Up-regulation of miR-124 inhibits invasion and proliferation of prostate cancer cells through mediating JAK-STAT3 signaling pathway

Z. Wu, W. Huang, B. Chen, P.-D. Bai, X.-G. Wang, J.-C. Xing

Department of Urology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, China. jinchunxingssb@163.com

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• Oncology

OBJECTIVE: Signal transducer and activator of transcription 3 (STAT3) is an important protein in Janus kinase (JAK)-STAT signaling pathway, and can facilitate expression of Bcl-2 and Cyclin D1 gene, thus playing a role in tumor pathogenesis. Bioinformatics analysis revealed targeted binding sites between mircroRNA-124 (miR-124) and 3’-UTR of STAT3 mRNA. This study aims to investigate the role of miR-124 in regulating STAT3 expression and proliferation, cycle, apoptosis and invasion of prostate cancer cells.

MATERIALS AND METHODS: Dual luciferase reporter gene assay demonstrated targeted correlation between miR-124 and STAT3. Expression of miR-124, STAT3, p-STAT3, Bcl-2 and Cyclin D1 was compared between normal human prostate epithelial cell RWPE-1 and prostate cancer cell DU145. In vitro cultured DU145 cells were treated with miR-124 mimic and/or si-STAT3, to compare expression of STAT3, phosphorylated STAT3 (p-STAT3), B-cell lymphoma-2 (Bcl-2) and Cyclin D1. Flow cytometry detected cell apoptosis and cycle, followed by clonal formation and transwell assay to test malignant proliferation and cell invasion.

RESULTS: Targeted regulation existed between miR-124 and STAT3. Comparing to RWPE-1, DU145 cells had lower miR-124 expression, G0/G1 phase ratio, or cell apoptosis, plus higher expression of STAT3, p-STAT3, Bcl-2 and Cyclin D1, ratio of S or G2/M phase. Transfection of miR-124 mimic and/or si-STAT3 remarkably decreased gene expression, weakened clonal formation, cell invasion, ratio of S and G2/M phase, cell apoptosis and increased G0/G1 ratio.

CONCLUSIONS: MiR-124 up-regulation significantly suppresses STAT3, pSTAT3 and downstream Bcl-2 and Cyclin D1 expression, weakens cell invasion or malignant proliferation potency, induces G0/G1 phase arrest, and facilitates cell apoptosis.

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