MicroRNA‑519a inhibits the proliferation and promotes the apoptosis of ovarian cancer cells through targeting signal transducer and activator of transcription 3

Ovarian cancer is a highly prevalent cancer among women. Recent studies have indicated that microRNAs (miRs) may serve important roles in the pathogenesis of ovarian cancer. miR‑519a was observed to be downregulated in tissue samples of patients with ovarian cancer; however, its role in ovarian cancer requires further investigation. The aim of the present study was to examine the role of miR‑519a in the pathogenesis of ovarian cancer and determine its direct target. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) was performed to examine the expression of miR‑519a in 20 patients ovarian cancer and 20 normal ovarian tissue samples. Subsequently, SKOV3 cells were cultured and transfected with miR‑519a mimics, while MTT and Annexin V assays were performed to investigate the role of miR‑519a in the proliferation and apoptosis of SKOV3 cells. In addition, RT‑qPCR and western blotting were used to determine the expression levels of miR‑519a, signal transducer and activator of transcription 3 (STAT3), myeloid cell leukemia 1 (Mcl‑1) and B‑cell lymphoma‑extra large (Bcl‑xl) in untransfected and miR‑519a mimic‑transfected SKOV3 cells. Dual‑luciferase reporter assay was also performed to confirm whether STAT3 was a direct target of miR‑519a. The results revealed that miR‑519a was significantly downregulated in tissue samples of patients with ovarian cancer as compared with the normal ovarian tissues. Furthermore, transient overexpression of miR‑519a inhibited the proliferation and promoted the apoptosis of SKOV3 cells, as well as decreased the mRNA and protein expression levels of STAT3, Mcl‑1 and Bcl‑xl. Finally, dual‑luciferase reporter assay confirmed that STAT3 was a direct target of miR‑519a. In conclusion, the present study proved for the first time that miR‑519a functions as a tumor suppressor by targeting STAT3 in ovarian cancer, suggesting that miR‑519a may be a potential biomarker for the diagnosis and treatment of ovarian cancer.