Abstract
Prostate cancer is one of the most common malignant tumors in men. Patients with local infiltration and distant metastasis often have a poor prognosis. The present study aimed to investigate the expression and regulatory mechanism of the circular RNA cerebellar degeneration-related protein 1, anti-sense (circCDR1as) in prostate cancer cell lines. MicroRNAs (miRNAs) regulated by circCDR1as and target genes regulated by miRNAs were predicted using bioinformatics software. Prostate cancer cell lines (LNCaP, 22Rv1 and PC-3), a normal prostate epithelial cell line (RWPE-1) and a human embryonic kidney cell line (293T) were cultured. Relative gene expression was detected using reverse transcription PCR. Small interfering RNAs (siRNAs) targeting circCDR1as and X-linked inhibitor of apoptosis protein (XIAP) and miRNA mimics were designed and transfected into the cell lines using Lipofectamine® 3000. Cell invasion was determined using a Transwell assay, the cell proliferation rate was detected using an MTT assay and cell migration was examined using a scratch assay. Relative protein expression was detected using western blotting. Double fluorescent reporter gene vectors and an anti-Ago2 RNA-binding protein immunoprecipitation assay were used to verify binding. Bioinformatics analyses indicated that there was a binding site between miR-641 and circCDR1as and between miR-641 and XIAP. The expression of circCDR1as and XIAP was higher and the expression of miR-641 was lower in the prostate cancer cell lines compared with the normal prostate epithelial cell line. After effectively reducing the expression of circCDR1as and XIAP and increasing the expression of miR-641 in PC-3 cells, the proliferation, invasion and migration of PC-3 cells were effectively inhibited. circCDR1as could bind to miR-641, which targeted the 3'-untranslated region of XIAP. Reducing the expression of circCDR1 promoted the expression of miR-641 and inhibited the expression of XIAP. Overall, the circCDR1as/miR-641/XIAP regulatory axis plays a role in the invasion and migration of the prostate cancer PC-3 cell line.