibitor and Smad7 overexpression plasmid exhibited the opposite trend. In conclusion, the expression levels of miR-96 were significantly elevated in breast cancer tissues compared with those in adjacent tissues. Overexpression of miR-96 was shown to promote the migration of breast cancer cells by downregulating the expression of Smad7. These findings indicated that miR-96 may serve as a prognostic marker for breast cancer.