H.P. Zhang

PPE protein (Rv3425) from DNA segment RD11 of Mycobacterium tuberculosis: a potential B-cell antigen used for serological diagnosis to distinguish vaccinated controls from tuberculosis patients

Proteins encoded by a 9.5-kb DNA segment, termed the region of difference (RD), of Mycobacterium tuberculosis have been demonstrated to be important in bacterial virulence, vaccine development and the design of diagnostic reagents. This study evaluated the immunogenic properties of Rv3425, a member of the PPE family of proteins, encoded by an open reading frame found in RD11 of M. tuberculosis, in comparison with two other well-known antigens, the early secreted antigen target 6 (ESAT-6) and the 10-kDa culture filtrate protein (CFP-10). RT-PCR demonstrated that Rv3425 mRNA is expressed in liquid culture by M. tuberculosis H37Rv. When tested in a conventional ELISA in the form of a His-tagged recombinant protein, Rv3425 revealed a statistically significant antigenic distinction between healthy bacille Calmette-Guérin (BCG)-vaccinated controls and tuberculosis (TB) patients (p <0.0001). The anti-IgG response to recombinant Rv3425 was almost equal to that for CFP-10, and was higher than that for ESAT-6. The results highlight the immunosensitive and immunospecific nature of Rv3425, which shows promise for use in the serodiagnosis of TB.

Genomic and oncogenic preference of HBV integration in hepatocellular carcinoma

Hepatitis B virus (HBV) can integrate into the human genome, contributing to genomic instability and hepatocarcinogenesis. Here by conducting high-throughput viral integration detection and RNA sequencing, we identify 4,225 HBV integration events in tumour and adjacent non-tumour samples from 426 patients with HCC. We show that HBV is prone to integrate into rare fragile sites and functional genomic regions including CpG islands. We observe a distinct pattern in the preferential sites of HBV integration between tumour and non-tumour tissues. HBV insertional sites are significantly enriched in the proximity of telomeres in tumours. Recurrent HBV target genes are identified with few that overlap. The overall HBV integration frequency is much higher in tumour genomes of males than in females, with a significant enrichment of integration into chromosome 17. Furthermore, a cirrhosis-dependent HBV integration pattern is observed, affecting distinct targeted genes. Our data suggest that HBV integration has a high potential to drive oncogenic transformation.

HBx regulates fatty acid oxidation to promote hepatocellular carcinoma survival during metabolic stress

Due to a high rate of nutrient consumption and inadequate vascularization, hepatocellular carcinoma (HCC) cells constantly undergo metabolic stress during tumor development. Hepatitis B virus (HBV) X protein (HBx) has been implicated in the pathogenesis of HBV-induced HCC. In this study, we investigated the functional roles of HBx in HCC adaptation to metabolic stress. Up-regulation of HBx increased the intracellular ATP and NADPH generation, and induced the resistance to glucose deprivation, whereas depletion of HBx via siRNA abolished these effects and conferred HCC cells sensitive to glucose restriction. Though HBx did not affect the glycolysis and oxidative phosphorylation capacity of HCC cells under normal culture conditions, it facilitated fatty acid oxidation (FAO) in the absence of glucose, which maintained NADPH and ATP levels. Further investigation showed that HBx expression, under glucose deprivation, stimulated phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) via a calcium/CaMKK-dependent pathway, which was required for the activation of FAO. Conversely, inhibition of FAO by etomoxir (ETO) restored the sensitivity of HBx-expressing cells to glucose deficiency in vitro and retarded xenograft tumor formation in vivo. Finally, HBx-induced activation of the AMPK and FAO pathways were also observed in xenograft tumors and HBV-associated HCC specimens. Our data suggest that HBx plays a key role in the maintenance of redox and energy homeostasis by activating FAO, which is critical for HCC cell survival under conditions of metabolic stress and might be exploited for therapeutic benefit.

POROUS NANOCOMPOSITE POLYMER ELECTROLYTE PREPARED BY A NON-SOLVENT INDUCED PHASE SEPARATION PROCESS

A non-solvent induced phase separation (NIPS) process was used to prepare a new kind of porous nanocomposite polymer electrolyte using glycerol as non-solvent for poly(vinylidene difluoride-co-hexafluoropropylene) copolymer. TiO2 nanoparticles were incorporated by in situ hydrolysis of Ti(OC4H9)4 and dispersed uniformly in the polymer matrix. They affected the porous structure of the obtained nanocomposite polymer membranes (NCPMs). When the amount of TiO2 arrived at 7.6 wt.%, the NCPM reached the maximum porosity of 70.5%. The resulting nanocomposite polymer electrolyte (NCPE) presents an ionic conductivity of up to 1.98 × 10-3 S · cm-1 at room temperature and an apparent activation energy for ion transport of 13.32 kJ · mol-1, suggesting its promising application in lithium ion batteries.

