MiR-34a affects G2 arrest in prostate cancer PC3 cells via Wnt pathway and inhibits cell growth and migration

OBJECTIVE To investigate the effect and mechanism of miRNA-34a overexpression on proliferation and migration of PC3 prostate cancer cells. PATIENTS AND METHODS Benign prostatic hyperplasia tissue (30 cases), prostate cancer tissue (30 cases), and prostate paracancerous tissue (30 cases) were collected. Levels of miRNA-34a in these fresh tissues were measured by fluorescence quantitative PCR. PC3 cells were divided into non-loaded group and overexpression group. Cells in the non-loaded group were transfected with non-loaded plasmid. Cells in the overexpression group were transfected with miRNA-34a plasmid, and the miRNA-34a level was determined by fluorescence quantitative PCR to confirm the overexpression. Cell proliferation was analyzed by CCK-8 assay. Cell migration rate was measured by cell scratch assay. Flow cytometry was used to detect apoptosis and analyze cell cycle. Western blot was used to measure the expression levels of β-catenin, E-cadherin and Vimentin. RESULTS The expression level of miRNA-34a in prostate cancer tissue was significantly lower than that in prostate paracancerous tissue. Dual-Luciferase reporter gene assay was used to analyze the transcriptional activity of Wnt1 gene. The proliferation and migration of PC3 cells were significantly decreased after overexpression of miRNA-34a, and the differences were statistically significant compared with those in the non-loaded group (p<0.05). Flow cytometry analysis showed that in the overexpression group, the apoptotic rate, as well as the proportion of cells in the G2 phase, was significantly higher than that in the non-loaded group (p<0.05). The β-catenin level in the nucleus of PC3 cells was significantly reduced after overexpression of miRNA-34a. The total protein levels of β-catenin and Vimentin were significantly decreased, whereas the level of E-cadherin in the overexpression group was apparently increased, compared with that in the non-loaded group. The Dual-Luciferase reporter gene showed a decrease in the relative fluorescence intensity of Wnt1 after overexpression of miR-34a (p<0.05). CONCLUSIONS Overexpression of miRNA-34a inhibits Wnt/β-catenin pathway by regulating the transcriptional activity of Wnt1, thereby regulating the proliferation and migration of PC3 cells and promoting apoptosis.