Hepatitis B virus-related hepatocellular carcinoma: paradigms for viral-related human carcinogenesis

Optimization and Synthesis of Pyridazinone Derivatives as Novel Inhibitors of Hepatitis B Virus by Inducing Genome-free Capsid Formation

The capsid of hepatitis B virus (HBV) plays a vital role in virus DNA replication. Targeting nucleocapsid function has been demonstrated as an effective approach for anti-HBV drug development. A high-throughput screening and mechanism study revealed the hit compound 4a as an HBV assembly effector (AEf), which could inhibit HBV replication by inducing the formation of HBV DNA-free capsids. The subsequent SAR study and drug-like optimization resulted in the discovery of the lead candidate 4r, with potent antiviral activity (IC₅₀ = 0.087 ± 0.002 μM), low cytotoxicity (CC₅₀ = 90.6 ± 2.06 μM), sensitivity to nucleoside analogue-resistant HBV mutants, and synergistic effect with nucleoside analogues in HepG2.2.15 cells.

Hepatitis B virus X protein binding to hepsin promotes C3 production by inducing IL-6 secretion from hepatocytes

Hepatitis B virus (HBV) X protein (HBx) is an important effector for HBV-associated pathogenesis. In this study, we identified hepsin as an HBx-interacting protein and investigated the effects of hepsin on HBx-mediated complement component 3 (C3) secretion in hepatocytes. In vivo and in vitro binding between HBx and hepsin was confirmed by co-immunoprecipitation and Glutathione S-transferase pull-down assays. HBx synergized with hepsin to promote C3 production by potentiating interleukin-6 (IL-6) secretion. Knockdown of endogenous hepsin attenuated C3 and IL-6 secretion induced by HBx in hepatic cells. In addition, levels of hepsin protein correlated positively with C3 expression in human non-tumor liver tissues. Further exploration revealed that HBx and hepsin increased C3 promoter activity by up-regulating the expression and phosphorylation of the transcription factor CAAT/enhancer binding protein beta (C/EBP-β), which binds to the IL-6/IL-1 response element in the C3 promoter. HBx and hepsin synergistically enhanced IL-6 mRNA levels and promoter activity by increasing the nuclear translocation of nuclear factor kappaB (NF-κB). Our findings show for the first time that binding between HBx and hepsin promotes C3 production by inducing IL-6 secretion in hepatocytes.

Molecular Pathogenesis of Hepatocellular Carcinoma

The pathogenesis of hepatocellular carcinoma (HCC) is a multistep process involving the progressive accumulation of molecular alterations pinpointing different molecular and cellular events. The next-generation sequencing technology is facilitating the global and systematic evaluation of molecular landscapes in HCC. There is emerging evidence supporting the importance of cancer metabolism and tumor microenvironment in providing a favorable and supportive niche to expedite HCC development. Moreover, recent studies have identified distinct surface markers of cancer stem cell (CSC) in HCC, and they also put forward the profound involvement of altered signaling pathways and epigenetic modifications in CSCs, in addition to the concomitant drug resistance and metastasis. Taken together, multiple key genetic and non-genetic factors, as well as liver CSCs, result in the development and progression of HCC.

X region mutations of hepatitis B virus related to clinical severity

Chronic hepatitis B virus (HBV) infection remains a major health problem, with more than 240 million people chronically infected worldwide and potentially 650000 deaths per year due to advanced liver diseases including liver cirrhosis and hepatocellular carcinoma (HCC). HBV-X protein (HBx) contributes to the biology and pathogenesis of HBV via stimulating virus replication or altering host gene expression related to HCC. The HBV X region contains only 465 bp encoding the 16.5 kDa HBx protein, which also contains several critical cis-elements such as enhancer II, the core promoter and the microRNA-binding region. Thus, mutations in this region may affect not only the HBx open reading frame but also the overlapped cis-elements. Recently, several types of HBx mutations significantly associated with clinical severity have been described, although the functional mechanism in most of these cases remains unsolved. This review article will mainly focus on the HBx mutations proven to be significantly related to clinical severity via epidemiological studies.

HBV-associated intrahepatic cholangiocarcinoma with high serum alpha-fetoprotein: a case report with review of literature

Background

Intrahepatic cholangiocarcinoma (ICC) is a rare malignant tumor. The etiology of ICC remains poorly understood. Recently, hepatitis B virus (HBV) infection has been implicated as a potential risk factor for ICC, particularly in HBV-endemic areas. Elevation of serum alpha-fetoprotein (AFP) is seen in approximately 20 % of ICC patients. However, serum AFP levels higher than 10,000 ng/mL have only been reported in a few ICC patients. We report an unusual case of HBV-associated ICC occurring in a male with a markedly elevated serum AFP.

Case presentation

A 60-year-old East Asian male presented with complaints of epigastric distention and right shoulder pain. Laboratory tests showed HBV infection, HBV deoxyribonucleic acid (DNA) slightly elevated (21 IU/mL) and serum AFP markedly elevated (12,310 ng/mL). Computed tomography (CT) scan found a large and irregular mass in the left lobe of the liver. The patient underwent the left hepatic lobe resection. Histopathological examination showed chronic hepatitis B in the background liver and the immunohistochemical (IHC) findings strongly supported the diagnosis of ICC with aberrant expression of AFP. Serum AFP and HBV DNA declined to normal level postoperatively. The patient received four cycles of gemcitabine plus oxaliplatin and took entecavir to prevent HBV reactivation. The patient kept disease free for 18 months in the latest follow-up.

Conclusion

ICC patients with HBV infection should be distinguished from other ICC cases, based on distinct clinicopathological features and favorable outcome. Screening for HBV infection should be carried out before initiation of chemotherapy. Antiviral therapy is indicated for prevention of HBV reactivation.

Dietary fatty acids and risk of hepatocellular carcinoma in the Singapore Chinese health study

BACKGROUND & AIM

Lipidomic signature of lipid metabolism suggests that omega-6 polyunsaturated fatty acids (PUFA) may play a role in oncogenesis of hepatocellular carcinoma (HCC). Hence, we examined the association between dietary fatty acids and risk of HCC.

METHODS

We used data from the Singapore Chinese Health Study, a population-based prospective cohort of 63 257 Chinese men and women aged 45-74 years enrolled between 1993 and 1998. Information on current diet assessed via a validated semi-quantitative food frequency questionnaire, medical history and lifestyle factors were obtained through in-person interview, and incidence of HCC recorded through 31 Dec 2010. We also examined the association between dietary fatty acids and HCC risk using a case-control set of 92 cases and 274 controls with available serological biomarkers of chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) nested within this cohort.

RESULTS

Among the dietary fat components examined, which included saturated, monounsaturated, omega-3 and omega-6 PUFA, only omega-6 PUFA intake displayed a dose-dependent, positive association with HCC risk (p for trend = 0.02). Compared to the lowest quartile, the hazard ratio for the highest quartile intake was 1.49 [(95% confidence interval (CI):1.08-2.07)]. In the nested case-control study, only among individuals negative for serology markers of chronic infection with HBV or HCV, those who consumed above median levels of dietary omega-6 PUFA had increased HCC risk (odds ratio = 4.36, 95% CI = 1.59-11.94) compared to those with lower intake.

CONCLUSION

Dietary omega-6 PUFA may be implicated in the risk of non-viral hepatitis related HCC.

