Guoyuan Liu

MDM2 SNP309T>G Polymorphism with Hepatocellular Carcinoma Risk: A Meta-analysis

BACKGROUND AND AIMS The murine double minute 2 (MDM2) gene encodes a negative regulator of the tumor protein p53. A single nucleotide polymorphism (SNP) in MDM2 promoter, SNP309 T>G, has been reported to alter MDM2 protein expression and accelerate tumor formation in humans. Studies investigating the association between the polymorphism and human hepatocellular carcinoma (HCC) risk reported conflicting results. We performed a meta-analysis to explore the association of this polymorphism and HCC risk. METHODS All eligible studies published were searched for in PubMed. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were assessed for the association using fixed- and random-effects models. RESULTS We identified five case-control studies including 738 cases and 1014 controls for the present meta-analysis. In studies with limited data, we detected significant associations for all genetic models in the overall analysis (OR = 2.51, 95% CI = 1.88-3.36 for GG vs. TT, p <0.001, P(het) = 0.666; OR = 1.71, 95% CI = 1.35-2.18 for TG vs. TT, p <0.001, P(het) = 0.925; OR = 1.94, 95% CI = 1.54-2.43 for dominant model TG + GG vs. TT, p <0.001, P(het) = 0.772; OR = 1.74, 95% CI = 1.39-2.20 for recessive model GG vs. TT + TG, p <0.001, P(het) = 0.656). Moreover, in the subgroup analysis based on Hardy-Weinberg equilibrium (HWE) in controls, sample size, and ethnicity, significant associations were observed in most genetic models. CONCLUSIONS This meta-analysis suggests that the MDM2 309 G allele probably acts as an important HCC risk factor. To further confirm our findings, well-designed studies with large sample sizes and representing different ethnicities are required.

PPE57 induces activation of macrophages and drives Th1-type immune responses through TLR2

Proline-glutamic acid (PE) and proline-proline-glutamic acid (PPE) are related proteins exclusive to Mycobacteria that play diverse roles in modulating critical innate immune pathways. In this study, we observed that the PPE57 protein is associated with the cell wall and is exposed on the cell surface. PPE57 enhances Mycobacterium spp. entering into macrophages and plays a role in macrophage phagocytosis. To explore the underlying mechanism, we demonstrated that PPE57 is able to recognise Toll-like receptor 2 (TLR2) and further induce macrophage activation by augmenting the expression of several cell surface molecules (CD40, CD80, CD86 and MHC class II) and pro-inflammatory cytokines (TNF-α, IL-6 and IL-12p40) within macrophages. These molecules are involved in the mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) signalling pathways. We demonstrated that PPE57 effectively polarises T cells to secrete interferon (IFN)-γ and IL-2 and to up-regulate CXCR3 expression in vivo and in vitro, suggesting that this protein may contribute to Th1 polarisation during the immune response. Moreover, recombinant Bacillus Calmette-Guérin (BCG) over-expressing PPE57 could provide better protective efficacy against Mycobacterium tuberculosis challenge compared with BCG. Taken together, our data provides several pieces of evidence that PPE57 may regulate innate and adaptive immunity by interacting with TLR2. These findings indicate that PPE57 protein is a potential antigen for the rational design of an efficient vaccine against M. tuberculosis.Key messagesPPE57 is located on the cell surface and enhances mycobacterium entry into macrophage.PPE57 interacts directly with TLR2 on macrophages.PPE57 plays a key role in the activation of macrophages in a TLR2-dependent manner.PPE57 induces a Th1 immune response via TLR2-mediated macrophage functions.Recombinant BCG over-expressing PPE57 could improve protective efficacy against M. tuberculosis.

Zinc finger transcription factor 191, directly binding to β‐catenin promoter, promotes cell proliferation of hepatocellular carcinoma

Activation of β‐catenin, the central effector of the canonical wingless‐type (Wnt) pathway, has been implicated in hepatocellular carcinoma (HCC). However, the transcription regulation mechanism of the β‐catenin gene in HCC remains unknown. Here we report that human zinc finger protein 191 (ZNF191) is a potential regulator of β‐catenin transcription. ZNF191, a Krüppel‐like protein, specifically interacts with the TCAT motif, which constitutes the HUMTH01 microsatellite in the tyrosine hydroxylase (TH) gene ex vivo. We demonstrate that ZNF191 is significantly overexpressed in human HCC specimens and is associated with growth of human HCC cells. Global profiling of gene expression in ZNF191 knockdown human hepatic L02 cells revealed that the important Wnt signal pathway genes β‐catenin and cyclin D1 messenger RNAs (mRNAs) are significantly down‐regulated. In agreement with transcription level, β‐catenin and cyclin D1 proteins are also down‐regulated in transient and stable ZNF191 knockdown L02 and hepatoma Hep3B cell lines. Moreover, significant correlation between ZNF191 and β‐catenin mRNA expression was detected in human HCCs. Promoter luciferase assay indicated that ZNF191 can increase transcription activity of the full‐length β‐catenin (CTNNB1) promoter, and nucleotide (nt)‐1407/‐907 of the CTNNB1 promoter exhibited the maximum transcriptional activity. Electrophoretic mobility shift assay showed that purified ZNF191 protein can directly bind to the CTNNB1 promoter, and the binding region is located at nt‐1254/‐1224. Finally, we demonstrate that the key binding sequence of ZNF191 in vivo is ATTAATT. Conclusion: ZNF191 can directly bind to the CTNNB1 promoter and activate the expression of β‐catenin and its downstream target genes such as cyclin D1 in hepatoma cell lines. This study uncovers a new molecular mechanism of transcription regulation of the β‐catenin gene in HCC. (HEPATOLOGY 2012;55:1830–1839)

