RETRACTED: MicroRNA-136 inhibits prostate cancer cell proliferation and invasion by directly targeting mitogen-activated protein kinase kinase 4 (Retracted article. See vol. 27, 2023)

Prostate cancer (PCa) is the second most common type of cancer and the 6th leading cause of cancer-associated mortality worldwide. Accumulated evidence suggests that PCa initiation and progression are controlled by microRNAs (miRNAs). Therefore, investigating PCa-associated miRNAs may provide novel biomarkers for the diagnosis and treatment of patients with PCa. In the present study it was demonstrated that miRNA-136 (miR-136) expression was significantly downregulated in PCa tissues and cell lines. The resumption of miR-136 expression suppressed cell proliferation and invasion in PCa cells. Bioinformatics analysis predicted that mitogen-activated protein kinase kinase 4 (MAP2K4) was a direct target of miR-136. This prediction was experimentally confirmed by a luciferase reporter assay, RT-qPCR and western blot analysis. MAP2K4 was highly expressed in PCa tissues and inversely correlated with the miR-136 expression level. Additionally, the restoration of MAP2K4 expression significantly blocked the inhibitory effects of miR-136 on cell proliferation and invasion in PCa cells. Therefore, miR-136 may suppress the proliferation and invasion of PCa cells by targeting MAP2K4 and may be a novel candidate target for cancer therapy against PCa.