HCV core protein-induced upregulation of microRNA-196a promotes aberrant proliferation in hepatocellular carcinoma by targeting FOXO1

The hepatitis C virus (HCV) core protein is critical in the development of hepatocellular carcinoma (HCC). Investigations on HCC have previously focused on microRNAs, a class of small non‑coding RNAs, which are crucial in cancer development and progression. The present study aimed to investigate whether microRNA (miR)‑196a is aberrantly regulated by the HCV core protein, and whether miR‑196a is involved in the regulation of the aberrant proliferation of HCV‑HCC cells. In the study, miRNA expression was detected by quantitative polymerase chain reaction analysis. An Ad‑HCV core adenovirus was constructed and cell proliferation was measured using a Cell Counting Kit-8 assay and a cell cycle assay following infection. The results of the present study demonstrated that the HCV core protein increased the expression of miR‑196a, and that overexpression of miR‑196a in the HepG2 and Huh‑7 HCC cell lines promoted cell proliferation by inducing the G1‑S transition. Furthermore, the present study demonstrated that forkhead box O1 (FOXO1) was directly regulated by miR‑196a, and was essential in mediating the biological effects of miR‑196a in HCC. The overexpression of FOXO1 markedly reversed the effect of miR‑196a in HCC cell proliferation. Taken together, the data obtained in the present study provided compelling evidence that elevated expression levels of miR‑196a by the HCV core protein can function as an onco‑microRNA during HCV‑induced cell proliferation by downregulating the expression of FOXO1, indicating a potential novel therapeutic target for HCV-related HCC.

Nuclear Expression of Hepatitis B Virus X Protein Is Associated with Recurrence of Early-Stage Hepatocellular Carcinomas: Role of Viral Protein in Tumor Recurrence

Background:

Hepatitis B virus (HBV) plays well-known roles in tumorigenesis of hepatocellular carcinoma (HCC) in infected patients. However, HBV-associated protein status in tumor tissues and the relevance to tumor behavior has not been reported. Our study aimed to examine the expression of HBV-associated proteins in HCC and adjacent nontumorous tissue and their clinicopathologic implication in HCC patients.

Methods:

HBV surface antigen (HBsAg), HBV core antigen (HBcAg), and HBV X protein (HBx) were assessed in 328 HBV-associated HCCs and in 155 matched nontumorous tissues by immunohistochemistry staining.

Results:

The positive rates of HBsAg and cytoplasmic HBx staining in tumor tissue were lower than those in nontumorous tissue (7.3% vs. 57.4%, p < .001; 43.4% vs. 81.3%, p < .001). Conversely, nuclear HBx was detected more frequently in tumors than in nontumorous tissue (52.1% vs. 30.3%, p < .001). HCCs expressing HBsAg, HBcAg, or cytoplasmic HBx had smaller size; lower Edmondson-Steiner (ES) nuclear grade, pT stage, and serum alpha-fetoprotein, and less angioinvasion than HCCs not expressing HBV-associated proteins. Exceptionally, nuclear HBx-positive HCCs showed higher ES nuclear grade and more frequent large-vessel invasion than did nuclear HBx-negative HCCs. In survival analysis, only nuclear HBx-positive HCCs had shorter disease-free survival than nuclear HBx-negative HCCs in pT1 and ES nuclear grade 1–2 HCC subgroup (median, 126 months vs. 35 months; p = .015).

Conclusions:

Our data confirmed that expression of normal HBV-associated proteins generally decreases in tumor cells in comparison to nontumorous hepatocytes, with the exception of nuclear HBx, which suggests that nuclear HBx plays a role in recurrence of well-differentiated and early-stage HCCs.

Structural and biochemical analysis of Bcl-2 interaction with the hepatitis B virus protein HBx

HBx is a hepatitis B virus protein that is required for viral infectivity and replication. Anti-apoptotic Bcl-2 family members are thought to be among the important host targets of HBx. However, the structure and function of HBx are poorly understood and the molecular mechanism of HBx-induced carcinogenesis remains unknown. In this study, we report biochemical and structural characterization of HBx. The recombinant HBx protein contains metal ions, in particular iron and zinc. A BH3-like motif in HBx (residues 110-135) binds Bcl-2 with a dissociation constant of ∼193 μM, which is drastically lower than that for a canonical BH3 motif from Bim or Bad. Structural analysis reveals that, similar to other BH3 motifs, the BH3-like motif of HBx adopts an amphipathic α-helix and binds the conserved BH3-binding groove on Bcl-2. Unlike the helical Bim or Bad BH3 motif, the C-terminal portion of the bound HBx BH3-like motif has an extended conformation and makes considerably fewer interactions with Bcl-2. These observations suggest that HBx may modulate Bcl-2 function in a way that is different from that of the classical BH3-only proteins.

Epigenetic impact of infection on carcinogenesis: mechanisms and applications

Viral and bacterial infections are involved in the development of human cancers, such as liver, nasopharyngeal, cervical, head and neck, and gastric cancers. Aberrant DNA methylation is frequently present in these cancers, and some of the aberrantly methylated genes are causally involved in cancer development and progression. Notably, aberrant DNA methylation can be present even in non-cancerous or precancerous tissues, and its levels correlate with the risk of cancer development, producing a so-called 'epigenetic field for cancerization'. Mechanistically, most viral or bacterial infections induce DNA methylation indirectly via chronic inflammation, but recent studies have indicated that some viruses have direct effects on the epigenetic machinery of host cells. From a translational viewpoint, a recent multicenter prospective cohort study demonstrated that assessment of the extent of alterations in DNA methylation in non-cancerous tissues can be used to predict cancer risk. Furthermore, suppression of aberrant DNA methylation was shown to be a useful strategy for cancer prevention in an animal model. Here, we review the involvement of aberrant DNA methylation in various types of infection-associated cancers, along with individual induction mechanisms, and we discuss the application of these findings for cancer prevention, diagnosis, and therapy.

Hepatitis B Virus HBx Activates Notch Signaling via Delta-Like 4/Notch1 in Hepatocellular Carcinoma

Hepatitis virus B (HBV) infection is one of the major causes of hepatocellular carcinomas (HCC). HBx protein encoded in HBV genome is one of the key viral factors leading to malignant transformation of infected cells. HBx functions by interfering with cellular functions, causing aberration in cellular behaviour and transformation. Notch signalling is a well-conserved pathway involved in cellular differentiation, cell survival and cell death operating in various types of cells. Aberration in the Notch signalling pathways is linked to various tumors, including HCC. The role of HBx on the Notch signalling in HCC, however, is still controversial. In this study, we reported that HBV genome-containing HCC cell line HepG2 (HepG2.2.15) expressed higher Notch1 and Delta-like 4 (Dll4), compared to the control HepG2 without HBV genome. This upregulation coincided with increased appearance of the cleavage of Notch1, indicating constitutively activated Notch signalling. Silencing of HBx specifically reduced the level of Dll4 and cleaved Notch1. The increase in Dll4 level was confirmed in clinical specimens of HCC lesion, in comparison with non-tumor lesions. Using specific signalling pathway inhibitors, we found that MEK1/2, PI3K/AKT and NF-κB pathways are critical for HBx-mediated Dll4 upregulation. Silencing of HBx clearly decreased the level of phosphorylation of Akt and Erk1/2. Upon silencing of Dll4 in HepG2.2.15, decreased cleaved Notch1, increased apoptosis and cell cycle arrest were observed, suggesting a critical role of HBx-Dll4-Notch1 axis in regulating cell survival in HCC. Furthermore, clonogenic assay confirmed the important role of Dll4 in regulating cell survival of HBV-genome containing HCC cell line. Taken together, we reported a link between HBx and the Notch signalling in HCC that affects cell survival of HCC, which can be a potential target for therapy.

Hepatocellular carcinoma mouse models: Hepatitis B virus-associated hepatocarcinogenesis and haploinsufficient tumor suppressor genes

The multifactorial and multistage pathogenesis of hepatocellular carcinoma (HCC) has fascinated a wide spectrum of scientists for decades. While a number of major risk factors have been identified, their mechanistic roles in hepatocarcinogenesis still need to be elucidated. Many tumor suppressor genes (TSGs) have been identified as being involved in HCC. These TSGs can be classified into two groups depending on the situation with respect to allelic mutation/loss in the tumors: the recessive TSGs with two required mutated alleles and the haploinsufficient TSGs with one required mutated allele. Hepatitis B virus (HBV) is one of the most important risk factors associated with HCC. Although mice cannot be infected with HBV due to the narrow host range of HBV and the lack of a proper receptor, one advantage of mouse models for HBV/HCC research is the numerous and powerful genetic tools that help investigate the phenotypic effects of viral proteins and allow the dissection of the dose-dependent action of TSGs. Here, we mainly focus on the application of mouse models in relation to HBV-associated HCC and on TSGs that act either in a recessive or in a haploinsufficient manner. Discoveries obtained using mouse models will have a great impact on HCC translational medicine.