Murine double minute 2 promoter SNP309 polymorphism and prostate cancer risk: A meta-analysis

Objective:  The murine double minute 2 gene encodes a negative regulator of the tumor protein p53. A single nucleotide polymorphism in murine double minute 2 promoter, SNP309 T>G, has been reported to alter murine double minute 2 protein expression and to accelerate tumor formation in humans. We carried out a meta‐analysis to explore the association between this polymorphism and prostate cancer risk.

Involvement of SEPT4_i1 in hepatocellular carcinoma: SEPT4_i1 regulates susceptibility to apoptosis in hepatocellular carcinoma cells

SEPT4 belongs to the Septin family with multiple functions in cell division, cytoskeletal organization and other processes. This study aims to investigate the relationship between SEPT4_i1 isoform and human hepatocellular carcinoma (HCC). We showed that over-expression of SEPT4_i1 in HCC cells was able to sensitize cells to serum starvation-induced apoptosis. By contrast, knockdown of SEPT4_i1 expression in HCC cells was able to rescue cells from apoptosis induced by serum deprivation and to promote cell growth. Expressional analysis of SEPT4_i1 in tumor tissues further revealed that SEPT4_i1 was significantly down-regulated in human HCC tissues. Taken together, these data suggests a tumor suppressor role of SEPT4_i1 in HCC through regulating HCC cell apoptosis.

Meta-analysis shows significant association of the TP53 Arg72Pro with ovarian cancer risk

Growing bodies of studies have been conducted on the association of TP53 Arg72Pro polymorphism with susceptibility to ovarian cancer and have yielded conflicting results. Thus, a meta-analysis was performed to summarize the possible association. 18 case–control studies, including 2,193 ovarian cancer cases and 5,175 controls were identified. The quality of the studies was assessed according to a predefined scale. The strength of the associations between TP53 Arg72Pro polymorphism and ovarian cancer was measured by crude odds ratios (ORs) with 95% confidence intervals (CIs). Overall, no significant association was found between TP53 Arg72Pro polymorphism and ovarian cancer risk when all studies pooled into the meta-analysis in all genetic model. In the subgroup analysis by ethnicity, still no association of this polymorphism with ovarian cancer risk was obtained for all comparison models. However, significantly decreased risks of ovarian cancer were found for Arg/Arg versus Arg/Pro+Pro/Pro (OR 0.84, 95% CI 0.74–0.96) when the analysis was restricted to high quality studies. Conversely, when it was restricted to low quality studies, significantly increased risks were observed for Arg/Arg versus Pro/Pro (OR 1.58, 95% CI 1.09–2.28) and Arg/Arg+Arg/Pro versus Pro/Pro: (OR 1.50, 95% CI 1.10–2.06), which might be spurious due to the poor design of these studies. In conclusion, this meta-analysis suggests that the Arg allele is at a moderately reduced risk for ovarian cancer and this polymorphism might protect against ovarian carcinogenesis.

Prime–boost bacillus Calmette–Guérin vaccination with lentivirus-vectored and DNA-based vaccines expressing antigens Ag85B and Rv3425 improves protective efficacy against Mycobacterium tuberculosis in mice

To prevent the global spread of tuberculosis (TB), more effective vaccines and vaccination strategies are urgently needed. As a result of the success of bacillus Calmette–Guérin (BCG) in protecting children against miliary and meningeal TB, the majority of individuals will have been vaccinated with BCG; hence, boosting BCG‐primed immunity will probably be a key component of future vaccine strategies. In this study, we compared the ability of DNA‐, protein‐ and lentiviral vector‐based vaccines that express the antigens Ag85B and Rv3425 to boost the effects of BCG in the context of immunity and protection against Mycobacterium tuberculosis in C57BL/6 mice. Our results demonstrated that prime–boost BCG vaccination with a lentiviral vector expressing the antigens Ag85B and Rv3425 significantly enhanced immune responses, including T helper type 1 and CD8+ cytotoxic T lymphocyte responses, compared with DNA‐ and protein‐based vaccines. However, lentivirus‐vectored and DNA‐based vaccines greatly improved the protective efficacy of BCG against M. tuberculosis, as indicated by a lack of weight loss and significantly reduced bacterial loads and histological damage in the lung. Our study suggests that the use of lentiviral or DNA vaccines containing the antigens Ag85B and Rv3425 to boost BCG is a good choice for the rational design of an efficient vaccination strategy against TB.

