MicroRNA­16­5p/BIMP1/NF­κB axis regulates autophagy to exert a tumor­suppressive effect on bladder cancer.

ABSTRACT

Bladder cancer (BC) is the second most common urological disease worldwide. Previous studies have reported that microRNA (miR)­16­5p is associated with the development of BC, but whether miR­16­5p regulates BC cell autophagy remains unknown. Thus, the aim of the present study was to investigate this issue. miR­16­5p expression in BC cells was assessed by reverse transcription­quantitative PCR. Cell viability and apoptosis were detected via Cell Counting Kit­8 and flow cytometry assays, respectively. For cell autophagy detection, autophagic flux was detected using a mCherry­green fluorescent protein­microtubule­associated proteins 1A/1B light chain 3B (LC3) puncta formation assay, followed by determination of autophagy­related protein markers. The targeting relationship between miR­16­5p and caspase recruitment domain family member 10 (BIMP1) was confirmed using a dual­luciferase reporter assay, followed by detection of the BIMP1/NF­κB signaling pathway. The results showed that miR­16­5p overexpression inhibited cell viability, whereas miR­16­5p knockdown promoted cell viability in BC. Furthermore, miR­16­5p overexpression induced autophagy, which was accompanied by increased autophagic flux and expression of the autophagy­related proteins LC3­II and beclin 1, as well as decreased p62 expression, whereas miR­16­5p silencing led to an inhibition of autophagy in BC cells. Moreover, autophagy inhibitor 3­methyladenine treatment inhibited cell autophagy and apoptosis in miR­16­5p­overexpressing cells. Mechanistic studies demonstrated that miR­16­5p could inhibit the BIMP1/NF­κB signaling pathway and this inhibition was achieved by directly targeting BIMP1. Furthermore, it was found that blockade of the BIMP1/NF­κB signaling pathway inversed the inhibitory effects of miR­16­5p knockdown on autophagy in BC cells. In vivo experiments further verified the tumor­suppressive effect on BC of the miR­16­5p/BIMP1/NF­κB axis. Therefore, the results of the present study indicated that miR­16­5p promotes autophagy of BC cells via the BIMP1/NF­κB signaling pathway, and an improved understanding of miR­16­5p function may provide therapeutic targets for clinical intervention in this disease.