Pathogenic mechanisms in HBV- and HCV-associated hepatocellular carcinoma

Status and development of anti-HBV drugs based on "HBF drug watch"

Hepatitis B virus (HBV) infection is a major public health threat globally. Present therapies can only suppress viral replication instead of viral elimination. With the application of direct anti-viral agents (DAAs) to hepatitis C virus (HCV) infection, many pharmaceutical industries pay their attention to investigating anti-HBV drugs. As a result, the update of anti-HBV drugs at the website http://www.hepb.org/professionals/hbf_drug_watch.htm speeds up. In this review, we summarize all the drugs available in the market and those in clinical trials based on this website.

Dysregulated signaling hubs of liver lipid metabolism reveal hepatocellular carcinoma pathogenesis

Hepatocellular carcinoma (HCC) has a high mortality rate and early detection of HCC is crucial for the application of effective treatment strategies. HCC is typically caused by either viral hepatitis infection or by fatty liver disease. To diagnose and treat HCC it is necessary to elucidate the underlying molecular mechanisms. As a major cause for development of HCC is fatty liver disease, we here investigated anomalies in regulation of lipid metabolism in the liver. We applied a tailored network-based approach to identify signaling hubs associated with regulation of this part of metabolism. Using transcriptomics data of HCC patients, we identified significant dysregulated expressions of lipid-regulated genes, across many different lipid metabolic pathways. Our findings, however, show that viral hepatitis causes HCC by a distinct mechanism, less likely involving lipid anomalies. Based on our analysis we suggest signaling hub genes governing overall catabolic or anabolic pathways, as novel drug targets for treatment of HCC that involves lipid anomalies.

Combined acoustic radiation force impulse, aminotransferase to platelet ratio index and Forns index assessment for hepatic fibrosis grading in hepatitis B

AIM: To investigate the combined diagnostic accuracy of acoustic radiation force impulse (ARFI), aspartate aminotransferase to platelet ratio index (APRI) and Forns index for a non-invasive assessment of liver fibrosis in patients with chronic hepatitis B (CHB).

METHODS: In this prospective study, 206 patients had CHB with liver fibrosis stages F0-F4 classified by METAVIR and 40 were healthy volunteers were measured by ARFI, APRI and Forns index separately or combined as indicated.

RESULTS: ARFI, APRI or Forns index demonstrated a significant correlation with the histological stage (all P < 0.001). According to the AUROC of ARFI and APRI for evaluating fibrotic stages more than F2, ARFI showed an enhanced diagnostic accuracy than APRI (P < 0.05). The combined measurement of ARFI and APRI exhibited better accuracy than ARFI alone when evaluating ≥ F2 fibrotic stage (Z = 2.77, P = 0.006). Combination of ARFI, APRI and Forns index did not obviously improve the diagnostic accuracy compared to the combination of ARFI and APRI (Z = 0.958, P = 0.338).

CONCLUSION: ARFI + APRI showed enhanced diagnostic accuracy than ARFI or APRI alone for significant liver fibrosis and ARFI + APRI + Forns index shows the same effect with ARFI + APRI.

Hepatitis C virus core protein regulates OCT4 expression and promotes cell cycle progression in hepatocellular carcinoma

Hepatitis C virus (HCV) core protein plays an important role in the development of hepatocellular carcinoma. octamer-binding protein 4 (OCT4) is critically essential for the pluripotency and self-renewal of embryonic stem cells. Abnormal expression of OCT4 has been detected in several human solid tumors. However, the relationship between HCV core and OCT4 remains uncertain. In the present study, we found that HCV core is capable of upregulating OCT4 expression. The effect of HCV core-induced OCT4 overexpression was abolished by RNAi-mediated scilencing of HCV core. In addition, HCV core-induced OCT4 overexpression resulted in enhanced cell proliferation and cell cycle progression. Inhibition of OCT4 reduced the CCND1 expression and induced G0/G1 cell cycle arrest. Furthermore, OCT4 protein directly binds to CCND1 promoter and transactivates CCND1. These findings suggest that HCV core protein regulates OCT4 expression and promotes cell cycle progression in hepatocellular carcinoma providing new insight into the mechanism of hepatocarcinogenesis by HCV infection.

