MicroRNA‑16‑5p/BIMP1/NF‑κB axis regulates autophagy to exert a tumor‑suppressive effect on bladder cancer.

Abstract

Bladder cancer (BC) is the second most common urological disease worldwide. Previous studies have reported that microRNA (miR)-16-5p is associated with the development of BC, but whether miR-16-5p regulates BC cell autophagy remains unknown. Thus, the aim of the present study was to investigate this issue. miR-16-5p expression in BC cells was assessed by reverse transcription-quantitative PCR. Cell viability and apoptosis were detected via Cell Counting Kit-8 and flow cytometry assays, respectively. For cell autophagy detection, autophagic flux was detected using a mCherry-green fluorescent protein-microtubule-associated proteins 1A/1B light chain 3B (LC3) puncta formation assay, followed by determination of autophagy-related protein markers. The targeting relationship between miR-16-5p and caspase recruitment domain family member 10 (BIMP1) was confirmed using a dual-luciferase reporter assay, followed by detection of the BIMP1/NF-κB signaling pathway. The results showed that miR-16-5p overexpression inhibited cell viability, whereas miR-16-5p knockdown promoted cell viability in BC. Furthermore, miR-16-5p overexpression induced autophagy, which was accompanied by increased autophagic flux and expression of the autophagy-related proteins LC3-II and beclin 1, as well as decreased p62 expression, whereas miR-16-5p silencing led to an inhibition of autophagy in BC cells. Moreover, autophagy inhibitor 3-methyladenine treatment inhibited cell autophagy and apoptosis in miR-16-5p-overexpressing cells. Mechanistic studies demonstrated that miR-16-5p could inhibit the BIMP1/NF-κB signaling pathway and this inhibition was achieved by directly targeting BIMP1. Furthermore, it was found that blockade of the BIMP1/NF-κB signaling pathway inversed the inhibitory effects of miR-16-5p knockdown on autophagy in BC cells. In vivo experiments further verified the tumor-suppressive effect on BC of the miR-16-5p/BIMP1/NF-κB axis. Therefore, the results of the present study indicated that miR-16-5p promotes autophagy of BC cells via the BIMP1/NF-κB signaling pathway, and an improved understanding of miR-16-5p function may provide therapeutic targets for clinical intervention in this disease.