Hepatitis B and elders: An underestimated issue

As the world's population becomes older, the burden of hepatitis B virus in elderly has to be considered. The liver changes with aging and its function is eventually altered. The prevalence of hepatitis B virus is paradoxically more important in elderly in areas having vaccination programs, because of a loosening of the prevention in older patients. Some differences in hepatitis B presentation must be enhanced in elderly: lower spontaneous hepatitis B surface antigen clearance after a recent contamination, major risk of cirrhosis and hepatocarcinoma. Acute hepatitis B seems to be more often symptomatic, with a great risk of chronicity. Hepatocarcinoma linked to hepatitis B virus has a higher prevalence and a different presentation in elderly. Its treatment is the same as in younger people but is less often possible. Liver transplantation is contraindicated after 70 years old. Hepatitis B treatment panel is the same as in younger people (pegylated interferon, nucleoside or nucleotide agents). It gives identical results with no particular adverse events if the precautions for use are followed. Vaccination is less efficient, as in immunocompromised patients, and needs specific protocols.

Association between hepatocellular carcinoma and tumor necrosis factor alpha polymorphisms in South Korea

AIM: To investigate associations between the tumor necrosis factor alpha (TNF-α) -1031 T>C, -863 C>A, -857 C>T, -308 G>A, and -238 G>A polymorphisms and HCC in Korea.

METHODS: Hepatocellular carcinoma (HCC) cases were diagnosed at CHA Bundang Medical Center from June 1996 to August 2008. The association between TNF-α polymorphisms and HCC was analyzed in 157 HCC patients and 201 controls using a polymerase chain reaction-restriction fragment length polymorphism assay. We investigated five TNF-α polymorphisms, which are TNF-α -1031 T>C, -863 C>A, -857 C>T, -308 G>A, and -238 G>A. The TNF-α genotype frequencies, genotype combinations and haplotypes were analyzed to disclose the association with HCC.

RESULTS: None of the TNF-α polymorphisms was significantly associated with HCC. However, nine genotype combinations had associations with increased likelihood of HCC. Among them, TNF-α -1031/-857/-238 TT/CC/GA (AOR = 18.849, 95%CI: 2.203-161.246, P = 0.007), TNF-α -1031/-308/-238 TT/GG/GA (AOR = 26.956, 95%CI: 3.071-236.584, P = 0.003), and TNF-α -1031/-238 TT/GA (AOR = 21.576, 95%CI: 2.581-180.394, P = 0.005) showed marked association with HCC. There were five haplotypes of TNF-α polymorphisms which were significantly associated with HCC. They are TNF-α -1031/-863/-857/-308/-238 T-C-C-G-A (OR = 25.824, 95%CI: 1.491-447.223, P = 0.0005), TNF-α -1031/-857/-308/-238 T-C-G-A (OR = 12.059, 95%CI: 2.747-52.950, P < 0.0001), TNF-α -1031/-857/-238 T-C-A (OR = 10.696, 95%CI: 2.428-47.110, P = 0.0001), TNF-α -1031/-308/-238 T-G-A (OR = 7.556, 95%CI: 2.173-26.280, P = 0.0002) and TNF-α -1031/-238 T-A (OR = 10.865, 95%CI: 2.473-47.740, P = 0.0001). Moreover, HCC Okuda stage III cases with the TNF-α -1031 CC genotype had better survival than those with the TT genotype (AOR = 5.795, 95%CI: 1.145-29.323).

CONCLUSION: Although no single TNF-α polymorphism is associated with HCC in this study, some TNF-α genotype combinations and haplotypes are associated with HCC. In addition, HCC Okuda stage III cases with the TNF-α -1031 TT genotype may have a better prognosis than those with the CC genotype.

Wild type HBx and truncated HBx: Pleiotropic regulators driving sequential genetic and epigenetic steps of hepatocarcinogenesis and progression of HBV-associated neoplasms

Hepatitis B virus (HBV) is one of the causative agents of hepatocellular carcinoma. The molecular mechanisms of tumorigenesis are complex. One of the host factors involved is apparently the long-lasting inflammatory reaction which accompanies chronic HBV infection. Although HBV lacks a typical viral oncogene, the HBx gene encoding a pleiotropic regulatory protein emerged as a major player in liver carcinogenesis. Here we review the tumorigenic functions of HBx with an emphasis on wild type and truncated HBx variants, and their role in the transcriptional dysregulation and epigenetic reprogramming of the host cell genome. We suggest that HBx acquired by the HBV genome during evolution acts like a cellular proto-onc gene that is activated by deletion during hepatocarcinogenesis. The resulting viral oncogene (v-onc gene) codes for a truncated HBx protein that facilitates tumor progression. Copyright © 2015 John Wiley & Sons, Ltd.

TCLP: an online cancer cell line catalogue integrating HLA type, predicted neo-epitopes, virus and gene expression

Human cancer cell lines are an important resource for research and drug development. However, the available annotations of cell lines are sparse, incomplete, and distributed in multiple repositories. Re-analyzing publicly available raw RNA-Seq data, we determined the human leukocyte antigen (HLA) type and abundance, identified expressed viruses and calculated gene expression of 1,082 cancer cell lines. Using the determined HLA types, public databases of cell line mutations, and existing HLA binding prediction algorithms, we predicted antigenic mutations in each cell line. We integrated the results into a comprehensive knowledgebase. Using the Django web framework, we provide an interactive user interface with advanced search capabilities to find and explore cell lines and an application programming interface to extract cell line information. The portal is available at http://celllines.tron-mainz.de.

The pan-cancer analysis of gene expression patterns in the context of inflammation

Although several studies have investigated the essential roles of inflammation in tumor progression, not many have systematically analyzed gene expression patterns across diverse cancers in the context of inflammation. In this study, in order to better understand the inflammatory scenario, we initially constructed the inflammatory timeline (IT) based on two gene expression profiles during inflammatory progression (inflammatory bowel disease and Helicobacter pylori infection). Then, we separately identified the differentially expressed genes (DEGs) from 25 cancer-related microarray data. By comparing the distributions of DEGs in the IT, we identified three novel pan-cancer gene expression patterns. In the first pattern, the up-regulated genes in cancers were over-expressed in the early phase of inflammation, while the down-regulated genes were over-expressed in the late phase of inflammation. The second pattern was the opposite of the first one. The third pattern appeared to be transitional between the first and second patterns. We found that some cancers with different tissue origins have similar gene expression patterns. Finally, we identified two sets of tissue-independent inflammatory signatures that were over-expressed in early and late phases of inflammation, respectively. The dominant biological processes of early inflammatory signatures were cell proliferation, DNA replication, and DNA repair, whereas the late inflammatory signatures were reflective of innate immune response, neutrophil migration, and antigen processing. These inflammatory signatures may be useful to predict gene expression patterns in human cancers. Therefore, the pan-cancer analysis of gene expression patterns in the context of inflammation provides a novel insight into cancers and an unprecedented opportunity to develop new therapies.

