Hepatitis B virus X protein promotes MAN1B1 expression by enhancing stability of GRP78 via TRIM25 to facilitate hepatocarcinogenesis.

BACKGROUND: GRP78 has been implicated in hepatocarcinogenesis. However, the clinical relevance, biological functions and related regulatory mechanisms of GRP78 in hepatitis B virus (HBV)-associated hepatoma carcinoma (HCC) remain elusive. METHODS: The association between GRP78 expression and HBV-related HCC was investigated. The effects of HBV X protein (HBX) on GRP78 and MAN1B1 expression, biological functions of GRP78 and MAN1B1 in HBX-mediated HCC cells and mechanisms related to TRIM25 on GRP78 upregulation to induce MAN1B1 expression in HBX-related HCC cells were examined. RESULTS: GRP78 expression was correlated with poor prognosis in HBV-positive HCC. HBX increased MAN1B1 protein expression depending on GRP78, and HBX enhanced the levels of MAN1B1 to promote proliferation, migration and PI3-K/mTOR signalling pathway activation in HCC cells. GRP78 activates Smad4 via its interaction with Smad4 to increase MAN1B1 expression in HBX-expressing HCC cells. TRIM25 enhanced the stability of GRP78 by inhibiting its ubiquitination. HBX binds to GRP78 and TRIM25 and accelerates their interaction of GRP78 and TRIM25, leading to an increase in GRP78 expression. CONCLUSIONS: HBX enhances the stability of GRP78 through TRIM25 to increase the expression of MAN1B1 to facilitate tumorigenesis, and we provide new insights into the molecular mechanisms underlying HBV-induced malignancy.

Insights into the impact of hepatitis B virus on hepatic stellate cell activation.

During chronic hepatitis B virus (HBV) infection, hepatic fibrosis is a serious pathological condition caused by virus-induced liver damage. The activation of hepatic stellate cells (HSCs) is a central event in the occurrence and progression of liver fibrosis. Although accumulating evidence has shown that HBV directly stimulates HSC activation, whether the virus infects and replicates in HSCs remains controversial. Inflammation is one of the obvious characteristics of chronic HBV infection, and it has been demonstrated that persistent inflammation has a predominant role in triggering and maintaining liver fibrosis. In particular, the regulation of HSC activation by HBV-related hepatocytes via various inflammatory modulators, including TGF-ß and CTGF, in a paracrine manner has been reported. In addition to these inflammation-related molecules, several inflammatory cells are essential for the progression of HBV-associated liver fibrosis. Monocytes, macrophages, Th17 cells, NK cells, as well as NKT cells, participate in the modulation of HBV-related liver fibrosis by interacting with HSCs. This review summarizes current findings on the effects of HBV and the relevant molecular mechanisms involved in HSC activation. Because HSC activation is essential for liver fibrosis, targeting HSCs is an attractive therapeutic strategy to prevent and reverse hepatic fibrosis induced by HBV infection. Video abstract.

The LncRNA AK018453 regulates TRAP1/Smad signaling in IL-17-activated astrocytes: A potential role in EAE pathogenesis.

The pro-inflammatory cytokine interleukin 17 (IL-17), that is mainly produced by Th17 cells, has been recognized as a key regulator in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). Reactive astrocytes stimulated by proinflammatory cytokines including IL-17 are involved in blood brain barrier destruction, inflammatory cells infiltration and spinal cord injury. However, the role of long non-coding RNAs (lncRNAs) induced by IL-17 in the pathogenesis of MS and EAE remains unknown. Herein, we found that an IL-17-induced lncRNA AK018453 promoted TGF-ß receptor-associated protein 1 (TRAP1) expression and Smad-dependent signaling in mouse primary astrocytes. Knockdown of AK018453 significantly suppressed astrocytosis, attenuated the phosphorylation of Smad2/3, reduced NF-κB p65 and CBP/P300 binding to the TRAP1 promoter, and diminished pro-inflammatory cytokine production in the IL-17-treated astrocytes. AK018453 knockdown in astrocytes by a lentiviral vector in vivo dramatically inhibited inflammation and prevented the mice from demyelination in the spinal cord during the progression of EAE. Together, these results suggest that AK018453 regulates IL-17-dependent inflammatory response in reactive astrocytes and potentially promotes the pathogenesis of EAE via the TRAP1/Smad pathway. Targeting this pathway may have a therapeutic potential for intervening inflammatory demyelinating diseases.

