HBx mediated Increase of SIRT1 Contributes to HBV-related Hepatocellular Carcinoma Tumorigenesis

ENPP1 inhibits the transcription activity of the hepatitis B virus pregenomic promoter by upregulating the acetylation of LMNB1

Current therapies for hepatitis B virus (HBV) infection can slow disease progression but cannot cure the infection, as it is difficult to eliminate or permanently silence HBV covalently closed circular DNA (cccDNA). The interaction between host factors and cccDNA is essential for their formation, stability, and transcriptional activity. Here, we focused on the regulatory role of the host factor ENPP1 and its interacting transcription factor LMNB1 in HBV replication and transcription to better understand the network of host factors that regulate HBV, which may facilitate the development of new antiviral drugs. Overexpression of ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) in Huh7 cells decreased HBV pregenomic RNA (pgRNA) and hepatitis B core antigen (HBcAg) expression levels, whereas knockdown of ENPP1 increased them. A series of HBV promoter and mutant plasmids were constructed, and a luciferase reporter assay showed that overexpression of ENPP1 caused inhibition of the HBV promoter and its mutants. A DNA pull-down assay showed that lamin B1 (LMNB1), but not ENPP1, interacts directly with the HBV enhancer II/ basic core promoter (EnhII/BCP). ZDOCK and PyMOL software were used to predict the interaction of ENPP1 with LMNB1. Overexpression of LMNB1 inhibited the activity of the HBV promoter and its mutant. The acetylation levels at the amino acids 111K, 261K, and 483K of LMNB1 were reduced compared to the control, and an LMNB1 acetylation mutant containing 111R, 261Q, 261R, 483Q, and 483R showed increased promoter activity. In summary, ENPP1 together with LMNB1 increased the acetylation level at 111K and 261K, and LMNB1 inhibited the activity of HBV promoter and downregulated the expression of pregenomic RNA and HBcAg. Our follow-up studies will investigate the expression, clinical significance, and relevance of ENPP1 and LMNB1 in HBV patient tissues, explore the effect of LMNB1 on post-transcriptional progression, and examine whether ENPP1 can reduce cccDNA levels in the nucleus.

SIRT1 Inhibition-Induced Mitochondrial Damage Promotes GSDME-Dependent Pyroptosis in Hepatocellular Carcinoma Cells

Hepatocellular carcinoma (HCC) is a malignant tumor that affects the liver and poses a significant threat to human health. Further investigation is necessary to fully understand the role of SIRT1, a protein linked to tumorigenesis, in HCC development. To investigate the effect of SIRT1 on HCC and elucidate the underlying mechanism. Eight pairs of HCC and paracancerous normal tissue specimens were collected. The levels of SIRT1 and GSDME in tissue samples were assessed using immunohistochemistry and western blotting. SIRT1 levels were determined in HCC (Huh7, HepG2, SNU-423, SNU-398, and HCCLM3) and L-02 cells using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. SNU-423 and HCCLM3 cells were transfected with si-SIRT1 and/or si-GSDME to knock down SIRT1 or GSDME expression. RT-qPCR and western blotting were performed to measure the expression of SIRT1, pro-casp-3, cl-casp-3, GSDME, GSDME-N, PGC-1α, Bax, and cytochrome c (Cyto C). Cell proliferation, migration, invasion, and apoptosis were assessed using the cell counting kit-8 (CCK-8), wound healing assay, Transwell invasion assay, and flow cytometry, respectively. The release of lactate dehydrogenase (LDH) was evaluated using an LDH kit. SIRT1 was upregulated in HCC tissues and cells, and a negative correlation was observed between SIRT1 and GSDME-N. SIRT1 silencing suppressed the proliferation, migration, and invasion of HCC cells while also promoting apoptosis and inducing mitochondrial damage. Additionally, the silencing of SIRT1 resulted in the formation of large bubbles on the plasma membrane of HCC cells, leading to cellular swelling and aggravated GSDME-dependent pyroptosis, resulting in an increase in LDH release. Inhibition of GSDME reduced SIRT1 silencing-induced cell swelling, decreased LDH release rate, and promoted apoptosis. SIRT1 silencing promotes GSDME-dependent pyroptosis in HCC cells by damaging mitochondria.

Oncoviruses: Induction of cancer development and metastasis by increasing anoikis resistance

The phenomenon of cell death is a vital aspect in the regulation of aberrant cells such as cancer cells. Anoikis is a kind of cell death that occurs when cells get separated from the extracellular matrix. Some cancer cells can inhibit anoikis in order to progress metastasis. One of the key variables that might be implicated in anoikis resistance (AR) is viral infections. The most important viruses involved in this process are Epstein-Barr virus, human papillomavirus, hepatitis B virus, human herpes virus 8, human T-cell lymphotropic virus type 1, and hepatitis C virus. A better understanding of how carcinogenic viruses suppress anoikis might be helpful in developing an effective treatment for virus-associated cancers. In the current study, we review the role of the mentioned viruses and their gene products in anoikis inhibition.