Regulation of HBV-specific CD8(+) T cell-mediated inflammation is diversified in different clinical presentations of HBV infection

Chronic HBV infection is the leading cause of liver cirrhosis and hepatic cancer, but the individual responses toward HBV infection are highly variable, ranging from asymptomatic to chronic active hepatitis B inflammation. In this study, we hypothesized that the different individual responses to HBV infection was associated with differences in HBV-specific CD8(+) T cell-mediated inflammation and cytotoxicity. Blood samples were collected from subjects with asymptomatic HBV-infection, subjects undergoing active chronic HBV flares (active CHB), and subjects with HBV-infected hepatocellular carcinoma (HBV-HCC). By tetramer staining, we found that all three groups had similar frequencies of HBVspecific CD8(+) T cells. However, after HBV peptide stimulation, the HBV-specific CD8(+) T cells in asymptomatic subjects had significantly stronger interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and CD107a expression than those in active CHB and HBV-HCC patients. Examination of surface marker expression revealed that the PD-1(-)Tim-3(-) double-negative cell population was the main contributor to HBV-specific inflammation. In active CHB patients and HBV-HCC patients, however, the frequencies of activated PD-1(-)Tim-3(-) cells were significantly reduced. Moreover, the serum HBV DNA titer was not correlated with the frequencies of HBV-specific CD8(+) T cells but was inversely correlated with the frequencies of IFN-g-expressing and CD107a-express cells in response to HBV stimulation. Together, our data demonstrated that the status of HBVspecific CD8(+) T cell exhaustion was associated with different clinical outcomes of chronic HBV infection.

[Management of hepatitis B virus and hepatitis C virus infection in chronic kidney failure]

Chronic infections by hepatitis B (HBV) and C virus (HCV) result in diagnosis and therapeutic issues in dialysis and kidney recipients patients. The exposure to nosocomial, including blood transfusion, risk explains the high prevalence of HBV and HCV infection in this setting. Chronic infection reduces the survival of both patients and allografts, including a specific risk of de novo glomerulonephritis. Cirrhosis was considered as a contra-indication to renal transplantation given the high risk of decompensation and death, questionning the indication of a combined liver and kidney transplantation. Thus, it is mandatory to screen HBV and HCV markers in all dialysis patients, whether or not they are candidates to transplantation. Liver biopsy allows evaluating the severity of the liver disease since the noninvasive markers of fibrosis appear to be less accurate in "renal" patients than in the general population and to better define antiviral therapeutic indications. HCV treatment was mainly based on pegylated interferon α (and low doses of ribavirin), which is contra-indicated in kidney recipients given the risk of graft rejection; HCV treatment is now based on the use of oral direct acting antivirals, which are very potent and well tolerated. HBV replication is now easily suppressed by second-generation nucleos(t)tidic analogues (entecavir and tenofovir), which will be indicated in all the dialysis patients with significant fibrosis (F2,3 or 4 according to the Metavir scoring system) and in any candidate to renal transplantation and to any HBsAg-positive kidney recipients. The best treatment remains preventive by anti-HBV vaccination for HBV and by the respect of universal hygiene rules for HCV.

Mouse Models of Hepatitis B Virus Pathogenesis

The host range of hepatitis B virus (HBV) is limited to humans and chimpanzees. As discussed in the literature, numerous studies in humans and chimpanzees have generated a great deal of information on the mechanisms that cause viral clearance, viral persistence, and disease pathogenesis during acute or chronic HBV infection. Relevant pathogenetic studies have also been performed in those few species representing natural hosts of hepadnaviruses that are related to HBV, such as the woodchuck hepatitis virus and the duck hepatitis virus. Further insight has been gained from multidisciplinary studies in transgenic or humanized chimeric mouse models expressing and/or replicating HBV to varying degrees. We provide here a concise summary of the available HBV mouse models as well as of the contributions of these models to our understanding of HBV pathogenesis.

New Insights into Orphan Nuclear Receptor SHP in Liver Cancer

Small heterodimer partner (SHP; NR0B2) is a unique orphan nuclear receptor (NR) that contains a putative ligand-binding domain but lacks a DNA-binding domain. SHP is a transcriptional corepressor affecting diverse metabolic processes including bile acid synthesis, cholesterol and lipid metabolism, glucose and energy homeostasis, and reproductive biology via interaction with multiple NRs and transcriptional factors (TFs). Hepatocellular carcinoma (HCC) is one of the most deadly human cancers worldwide with few therapeutic options and poor prognosis. Recently, it is becoming clear that SHP plays an antitumor role in the development of liver cancer. In this review, we summarize the most recent findings regarding the new SHP interaction partners, new structural insights into SHP’s gene repressing activity, and SHP protein posttranslational modifications by bile acids. We also discuss the pleiotropic role of SHP in regulating cell proliferation, apoptosis, DNA methylation, and inflammation that are related to antitumor role of SHP in HCC. Improving our understanding of SHP’s antitumor role in the development of liver cancer will provide new insights into developing novel treatments or prevention strategies. Future research will focus on developing more efficacious and specific synthetic SHP ligands for pharmaceutical applications in liver cancer and several metabolic diseases such as hypercholesterolemia, obesity, diabetes, and fatty liver disease.

Identification of HBV-MLL4 Integration and Its Molecular Basis in Chinese Hepatocellular Carcinoma

To gain molecular insights of HBV integration that may contribute to HCC tumorigenesis, we performed whole transcriptome sequencing and whole genome copy number profiling of hepatocellular carcinoma (HCC) samples from 50 Chinese patients. We identified a total of 33 HBV-human integration sites in 16 of 44 HBV-positive HCC tissues, which were enriched in HBV genotype C-infected patients. In addition, significantly recurrent HBV-MLL4 integration (18%; 8/44) was found in this cohort of patients. Using long-range PCR and Sanger sequencing, we comprehensively characterized gDNA and cDNA sequences that encode for the HBV-MLL4 transcripts, and we revealed that HBV integration into MLL4 exons led to much higher mRNA expression of MLL4 than the integration into MLL4 introns due to an alternative splicing mechanism. Moreover, the HBV-MLL4 integration occurred almost exclusively in CTNNB1 and TP53 wild-type patients. The integration was also associated with a distinct gene expression profile. In conclusion, this is the first report on the molecular basis of the MLL4 integration driving MLL4 over-expression. HBV-MLL4 integration occurred frequently in Chinese HCC patients, representing a unique molecular segment for HCC with HBV infection.

S100A9 promotes human hepatocellular carcinoma cell growth and invasion through RAGE-mediated ERK1/2 and p38 MAPK pathways

S100A9 belongs to the S100 family of calcium-binding proteins and is over-expressed in many human tumors including hepatocellular carcinoma (HCC). Recent study demonstrated that S100A9 is significantly elevated and is associated with tumor differentiation and vascular invasion in HCC. The functional role of S100A9 is, however, poorly understood. Here, we demonstrated that S100A9 treatment increased viability, invasiveness and clone formation in three HCC cell lines (HepG2, SMMC-7721 and Huh7). S100A9 also promoted tumor growth in vivo by a xenograft mouse model. In addition, we observed a co-localization of S100A9 with receptor for advanced glycation end products (RAGE) in human HCC intratumoral tissues and an interaction of S100A9 with RAGE in vitro. Treatment with RAGE blocking antibody blocked the enhanced viability, invasion, clone formation and tumor growth in vivo resulted by S100A9, suggesting that these effects were mediated via RAGE ligation. In order to investigate the signaling pathways, mitogen-activated protein kinase (MAPK) phosphorylation was characterized. S100A9 caused a significant increase in p-p38 and p-ERK1/2 levels, and inhibition of which blocked enhanced invasion and viability resulted by S100A9, respectively. Furthermore, treatment with RAGE blocking antibodies also abrogated the S100A9-induced p38 and ERK1/2 activation, suggesting that S100A9-induced MAPK activation is mediated via RAGE ligation. Our data demonstrate that S100A9 binds to RAGE and stimulates RAGE-dependent MAPK signaling cascades, promoting cell growth and invasion in HCC.