Regulation of epithelial-mesenchymal transition by protein lysine acetylation.

The epithelial-mesenchymal transition (EMT) is a vital driver of tumor progression. It is a well-known and complex trans-differentiation process in which epithelial cells undergo morphogenetic changes with loss of apical-basal polarity, but acquire spindle-shaped mesenchymal phenotypes. Lysine acetylation is a type of protein modification that favors reversibly altering the structure and function of target molecules via the modulation of lysine acetyltransferases (KATs), as well as lysine deacetylases (KDACs). To date, research has found that histones and non-histone proteins can be acetylated to facilitate EMT. Interestingly, histone acetylation is a type of epigenetic regulation that is capable of modulating the acetylation levels of distinct histones at the promoters of EMT-related markers, EMT-inducing transcription factors (EMT-TFs), and EMT-related long non-coding RNAs to control EMT. However, non-histone acetylation is a post-translational modification, and its effect on EMT mainly relies on modulating the acetylation of EMT marker proteins, EMT-TFs, and EMT-related signal transduction molecules. In addition, several inhibitors against KATs and KDACs have been developed, some of which can suppress the development of different cancers by targeting EMT. In this review, we discuss the complex biological roles and molecular mechanisms underlying histone acetylation and non-histone protein acetylation in the control of EMT, highlighting lysine acetylation as potential strategy for the treatment of cancer through the regulation of EMT. Video Abstract.

The interaction of canonical Wnt/ß-catenin signaling with protein lysine acetylation.

Canonical Wnt/ß-catenin signaling is a complex cell-communication mechanism that has a central role in the progression of various cancers. The cellular factors that participate in the regulation of this signaling are still not fully elucidated. Lysine acetylation is a significant protein modification which facilitates reversible regulation of the target protein function dependent on the activity of lysine acetyltransferases (KATs) and the catalytic function of lysine deacetylases (KDACs). Protein lysine acetylation has been classified into histone acetylation and non-histone protein acetylation. Histone acetylation is a kind of epigenetic modification, and it can modulate the transcription of important biological molecules in Wnt/ß-catenin signaling. Additionally, as a type of post-translational modification, non-histone acetylation directly alters the function of the core molecules in Wnt/ß-catenin signaling. Conversely, this signaling can regulate the expression and function of target molecules based on histone or non-histone protein acetylation. To date, various inhibitors targeting KATs and KDACs have been discovered, and some of these inhibitors exert their anti-tumor activity via blocking Wnt/ß-catenin signaling. Here, we discuss the available evidence in understanding the complicated interaction of protein lysine acetylation with Wnt/ß-catenin signaling, and lysine acetylation as a new target for cancer therapy via controlling this signaling.

ß-Catenin Is Required for the cGAS/STING Signaling Pathway but Antagonized by the Herpes Simplex Virus 1 US3 Protein.

The cGAS/STING-mediated DNA-sensing signaling pathway is crucial for interferon (IFN) production and host antiviral responses. Herpes simplex virus I (HSV-1) is a DNA virus that has evolved multiple strategies to evade host immune responses. Here, we demonstrate that the highly conserved ß-catenin protein in the Wnt signaling pathway is an important factor to enhance the transcription of type I interferon (IFN-I) in the cGAS/STING signaling pathway, and the production of IFN-I mediated by ß-catenin was antagonized by HSV-1 US3 protein via its kinase activity. Infection by US3-deficienct HSV-1 and its kinase-dead variants failed to downregulate IFN-I and IFN-stimulated gene (ISG) production induced by ß-catenin. Consistent with this, absence of ß-catenin enhanced the replication of US3-deficienct HSV-1, but not wild-type HSV-1. The underlying mechanism was the interaction of US3 with ß-catenin and its hyperphosphorylation of ß-catenin at Thr556 to block its nuclear translocation. For the first time, HSV-1 US3 has been shown to inhibit IFN-I production through hyperphosphorylation of ß-catenin and to subvert host antiviral innate immunity.IMPORTANCE Although increasing evidence has demonstrated that HSV-1 subverts host immune responses and establishes lifelong latent infection, the molecular mechanisms by which HSV-1 interrupts antiviral innate immunity, especially the cGAS/STING-mediated cellular DNA-sensing signaling pathway, have not been fully explored. Here, we show that ß-catenin promotes cGAS/STING-mediated activation of the IFN pathway, which is important for cellular innate immune responses and intrinsic resistance to DNA virus infection. The protein kinase US3 antagonizes the production of IFN by targeting ß-catenin via its kinase activity. The findings in this study reveal a novel mechanism for HSV-1 to evade host antiviral immunity and add new knowledge to help in understanding the interaction between the host and HSV-1 infection.

