Objective: To investigate the expression of micro ribonucleic acid (miR)-219-5p in prostate cancer (PCa), its influences on the biological functions of PCa, and its mechanism.
Patients and methods: The expression differences of miR-219-5p and high mobility group protein A2 (HMGA2) in 30 pairs of PCa tissues and para-carcinoma tissues were detected via quantitative Real Time-Polymerase Chain Reaction (qRT-PCR), and the difference in miR-219-5p expression in PCa cell lines and normal prostatic epithelial cells was also determined via qRT-PCR. The human PC-3 cells were divided into negative control group and miR-219-5p overexpression group. Methyl thiazolyl tetrazolium (MTT) and colony formation assays were adopted to detect the cell proliferative ability, and flow cytometry was applied to determine the cell apoptosis. The expression of apoptosis-related proteins was measured via Western blotting, and the invasive and migratory abilities of the cells were examined through wound-healing and transwell assays. Bioinformatics prediction software and luciferase reporter assay were employed to verify the targets that might be controlled by miR-219-5p. Rescue experiment was conducted to clarify whether the inhibitory effects of miR-219-5p on the growth and metastasis of PC-3 cells depend on the inhibition of HMGA2.
Results: It was shown in qRT-PCR results that the expression level of miR-219-5p was downregulated remarkably in PCa tissues and cell lines, but overexpressed miR-219-5p could repress the proliferation and promote the apoptosis of PC-3 cells notably. The results of wound-healing and transwell assays indicated that overexpressed miR-219-5p was able to suppress the invasion and metastasis of PC-3 cells. According to Western blotting results, overexpressed miR-219-5p could up-regulate the expressions of pro-apoptotic proteins [Bax, cleaved-caspase-3 and cleaved-poly-ADP-ribose-polymerase (PARP)] and reverse the epithelial-mesenchymal transition (EMT) of PCa cells. It was predicted via the bioinformatics software that HMGA2 gene might be a target gene of miR-219-5p. The Dual-Luciferase reporter assay confirmed that there was a direct regulatory relationship between miR-219-5p and HMGA2. The rescue experiment manifested that overexpressed HMGA2 could reverse the inhibition of miR-219-5p on the growth and metastasis of PC-3 cells.
Conclusions: MiR-219-5p suppresses the growth and metastasis abilities of prostate cancer cells by directly repressing the expression of HMGA2.