Rab17 inhibits the tumourigenic properties of hepatocellular carcinomas via the Erk pathway

The small GTPase Rab17 is a member of the Rab family and plays a critical role in the regulation of membrane trafficking polarized eukaryotic cells. However, the role of Rab17 in hepatocellular carcinoma (HCC) is not clear. In the present study, we investigated the role of Rab17 in HCC tumourgenesis. The expressions of Rab17 in non-tumour hepatic tissues and HCCs were detected via immunohistochemistry. Rab17 was found in 31 of 48 (64.6 %) and in 23 of 62 (37.1 %) of non-tumour hepatic tissue samples and HCCs (P = 0.0068), respectively, and there were significant correlations between Rab17 reductions and unfavourable variables including tumour size (P = 0.0171), differentiation level (P = 0.0126), and lymph nodal (P = 0.0044) and distant metastases (P = 0.0047). To elucidate the role of Rab17 in HCC, we generated two Rab17-overexpressing HCC cell lines. Rab17 overexpression significantly inhibited the tumourigenic properties of HCC cells in vitro and in vivo as demonstrated by reduced cell proliferation and migration, elevated G1 arrest, and decreased tumour xenograft growth. However, the attenuated tumourigenic properties of the HCC cells that were induced by Rab17 overexpression were significantly rescued by the activator of the Erk pathway EGF, which indicates that the Erk pathway plays a critical role in the Rab17 up-regulation-induced reduced tumourigenic properties of HCC cells. Rab17 might act as a tumour suppressor gene in HCCs, and the anti-tumour effects of Rab17 might be partially mediated by the Erk pathway.

The direct and indirect roles of HBV in liver cancer: prospective markers for HCC screening and potential therapeutic targets

Chronic hepatitis B virus (HBV) infection remains the number one risk factor for hepatocellular carcinoma (HCC), accounting for more than 600 000 deaths/year. Despite highly effective antiviral treatment options, chronic hepatitis B (CHB), subsequent end-stage liver disease and HCC development remain a major challenge worldwide. In CHB, liver damage is mainly caused by the influx of immune cells and destruction of infected hepatocytes, causing necro-inflammation. Treatment with nucleoside/nucleotide analogues can effectively suppress HBV replication in patients with CHB and thus decrease the risk for HCC development. Nevertheless, the risk of HCC in treated patients showing sufficient suppression of HBV DNA replication is significantly higher than in patients with inactive CHB, regardless of the presence of baseline liver cirrhosis, suggesting direct, long-lasting, predisposing effects of HBV. Direct oncogenic effects of HBV include integration in the host genome, leading to deletions, cis/trans-activation, translocations, the production of fusion transcripts and generalized genomic instability, as well as pleiotropic effects of viral transcripts (HBsAg and HBx). Analysis of these viral factors in active surveillance may allow early identification of high-risk patients, and their integration into a molecular classification of HCC subtypes might help in the development of novel therapeutic approaches.

C-terminal-truncated hepatitis B virus X protein enhances the development of diethylnitrosamine-induced hepatocellular carcinogenesis

Hepatitis B virus X protein (HBx) is involved in the development of hepatocellular carcinoma (HCC). The HBx sequence is a preferential site of integration into the human genome, leading to the formation of C-terminal-truncated HBx proteins (Ct-HBx). We previously reported that Ct-HBx proteins were able to potentiate cell transformation in vitro. Our present goal was to compare the ability of Ct-HBx and full-length HBx (FL-HBx) proteins to develop or enhance HCC in transgenic mice. In the absence of treatment, neither Ct-HBx- nor FL-HBx-transgenic mice developed HCC. In young mice treated with diethylnitrosamine (DEN) at 8 months of age, a significantly higher incidence and number of liver lesions were observed in Ct-HBx mice than in FL-HBx and control mice. The earlier development of tumours in Ct-HBx-transgenic mice was associated with increased liver inflammation. At 10 months, macroscopic and microscopic analyses showed that, statistically, FL-HBx mice developed more liver lesions with a larger surface area than control mice. Furthermore, during DEN-induced initiation of HCC, Ct-HBx- and FL-HBx-transgenic mice showed higher expression of IL-6, TNF-α and IL-1β transcripts, activation of STAT3, ERK and JNK proteins and an increase in cell apoptosis. In conclusion, in DEN-treated transgenic mice, the expression of Ct-HBx protein causes a more rapid onset of HCC than does FL-HBx protein. HBV genome integration leading to the expression of a truncated form of HBx protein may therefore facilitate HCC development in chronically infected patients.

Serum microRNAs; miR-30c-5p, miR-223-3p, miR-302c-3p and miR-17-5p could be used as novel non-invasive biomarkers for HCV-positive cirrhosis and hepatocellular carcinoma

Recently, serum miRNAs have been evolved as possible biomarkers for different diseases including hepatocellular carcinoma and other types of cancers. Investigating certain serum miRNAs as novel non-invasive markers for early detection of HCV-positive cirrhosis and hepatocellular carcinoma (HCC). The expression profiles of 58 miRNA were analyzed in patient's plasma of chronic hepatitis C (CHC), HCV-positive cirrhosis and HCV-positive HCC and compared with control group samples. Totally 94 plasma samples; 64 patient plasma (26 CHC, 30 HCV-positive cirrhosis, 8 HCV-positive HCC) and 28 control group plasma, were included. The expression profiles of 58 miRNAs were detected for all patient and control group plasma samples by qRT-PCR using BioMarkTM 96.96 Dynamic Array (Fluidigm Corporation) system. In CHC group, expression profiles of miR-30a-5p, miR-30c-5p, miR-206 and miR-302c-3p were found significantly deregulated (p < 0.05) when compared versus control group. In HCV-positive cirrhosis group, expression profiles of miR-30c-5p, miR-223-3p, miR-302c-3p, miR-17-5p, miR-130a-3p, miR-93-5p, miR-302c-5p and miR-223-3p were found significantly deregulated (p < 0.05). In HCV-positive HCC group, expression profiles of miR-17-5p, miR-223-3p and miR-24-3p were found significant (p < 0.05). When all groups were compared versus control, miR-30c-5p, miR-223-3p, miR-302c-3p and miR-17-5p were found significantly deregulated for cirrhosis and HCC. These results imply that miR-30c-5p, miR-223-3p, miR-302c-3p and miR-17-5p could be used as novel non-invasive biomarkers of HCV-positive HCC in very early, even at cirrhosis stage of liver disease.

The hepatitis B virus (HBV) HBx protein activates AKT to simultaneously regulate HBV replication and hepatocyte survival

Chronic infection with hepatitis B virus (HBV) is a risk factor for developing liver diseases such as hepatocellular carcinoma (HCC). HBx is a multifunctional protein encoded by the HBV genome; HBx stimulates HBV replication and is thought to play an important role in the development of HBV-associated HCC. HBx can activate the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway in some cell lines; however, whether HBx regulates PI3K/AKT signaling in normal hepatocytes has not been evaluated. In studies described here, we assessed HBx activation of PI3K/AKT signaling in an ex vivo model of cultured primary hepatocytes and determined how this HBx activity affects HBV replication. We report that HBx activates AKT in primary hepatocytes and that the activation of AKT decreases HBV replication and HBV mRNA and core protein levels. We show that the transcription factor hepatocyte nuclear factor 4α (HNF4α) is a target of HBx-regulated AKT, and we link HNF4α to HBx-regulated AKT modulation of HBV transcription and replication. Although we and others have shown that HBx stimulates and is likely required for HBV replication, we now report that HBx also activates signals that can diminish the overall level of HBV replication. While this may seem counterintuitive, we show that an important effect of HBx activation of AKT is inhibition of apoptosis. Consequently, our studies suggest that HBx balances HBV replication and cell survival by stimulating signaling pathways that enhance hepatocyte survival at the expense of higher levels of HBV replication.