Profile and clinical significance of interferon gamma-inducible protein-10 (IP-10) and its receptor in patients with hepatocellular carcinoma

BACKGROUND

Chemokines play a vital role in tumor progression, metastasis and prognosis; however, the profile and clinical significance of gamma interferon-inducible protein-10 (IP-10) and its receptor (CXCR3) in patients with hepatocellular carcinoma (HCC) have not been well evaluated.

METHODS

Liquid-phase chip technology was used to detect the serum IP-10 in 85 patients with HBV-related HCC, 50 patients with chronic hepatitis B (CHB) and 50 liver cirrhosis subjects (CS); simultaneously, the CXCR3 and Alpha fetoprotein (AFP) were determined. Additionally, their mRNA or protein expression levels in peripheral blood mononuclear cells (PBMC), liver tumor and paracancerous tissues were quantified using qRT-PCR or ELISA. Moreover, the IP-10 and CXCR3 expression was verified by the online data from Gene Expression Omnibus. Furthermore, the relationships of serum IP-10, CXCR3 and AFP levels with their overall survival rate were also analyzed.

RESULTS

The levels of IP-10 and CXCR3 in HCC group were significantly higher than those in CHB and CS groups, and their mRNA of PBMC is significantly positive correlation with those in their liver tissues or HBV DNA load (P < 0.0001), respectively. The serum IP-10 and CXCR3 in HCC were significantly correlated with tumor differentiation, metastases staging and distant metastasis (P < 0.05), but not related to gender, age and tumor size (P > 0.05, except IP-10 based on age).

CONCLUSIONS

The serum IP-10 (142.6 pg/mL) and CXCR3 (241.2 pg/mL) could be differential diagnostic surrogates that distinguish HCC from CS, and the lower IP-10 level may be conducive to the postoperative survival of HCC patients. Moreover, the IP-10 and CXCR3 would be related to anti-tumor immunity in HCC patients and be a potential target for treatment of HCC.

The glucose metabolic reprogramming in hepatitis B virus infection and hepatitis B virus associated diseases

Hepatitis B virus (HBV) infection is closely related to viral hepatitis, liver cirrhosis, and hepatocellular carcinoma. HBV infection can reprogram metabolism processes of the host cells including glucose metabolism. The aberrant glucose metabolism may aid in viral infection and immune escape and may contribute to liver associated pathology. In this review, we discussed the interplay between HBV infection and glucose metabolism, which may provide new insights into HBV infection and pathology, novel intervention targets for HBV-related diseases.

The role of regulatory T cells and follicular T helper cells in HBV infection

Hepatitis B has become one of the major global health threats, especially in developing countries and regions. Hepatitis B virus infection greatly increases the risk for liver diseases such as cirrhosis and cancer. However, treatment for hepatitis B is limited when considering the huge base of infected people. The immune response against hepatitis B is mediated mainly by CD8+ T cells, which are key to fighting invading viruses, while regulatory T cells prevent overreaction of the immune response process. Additionally, follicular T helper cells play a key role in B-cell activation, proliferation, differentiation, and formation of germinal centers. The pathogenic process of hepatitis B virus is generally the result of a disorder or dysfunction of the immune system. Therefore, we present in this review the critical functions and related biological processes of regulatory T cells and follicular T helper cells during HBV infection.

Role of sirtuins in hepatocellular carcinoma progression and multidrug resistance: Mechanistical and pharmacological perspectives

Hepatocellular carcinoma (HCC) is the third most common cause of death from cancer worldwide. Therapeutic strategies are still challenging due to the high relapse rate after surgery and multidrug resistance (MDR). It is essential to better understand the mechanisms for HCC progression and MDR for the development of new therapeutic strategies. Mammalian sirtuins (SIRTs), a family of seven members, are related to tumor progression, MDR and prognosis and were proposed as potential prognostic markers, as well as therapeutic targets for treating cancer. SIRT1 is the most studied member and is overexpressed in HCC, playing an oncogenic role and predicting poor prognosis. Several manuscripts describe the role of SIRTs2-7 in HCC; most of them report an oncogenic role for SIRT2 and -7 and a suppressive role for SIRT3 and -4. The scenario is more confusing for SIRT5 and -6, since information is contradictory and scarce. For SIRT1 many inhibitors are available and they seem to hold therapeutic promise in HCC. For the other members the development of specific modulators has just started. This review is aimed to describe the features of SIRTs1-7 in HCC, and the role they play in the onset and progression of the disease. Also, when possible, we will depict the information related to the SIRTs modulators that have been tested in HCC and their possible implication in MDR. With this, we hope to clarify the role of each member in HCC and to shed some light on the most successful strategies to overcome MDR.

