Long non-coding RNA UCA1 promotes glutamine metabolism by targeting miR-16 in human bladder cancer.

OBJECTIVE: Long non-coding ribonucleic acid urothelial carcinoma-associated 1 has been found to be a participant in cancer development and glucose metabolism in bladder cancer. However, the role of urothelial carcinoma-associated 1 in metabolic reprogramming in cancer remains to be clarified. In this study, we aim to elucidate the molecular mechanism underlying the regulation of glutamine metabolism by urothelial carcinoma-associated 1 in bladder cancer.

METHODS: The RNA levels of urothelial carcinoma-associated 1, GLS2 and miR-16 in bladder tissues and cell lines were examined by real-time reverse transcriptase-polymerase chain reaction. The protein levels of GLS2 were detected by western blot analysis. Reactive oxygen species generation was examined by the fluorescein isothiocyanate mean value and fluorescence microscope. Glutamine consumption was analyzed using the glutamine assay kit. Additionally, we performed luciferase reporter assays to validate urothelial carcinoma-associated 1 sequence whether contains miR-16 binding site and the interaction between the 3'UTR sequence of GLS2 and mature miR-16.

RESULTS: Real-time reverse transcriptase-polymerase chain reaction demonstrated that the RNA level of urothelial carcinoma-associated 1 and GLS2 was positively correlated in bladder cancer tissues and cell lines. The expression of GLS2 mRNA and protein increased in cells which overexpression of urothelial carcinoma-associated 1 and decreased in cells which knocked-down of urothelial carcinoma-associated 1 cell lines. urothelial carcinoma-associated 1 reduced ROS production, and promoted mitochondrial glutaminolysis in human bladder cancer cells. Furthermore, luciferase reporter assays indicated that there was a miR-16 binding site in urothelial carcinoma-associated 1, and it showed appreciable levels of sponge effects on miR-16 as readouts in a dose-dependent manner. Moreover, the 'seed region' of miR-16 directly bound to the 3'UTR of GLS2 mRNA and regulated GLS2 expression level.

CONCLUSIONS: Together, our results revealed that urothelial carcinoma-associated 1 regulated the expression of GLS2 through interfering with miR-16, and repressed ROS formation in bladder cancer cells.