IMPORTANCE

Chronic hepatitis B virus (HBV) infection is a common cause of the development of liver cancer. Regulation of cell signaling pathways by the HBV HBx protein is thought to influence the development of HBV-associated liver cancer. HBx stimulates, and may be essential for, HBV replication. We show that HBx activates AKT in hepatocytes to reduce HBV replication. While this seems contradictory to an essential role of HBx during HBV replication, HBx activation of AKT inhibits hepatocyte apoptosis, and this may facilitate persistent, noncytopathic HBV replication. AKT regulates HBV replication by reducing the activity of the transcription factor hepatocyte nuclear factor 4α (HNF4α). HBx activation of AKT may contribute to the development of liver cancer by facilitating persistent HBV replication, augmenting the dedifferentiation of hepatocytes by inhibiting HNF4α functions, and activating AKT-regulated oncogenic pathways. AKT-regulated factors may provide therapeutic targets for inhibiting HBV replication and the development of HBV-associated liver cancer.

Viral carcinogenesis: factors inducing DNA damage and virus integration

Viruses are the causative agents of 10%-15% of human cancers worldwide. The most common outcome for virus-induced reprogramming is genomic instability, including accumulation of mutations, aberrations and DNA damage. Although each virus has its own specific mechanism for promoting carcinogenesis, the majority of DNA oncogenic viruses encode oncogenes that transform infected cells, frequently by targeting p53 and pRB. In addition, integration of viral DNA into the human genome can also play an important role in promoting tumor development for several viruses, including HBV and HPV. Because viral integration requires the breakage of both the viral and the host DNA, the integration rate is believed to be linked to the levels of DNA damage. DNA damage can be caused by both endogenous and exogenous factors, including inflammation induced by either the virus itself or by co-infections with other agents, environmental agents and other factors. Typically, cancer develops years to decades following the initial infection. A better understanding of virus-mediated carcinogenesis, the networking of pathways involved in transformation and the relevant risk factors, particularly in those cases where tumorigenesis proceeds by way of virus integration, will help to suggest prophylactic and therapeutic strategies to reduce the risk of virus-mediated cancer.

Superinfection with woodchuck hepatitis virus strain WHVNY of livers chronically infected with strain WHV7

The determinants of the maintenance of chronic hepadnaviral infection are yet to be fully understood. A long-standing unresolved argument in the hepatitis B virus (HBV) research field suggests that during chronic hepadnaviral infection, cell-to-cell spread of hepadnavirus is at least very inefficient (if it occurs at all), virus superinfection is an unlikely event, and chronic hepadnavirus infection can be maintained exclusively via division of infected hepatocytes in the absence of virus spread. Superinfection exclusion was previously shown for duck HBV, but it was not demonstrated for HBV or HBV-related woodchuck hepatitis virus (WHV). Three woodchucks, which were chronically infected with the strain WHV7 and already developed WHV-induced hepatocellular carcinomas (HCCs), were superinfected with another WHV strain, WHVNY. Six weeks after the superinfection, the woodchucks were sacrificed and tissues of the livers and HCCs were examined. The WHVNY superinfection was demonstrated by using WHV strain-specific PCR assays and (i) finding WHVNY relaxed circular DNA in the serum samples collected from all superinfected animals during weeks one through six after the superinfection, (ii) detecting replication-derived WHVNY RNA in the tissue samples of the livers and HCCs collected from three superinfected woodchucks, and (iii) finding WHVNY DNA replication intermediates in tissues harvested after the superinfection. The results are consistent with the occurrence of continuous but inefficient hepadnavirus cell-to-cell spread and superinfection during chronic infection and suggest that the replication space occupied by the superinfecting hepadnavirus in chronically infected livers is limited. The findings are discussed in the context of the mechanism of chronic hepadnavirus infection.

IMPORTANCE

This study aimed to better understand the determinants of the maintenance of chronic hepadnavirus infection. The generated data suggest that in the livers chronically infected with woodchuck hepatitis virus, (i) hepadnavirus superinfection and cell-to-cell spread likely continue to occur and (ii) the virus spread is apparently inefficient, which is consistent with the interpretation that a limited number of cells in the livers facilitates the spread of hepadnavirus. The limitations of the cell-to-cell virus spread most likely are mediated at the level of the cells and do not reflect the properties of the virus. Our results further advance the understanding of the mechanism of chronic hepadnavirus infection. The significance of the continuous but limited hepadnavirus spread and superinfection for the maintenance of the chronic state of infection should be further evaluated in follow-up studies in order to determine whether blocking the virus spread would facilitate the suppression of chronic hepadnavirus infection.

The collagen triple helix repeat containing 1 facilitates hepatitis B virus-associated hepatocellular carcinoma progression by regulating multiple cellular factors and signal cascades

Hepatitis B virus (HBV) infection is one of the major causes of acute and chronic liver diseases, fulminant hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). HCC accounts for more than 85% of primary liver cancers and is the seventh most common cancer and the third leading cause of cancer-related deaths. However, the mechanism by which HBV induces HCC is largely unknown. Collagen triple helixes repeat containing 1 (CTHRC1) is a secreted protein and has characteristics of a circulating hormone with potentially broad implications for cell metabolism and physiology. CTHRC1 is associated with human cancers, but its effect on HCC is unknown. Here, we revealed that CTHRC1 expression is highly correlated with HCC progression in HBV-infected patients, and demonstrated that HBV stimulates CTHRC1 expression by activating nuclear factor-kappa B (NF-κB) and cAMP response element binding protein (CREB), through extracellular signal-regulated kinase/c-Jun N-terminal kinase (ERK/c-JNK) pathway. In addition, CTHRC1 activates hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF) through regulating phosphoinosmde-3-kinase/protein kinase B/mammalian target of rapamycin (PI-3K/AKT/mTOR) pathway. More interestingly, CTHRC1 enhances colony formation, migration, and invasion of hepatoma cells by regulating p53 and stimulating matrix metalloproteinase-9 (MMP-9) expression. In addition, knock-down of CTHRC1 results in the repression of HBV-associated carcinogenesis in nude mice. Thus, we revealed a novel mechanism by which HBV facilitates HCC development through activating the oncoprotein CTHRC1, which in turn enhances HBV-related HCC progression by stimulates colony formation, migration, and invasion of hepatoma cells through regulating multiple cellular factors and signal cascades.

Clinicopathological analysis of CD8-positive lymphocytes in the tumor parenchyma and stroma of hepatocellular carcinoma

Tumor-infiltrating lymphocytes may be a manifestation of antitumor immunity. In the present study, hepatocellular carcinoma (HCC) and pericancerous non-tumor liver tissues samples were obtained from 86 surgical patients who had not received preoperative treatment. The cellular expression levels of CD4 and CD8 were immunohistochemically examined in the two tissue groups using tissue microarrays, to evaluate their clinicopathological relevance. Immunohistochemically, CD4 and CD8 T cells were observed in the tumor parenchyma and tumor stroma, and the intensity of CD4 and CD8 immunoreactivity was homogeneous in all HCC samples examined. Morphometrically, the average numbers of CD4- and CD8-positive T cells were significantly increased in the tumor stroma, compared with those in the tumor parenchyma (tumor stroma versus tumor parenchyma: 22±3.6 versus 7.4±0.9 in CD4, 32.8±4.2 versus 16±2.5 in CD8; both P<0.01). Furthermore, the average numbers of CD8-positive T cells in the tumor parenchyma and stroma were significantly increased, compared with the average numbers of CD4-positive cells (P<0.05). In addition, in the tumor parenchyma and stroma, the average numbers of CD8 T cells were significantly higher in patients with tumor diameters ≤5 cm compared with those in patients with tumor diameters >5 cm (diameter ≤5 cm versus diameter >5 cm: 18.1±3.3 versus 12.2±3.8 in tumor parenchyma, 36.5±4.8 versus 21.9±8.9 in tumor stroma; both P<0.05). In addition, CD8 expression was significantly enhanced in patients with chronic hepatitis and cirrhosis, compared with paired tumor parenchymal tissues (P<0.01). Furthermore, a significant positive correlation was observed between CD4 and CD8 expression in the tumor parenchyma and stroma (both P<0.001). These observations suggest that tumor parenchyma- or stroma-infiltrating CD8 T cells may be involved in HCC tumor diameter control.