Potential of Radiofrequency Ablation in Combination with Immunotherapy in the Treatment of Hepatocellular Carcinoma

Radiofrequency ablation (RFA) is an important treatment option for patients with early hepatocellular carcinoma (HCC). RFA offers a reliable, reproducible modality to effectively treat hepatic lesions with minimal collateral damage to the surrounding hepatic parenchyma. In addition to traditional open operative techniques, RFA can be performed percutaneously or laparoscopically to minimize the physiologic insult to the patient. Due to the concomitant hepatic damage and dysfunction that often is present in patients with HCC these factors make RFA a frequently utilized therapeutic option. However, RFA is most efficacious in treating smaller tumors (≤ 2 cm), particularly when an ablation margin of ≥ 4-5 mm can be obtained. RFA has diminishing utility in larger tumors, resulting in reduced three and five year overall survival rates when compared to surgical resection. Multimodal approaches to include RFA with other standard and investigational approaches have become a subject of recent interest. RFA capably produces cellular destruction causing liberation of a substantial amount of antigens, many of which are tumor-specific providing a favorable environment for immune recognition. We propose that utilizing an immunotherapeutic approach in conjunction with RFA is the next logical step in the treatment of HCC. In this review, we summarize how RFA modulates antitumor immunity and works in concert with immunotherapy in the treatment of HCC. The information provided is expected to help the future design of novel RFA-integrated immunotherapies which are able to generate durable and powerful antitumor immune response to achieve optimal tumor control.

Polymorphisms in sodium taurocholate cotransporting polypeptide are not associated with hepatitis B virus clearance in Chinese Tibetans and Uygurs

An association between polymorphisms in the sodium taurocholate cotransporting polypeptide (NTCP) and the natural course of hepatitis B virus (HBV) infection in the Chinese Han population has been noted. However, it is not known whether these polymorphisms are associated with the risk of developing chronic HBV infection in other racial or ethnic populations. Accordingly, we conducted a candidate single nucleotide polymorphism (SNP) association study in Tibetan and Uygur HBV-infected patients. A total of 1302 subjects including 871 Tibetans and 431 Uygurs were recruited. According to their serological and clinical characteristics, each ethnic group was divided into two groups comprising spontaneous clearance individuals and persistently infected patients. Three SNPs were genotyped by a high resolution melting curve methodology. Among the SNPs, rs2296651 exhibited a minor allele frequency of <0.01. The frequency of allele A at rs4646287 was much higher in Tibetans (9.4% for Tibetans and 4.6% for Uygurs, p<0.001) than in Uygurs, but the frequency of allele A at rs7154439 was the opposite (15.7% for Tibetans and 20.5% for Uygurs, p=0.002). Irrespective of race, no significant differences in the frequency distributions of the three SNP alleles or genotypes were observed between the case and clearance groups. Moreover, none of the NTCP haplotypes were statistically different between the two groups. Data from the Tibetan patients could be grouped by HBeAg status, viral load and HBV genotype; however, no significant differences were found in the SNP genotype distribution for each characteristic. In conclusion, the NTCP polymorphisms we identified tended to be ethnicity-dependent. For Tibetans and Uygurs, no association of the three SNPs (rs7154439, rs4646287 and rs2296651) and their haplotypes with HBV chronicity was observed. Examination of SNPs in NTCP for their specific associations with the course of HBV infection in other ethnic minority groups is now required.

Variable Intra-Tumor Genomic Heterogeneity of Multiple Lesions in Patients With Hepatocellular Carcinoma

BACKGROUND & AIMS

Many patients with hepatocellular carcinoma (HCC) have multiple lesions (primary tumors, intrahepatic metastases, multiple occurrences, satellite nodules, and tumor thrombi); these have been associated with a poor prognosis and tumor recurrence after surgery. We investigated the clonal relationship among these lesions on the basis of genetic features.

METHODS

We collected 43 lesions and 10 matched control samples (blood or nontumorous liver) from 10 patients with hepatitis B virus-associated HCC treated at Tianjin Cancer Hospital (China) from January 2013 through May 2014. We performed exome and low-depth, whole-genome sequencing on these samples. Genomic aberrations, including somatic mutations and copy number variations, were identified using germline DNA as control. We compared the genetic features of different lesions from each patient and constructed phylogenetic trees to depict their evolutionary histories.

RESULTS

In each patient, mutations shared by all the lesions were called ubiquitous mutations. The percentage of ubiquitous mutations varied from 8% to 97% among patients, indicating variation in the extent of intratumor heterogeneity. Branched evolution was evident, with somatic mutations, hepatitis B virus integrations, and copy number variations identified on both the trunks and branches of the phylogenetic trees. Intrahepatic metastases and tumor thrombi contained some, but not all, of the mutations detected in their matched primary lesions. By contrast, satellite nodules shared approximately 90% of mutations detected in primary lesions. In a patient with multicentric tumors, 6 lesions were assigned to 2 distinct groups, based on significant differences in genetic features. In another patient with combined hepatocellular and intrahepatic cholangiocarcinoma, the physically separate HCC and cholangiocarcinoma lesions shared 102 mutations.

CONCLUSIONS

The extent of intratumor heterogeneity varies considerably among patients with HCC. Therefore, sequence analysis of a single lesion cannot completely characterize the genomic features of HCC in some patients. Genomic comparisons of multiple lesions associated with HCCs will provide important information on the genetic changes associated with tumor progression.

