Reduced Expression of DNA Damage Repair Genes High Mobility Group Box1 and Poly(ADP-ribose) Polymerase1 in Inactive Carriers of Hepatitis B Virus Infection-A Possible Stage of Viral Integration

Early Treatment Consideration in Patients with Hepatitis B 'e' Antigen-Positive Chronic Infection: Is It Time for a Paradigm Shift?

Chronic hepatitis B (CHB) is associated with significant morbidity and mortality, due to the adverse sequelae of cirrhosis and hepatocellular carcinoma (HCC). To date, antiviral therapy has been reserved for patients with ostensibly active liver disease, fibrosis or cirrhosis, and/or increased risk of HCC. Historically, patients with hepatitis B 'e' antigen (HBeAg)-positive chronic infection, were not offered antiviral therapy. Nevertheless, there has been compelling evidence emerging in recent years, demonstrating that this disease phase is in fact not characterized by immunological tolerance. HBV integration into the human genome is a frequent event found in these patients. Additionally, it may well be associated with active inflammation and fibrosis, even in the presence of persistently normal liver enzymes. Likewise, it appears that the mechanisms of hepatocarcinogenesis are already present during this early stage of the disease. This was reflected in the European Association for the Study of the Liver (EASL) guidelines, where treating patients above the age of 30 years with HBeAg-positive chronic infection was proposed. Lowering the treatment threshold to broaden treatment eligibility is likely to slow disease progression and reduce the risk of developing HCC. The current review discusses the reasons to consider early antiviral therapy in HBeAg-positive chronic infection.

HMGB1: An overview of its roles in the pathogenesis of liver disease

High-mobility group box 1 (HMGB1) is an abundant architectural chromosomal protein that has multiple biologic functions: gene transcription, DNA replication, DNA-damage repair, and cell signaling for inflammation. HMGB1 can be released passively by necrotic cells or secreted actively by activated immune cells into the extracellular milieu after injury. Extracellular HMGB1 acts as a damage-associated molecular pattern to initiate the innate inflammatory response to infection and injury by communicating with neighboring cells through binding to specific cell-surface receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation end products (RAGE). Numerous studies have suggested HMGB1 to act as a key protein mediating the pathogenesis of chronic and acute liver diseases, including nonalcoholic fatty liver disease, hepatocellular carcinoma, and hepatic ischemia/reperfusion injury. Here, we provide a detailed review that focuses on the role of HMGB1 and HMGB1-mediated inflammatory signaling pathways in the pathogenesis of liver diseases.

Extracellular HMGB1 promotes CD44 expression in hepatocellular carcinoma via regulating miR-21

As a member of damage-associated molecular patterns (DAMPs), extracellular high-mobility group box 1 (HMGB1) plays a critical role in hepatocellular carcinoma (HCC) progression. Cluster differentiation 44 (CD44) has been demonstrated to participate in HCC progression. However, the relationship between extracellular HMGB1 and CD44 remains unclear. In this study, our results indicated that extracellular HMGB1 promoted the invasion, sphere formation and EMT process of HCC by increasing CD44 expression, which was dependent on miR-21. Moreover, miR-21 upregulated CD44 expression via activating OCT4/TGF-β1 signaling. Finally, we demonstrated the activation of Rage/JNK signaling caused by extracellular HMGB1 was responsible for miR-21 overexpression. Together, these findings reveal an important role of extracellular HMGB1 in HCC progression through upregulating miR-21/CD44.

Elevated HMGB1 expression induced by hepatitis B virus X protein promotes epithelial-mesenchymal transition and angiogenesis through STAT3/miR-34a/NF-κB in primary liver cancer

HBV infection plays a crucial role in primary liver cancer development. Also, HBV related liver cancer has higher invasiveness and earlier discovered distant metastasis. HBV-encoded X protein (HBx) exerts various biological functions on liver cancer progression, including proliferation, invasion, and venous metastasis. There is evidence that High-mobility group box 1 (HMGB1) promotes epithelial-mesenchymal transition (EMT) and angiogenesis of tumors, including liver cancer. Therefore, this study investigates whether HMGB1 mediates HBx-induced EMT and angiogenesis in HBV related liver cancer. We collected 76 tumor samples of primary liver cancer patients to analyze the relationship between HMGB1 and portal vein tumor thrombus (PVTT) in HBV related liver cancer. To test the influence of HMGB1 on EMT and angiogenesis, we constructed HBx lentivirus transfected HepG2/Huh7 cell lines and performed invasion assays, tube formation and in vivo metastatic experiments. We evaluated HMGB1 and STAT3/miR-34a/NF-κB pathway in vivo and in vitro by immunoblot, quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence and immunohistochemistry analysis. Subsequent RNA interference (RNAi) and luciferase reporter assay were conducted to detect the functional correlation between HMGB1 and STAT3/miR-34a/NF-κB pathway. Our results showed enhanced expression of HMGB1 in HBV related liver cancer, especially with PVTT, while HMGB1 expression was associated with tumor invasion and metastasis. Further experiments indicated that the activation of STAT3 mediated HBx-induced HMGB1, which is involved in EMT and tumor angiogenesis. Besides, HMGB1 expression stimulated by HBx was dependent on the activation of the NF-κB signaling pathway, which was inhibited by miR-34a, while STAT3 suppressed the expression of miR-34a. Moreover, extracellular HMGB1 induced the IL-6/STAT3/miR-34a axis activation, which indicated a reciprocal relationship between HMGB1 and miR-34a. Collectively, our study provided evidence to reveal that HBx-mediated high expression of HMGB1 accounted for EMT and tumor angiogenesis in HBV related liver cancer, and HMGB1 may be a potential target for predicting venous metastasis.