Hepatitis B virus, HBx mutants and their role in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of death induced by cancer in the modern world and majority of the cases are related to chronic hepatitis B virus (HBV) infection. HBV-encoded X protein (HBx) is known to play a pivotal role in the pathogenesis of viral induced HCC. HBx is a multifunctional protein of 17 kDa which modulates several cellular processes by direct or indirect interaction with a repertoire of host factors resulting in HCC. HBX might interfere with several cellular processes such as oxidative stress, DNA repair, signal transduction, transcription, protein degradation, cell cycle progression and apoptosis. A number of reports have indicated that HBx is one of the most common viral ORFs that is often integrated into the host genome and its sequence variants play a crucial role in HCC. By mutational or deletion analysis it was shown that carboxy terminal of HBx has a likely role in protein-protein interactions, transcriptional transactivation, DNA repair, cell, signaling and pathogenesis of HCC. The accumulated evidence thus far suggests that it is difficult to understand the mechanistic nature of HBx associated HCC, and HBx mediated transcriptional transactivation and signaling pathways may be a major determinant. This article addresses the role of HBx in the development of HCC with particular emphasis on HBx mutants and their putative targets.

Hepatitis B virus X protein promotes hepatocellular carcinoma transformation through interleukin-6 activation of microRNA-21 expression

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and chronic hepatitis B virus (HBV) infection is the major risk factor of HCC. The virus encodes HBV X (HBx) protein that plays a critical role in the development of HCC. Studies have revealed numerous HBx-altered genes and signalling pathways that heavily contribute to tumourigenesis of non-tumour hepatocytes. However, the role of HBx in regulating other critical gene regulators such as microRNAs is poorly understood, which impedes the exploration of a complete HBx-associated carcinogenic network. Besides, critical microRNAs that drive the transformation of non-tumour hepatocytes are yet to be identified. Here, we overexpressed C-terminal truncated HBx protein in a non-tumour hepatocyte cell line MIHA, and measured a panel of cancer-associated miRNAs. We observed that oncogenic miR-21 was upregulated upon ectopic expression of this viral protein variant. HBx-miR-21 pathway was prevalent in HCC cells as inhibition of HBx in Hep3B and PLC/PRF/5 cells significantly suppressed miR-21 expression. Subsequently, we showed that the upregulation of miR-21 was mediated by HBx-induced interleukin-6 pathway followed by activation of STAT3 transcriptional factor. The high dependency of miR-21 expression to HBx protein suggested a unique viral oncogenic pathway that could aberrantly affect a network of gene expression. Importantly, miR-21 was essential in the HBx-induced transformation of non-tumour hepatocytes. Inhibition of miR-21 effectively attenuated anchorage-independent colony formation and subcutaneous tumour growth of MIHA cells. Our study suggested that overexpression of miR-21 was critical to promote early carcinogenesis of hepatocytes upon HBV infection.

Hepatitis B Virus-Related Hepatocellular Carcinoma: Pathogenic Mechanisms and Novel Therapeutic Interventions

BACKGROUND

Infection with the hepatitis B virus (HBV) is one of most important risk factors for hepatocellular carcinoma (HCC). Indeed, HBV is considered a group 1 human carcinogen and is a highly oncogenic agent. HBV cannot be effectively controlled or completely eliminated, so chronic HBV infection is a public health challenge worldwide.

SUMMARY

It is now believed that HBV-induced HCC involves a complex interaction between multiple viral and host factors. Many factors contribute to HBV-associated HCC, including products of HBV, viral integration and mutation, and host susceptibility. This review outlines the main pathogenic mechanisms with a focus on those that suggest novel targets for the prevention and treatment of HCC.

KEY MESSAGE

HBV infection is an important risk factor for HCC. Understanding the interaction between viral and host factors in HBV-induced HCC will reveal potential targets for future therapies.

PRACTICAL IMPLICATIONS

The two main therapeutic strategies consist of antiviral agents and immunotherapy-based approaches. Dendritic cell-based immunotherapy is promising for restoring the T cell-mediated antiviral immune response. Another approach is the specific expansion of the host's pool of HBV-specific T cells. Stimulation of the Toll-like receptors (TLRs), particularly TLR9, provides another means of boosting the antiviral response. Combination therapy with cytokines (interferon gamma and tumor necrosis factor alpha) plus lamivudine is more effective than these agents used alone. Therapeutic vaccines are being developed as an alternative to long-term antiviral treatment or as an adjunct.

Research progress on the anticarcinogenic actions and mechanisms of ellagic acid

Cancer is a leading cause of death worldwide. Cancer treatments by chemotherapeutic agents, surgery, and radiation have not been highly effective in reducing the incidence of cancers and increasing the survival rate of cancer patients. In recent years, plant-derived compounds have attracted considerable attention as alternative cancer remedies for enhancing cancer prevention and treatment because of their low toxicities, low costs, and low side effects. Ellagic acid (EA) is a natural phenolic constituent. Recent in vitro and in vivo experiments have revealed that EA elicits anticarcinogenic effects by inhibiting tumor cell proliferation, inducing apoptosis, breaking DNA binding to carcinogens, blocking virus infection, and disturbing inflammation, angiogenesis, and drug-resistance processes required for tumor growth and metastasis. This review enumerates the anticarcinogenic actions and mechanisms of EA. It also discusses future directions on the applications of EA.

Interleukin-37 mediates the antitumor activity in hepatocellular carcinoma: role for CD57+ NK cells

The biological role of interleukin-37 (IL-37) in cancer is large unknown. Through immunohistochemical detection using 163 primary hepatocellular carcinoma (HCC) clinical specimens, we found the expression of IL-37 was decreased in tumor tissues, and the expression level was negatively correlated with tumor size. High expression of IL-37 in HCC tumor tissues was associated with better overall survival (OS) and disease-free survival (DFS). IL-37 expression in tumor tissues was positively associated with the density of tumor-infiltrating CD57+ natural killer (NK) cells, but not with the CD3+ and CD8+ T cells. Consistently, in vitro chemotaxis analysis showed that IL-37- overexpressing HCC cells could recruit more NK cells. The in vivo mouse model experiments also revealed that overexpression IL-37 in HCC cells significantly delayed tumor growth and recruited more NK cells into tumors tissues. Our finding suggested that IL-37 might play an important role for the prognosis of HCC patients via regulating innate immune-action.

Role of hepatitis B virus DNA integration in human hepatocarcinogenesis

Liver cancer ranks sixth in cancer incidence, and is the third leading cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) is the most common type of liver cancer, which arises from hepatocytes and accounts for approximately 70%-85% of cases. Hepatitis B virus (HBV) frequently causes liver inflammation, hepatic damage and subsequent cirrhosis. Integrated viral DNA is found in 85%-90% of HBV-related HCCs. Its presence in tumors from non-cirrhotic livers of children or young adults further supports the role of viral DNA integration in hepatocarcinogenesis. Integration of subgenomic HBV DNA fragments into different locations within the host DNA is a significant feature of chronic HBV infection. Integration has two potential consequences: (1) the host genome becomes altered (“cis” effect); and (2) the HBV genome becomes altered (“trans” effect). The cis effect includes insertional mutagenesis, which can potentially disrupt host gene function or alter host gene regulation. Tumor progression is frequently associated with rearrangement and partial gain or loss of both viral and host sequences. However, the role of integrated HBV DNA in hepatocarcinogenesis remains controversial. Modern technology has provided a new paradigm to further our understanding of disease mechanisms. This review summarizes the role of HBV DNA integration in human carcinogenesis.