Hepatitis B virus X protein and endoplasmic reticulum stress

Persistent hepatitis B virus (HBV) infection is closely related to chronic hepatitis, cirrhosis and liver cancer. China is a country with a high prevalence of HBV infection, where the infection rate is up to 60%-70%, bringing great threat and harm to public health. What's worse is that HBV infection is the main etiology factor of primary hepatocellular carcinoma (HCC). However, the underlying mechanisms of virus-induced tumor formation remain controversial. Numerous studies indicate that HBV X protein (HBx) plays a prominent role in HBV-induced liver cell damage, hepatitis, liver fibrosis and malignant transformation, and is related to liver cancer induced by environmental exposure factors. As a multifunctional regulatory protein, HBx regulates a variety of cell signal transduction pathways, including the endoplasmic reticulum (ER) stress response. ER stress refers to the dysfunction of the ER, and misfolded or unfolded proteins gather in the ER. It is noteworthy that the expression of HBx can induce or effect ER stress, although the molecular mechanism remains unclear. This review summarizes the role of HBx in ER stress pathways, providing clues for the liver injury induced by HBV infection.

Pseudogene INTS6P1 regulates its cognate gene INTS6 through competitive binding of miR-17-5p in hepatocellular carcinoma

The complex regulation of tumor suppressive gene and its pseudogenes play key roles in the pathogenesis of hepatocellular cancer (HCC). However, the roles played by pseudogenes in the pathogenesis of HCC are still incompletely elucidated. This study identifies the putative tumor suppressor INTS6 and its pseudogene INTS6P1 in HCC through the whole genome microarray expression. Furthermore, the functional studies – include growth curves, cell death, migration assays and in vivo studies – verify the tumor suppressive roles of INTS6 and INTS6P1 in HCC. Finally, the mechanistic experiments indicate that INTS6 and INTS6P1 are reciprocally regulated through competition for oncomiR-17-5p. Taken together, these findings demonstrate INTS6P1 and INTS6 exert the tumor suppressive roles through competing for oncomiR-17-5p. Our investigation of this regulatory circuit reveals novel insights into the underlying mechanisms of hepatocarcinogenesis.

Serum viral duplex-linear DNA proportion increases with the progression of liver disease in patients infected with HBV

OBJECTIVE

HBV has two forms of genomic DNA, relaxed-circular DNA (rcDNA) and duplex-linear DNA (dlDNA). Compared to rcDNA, dlDNA has been demonstrated to integrate more frequently into host cellular chromosomes, which may have oncogenic consequences. However, the dlDNA proportion relative to total HBV DNA and its clinical significance in patients remain to be investigated.

DESIGN

Based on the structural difference between rcDNA and dlDNA, we developed a peptide nucleic acid (PNA)-mediated quantitative real-time PCR (qPCR) clamping assay to measure the proportions of dlDNA in total HBV DNA in sera obtained from patients with chronic hepatitis B (CHB), liver cirrhosis (LC) or LC-developed hepatocellular carcinoma (HCC). The factors that influence the proportion of dlDNA were also investigated.

RESULTS

The average dlDNA proportion was approximately 7% in the sera of chronic HBV-infected patients and was elevated in CHB patients with abnormal levels of alanine aminotransferase. The sera dlDNA proportions increased to approximately 14% and 20% in the patients with LC and HCC, respectively. Interferon-α treatment slightly increased the dlDNA proportion in the responders; and nucleotide analogue therapy spuriously elevated the proportion. Moreover, treatment of human hepatoma cells supporting HBV replication with inflammatory cytokines significantly altered the dlDNA proportion in vitro.

CONCLUSIONS

Using a novel PNA-mediated qPCR clamping assay, we first showed that serum dlDNA proportions progressively increased during the development of HBV-related liver diseases. The dlDNA proportion can be regulated by inflammatory cytokines, suggesting an association among inflammation, increased production of HBV dlDNA and development of HCC.

Herbal Medicine Offered as an Initiative Therapeutic Option for the Management of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignant cancer and is the third leading cause of death worldwide. Effective treatment of this disease is limited by the complicated molecular mechanism underlying HCC pathogenesis. Thus, therapeutic options for HCC management are urgently needed. Targeting the Wnt/β-catenin, Hedgehog, Notch, and Hippo-YAP signaling pathways in cancer stem cell development has been extensively investigated as an alternative treatment. Herbal medicine has emerged as an initiative therapeutic option for HCC management because of its multi-level, multi-target, and coordinated intervention effects. In this article, we summarized the recent progress and clinical benefits of targeting the above mentioned signaling pathways and using natural products such as herbal medicine formulas to treat HCC. Proving the clinical success of herbal medicine is expected to deepen the knowledge on herbal medicine efficiency and hasten the adoption of new therapies. Copyright © 2016 John Wiley & Sons, Ltd.

Molecularly targeted therapy for advanced hepatocellular carcinoma - a drug development crisis?

