MiR-145 affected the circular RNA expression in prostate cancer LNCaP cells

Recent evidence has demonstrated that circular RNAs (circRNAs) played crucial roles in fine-tuning the levels of gene expression by sequestering the corresponding microRNA (miRNAs). Their interaction with disease-associated miRNAs indicates that circRNAs are important for the development of disease, and miR-145 has been previously shown to have antitumor effect in prostate cancer. In the current study, we successfully established the miR-145-overexpressed prostate cancer LNCaP cells (LNCaP-miR-145) using lentiviral vectors. LNCaP cells expressing the empty vector (LNCaP-NC) were used as the negative control. The circRNA expression in LNCaP-miR-145 cells was detected by microarray analysis, and the miRNA targets of circRNAs were predicted using the bioinformatics software TargetScan and miRanda. Quantitative reverse transcription polymerase chain reaction was used to detect the expression levels of circRNAs in the prostate cancer tissue, nonmalignant tissue, LNCaP-miR-145 cells, and LNCaP-NC cells. The interaction of miRNA and circRNA was further confirmed by the dual-luciferase reporter assay. A total of 267 and 149 circRNAs were significantly up- and downregulated in LNCaP-miR-145 cells, respectively. hsa_circRNA_101981, hsa_circRNA_101996 and hsa_circRNA_09142 were the 3 circRNAs that interacted with hsa-miR-145-5p; hsa_circRNA_008068 and hsa_circRNA_406557 were the 2 circRNAs that interacted with hsa-miR-145-3p. Most of the circRNAs corresponded to the protein-coding exons. The expression levels of hsa_circRNA_101981, hsa_circRNA_00806, and hsa_circRNA_406557 were upregulated in the LNCaP-miR-145 cells, but downregulated in the prostate cancer tissue. In contrast, the expression levels of hsa_circRNA_101996 and hsa_circRNA_091420 were downregulated in the LNCaP-miR-145 cells, but upregulated in the prostate cancer tissue. Moreover, miR-145-5P might regulate the expression of hsa_circRNA_101981, hsa_circRNA_101996, and hsa_circRNA_09142, while miR-145-3P might regulate the expression of hsa_circRNA_008068 and hsa_circRNA_406557. Overexpression of miR-145 promoted the expression of hsa_circRNA_101981, hsa_circRNA_008068, and hsa_circRNA_406557 but suppressed the expressions of hsa_circRNA_101996 and hsa_circRNA_091420 in LNCaP cells. The results from the current study should give us a clue to clarify the tumor suppressive effect of miR-145.