Cellular retinol binding protein-1 inhibits cancer stemness via upregulating WIF1 to suppress Wnt/ß-catenin pathway in hepatocellular carcinoma.

BACKGROUND: CRBP-1, a cytosolic chaperone of vitamin A, is identified in a serious number of cancers; however, its biological role in hepatocellular carcinoma (HCC) needs to be further explored. The aim of our present study is to explore the roles and mechanisms of CRBP-1 in regulating liver cancer by using in vitro and in vivo biology approaches. METHODS: The expression level of CRBP-1 was detected using immunohistochemistry in HCC and matching adjacent non-tumorous liver tissues. Following established stable CRBP-1 overexpressed HCC cell lines, the cell growth and tumorigenicity were investigated both in vitro and in vivo. Intracellular retinoic acid was quantified by ELISA. The relationship between CRBP-1 and WIF1 was validated by using dual luciferase and ChIP analyses. RESULTS: The low expression of CRBP-1 was observed in HCC tissues compared to the normal liver tissues, while high CRBP-1 expression correlated with clinicopathological characteristics and increased overall survival in HCC patients. Overexpression of CRBP-1 significantly inhibited cell growth and tumorigenicity both in vitro and in vivo. Moreover, overexpression of CRBP-1 suppressed tumorsphere formation and cancer stemness related genes expression in HCC. Mechanically, CRBP-1 inhibited Wnt/ß-catenin signaling pathway to suppress cancer cell stemness of HCC. Furthermore, our results revealed that CRBP-1 could increase the intracellular levels of retinoic acid, which induced the activation of RARs/RXRs leading to the transcriptional expression of WIF1, a secreted antagonist of the Wnt/ß-catenin signaling pathway, by physically interacting with the region on WIF1 promoter. CONCLUSION: Our findings reveal that CRBP-1 is a crucial player in the initiation and progression of HCC, which provide a novel independent prognostic biomarker and therapeutic target for the diagnosis and treatment of HCC.

Calcium signaling in hepatitis B virus infection and its potential as a therapeutic target.

As a ubiquitous second messenger, calcium (Ca2+) can interact with numerous cellular proteins to regulate multiple physiological processes and participate in a variety of diseases, including hepatitis B virus (HBV) infection, which is a major cause of hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. In recent years, several studies have demonstrated that depends on the distinct Ca2+ channels on the plasma membrane, endoplasmic reticulum, as well as mitochondria, HBV can elevate cytosolic Ca2+ levels. Moreover, within HBV-infected cells, the activation of intracellular Ca2+ signaling contributes to viral replication via multiple molecular mechanisms. Besides, the available evidence indicates that targeting Ca2+ signaling by suitable pharmaceuticals is a potent approach for the treatment of HBV infection. In the present review, we summarized the molecular mechanisms related to the elevation of Ca2+ signaling induced by HBV to modulate viral propagation and the recent advances in Ca2+ signaling as a potential therapeutic target for HBV infection. Video Abstract.

Hepatitis B virus X protein promotes vimentin expression via LIM and SH3 domain protein 1 to facilitate epithelial-mesenchymal transition and hepatocarcinogenesis.

