Abstract
A total of 60 breast cancer (BC) tissues and adjacent healthy tissues from patients who underwent surgery in Renmin Hospital of Wuhan University were collected for analysis in the present study. Results from reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) demonstrated that, compared with the adjacent healthy tissues, the expression levels of microRNA (miR)‑142‑5p were significantly elevated in BC tissues. Bioinformatics analysis was performed using TargetScan for the prediction of potential target sites that matched the seed region of miR‑142‑5p; phosphatase and tensin homolog (PTEN) exhibited the highest score and was selected for further analysis. Results of RT‑qPCR analysis demonstrated that, compared with the adjacent healthy tissues, the mRNA expression levels of PTEN were significantly decreased in breast cancer tissues. miR‑142‑5p and PTEN expression levels were positively and negatively associated, respectively, with patient tumor size and metastasis. MDA‑MB‑231 cells were divided into three groups including the Control group, the miR‑NC inhibitor group and the miR‑142‑5p inhibitor group. As for alterations in cell behavior, including cell viability and cell apoptosis, and protein expression levels, there were no significant differences between Control and miR‑NC inhibitor groups. MTT assay results revealed that, compared with Control and miR‑NC inhibitor groups, miR‑142‑5p inhibitor reduced MDA‑MB‑231 cell proliferation. Flow cytometric analysis demonstrated that, compared with Control and miR‑NC inhibitor groups, miR‑142‑5p inhibitor treatment induced MDA‑MB‑231 cell apoptosis. Western blotting results demonstrated that, compared with Control and miR‑NC inhibitor groups, miR‑142‑5p inhibitor treatment significantly increased the expression of PTEN, reduced the activation of phosphatidylinositol‑4,5‑bisphosphate 3‑kinase/RACα serine/threonine‑protein kinase signaling. Finally, PTEN was demonstrated to interact with miR‑142‑5p from the results of dual‑luciferase reporter assay in the present study. The findings of the present study suggested that miR‑142‑5p may be a potential therapeutic target for the future investigations and insights for breast cancer.