N­Myc downstream­regulated gene 2 suppresses the proliferation of T24 human bladder cancer cells via induction of oncosis.

Previous studies have reported the antitumor activity of N­Myc downstream­regulated gene 2 (NDRG2), a novel p53­inducible gene, in several types of cancer. The present study aimed to investigate the effects of NDRG2 expression on the proliferation of a human bladder cancer cell line. NDRG2 and control green fluorescent protein (GFP) recombinant adenovirus plasmids were constructed and transfected into a bladder cancer cell line with mutant p53 (T24 cells). NDRG2 expression was analyzed using western blot analysis and immunofluorescence assay (IFA); in addition, the subcellular localization of NDRG2 was detected using a confocal microscope. The proliferation rate of cells was measured using colony formation and MTT assays. Furthermore, the cell cycle of transfected T24 cells was detected by flow cytometry. The results indicated that T24 cells expressed low levels of NDRG2 prior to infection with GFP­NDRG2 recombinant adenovirus; by contrast, following infection, NDRG2 was primarily overexpressed in mitochondria. The proliferation rate of T24 cells was significantly reduced by NDRG2 expression (P<0.01). In addition, 82.1% of NDRG2­expressing cells were in S­phase, compared to 74.4% in the control virus­infected cells (P<0.05). Furthermore, upregulation of NDRG2 induced an increase in oncosis, rather than apoptosis, in T24 cell. In conclusion, the results of the present study indicated that NDRG2 expression in mitochondria may arrest bladder cancer cells in S­phase as well as decrease cell proliferation through inducing oncosis. It was therefore proposed that NDRG2 was not only a biomarker, but also a tumor suppressor for bladder cancer.