LncRNA LINC00924 upregulates NDRG2 to inhibit epithelial-mesenchymal transition via sponging miR-6755-5p in hepatitis B virus-related hepatocellular carcinoma

Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) is a life-threatening cancer. Long noncoding RNAs participate in HBV-related HCC progression. Based on the bioinformatics analysis, LINC00924 downregulation is positively related to unfavorable outcomes in patients with HBV-related HCC. Herein, we detected the biological functions and regulatory system of LINC00924 in HCC. The LINC00924 downregulation in HBV-related HCC tissues and cells was revealed by reverse transcription-quantitative polymerase chain reaction. Functionally, as Transwell assays and western blotting indicated, LINC00924 elevation inhibited HCC cell invasion and epithelial-mesenchymal transition (EMT). The binding site between LINC00924 and miR-6755-5p was determined by luciferase reporter assays. miR-6755-5p was confirmed to target NDRG2. miR-6755-5p upregulation decreased NDRG2 messenger RNA (mRNA) and protein levels. The mRNA and protein levels of NDRG2 were downregulated in tissues and cells. NDRG2 knockdown attenuated the inhibition induced by LINC00924 overexpression on invasion and EMT of HCC cells. In summary, LINC00924 increases NDRG2 expression to inhibit EMT by targeting miR-6755-5p in HBV-related HCC.

The effect and mechanism of cypermethrin-induced hippocampal neurotoxicity as determined by network pharmacology analysis and experimental validation

Cypermethrin (CMN) is a widely used artificial synthetic pesticide that causes neurotoxicity in the hippocampus. However, the underlying toxicological targets and mechanisms remain unclear. In this study, network pharmacology analysis and in vitro models were integrated to investigate the effect and mechanism of CMN-induced hippocampal neurotoxicity. A total of 88 targets of CMN-induced hippocampal neurotoxicity were predicted. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment (KEGG) analyses suggested that these targets were related to multiple GO terms and signaling pathways. To further investigate underlying mechanism, the top 10 hub targets (Akt1, Tnf, Ptgs2, Casp3, Igf1, Sirt1, Jun, Cat, Il10, and Bcl2l1) were screened. Furthermore, cell viability and lactate dehydrogenase (LDH) assays demonstrated that CMN was toxic to HT22 cells in a time- and dose-dependent manner. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining revealed that treatment with CMN increased the proportion of apoptotic cells. In addition, the real-time quantitative polymerase chain reaction (RT-qPCR) results indicated that CMN altered the mRNA expression levels of most of the hub targets, with the exceptions of Igf1 and Jun. The results demonstrated that multiple targets and signaling pathways were involved in CMN-induced hippocampal neurotoxicity. These findings provided reference values for subsequent studies of the toxicological mechanism of CMN.

Sirtuins as Potential Therapeutic Targets for Hepatitis B Virus Infection

Sirtuins (SIRTs) are well-known histone deacetylases that are capable of modulating various cellular processes in numerous diseases, including the infection of hepatitis B virus (HBV), which is one of the primary pathogenic drivers of liver cirrhosis and hepatocellular carcinoma. Mounting evidence reveals that HBV can alter the expression levels of all SIRT proteins. In turn, all SIRTs regulate HBV replication via a cascade of molecular mechanisms. Furthermore, several studies suggest that targeting SIRTs using suitable drugs is a potential treatment strategy for HBV infection. Here, we discuss the molecular mechanisms associated with SIRT-mediated upregulation of viral propagation and the recent advances in SIRT-targeted therapy as potential therapeutic modalities against HBV infection.

NAMPT promotes hepatitis B virus replication and liver cancer cell proliferation through the regulation of aerobic glycolysis

Nicotinamide phosphoribosyltransferase (NAMPT) is a critical rate-limiting enzyme involved in NAD synthesis that has been shown to contribute to the progression of liver cancer. However, the potential role and mechanism of NAMPT in hepatitis B virus (HBV)-associated liver cancer remain unclear. The present study assessed the expression of NAMPT in HBV-positive and -negative liver cancer cells, and investigated whether HBV-induced NAMPT expression is dependent on HBV X protein (HBx). In addition, the role of NAMPT in HBV replication and transcription, and in HBV-mediated liver cancer cell growth was explored. The effects of NAMPT on the glycolytic pathway were also evaluated. Reverse transcription-quantitative PCR and western blotting results revealed that NAMPT expression levels were significantly higher in HBV-positive liver cancer cells than in HBV-negative liver cancer cells, and this effect was HBx-dependent. Moreover, the activation of NAMPT was demonstrated to be required for HBV replication and transcription. The NAMPT inhibitor FK866 repressed cell survival and promoted cell death in HBV-expressing liver cancer cells, and these effects were attenuated by nicotinamide mononucleotide. Furthermore, the inhibition of NAMPT was associated with decreased glucose uptake, decreased lactate production and decreased ATP levels in HBV-expressing liver cancer cells, indicating that NAMPT may promote the aerobic glycolysis. Collectively, these findings reveal a positive feedback loop in which HBV enhances NAMPT expression and the activation of NAMPT promotes HBV replication and HBV-mediated malignant cell growth in liver cancer. The present study highlights the important role of NAMPT in the regulation of aerobic glycolysis in HBV-mediated liver cancer, and suggests that NAMPT may be a promising treatment target for patients with HBV-associated liver cancer.