Decreased Expression of the High Mobility Group Box 1 (HMGB1) Gene in Peripheral Blood in Patients with Mild or Moderate Clostridioides difficile Infection

Cytokines are mediators of inflammation induced in the course of Clostridioides difficile infection (CDI). High Mobility Group Box 1 (HMGB1) is a cytokine playing an important role in the pathogenesis of numerous inflammatory and autoimmune diseases. The aim of the study was to assess the HMGB1 gene expression in the course of CDI. We have performed a prospective case-control study- including 55 adult patients, among them 27 with CDI, who were hospitalized from October 2018 to February 2020 and 28 healthy volunteers. We assessed: a complete blood count with differential leukocyte count, blood creatinine, albumin, and C-reactive protein (CRP) levels. Then, the expression of the HMGB1 gene was evaluated using quantitative Real-Time PCR. Patients with CDI were found to have a significant increase in white blood cells (WBC), neutrophil count, and CRP levels, they also exhibited decreased levels of albumin compared with controls. The HMGB1 gene expression was significantly lower among patients with CDI compared with the control group and significantly, inversely correlated with CRP level in blood. In conclusion, we have observed a decreased expression of the HMGB1 gene in peripheral blood of patients with mild or moderate CDI, which hypothetically could reflect their diminished capability to fight the pathogen.

Recent advances in the molecular mechanism of sex disparity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is more frequently observed and aggressive in men compared with women. Increasing evidence demonstrates that the sex disparity appears to be mediated by the stimulatory effects of androgens and the protective effects of estrogen in the development and progression of HCC. In the past few decades, studies on the sex difference of HCC mainly focused on the effect of sex hormones on the transactivation of hepatitis B virus X protein and the release of inflammatory cytokines, and these studies have further intensified in recent years. Sex hormones are also involved in genetic alterations and DNA damage repair in hepatocytes through binding to their specific cellular receptors and affecting the corresponding signaling pathways. Furthermore, the theory of sex chromosomes participating in HCC has been considered. The present review discussed the recent advances in the molecular mechanisms of sex disparity in HCC, with the aim of improving the understanding of the underlying critical factors and exploring more effective methods for the prevention and treatment of HCC.

iTRAQ-Based Quantitative Proteomic Analysis of the Inhibitory Effects of Polysaccharides from Viscum coloratum (Kom.) Nakai on HepG2 Cells

Viscum coloratum (Kom.) Nakai is one of active medicinal plants, and its active components, especially polysaccharides, have been shown to exhibit bioactivity. In this study, we examined the effects of three polysaccharide fractions from Viscum coloratum (Kom.) Nakai on HepG2 cell growth in a dose-dependent manner by using a CCK-8 assay kit. Flow cytometry analysis showed that VCP2 treatment delayed the cell cycle in the G1 phase and induced apoptosis in HepG2 cells, a result possibly due to the increased expression of p21Wafl/Cip1 and Cyclin D and the decreased expression of Cyclin E and CDK4. The increased expression of Bad, Smac and Caspase-3 and the decreased expression of Bcl-XL and XIAP may be some of the reasons for the induction of apoptosis in VCP2-treated HepG2 cells. Through iTRAQ and 2D-LC-MSMS, 113 and 198 differentially expressed proteins were identified in normal and VCP2-treated HepG2 and Caco2 cells. The mRNA and protein levels of Histone H3.1, Cytoskeletal 9 and Vitronectin agreed with iTRAQ proteomic results. GO, pathways and the PPI of differentially expressed proteins were further analyzed. These findings broaden the understanding of the anti-tumor mechanisms of mistletoe polysaccharides and provide new clues for screening proteins that are responsive to polysaccharides.

Hepatitis B virus X protein stimulates high mobility group box 1 secretion and enhances hepatocellular carcinoma metastasis

Hepatitis B virus X protein (HBx) plays an important role in the progression of hepatocellular carcinoma. Here we reported that overexpression of HBx in hepatocellular carcinoma (HCC) cells could induce the secretion of high-mobility group box 1 (HMGB1) to promote invasion and metastasis of HCC in an autocrine/paracrine manner. HBx triggered an increase of cytoplasmic calcium and activated CAMKK/CAMKIV pathway, leading to subsequent translocation and release of HMGB1. HMGB1 neutralizing antibody, as well as calcium chelator or inhibitors of CAMKK/CAMKIV, could remarkably reduce invasion and metastasis of HCC cells in vitro and in a murine HCC metastasis model in vivo. Furthermore, the level of HMGB1 in patient serum and tumor tissues was positively correlated with HBV DNA load. We demonstrate an inverse relationship between HMGB1 in tumor cytoplasm and overall prognosis of HCC patients.

CONCLUSION

HBx promotes the progression of HCC through translocation and secretion of HMGB1 from tumor cells via calcium dependent cascades. These data indicates that HMGB1 could serve as a novel prognostic biomarker and potential therapeutic target for HBV-related HCC.