Hepatocellular carcinoma is the fastest growing cause of cancer related death globally. Sorafenib, a multi-targeted kinase inhibitor, is the only drug proven to improve outcomes in patients with advanced disease offering modest survival benefit. Although comprehensive genomic mapping has improved understanding of the genetic aberrations in hepatocellular cancer (HCC), this knowledge has not yet impacted clinical care. The last few years have seen the failure of several first and second line phase III clinical trials of novel molecularly targeted therapies, warranting a change in the way new therapies are investigated in HCC. Potential reasons for these failures include clinical and molecular heterogeneity, trial design and a lack of biomarkers. This review discusses the current crisis in HCC drug development and how we should learn from recent trial failures to develop a more effective personalised treatment paradigm for patients with HCC.

Differential timing of oxidative DNA damage and telomere shortening in hepatitis C and B virus-related liver carcinogenesis

In viral hepatitis, inflammation is correlated with chronic oxidative stress, one of the biological events leading to DNA damage and hepatocellular carcinoma (HCC) development. Aim of this study was to investigate the complex molecular network linking oxidative damage to telomere length and telomerase activity and regulation in hepatitis C and B virus-related liver carcinogenesis. We investigated 142 patients: 21 with HCC (in both tumor and peritumor tissues) and 121 with chronic viral hepatitis in different stages. We evaluated 8-hydroxydeoxyguanosine (8-OHdG), marker of oxidative DNA damage, OGG1 gene polymorphism, telomere length, telomerase activity, TERT promoter methylation, and mitochondrial TERT localization. In hepatitis C-related damage, 8-OHdG levels increased since the early disease stages, whereas hepatitis B-related liver disease was characterized by a later and sharper 8-OHdG accumulation (P = 0.005). In C virus-infected patients, telomeres were shorter (P = 0.03), whereas telomerase activity was higher in tumors than that in the less advanced stages of disease in both groups (P = 0.0001, P = 0.05), with an earlier increase in hepatitis C. Similarly, TERT promoter methylation was higher in tumor and peritumor tissues in both groups (P = 0.02, P = 0.0001). Finally, TERT was localized in mitochondria in tumor and peritumor samples, with 8-OHdG levels significantly lower in mitochondrial than those in genomic DNA (P = 0.0003). These data describe a pathway in which oxidative DNA damage accumulates in correspondence with telomere shortening, telomerase activation, and TERT promoter methylation with a different time course in hepatitis B and C virus-related liver carcinogenesis. Finally, TERT localizes in mitochondria in HCC, where it lacks a canonical function.

HBx triggers either cellular senescence or cell proliferation depending on cellular phenotype

Replicative senescence is a hallmark of chronic liver diseases including chronic hepatitis B virus (HBV) infection, whereas HBV-encoded oncoproteins HBx and preS2 have been found to overcome senescence. HBx possesses a C-terminal truncation mainly in hepatocellular carcinomas but also in noncancerous liver tissues. Here, by cell counting, BrdU incorporation, MTT proliferation assay, cell cycle analysis, SA-βgal staining and Western blotting in primary and malignant cells, we investigated the effect of HBx C-terminal mutants on cellular senescence. HBx C-terminal mutants were found to trigger cellular senescence in primary MRC5 cells, and malignant liver cells Huh7, and SK-Hep1. In contrast, these mutants promoted the proliferation of HepG2 malignant liver cells. The pro-senescent effect of HBx relied on an increased p16(INK4a) and p21(Waf1/Cip1) expression, and a decreased phosphorylation of Rb. Together, these results suggest that the two main variants of HBx present in HBV-infected liver possess opposite effects on cellular senescence that depend on the phenotype of infected cells.

Significance of hepatitis virus infection in the oncogenic initiation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Chronic infection of hepatitis B virus (HBV) and/or hepatitis C virus (HCV) is a major risk factor in the development of the HCC, independently from excessive alcohol abuse and metabolic disease. Since the biology of HBV and HCV is different, their oncogenic effect may go through different mechanisms, direct and/or indirect. Viral hepatitis infection is associated with cellular inflammation, oxidative stress, and DNA damage, that may lead to subsequent hepatic injuries such as chronic hepatitis, fibrosis, cirrhosis, and finally HCC. Direct oncogenic properties of these viruses are related with their genotypic characteristics and the ability of viral proteins to interact with host proteins, thus altering the molecular pathways balance of the cells. In addition, the integration of HBV DNA, especially the gene S and X, in a particular site of the host genome can disrupt chromosomal stability and may activate various oncogenic mechanisms, including those in hematopoietic cells. Recently, several studies also had demonstrated that viral hepatitis could trigger the population of hepatic cancer stem cells. This review summarize available pre-clinical and clinical data in literature regarding oncogenic properties of HBV and HCV in the early initiation of HCC.