Involvement of DNA damage response pathways in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been known as one of the most lethal human malignancies, due to the difficulty of early detection, chemoresistance, and radioresistance, and is characterized by active angiogenesis and metastasis, which account for rapid recurrence and poor survival. Its development has been closely associated with multiple risk factors, including hepatitis B and C virus infection, alcohol consumption, obesity, and diet contamination. Genetic alterations and genomic instability, probably resulted from unrepaired DNA lesions, are increasingly recognized as a common feature of human HCC. Dysregulation of DNA damage repair and signaling to cell cycle checkpoints, known as the DNA damage response (DDR), is associated with a predisposition to cancer and affects responses to DNA-damaging anticancer therapy. It has been demonstrated that various HCC-associated risk factors are able to promote DNA damages, formation of DNA adducts, and chromosomal aberrations. Hence, alterations in the DDR pathways may accumulate these lesions to trigger hepatocarcinogenesis and also to facilitate advanced HCC progression. This review collects some of the most known information about the link between HCC-associated risk factors and DDR pathways in HCC. Hopefully, the review will remind the researchers and clinicians of further characterizing and validating the roles of these DDR pathways in HCC.

Hepatitis B splice-generated protein antibodies in Syrian chronic hepatitis B patients: incidence and significance

BACKGROUND

Previous studies have suggested hepatitis B splice-generated protein (HBSP), when expressed, is involved in the pathogenesis of HBV infection.

OBJECTIVES

We aimed to evaluate anti-HBSP incidence and association with several HBV infection parameters in a group of Syrian chronic hepatitis B patients.

PATIENTS AND METHODS

Eighty treatment-naïve HBsAg-positive adult chronic hepatitis B patients' sera were included in our prospective targeted study. Liver function, virological and histological tests results were obtained from patients' medical files. Three variants of a 20-mer HBSP-derived peptide were designed based on HBV genome sequences obtained from Syrian patients' sera (GenBank Accession No. JN257148-JN257217). Microtiter plate wells were coated with the synthetic peptides and used to detect anti-HBSP antibodies by an optimized indirect enzyme-linked immunosorbent assay (ELISA). Samples were considered positive when showed optical density (OD) values higher than the cut-off value for at least one peptide variant.

RESULTS

Seven out of eighty (9%) CHB patients were positive for anti-HBSP antibodies. Mean OD values were not significantly different between HBeAg-positive and -negative patients (P > 0.05). OD values showed weak positive correlation with ALT and AST values (P < 0.05), and weak to moderate positive correlation with liver biopsy staging ranks (P < 0.05). No significant correlation was revealed with viral load values or liver biopsy grading ranks (P > 0.05).

CONCLUSIONS

We introduced an anti-HBSP antibodies ELISA, designed for locally circulating HBV strains. Correlation observed of Anti-HBSP with liver fibrosis staging regardless of viral replication and liver inflammation suggests anti-HBSP antibodies as possible indicator for HBV-associated liver fibrosis.

Viral-human chimeric transcript predisposes risk to liver cancer development and progression

The mutagenic effect of hepatitis B (HBV) integration in predisposing risk to hepatocellular carcinoma (HCC) remains elusive. In this study, we performed transcriptome sequencing of HBV-positive HCC cell lines and showed transcription of viral-human gene fusions from the site of genome integrations. We discovered tumor-promoting properties of a chimeric HBx-LINE1 that, intriguingly, functions as a hybrid RNA. HBx-LINE1 can be detected in 23.3% of HBV-associated HCC tumors and correlates with poorer patient survival. HBx-LINE1 transgenic mice showed heightened susceptibility to diethylnitrosamine-induced tumor formation. We further show that HBx-LINE1 expression affects β-catenin transactivity, which underlines a role in activating Wnt signaling. Thus, this study identifies a viral-human chimeric fusion transcript that functions like a long noncoding RNA to promote HCC.

Mutation profiling of the hepatitis B virus strains circulating in North Indian population

AIMS

The aim of this study was to investigate the genomic mutations in the circulating Hepatitis B virus strains causing infection in the Indian population. Further, we wanted to analyze the biological significance of these mutations in HBV mediated disease.

METHODS

222 HBsAg positive patients were enrolled in the study. The genotype and mutation profile was determined for the infecting HBV isolate by sequencing overlapping fragments. These sequences were analyzed by using different tools and compared with previously available HBV sequence information. Mutation Frequency Index (MFI) for the Genes and Diagnosis group was also calculated.

RESULTS

HBV Genotype D was found in 55% (n = 121) of the patient group and genotype A was found in 30% (n = 66) of samples. The majority (52%) of the HBV-infected individuals in the present study were HBeAg-negative in all the age groups studied. Spontaneous drug associated mutations implicated in resistance to antiviral therapy were also identified in about quarter of our patients, which is of therapeutic concern. The MFI approach used in the study indicated that Core peptide was the most conserved region in both genotypes and Surface peptide had highest mutation frequency. Few mutations in X gene (T36A and G50R) showed high frequency of association with HCC. A rare recombinant strain of HBV genotype A and D was also identified in the patient group.

CONCLUSIONS

HBV genotype D was found out to be most prevalent. More than half of the patients studied had HBeAg negative disease. Core region was found to be most conserved. Drug Associated mutations were detected in 22% of the patient group and T36A and G50R mutations in X gene were found to be associated with HCC.

Profiles of serum microRNAs; miR-125b-5p and miR223-3p serve as novel biomarkers for HBV-positive hepatocellular carcinoma

Recently, circulating miRNAs have been reported as promising biomarkers for various pathologic conditions including cancer. Certain microRNAs (miRNAs) have been shown early diagnostic potential for many types of cancer. The objective of this study was to investigate the potential of certain serum/plasma miRNAs as novel non-invasive biomarkers for early diagnosis of hepatitis B virus (HBV) related hepatocellular carcinoma (HCC). For this reason, the expression levels of 24 miRNA (let-7c, miR-92a-3p, 423-5p, 150-5p, 223-3p, 125b-5p, 342-3p, miR-206, 122-5p, 375, 223-5p, 10a-5p, 23b-5p, 99a-5p, 23a-5p, 10a-3p, 122-3p, 125b-1-3p, 23b-3p, 125b-2-3p, 23a-3p, 92a-1-5p, 92a-2-5p, 99a-3p) were analyzed in plasma of patients with chronic hepatitis B, HBV-positive cirrhosis and HBV-positive HCC and compared with control group samples. Totally 94 plasma samples; 28 control and 66 patient plasma (24 CHB, 22 HBV-positive cirrhosis, 20 HBV-positive HCC) and were included in this study. The expression levels of 24 miRNAs were detected for all control and patient group plasma samples by qRT-PCR using BioMark™ 96.96 Dynamic Array (Fluidigm Corporation) system. The expression levels of miR-125b-5p were detected 2.85 fold, 2.46 fold and 1.89 fold (p = 0.01513, p = 0.0009440, p = 0.0001446) up regulated in CHB, HBV-positive cirrhosis and HBV-positive HCC, respectively when compared versus control group individually by Mann-Whitney U test. The expression levels of miR-223-3p were detected 5.55 fold, 13.88 fold and 12.65 fold (p = 0.01513, p = 0.0009440, p = 0.0001446) down regulated in same comparisons. When all groups were compared versus control group by one-way ANOVA test, the expression levels of miR-223-3p were also found statistically significant (p < 0.05). Although not statistically significant, miR-125b-5p tended to be upregulated. (p = 0.07192). These results significantly imply that miR-125b-5p and miR223-3p could be used as novel non-invasive biomarkers of HBV-positive HCC in very early, even at CHB stage of liver disease.

Does the measles virus contribute to carcinogenesis? - a review

An association between the measles virus and classical Hodgkin lymphoma has previously been suggested by us. This has been refuted by two European groups. A reevaluation of the arguments held against our thesis was carried out and further evidence for a relationship between the measles virus and additional solid tumors has been presented. We have suggested a molecular mechanism to support a possible contribution of the virus to carcinogenesis in classical Hodgkin lymphoma.