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Objective It has been reported that intrinsic apoptosis is associated with the progression of bladder cancer (BC). Recent evidence suggests that polyribonucleotide nucleotidyltransferase 1 (PNPT1) is a pivotal mediator involved in RNA decay and cell apoptosis. However, the regulation and roles of PNPT1 in bladder cancer remain largely unclear. Methods The upstream miRNA regulators were predicted by in silico analysis. The expression levels of PNPT1 were evaluated by real-time PCR, Western blotting, and immunohistochemistry (IHC), while miR-183-5p levels were evaluated by qPCR in BC cell lines and tissues. In vitro and in vivo assays were performed to investigate the function of miR-183-5p and PNPT1 in apoptotic RNA decay and the tumorigenic capability of bladder cancer cells. Results PNPT1 expression was decreased in BC tissues and cell lines. Overexpression of PNPT1 significantly promoted cisplatin-induced intrinsic apoptosis of BC cells, whereas depletion of PNPT1 potently alleviated these effects. Moreover, oncogenic miR-183-5p directly targeted the 3′ UTR of PNPT1 and reversed the tumor suppressive role of PNPT1. Intriguingly, miR-183-5p modulated not only PNPT1 but also Bcl2 modifying factor (BMF) to inhibit the mitochondrial outer membrane permeabilization (MOMP) in BC cells. Conclusion Our results provide new insight into the mechanisms underlying intrinsic apoptosis in BC, suggesting that the miR-183-5p-PNPT1 regulatory axis regulates the apoptosis of BC cells and might represent a potential therapeutic avenue for the treatment of BC.

Combined hepatocellular-cholangiocarcinoma (CHC) is a mixed tumor containing elements of both hepatocellular carcinoma (HCC) and cholangiocarcinoma (CC). Its remarkable histological heterogeneity has been linked to putative hepatic progenitor cell (HPC) origin. However, detailed histological or phenotypic description is rarely documented. In the present study, we reassessed 68 cases previously diagnosed as hepatitis B-related CHCs by immunohistochemistry and double-fluorescence immunostaining, focusing on HPC associated phenotypic observation of intermediate area of the tumor. It was found that tumor cells showed remarkable heterogeneity in intermediate area. Tumor cells with intermediate morphology between hepatocytes and cholangiocytes were oval-shaped and small with scant cytoplasm and hyperchromatic nuclei, arranging in solid nests mostly. By Keratin 7 (K7) staining, it appeared that the nests of tumor cells represented a maturation process from the undifferentiated small cells to mature hepatocytes through the "transitional" cells. Then, these small cells were further confirmed with intermediate phenotype as HPC by exploring immature hepatocellular marker and HPC/biliary markers co-localization. In conclusion, the HPC associated trait in CHC can be interpreted by HPC origin or gain of "stemness" by dedifferentiation. It is still too soon to give a final word that it is innate or acquired signature of HPC associated trait in CHC.

We conclude that insulin inhibits AMPK through Akt phosphorylation in L6 myotubes, which may serve as a possible signalling pathway for the down-regulation of protein degradation. Besides, decreased expression of AMPK α2 may partially participate in inhibiting the activity of AMPK., While insulin is an anabolic hormone, AMP-activated protein kinase (AMPK) is not only a key energy regulator, but it can also control substrate metabolism directly by inducing skeletal muscle protein degradation. The hypothesis of the present study was that insulin inhibits AMPK and thus down-regulates the expression of the ubiquitin E3 ligases, muscle atrophy F-box (MAFbx) and muscle RING finger 1 (MuRF1) in skeletal muscle cells. Differentiated L6 myotubes were treated with 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR) and/or compound C to stimulate and/or block AMPK respectively. These treatments were also conducted in the presence or absence of insulin and the cells were analysed by western blot and quantitative real-time PCR. In addition, nuleotide levels were determined using HPLC. The activation of AMPK with AICAR enhanced the mRNA levels of MAFbx and MuRF1. Insulin reduced the phosphorylation and activity AMPK, which was accompanied by reduced MAFbx and MuRF1 mRNA levels. Using a protein kinase B (PKB/Akt) inhibitor, we found that insulin regulates AMPK through the activation of Akt. Furthermore, insulin down-regulated AMPK α2 mRNA. We conclude that insulin inhibits AMPK through Akt phosphorylation in L6 myotubes, which may serve as a possible signalling pathway for the down-regulation of protein degradation. In addition, decreased expression of AMPK α2 may partially participate in inhibiting the activity of AMPK.