circFMN2 Sponges miR-1238 to Promote the Expression of LIM-Homeobox Gene 2 in Prostate Cancer Cells

Circular RNAs (circRNAs) regulate gene expression in different malignancies. However, the molecular mechanisms that link circRNAs with the tumorigenesis of prostate cancer (PCa) are not well understood. In the present study, we attempted to provide a novel basis for targeted therapy for PCa from the aspect of circRNA-microRNA (miRNA)-mRNA interaction. We investigated the expression of circRNAs in 5 paired PCa tissues and adjacent non-tumor tissues by microarray analysis. We focused on hsa_circ_0005100, which is located on chromosome 1 and derived from FMN2, and thus we named it circFMN2. The qRT-PCR was used to detect circFMN2 and target miRNA expression in PCa tissues and cell lines. Biological functional experiments were performed to detect the effects of circFMN2 on the biological behavior of PCa cells in vivo and in vitro. Bioinformatic analysis was utilized to predict potential miRNA target sites on circFMN2. High expression of circFMN2 was associated with PCa progression. Function assays revealed that knockdown of circFMN2 significantly reduced PCa cell growth in vitro and in vivo. Finally, we found that circFMN2 acts as a competing endogenous RNA (ceRNA) for miR-1238 to regulate LIM-homeobox gene 2 (LHX2) expression. circFMN2 regulates the miR-1238/LHX2 axis to promote PCa progression.