Ultrasensitive, Multiplex Raman Frequency Shift Immunoassay of Liver Cancer Biomarkers in Physiological Media

Highly sensitive multiplex biomarker detection is critical for the early diagnosis of liver cancer. Here, a surface-enhanced Raman scattering (SERS) frequency-shift immunoassay is developed for detection of liver cancer biomarkers α-fetoprotein and Glypican-3 down to subpicomolar concentrations in saline solution. A high temperature modification of the Tollen's method affords silver nanoparticle films with excellent SERS response upon which ordered domains of Raman reporters are chemisorbed by microcontact printing. Shifts in the reporters SERS spectrum in response to a bound antibody's biomarker recognition constitutes the frequency shift assay, exhibiting here exceptional sensitivity and specificity and shown to function in fetal calf serum and in the serum of a patient with hepatocellular carcinoma.

Critical role for the long non-coding RNA AFAP1-AS1 in the proliferation and metastasis of hepatocellular carcinoma

Increasing evidence has indicated that dysregulation of long non-coding RNAs (lncRNAs) can contribute to the progression and metastasis of human cancer, including HCC. Previous studies have shown that the lncRNA AFAP1-AS1 plays a critical role in cancer. However, the roles of AFAP1-AS1 in HCC remain to be determined. In the present study, AFAP1-AS1 was found to be increased in HCC tissues, and high AFAP1-AS1 expression was associated with tumor size, TNM stage, vascular invasion, and poor prognosis. Silencing of AFAP1-AS1 significantly reduced cell proliferation, clonal growth, cell migration, and invasion and increased apoptosis in vitro. Furthermore, AFAP1-AS1 silencing markedly reduced tumor growth in a murine allograft model in vivo. The results suggested that AFAP1-AS1 is important in HCC development and serves as a therapeutic target of HCC.

Autologous Tumor Cell Lysate-Loaded Dendritic Cell Vaccine Inhibited Tumor Progression in an Orthotopic Murine Model for Hepatocellular Carcinoma

The immune status of the tumor microenvironment influences tumor progression, and hepatocellular carcinoma (HCC) with an immunosuppressive signature often is associated with a poor prognosis. This study examined the impact of a bone marrow-derived dendritic cell (DC) vaccine loaded with autologous tumor cell lysate on tumor progression and the tumor microenvironment using an orthotopic murine HCC model. An orthotopic murine HCC was established by implantation of Hepa1-6 cells in the liver. The impact of DC vaccine loaded with Hepa1-6 cell lysate on tumor progression, survival, and tumor-infiltrating lymphocytes and cytokines was examined. Treating mice with DC vaccine loaded with Hepa1-6 cell lysate inhibited the progression of murine HCC generated through orthotopic implantation of Hepa1-6 cells and resulted in a 90 % survival rate by day 60 compared with a survival rate lower than 5 % for untreated mice. This anti-tumor response was associated with inhibition of STAT3 phosphorylation within the tumor. The DC vaccine reduced accumulation of Foxp3⁺CD4⁺ regulatory T cells within the tumor microenvironment and prevented TGF-β production from the tumor tissue. Tumor cell lysate-loaded DC vaccine prevented HCC progression in a clinically relevant orthotopic murine HCC model. The effect of DC vaccine on the accumulation of Foxp3⁺CD4⁺ regulatory T cells within the tumor microenvironment and on the production of TGF-β suggests that tumor regression by DC vaccination may be associated with an altered immunosuppressive tumor microenvironment.

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.

Molecular imaging and therapy targeting copper metabolism in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide. Significant efforts have been devoted to identify new biomarkers for molecular imaging and targeted therapy of HCC. Copper is a nutritional metal required for the function of numerous enzymatic molecules in the metabolic pathways of human cells. Emerging evidence suggests that copper plays a role in cell proliferation and angiogenesis. Increased accumulation of copper ions was detected in tissue samples of HCC and many other cancers in humans. Altered copper metabolism is a new biomarker for molecular cancer imaging with position emission tomography (PET) using radioactive copper as a tracer. It has been reported that extrahepatic mouse hepatoma or HCC xenografts can be localized with PET using copper-64 chloride as a tracer, suggesting that copper metabolism is a new biomarker for the detection of HCC metastasis in areas of low physiological copper uptake. In addition to copper modulation therapy with copper chelators, short-interference RNA specific for human copper transporter 1 (hCtr1) may be used to suppress growth of HCC by blocking increased copper uptake mediated by hCtr1. Furthermore, altered copper metabolism is a promising target for radionuclide therapy of HCC using therapeutic copper radionuclides. Copper metabolism has potential as a new theranostic biomarker for molecular imaging as well as targeted therapy of HCC.