BACKGROUND: Hepatitis B virus (HBV) X protein (HBX) has been reported to be responsible for the epithelial-mesenchymal transition (EMT) in HBV-related hepatocellular carcinoma (HCC). Vimentin is an EMT-related molecular marker. However, the importance of vimentin in the pathogenesis of HCC mediated by HBX has not been well determined. METHODS: The expression of vimentin induced by HBX, and the role of LIM and SH3 domain protein 1 (LASP1) in HBX-induced vimentin expression in hepatoma cells were examined by western blot and immunohistochemistry analysis. Both the signal pathways involved in the expression of vimentin, the interaction of HBX with vimentin and LASP1, and the stability of vimentin mediated by LASP1 in HBX-positive cells were assessed by western blot, Co-immunoprecipitation, and GST-pull down assay. The role of vimentin in EMT, proliferation, and migration of HCC cells mediated by HBX and LASP1 were explored with western blot, CCK-8 assay, plate clone formation assay, transwell assay, and wound healing assay. RESULTS: Vimentin expression was increased in both HBX-positive hepatoma cells and HBV-related HCC tissues, and the expression of vimentin was correlated with HBX in HBV-related HCC tissues. Functionally, vimentin was contributed to the EMT, proliferation, and migration of hepatoma cells mediated by HBX. The mechanistic analysis suggested that HBX was able to enhance the expression of vimentin through LASP1. On the one hand, PI3-K, ERK, and STAT3 signal pathways were involved in the upregulation of vimentin mediated by LASP1 in HBX-positive hepatoma cells. On the other hand, HBX could directly interact with vimentin and LASP1, and dependent on LASP1, HBX was capable of promoting the stability of vimentin via protecting it from ubiquitination mediated protein degradation. Besides these, vimentin was involved in the growth and migration of hepatoma cells mediated by LASP1 in HBX-positive hepatoma cells. CONCLUSION: Taken together, these findings demonstrate that, dependent on LASP1, vimentin is crucial for HBX-mediated EMT and hepatocarcinogenesis, and may serve as a potential target for HBV-related HCC treatment. Video abstract.

Hepatitis B virus core protein promotes the expression of neuraminidase 1 to facilitate hepatocarcinogenesis.

Neuraminidase 1 (NEU1) has been reported to be associated with hepatocellular carcinoma (HCC). However, the function and associated molecular mechanisms of NEU1 in hepatitis B virus (HBV)-related HCC have not been well investigated. In the present study, the expression of NEU1 mediated by HBV and HBV core protein (HBc) was measured in hepatoma cells. The expression of NEU1 protein was detected via immunohistochemical analysis in HBV-associated HCC tissues. The role of NEU1 in the activation of signaling pathways and epithelial-mesenchymal transition (EMT) and the proliferation and migration of hepatoma cells mediated by HBc was assessed. We found that NEU1 was upregulated in HBV-positive hepatoma cells and HBV-related HCC tissues. HBV promoted NEU1 expression at the mRNA and protein level via HBc in hepatoma cells. Mechanistically, HBc was able to enhance the activity of the NEU1 promoter through NF-κB binding sites. In addition, through the increase in NEU1 expression, HBc contributed to activation of downstream signaling pathways and EMT in hepatoma cells. Moreover, NEU1 facilitated the proliferation and migration of hepatoma cells mediated by HBc. Taken together, our findings provide novel insight into the molecular mechanism underlying the oncogenesis mediated by HBc and demonstrate that NEU1 plays a vital role in HBc-mediated functional abnormality in HCC. Thus, NEU1 may serve as a potential therapeutic target in HBV-associated HCC.

Prognostic implications of alcohol dehydrogenases in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is a malignancy with high incidence and mortality rates worldwide. Alcohol dehydrogenases (ADHs) are huge family of dehydrogenase enzymes and associated with the prognosis of various cancers. However, comprehensive analysis of prognostic implications related to ADHs in HCC is still lacking and largely unknown. METHODS: The expression profiles and corresponding clinical information of HCC were obtained from The Cancer Genome Atlas (TCGA). Wilcoxon signed-rank test was employed to evaluate the expression of ADHs. Cox regression and Kaplan-Meier analyses were used to investigate the association between clinicopathological characteristics and survival. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) enrichment analyses were performed and visualized using R/BiocManager package. RESULTS: We found that the expression of ADH1A, ADH1B, ADH1C, ADH4, and ADH6 was significantly downregulated in HCC samples compared to normal liver samples. Our univariate and multivariate Cox regression analyses results showed that high expression of ADH1A, ADH1B, ADH1C, ADH4, and ADH6 was considered as an independent factor with an improved prognosis for the survival of HCC patients. Moreover, our Kaplan-Meier analysis results also revealed that high expression of AHD1A, ADH1B, ADH1C, ADH4, and ADH6 was significantly associated with good survival rate in HCC patients. In addition, GO, KEGG, and GSEA analyses unveiled several oncogenic signaling pathways were negatively associated high expression of ADHs in HCC. CONCLUSION: In the present study, our results provide the potential prognostic biomarkers or molecular targets for the patients with HCC.

Correction to: Role of hepatitis B virus X protein in regulating LIM and SH3 protein 1 (LASP-1) expression to mediate proliferation and migration of hepatoma cells.