Activation of AKT pathway by Nrf2/PDGFA feedback loop contributes to HCC progression

Nuclear factor erythroid-2-related factor 2 (Nrf2), a master transcription factor in the antioxidant response, has been found to be ubiquitously expressed in various cancer cells and in the regulation tumor proliferation, invasion, and chemoresistance activities. The regulatory roles of Nrf2 in controlling Hepatocellular carcinoma (HCC) progression remain unclear. In this study, we demonstrated that Nrf2 was significantly elevated in HCC cells and tissues and was correlated with poor prognosis of HCCs. Consistently, Nrf2 significantly promoted HCC cell growth both in vitro and in vivo. Further investigation suggested a novel association of Nrf2 with Platelet-Derived Growth Factor-A (PDGFA). Nrf2 promoted PDGFA transcription by recruiting specificity protein 1 (Sp1) to its promoter, resulting in increased activation of the AKT/p21 pathway and cell cycle progression of HCC cells. As a feedback loop, PDGFA enhanced Nrf2 expression and activation in an AKT dependent manner. In line with these findings, expression of Nrf2 and PDGFA were positively correlated in HCC tissues. Taken together, this study uncovers a novel mechanism of the Nrf2/PDGFA regulatory loop that is crucial for AKT-dependent HCC progression, and thereby provides potential targets for HCC therapy.

A novel recombinant BCG-expressing pro-apoptotic protein BAX enhances Th1 protective immune responses in mice.

One-third of the worlds population is infected with Mycobacterium tuberculosis (MTB). The protective efficacy of bacille Calmette Guérin (BCG) vaccine against tuberculosis (TB) in adults is highly controversial even though the BCG vaccine has been available for more than 90 years. Because BCG is effective against infantile tuberculosis meningitis and miliary tuberculosis in young children and provides cost-effective prevention from tuberculosis for developing countries, it would be desirable to modify the existing BCG vaccine to provide more comprehensive protection. In our study, we constructed a novel recombinant BCG strain expressing pro-apoptotic BAX (rBCG::BAX) and demonstrated that it significantly induced the apoptosis of macrophages infected with rBCG::BAX both in vitro and in vivo. In addition, it significantly enhanced Ag85B-specific IFN-γ enzyme-linked immunospot responses, IFN-γ secretion, IL-2 secretion and the ratio of Ag85B-specific IgG2b/IgG1, and it significantly decreased Ag85B-specific IL-4. Furthermore, it presumably facilitated antigen presentation by inducing a significant up-regulation in the expression of MHC-II and B7.1 (CD80) co-stimulatory molecules on macrophages. In conclusion, these results suggest that the rBCG::BAX strain elicited predominantly a Th1 protective immune responses and might be a potential tuberculosis vaccine candidate for further study.

Zinc finger protein 191 inhibits hepatocellular carcinoma metastasis through discs large 1-mediated yes-associated protein inactivation.

Interplay between cell polarity module Scribble‐Lethal Giant Larvae‐Discs Large 1 (DLG1) and Yes‐associated protein (YAP) appears critical in tumor metastasis. We identified zinc finger protein 191 (ZNF191) as a metastasis suppressor acting through DLG‐YAP crosstalk in hepatocellular carcinoma (HCC). Overexpression of ZNF191 in HCC cells impaired cell motility, while ZNF191 depletion promoted cell migration in vitro and metastasis in vivo through triggering YAP signaling. Chromatin immunoprecipitation‐sequencing revealed that ZNF191 specifically bound to the promoter of DLG1, a cell polarity maintainer and a negative regulator of YAP. The binding sequence of ZNF191 at the DLG1 promoter is a seven‐repeat of TCAT motif. Double‐knockdown experiments inferred that DLG1 was not only the mediator of the function of ZNF191 to suppress migration but also a link between ZNF191 and YAP signaling. Decreased expression of ZNF191 in human metastatic HCC specimens correlated positively with DLG1 levels but inversely with YAP activation. Our findings illustrate a YAP‐targeting, antimetastasis function of ZNF191, thereby representing a possible prognostic marker and a potential target for metastasis therapy. Conclusion: ZNF191 directly binds to the DLG1 promoter at a typical TCAT repeating motif and activates the expression of DLG1; through up‐regulating DLG1, ZNF191 inhibits cell migration and YAP activation in HCC cells and eventually inhibits metastasis. (Hepatology 2016;64:1148‐1162)