Ion Channels and Oxidative Stress as a Potential Link for the Diagnosis or Treatment of Liver Diseases

Oxidative stress results from a disturbed balance between oxidation and antioxidant systems. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) may be either harmful or beneficial to the cells. Ion channels are transmembrane proteins that participate in a large variety of cellular functions and have been implicated in the development of a variety of diseases. A significant amount of the available drugs in the market targets ion channels. These proteins have sulfhydryl groups of cysteine and methionine residues in their structure that can be targeted by ROS and RNS altering channel function including gating and conducting properties, as well as the corresponding signaling pathways associated. The regulation of ion channels by ROS has been suggested to be associated with some pathological conditions including liver diseases. This review focuses on understanding the role and the potential association of ion channels and oxidative stress in liver diseases including fibrosis, alcoholic liver disease, and cancer. The potential association between ion channels and oxidative stress conditions could be used to develop new treatments for major liver diseases.

Hepatitis B and C virus-induced hepatitis: Apoptosis, autophagy, and unfolded protein response

AIM

To investigate the co-incidence of apoptosis, autophagy, and unfolded protein response (UPR) in hepatitis B (HBV) and C (HCV) infected hepatocytes.

METHODS

We performed immunofluorescence confocal microscopy on 10 liver biopsies from HBV and HCV patients and tissue microarrays of HBV positive liver samples. We used specific antibodies for LC3β, cleaved caspase-3, BIP (GRP78), and XBP1 to detect autophagy, apoptosis and UPR, respectively. Anti-HCV NS3 and anti-HBs antibodies were also used to confirm infection. We performed triple blind counting of events to determine the co-incidence of autophagy (LC3β punctuate), apoptosis (cleaved caspase-3), and unfolded protein response (GRP78) with HBV and HCV infection in hepatocytes. All statistical analyses were performed using SPSS software for Windows (Version 16 SPSS Inc, Chicago, IL, United States). P-values < 0.05 were considered statistically significant. Statistical analyses were performed with Mann-Whitney test to compare incidence rates for autophagy, apoptosis, and UPR in HBV- and HCV-infected cells and adjacent non-infected cells.

RESULTS

Our results showed that infection of hepatocytes with either HBV and HCV induces significant increase (P < 0.001) in apoptosis (cleavage of caspase-3), autophagy (LC3β punctate), and UPR (increase in GRP78 expression) in the HCV- and HBV-infected cells, as compared to non-infected cells of the same biopsy sections. Our tissue microarray immunohistochemical expression analysis of LC3β in HBV(Neg) and HBV(Pos) revealed that majority of HBV-infected hepatocytes display strong positive staining for LC3β. Interestingly, although XBP splicing in HBV-infected cells was significantly higher (P < 0.05), our analyses show a slight increase of XBP splicing was in HCV-infected cells (P > 0.05). Furthermore, our evaluation of patients with HBV and HCV infection based on stage and grade of the liver diseases revealed no correlation between these pathological findings and induction of apoptosis, autophagy, and UPR.

CONCLUSION

The results of this study indicate that HCV and HBV infection activates apoptosis, autophagy and UPR, but slightly differently by each virus. Further studies are warranted to elucidate the interconnections between these pathways in relation to pathology of HCV and HBV in the liver tissue.

Liver cell injury caused by bad habits

Apoptosis and necrosis of liver cells induced by environmental or genetic factors are the main features of liver injury. Liver injury is usually caused by apoptosis of liver cells, which is controlled by a complex regulatory system involved in liver damage and secondary inflammation. This article aims to review liver injury caused by bad habits and the underlying molecular mechanisms.

Liver epithelial cells inhibit proliferation and invasiveness of hepatoma cells

Hepatocellular carcinoma (HCC) is a worldwide malignancy with poor prognosis. Liver progenitors or stem cells could be a potential therapy for HCC treatment since they migrate toward tumors. Rat liver epithelial (RLE) cells have both progenitor and stem cell-like properties. Therefore, our study elucidated the therapeutic effect of RLE cells in rat hepatoma cells. RLE cells were isolated from 10-day old rats and characterized for stem cell marker expression. RLE cells and rat hepatoma cells (H4-IIE-C3 cells) were co-cultured and divided into four groups with different ratios of RLE and hepatoma cells. Group A had only rat hepatoma cells as a control group. The ratios of rat hepatoma and RLE cells in group B, C and D were 5:1, 1:1 and 1:5, respectively. Effective inhibition of cell proliferation and migration was found in group D when compared to group A. There was a significant decrease in Bcl2 expression and increase in late apoptosis of rat hepatoma cells when adding more RLE cells. RLE cells reduced cell proliferation and migration of rat hepatoma cells. These results suggested that RLE cells could be used as a potential cell therapy.