An amendment to this paper has been published and can be accessed via the original article.

Herpes Simplex Virus 1 UL36USP Antagonizes Type I Interferon-Mediated Antiviral Innate Immunity.

Type I interferons (IFNs), as major components of the innate immune system, play a vital role in host resistance to a variety of pathogens. Canonical signaling mediated by type I IFNs activates the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway through binding to the IFN-α/ß receptor (IFNAR), resulting in transcription of IFN-stimulated genes (ISGs). However, viruses have evolved multiple strategies to evade this process. Here, we report that herpes simplex virus 1 (HSV-1) ubiquitin-specific protease (UL36USP) abrogates the type I IFN-mediated signaling pathway independent of its deubiquitinase (DUB) activity. In this study, ectopically expressed UL36USP inhibited IFN-ß-induced activation of ISRE promoter and transcription of ISGs, and overexpression of UL36USP lacking DUB activity did not influence this effect. Furthermore, UL36USP was demonstrated to antagonize IFN-ß-induced activation of JAKs and STATs via specifically binding to the IFNAR2 subunit and blocking the interaction between JAK1 and IFNAR2. More importantly, knockdown of HSV-1 UL36USP restored the formation of JAK1-IFNAR2 complex. These findings underline the roles of UL36USP-IFNAR2 interaction in counteracting the type I IFN-mediated signaling pathway and reveal a novel evasion mechanism of antiviral innate immunity by HSV-1.IMPORTANCE Type I IFNs mediate transcription of numerous antiviral genes, creating a remarkable antiviral state in the host. Viruses have evolved various mechanisms to evade this response. Our results indicated that HSV-1 encodes a ubiquitin-specific protease (UL36USP) as an antagonist to subvert type I IFN-mediated signaling. UL36USP was identified to significantly inhibit IFN-ß-induced signaling independent of its deubiquitinase (DUB) activity. The underlying mechanism of UL36USP antagonizing type I IFN-mediated signaling was to specifically bind with IFNAR2 and disassociate JAK1 from IFNAR2. For the first time, we identify UL36USP as a crucial suppressor for HSV-1 to evade type I IFN-mediated signaling. Our findings also provide new insights into the innate immune evasion by HSV-1 and will facilitate our understanding of host-virus interplay.

Herpes Simplex Virus 1 Tegument Protein VP22 Abrogates cGAS/STING-Mediated Antiviral Innate Immunity.

Cytosolic DNA arising from intracellular pathogens is sensed by cyclic GMP-AMP synthase (cGAS) and triggers a powerful innate immune response. However, herpes simplex virus 1 (HSV-1), a double-stranded DNA virus, has developed multiple mechanisms to attenuate host antiviral machinery and facilitate viral infection and replication. In the present study, we found that HSV-1 tegument protein VP22 acts as an inhibitor of cGAS/stimulator of interferon genes (cGAS/STING)-mediated production of interferon (IFN) and its downstream antiviral genes. Our results showed that ectopic expression of VP22 decreased cGAS/STING-mediated IFN-ß promoter activation and IFN-ß production. Infection with wild-type (WT) HSV-1, but not VP22-deficient virus (ΔVP22), inhibited immunostimulatory DNA (ISD)-induced activation of the IFN signaling pathway. Further study showed that VP22 interacted with cGAS and inhibited the enzymatic activity of cGAS. In addition, stable knockdown of cGAS facilitated the replication of ΔVP22 virus but not the WT. In summary, our findings indicate that HSV-1 VP22 acts as an antagonist of IFN signaling to persistently evade host innate antiviral responses.IMPORTANCE cGAS is very important for host defense against viral infection, and many viruses have evolved ways to target cGAS and successfully evade the attack by the immune system of their susceptible host. This study demonstrated that HSV-1 tegument protein VP22 counteracts the cGAS/STING-mediated DNA-sensing antiviral innate immunity signaling pathway by inhibiting the enzymatic activity of cGAS. The findings in this study will expand our understanding of the interaction between HSV-1 replication and the host DNA-sensing signaling pathway.

The interaction of hepatitis B virus with the ubiquitin proteasome system in viral replication and associated pathogenesis.

