Hepatitis B virus X protein (HBx) plays critical roles in the pathogenesis of hepatocellular carcinoma (HCC). Here, we were interested in knowing whether the oncogene Lin28A and its homolog Lin28B are involved in the hepatocarcinogenesis mediated by HBx. We showed that the expression levels of Lin28A and Lin28B were increased in clinical HCC tissues, HepG2.2.15 cell line and liver tissues of p21-HBx transgenic mice. Interestingly, the expression levels of HBx were positively associated with those of Lin28A/Lin28B in clinical HCC tissues. Moreover, the overexpression of HBx resulted in the upregulation of Lin28A/Lin28B in hepatoma HepG2/H7402 cell lines by transient transfection, suggesting that HBx was able to upregulate Lin28A and Lin28B. Then, we examined the mechanism by which HBx upregulated Lin28A and Lin28B. We identified that the promoter region of Lin28A regulated by HBx was located at nt -235/-66 that contained Sp-1 binding element. Co-immunoprecipitation showed that HBx was able to interact with Sp-1 in HepG2-X cells. Moreover, chromatin immunoprecipitation (ChIP) demonstrated that HBx could bind to the promoter of Lin28A, which failed to work when Sp-1 was silenced. Electrophoretic mobility shift assay (EMSA) further identified that HBx was able to interact with Sp-1 element in Lin28A promoter via transcription factor Sp-1. In addition, we found that c-Myc was involved in the activation of Lin28B mediated by HBx. In function, Lin28A/Lin28B played important roles in HBx-enhanced proliferation of hepatoma cells in vitro and in vivo. In conclusion, HBx activates Lin28A/Lin28B through Sp-1/c-Myc in hepatoma cells. Lin28A/Lin28B serves as key driver genes in HBx-induced hepatocarcinogenesis.

The aim of the present study was to investigate whether cognitive behavioral impairment, induced by nicotine in offspring rats, was associated with the alteration of hippocampal short-term potentiation (STP) and long-term potentiation (LTP) and to discuss the potential underlying mechanism. Young adult offspring rats were randomly divided into three groups. The groups include: control group (CC), nicotine group 1 (NC), in which their mothers received nicotine from gestational day 3 (GD3) to GD18, and nicotine group 2 (CN), in which young adult offspring rats received nicotine from postnatal day 42 (PD42) to PD56. Morris water maze (MWM) test was performed and then field excitatory postsynaptic potentials elicited by the stimulation of perforant pathway were recorded in the hippocampal dentate gyrus region. The results of the MWM test showed that learning and memory were impaired by either prenatal or postnatal nicotine exposure. In addition, it was found that there was no statistical difference of the MWM data between both nicotine treatments. In the electrophysiological test, LTP and STP were significantly inhibited in both NC and CN groups in comparison with the CC group. Notably, STP in CN group was also lower than that in the NC group. These findings suggested that both prenatal and postnatal exposure to nicotine induced learning and memory deficits, while the potential mechanism might be different from each other due to their dissimilar impairments of synaptic plasticity.

Due to its high nitrogen content, melamine was deliberately added to raw milk for increasing the apparent protein content. Previous studies showed that melamine-induced apoptosis and oxidative damage on PC12 cells and rats' hippocampus. Several evidences suggested that vitamin antioxidant reduced oxidative stress and improved organic function. Whether treatments with antioxidant vitamins C or E, otherwise combination of them can attenuate oxidative stress after melamine administration remains to be elucidated. In this study, the reversible effects of vitamin antioxidants was investigated on melamine-induced neurotoxicity in cultured PC12 cells, an in vitro model of neuronal cells. When comparing vitamin C and E, the combination of both statistically increased PC12 cells viability. The results further showed that vitamin complex has effectively reduced the formation of reaction oxygen species, decreased the level of malondialdehyde, and elevated the activities of antioxidative enzymes. Hoechst 33342 staining and flow cytometric analysis of apoptosis showed that vitamin combination treatment effectively prevented PC12 cells from this melamine-induced apoptosis. It revealed the apoptotic nuclear features of the melamine-induced cell death. Additionally, a combination treatment of vitamins effectively inhibited apoptosis via blocking the increased activation of caspase-3. In summary, the vitamin E and C combination treatment could rescue PC12 cells from the injury induced by melamine through the downregulation of oxidative stress and prevention of melamine-induced apoptosis.