Transcriptomic Analysis of Chronic Hepatitis B and C and Liver Cancer Reveals MicroRNA-Mediated Control of Cholesterol Synthesis Programs

Chronic hepatitis B (CHB), chronic hepatitis C (CHC), and associated hepatocellular carcinoma (HCC) are characterized by cholesterol imbalance and dyslipidemia; however, the key regulatory drivers of these phenotypes are incompletely understood. Using gene expression microarrays and high-throughput sequencing of small RNAs, we performed integrative analysis of microRNA (miRNA) and gene expression in nonmalignant and matched cancer tissue samples from human subjects with CHB or CHC and HCC. We also carried out follow-up functional studies of specific miRNAs in a cell-based system. These studies led to four major findings. First, pathways affecting cholesterol homeostasis were among the most significantly overrepresented among genes dysregulated in chronic viral hepatitis and especially in tumor tissue. Second, for each disease state, specific miRNA signatures that included miRNAs not previously associated with chronic viral hepatitis, such as miR-1307 in CHC, were identified. Notably, a few miRNAs, including miR-27 and miR-224, were components of the miRNA signatures of all four disease states: CHB, CHC, CHB-associated HCC, and CHC-associated HCC. Third, using a statistical simulation method (miRHub) applied to the gene expression data, we identified candidate master miRNA regulators of pathways controlling cholesterol homeostasis in chronic viral hepatitis and HCC, including miR-21, miR-27, and miR-33. Last, we validated in human hepatoma cells that both miR-21 and miR-27 significantly repress cholesterol synthesis and that miR-27 does so in part through regulation of the gene that codes for the rate-limiting enzyme 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase (HMGCR).

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are phylogenetically unrelated hepatotropic viruses that persistently infect hundreds of millions of people world-wide, often leading to chronic liver disease and hepatocellular carcinoma (HCC). Chronic hepatitis B (CHB), chronic hepatitis C (CHC), and associated HCC often lead to cholesterol imbalance and dyslipidemia. However, the regulatory mechanisms underlying the dysregulation of lipid pathways in these disease states are incompletely understood. MicroRNAs (miRNAs) have emerged as critical modulators of lipid homeostasis. Here we use a blend of genomic, molecular, and biochemical strategies to identify key miRNAs that drive the lipid phenotypes of chronic viral hepatitis and HCC. These findings provide a panoramic view of the miRNA landscape in chronic viral hepatitis, which could contribute to the development of novel and more-effective miRNA-based therapeutic strategies.

Dendritic cells pulsed with Hsp70 and HBxAg induce specific antitumor immune responses in hepatitis B virus-associated hepatocellular carcinoma

Previous studies have drawn attention to dendritic cell (DC) vaccines; particularly the application of the tumor-associated antigen-targeted DC vaccine. The present study analyzed DCs derived from a normal individual and pulsed the cells with heat shock protein 70 peptide (Hsp70) and/or hepatitis B virus x antigen (HBxAg), a hepatocellular carcinoma (HCC)-associated antigen. It was then investigated whether this method of vaccination induced strong therapeutic antitumor immunity. The results revealed that the Hsp70/HBxAg complex-activated phenotype improves the functional maturation of DCs compared with using Hsp70 or HBxAg alone. Compared with either Hsp70 or HBxAg alone, matured DCs pulsed with the Hsp70/HBxAg complex stimulated a high level of autologous T-cell proliferation and induced HCC-specific cytotoxic T lymphocytes, which specifically killed HCC cells through a major histocompatibility complex class I mechanism. These results indicated that a vaccination therapy using DCs co-pulsed with the Hsp70/HBxAg complex is an effective strategy for immunotherapy and may offer a useful approach to protect against HCC.

Immune-based Therapy Clinical Trials in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality and continues to increase. Current standard of care for patients with HCC only provides limited therapeutic benefit. Development of innovative strategies is urgently needed. Experience with immunotherapy in HCC is quite early, but rapidly rise in the recent 15 years. Multifaceted immune-based approaches have shown efficacy in achieving disease regression, representing the most promising new treatment approach. Here, we classify the ongoing or completed clinical trials in HCC in terms of the immune strategies to be used and assess their clinical outcomes. The generated information may be helpful in the design of future immune-based therapies for achieving ideal tumor control and maximizing anti-tumor immunity.

Early inhibition of hepatocyte innate responses by hepatitis B virus

BACKGROUND & AIMS

The outcome of hepatitis B virus (HBV) infection may be influenced by early interactions between the virus and hepatocyte innate immune responses. To date, the study of such interactions during the very early step of infection has not been adequately investigated.

METHODS

We used the HepaRG cell line, as well as primary human hepatocytes to analyze, within 24h of exposure to HBV, either delivered by a physiologic route or baculovirus vector (Bac-HBV), the early modulation of the expression of selected antiviral/pro-inflammatory cytokines and interferon stimulated genes. Experiments were also performed in the presence or absence of innate receptor agonists to investigate early HBV-induced blockade of innate responses.

RESULTS

We show that hepatocytes themselves could detect HBV, and express innate genes when exposed to either HBV virions or Bac-HBV. Whereas Bac-HBV triggered a strong antiviral cytokine secretion followed by the clearance of replicative intermediates, a physiologic HBV exposure led to an abortive response. The early inhibition of innate response by HBV was mainly evidenced on Toll-like receptor 3 and RIG-I/MDA5 signaling pathways upon engagement with exogenous agonist, leading to a decreased expression of several pro-inflammatory and antiviral cytokine genes. Finally, we demonstrate that this early inhibition of dsRNA-mediated response is due to factor(s) present in the HBV inoculum, but not being HBsAg or HBeAg themselves, and does not require de novo viral protein synthesis and replication.