BACKGROUND: The ubiquitin proteasome system (UPS) regulates the expression levels of cellular proteins by ubiquitination of protein substrates followed by their degradation via the proteasome. As a highly conserved cellular degradation mechanism, the UPS affects a variety of biological processes and participates in viral propagation. MAIN BODY: During hepatitis B virus (HBV) infection, the UPS is shown to act as a double-edged sword in viral pathogenesis. On the one hand, the UPS acts as a host defense mechanism to selectively recognize HBV proteins as well as special cellular proteins that favor the viral life cycle and induces their ubiquitin-dependent proteasomal degradation to limit HBV infection. On the other hand, the HBV has evolved to subvert the UPS function for its own advantage. Moreover, in the infected hepatocytes, certain cellular proteins that are dependent on the UPS are involved in abnormal biological processes which are mediated by HBV. CONCLUSION: The molecular interaction of HBV with the UPS to modulate viral propagation and pathogenesis is summarized in the review. Considering the important role of the UPS in HBV infection, a better understanding of the HBV-UPS interaction could provide novel insight into the mechanisms that are involved in viral replication and pathogenesis and help to develop potential treatment strategies targeting the UPS.

HBX protein promotes LASP-1 expression through activation of c-Jun in human hepatoma cells.

LIM and SH3 domain protein 1 (LASP-1) is known to participate in the progression of hepatocellular carcinoma (HCC). We previously showed that ectopic expression of hepatitis B virus (HBV) X protein (HBX) enhanced the expression of LASP-1, which promoted proliferation and migration of HCC cells. Here, we further demonstrated the molecular mechanism underlying upregulation of LASP-1, mediated by HBX, in HBV-infected HCC cells. Through a luciferase activity assay, we discovered that the LASP-1 promoter region regulated by HBX contained an AP-1 binding element in human hepatoma cells. Interestingly, c-Jun, one subunit of AP-1, was mainly responsible for activation, mediated by HBX, of the LASP-1 promoter. Furthermore, HBX was shown not only to interact with phosphorylated c-Jun in HCC cells but also to activate c-Jun by increasing the activation of PI3-K/JNK signaling. Chromatin immunoprecipitation (ChIP) assay demonstrated that HBX was capable of binding to the LASP-1 promoter with c-Jun. Further, the expression levels of HBX were shown to be significantly positively correlated with that of LASP-1 and phosphorylatedc-Jun in HBV-related HCC tissues by immunohistochemistry analysis. In addition, the N-terminus of HBX was found to be responsible for the activation of c-Jun, as well as the expression of LASP-1. Taken together, these results suggest that HBX contributes to LASP-1 expression via the activation of c-Jun to increase the promoter activity of LASP-1 in HBV-related HCC cells.

The enhanced expression of death receptor 5 (DR5) mediated by HBV X protein through NF-kappaB pathway is associated with cell apoptosis induced by (TNF-α related apoptosis inducing ligand) TRAIL in hepatoma cells.

BACKGROUND: HBV X protein (HBX) is associated with cell apoptosis mediated by TNF-α related apoptosis inducing ligand (TRAIL), while the role of HBX on the expressions of TRAIL receptors death receptor 4 (DR4) and DR5 are unclear. In this study, we detected the cell apoptosis induced by TRAIL as well as gene and protein expressions of DR4 and DR5 in Huh-7 cells steadily transfected with HBX (Huh-7-HBX cells). In addition, we investigated the activation of different pathways associated with the expressions of TRAIL receptors in Huh-7-HBX cells. METHODS: The apoptosis of Huh-7-HBX cells induced by TRAIL was evaluated by flow cytometry analysis. The levels of DR4 and DR5 expression in cells were determined by real-time PCR and western blotting analysis. The activities of JNK pathway and NF-kappaB (NF-κB) pathway were demonstrated by western blotting assay. RESULTS: Compared to control cells, the percentage of cell apoptosis was increased in Huh-7-HBX cells. The increased expressions of DR4 and DR5 on gene and protein levels were observed in Huh-7-HBX cells. Further researches suggested that activation of JNK pathway was increased but not involved in the expression of TRAIL receptors in HBX positive cells. The activation of NF-κB pathway increased and was responsible for DR5 expression and cell apoptosis in HBX positive cells. CONCLUSIONS: These results demonstrate that increased apoptosis induced by TRAIL is associated with increased expression of DR5 that mediated by HBX through NF-κB pathway. This finding provides a critical insight into the mechanism of hepatocyte apoptosis mediated by HBX in HBV infection.