miRNA-182-5p promotes human bladder cancer proliferation and migration through the FOXF2/SHH axis

Increasing evidence suggests that microRNAs (miRNAs) play critical roles in bladder tumorigenesis and development by combining with the 3' untranslated regions (3'-UTRs) of the corresponding mRNAs to negatively regulate gene expression. The role of miR-182-5p in bladder cancer (BC) remains unclear. Therefore, this study aimed to clarify the functional role of miR-182-5p in BC. We predicted candidate mRNAs for miR-182-5p via three databases (TarBase, ENCORI, and miRDB). Dual-luciferase reporter assays and target prediction confirmed FOXF2 as a potential target of miR-182-5p. Quantitative RT-PCR (qRT-PCR) showed that endogenous miR-182-5p expression was significantly upregulated in BC cell lines and clinical samples of BC patients. IHC, western blotting, and qRT-PCR assays indicated that FOXF2 expression was concurrently downregulated in BC tissues and BC cell lines. Gain- and loss-of-function studies showed that the overexpression of miR-182-5p enhanced the proliferation and migration of BC cells, while the downregulation of miR-182-5p showed the opposite results. The effects induced by miR-182-5p were attenuated with the restoration of FOXF2 expression. In BC cells, the upregulation of miR-182-5p not only decreased FOXF2 expression but also markedly increased Sonic hedgehog (SHH) pathway levels. These findings suggested that FOXF2 directly binds to miR-182-5p and that miR-182-5p acts as a tumor promoter in BC genesis and metastasis by targeting FOXF2. In addition, miR-182-5p plays a pro-cancer role by downregulating FOXF2 and activating the SHH pathway.