A splicing variant of Merlin promotes metastasis in hepatocellular carcinoma

Merlin, which is encoded by the tumour suppressor gene Nf2, plays a crucial role in tumorigenesis and metastasis. However, little is known about the functional importance of Merlin splicing forms. In this study, we show that Merlin is present at low levels in human hepatocellular carcinoma (HCC), particularly in metastatic tumours, where it is associated with a poor prognosis. Surprisingly, a splicing variant of Merlin that lacks exons 2, 3 and 4 (Δ2–4Merlin) is amplified in HCC and portal vein tumour thrombus (PVTT) specimens and in the CSQT2 cell line derived from PVTT. Our studies show that Δ2–4Merlin interferes with the capacity of wild-type Merlin to bind β-catenin and ERM, and it is expressed in the cytoplasm rather than at the cell surface. Furthermore, Δ2–4Merlin overexpression increases the expression levels of β-catenin and stemness-related genes, induces the epithelium–mesenchymal-transition phenotype promoting cell migration in vitro and the formation of lung metastasis in vivo. Our results indicate that the Δ2–4Merlin variant disrupts the normal function of Merlin and promotes tumour metastasis.

Blocking preferential glucose uptake sensitizes liver tumor-initiating cells to glucose restriction and sorafenib treatment.

Cancer cells display altered metabolic phenotypes characterized by a high level of glycolysis, even under normoxic conditions. Because of a high rate of glycolytic flux and inadequate vascularization, tumor cells often suffer from nutrient deficiency and require metabolic adaptations to address such stresses. Although tumor-initiating cells (T-ICs) have been identified in various malignancies, the cells metabolic phenotypes remain elusive. In this study, we observed that liver T-ICs preferentially survived under restricted glucose treatment. These cell populations compete successfully for glucose uptake by preferentially expressing glucose transporters (GLUT1 and GLUT3), whereas inhibition of GLUT1 or GLUT3 abolished the survival advantage and suppressed the tumorigenic potential of liver T-ICs. Among signaling pathways related to T-ICs, IL-6/STAT3 was identified to be responsible for the elevation of glucose uptake in liver T-ICs under glucose limitation. Further investigation revealed that IL-6 stimulation upregulated GLUT1 and GLUT3 expressions in CD133+ cells, particularly during glucose deprivation. More importantly, inhibition of glucose uptake sensitized liver T-ICs to sorafenib treatment and enhanced the therapeutic efficacy inxa0vivo. Our findings suggest that blocking IL-6/STAT3-mediated preferential glucose uptake might be exploited for novel therapeutic targets during hepatocellular carcinoma (HCC) progression.

Inhibition of dipeptidyl peptidase IV prevents high fat diet-induced liver cancer angiogenesis by downregulating chemokine ligand 2

Obesity is a major risk factor for hepatocellular carcinoma (HCC) and is typically accompanied by higher levels of serum dipeptidyl peptidase 4 (DPP4). However, the role of DPP4 in obesity-promoted HCC is unclear. Here, we found that consumption of a high-fat diet (HFD) promoted HCC cell proliferation and metastasis and led to poor survival in a carcinogen-induced model of HCC in rats. Notably, genetic ablation of DPP4 or treatment with a DPP4 inhibitor (vildagliptin) prevented HFD-induced HCC. Moreover, HFD-induced DPP4 activity facilitated angiogenesis and cancer cell metastasis inxa0vitro and inxa0vivo, and vildagliptin prevented tumor progression by mediating the pro-angiogenic role of chemokine ligand 2 (CCL2). Loss of DPP4 effectively reversed HFD-induced CCL2 production and angiogenesis, indicating that the DPP4/CCL2/angiogenesis cascade had key roles in HFD-associated HCC progression. Furthermore, concomitant changes in serum DPP4 and CCL2 were observed in 210 patients with HCC, and high serum DPP4 activity was associated with poor clinical prognosis. These results revealed a link between obesity-related high serum DPP4 activity and HCC progression. Inhibition of DPP4 may represent a novel therapeutic intervention for patients with HCC.

Microbiota transplantation reveals beneficial impact of berberine on hepatotoxicity by improving gut homeostasis

Berberine has been shown to reduce acute liver injury although the underlying mechanism is not fully understood. Because of the anatomic connection, the liver is constantly exposed to gut-derived bacterial products and metabolites. In this study, we showed that berberine has beneficial effects on both hepatotoxicity and intestinal damage in a rat model of chronic or acute liver injury. Microbiota transplantation from the rats with chronic hepatotoxicity could aggravate acute hepatotoxicity in mice treated with diethylnitrosamine (DEN). In rat models with gut homeostasis disruption induced by penicillin or dextran sulfate sodium (DSS), their fecal microbiota could also cause an enhanced hepatotoxicity of recipient mice. When treated with berberine, the DSS-induced enteric dysbacteriosis could be mitigated and their fecal bacteria were able to reduce acute hepatotoxicity in recipient mice. This study indicates that berberine could improve intestinal dysbacteriosis, which reduces the hepatotoxicity caused by pathological or pharmacological intervention. Fecal microbiota transplantation might be a useful method to directly explore homeostatic alteration in gut microbiota.