miR-5195-3p Inhibits Proliferation and Invasion of Human Bladder Cancer Cells by Directly Targeting Oncogene KLF5.

miRNAs play a key role in the carcinogenesis of many cancers, including bladder cancer. In the current study, the role of miR-5195-3p, a quite recently discovered and poorly studied miRNA, in the proliferation and invasion of human bladder cancer cells was investigated. Our data displayed that, compared with healthy volunteers (control) and SU-HUC-1 normal human bladder epithelial cells, miR-5195-3p was sharply downregulated in bladder cancer patients and five human bladder cancer cell lines. The oligo miR-5195-3p mimic or miR-5195-3p antagomir was subsequently transfected into both T24 and BIU-87 bladder cancer cell lines. The miR-5195-3p mimic robustly increased the miR-5195-3p expression level and distinctly reduced the proliferation and invasion of T24 and BIU-87 cells. In contrast, the miR-5195-3p antagomir had an opposite effect on miR-5195-3p expression, cell proliferation, and invasion. Our data from bioinformatic and luciferase reporter gene assays identified that miR-5195-3p targeted the mRNA 3'-UTR of Krüppel-like factor 5 (KLF5), which is a proven proto-oncogene in bladder cancer. miR-5195-3p sharply reduced KLF5 expression and suppressed the expression or activation of its several downstream genes that are kinases improving cell survival or promoting cell cycle regulators, including ERK1/2, VEGFA, and cyclin D1. In conclusion, miR-5195-3p suppressed proliferation and invasion of human bladder cancer cells via suppression of KLF5.