CONCLUSIONS

Our data provide strong evidence that HBV viral particles themselves can readily inhibit host innate immune responses upon virion/cell interactions, and may explain, at least partially, the "stealthy" character of HBV.

Interactions of Hepatitis B Virus Infection with Nonalcoholic Fatty Liver Disease: Possible Mechanisms and Clinical Impact

Hepatitis B virus (HBV) infection is a major etiology of chronic liver disease worldwide. In the past decade, nonalcoholic fatty liver disease (NAFLD) has emerged as a common liver disorder in general population. Accordingly, the patient number of chronic hepatitis B (CHB) concomitant with NAFLD grows rapidly. The present article reviewed the recent studies aiming to explore the relationship between CHB and NAFLD from different aspects, including the relevant pathogenesis of CHB and NAFLD, the intracellular molecular mechanisms overlaying HBV infection and hepatic steatosis, and the observational studies with animal models and clinical cohorts for analyzing the coincidence of the two diseases. It is concluded that although numerous cross-links have been suggested between the molecular pathways in HBV infection and NAFLD pathogenesis, regarding whether HBV infection can substantially interfere with the occurrence of NAFLD or vice versa in the patients, there is still far from a conclusive agreement.

European Code against Cancer 4th Edition: Infections and Cancer

Of the 2,635,000 new cancer cases (excluding non-melanoma skin cancers) occurring in the European Union (EU) in 2012, it is estimated that approximately 185,000 are related to infection with human papillomaviruses (HPVs), hepatitis B and C viruses (HBV and HCV), and Helicobacter pylori (H. pylori). Chronic infection with these agents can lead to cancers of the cervix uteri, liver, and stomach, respectively. Chronic infection with HCV can also lead to B-cell non-Hodgkin lymphoma. Human immunodeficiency virus (HIV) infection continues to be of major public health importance in several EU countries and increases cancer risk via HIV-induced immunosuppression. The fourth edition of the European Code Against Cancer presents recommendations on effective and safe preventive interventions in order to reduce the risk of infection-related cancers in EU citizens. Based on current available evidence, the fourth edition recommends that parents ensure the participation of their children in vaccination programs against HBV (for newborns) and HPV (for girls). In the 'Questions and Answers' (Q&As) section about vaccination and infections in the website for the European Code Against Cancer, individuals who are at risk of chronic HBV or HCV are advised to seek medical advice about testing and obtaining treatment when appropriate. Individuals most at risk of HIV are advised to consult their doctor or healthcare provider to access counselling and, if needed, testing and treatment without delay. Information about H. pylori testing and treatment is also provided as testing might currently be offered in some high-risk areas in Europe. The rationale and supporting evidence for the recommendations on vaccination in the European Code Against Cancer, and for the main recommendations on vaccination and infection in the Q&As, are explained in the present review.

Hepatitis B virus therapy: What’s the future holding for us?

Hepatitis B is one of the leading causes of liver cancer worldwide and unfortunately the number of people affected with hepatitis B virus (HBV) infection is still on the rise. Although the HBV has been known to cause fatal illness since decades but the population effected by this lethal virus have still only a few options for its management. The major treatment strategies include interferons and nucleos(t)ide analogues. These agents have so far produced unsatisfactory results in terms of complete virus eradication. Interferons cannot be used for long term therapy because of their potential side effects. Prolong treatment with nucleos(t)ide analogues has also been reported to cause serious side effects besides the increasing resistance by the virus. The need for new innovative solutions for treatment of HBV has been realized by global research institutes and pharmaceutical industry. Present review focuses in detail on the new ideas that are being transformed into therapeutic tools for use as future therapies in HBV infection. Modern drug designing and screening methods have made the drug discovery process shorter and more reliable. HBV therapeutics will take a new turn in coming years owing to these intelligent drug designing and screening methods. Future therapy of HBV is aiming to include the use of vaccines (both prophylactic and therapeutic), immunomodulators such as antibodies, non-nucleoside antivirals such as RNAi and inhibitors of viral life cycle.

Protein-protein interactions among signaling pathways may become new therapeutic targets in liver cancer (Review)

Numerous signaling pathways have been shown to be dysregulated in liver cancer. In addition, some protein-protein interactions are prerequisite for the uncontrolled activation or inhibition of these signaling pathways. For instance, in the PI3K/AKT signaling pathway, protein AKT binds with a number of proteins such as mTOR, FOXO1 and MDM2 to play an oncogenic role in liver cancer. The aim of the present review was to focus on a series of important protein-protein interactions that can serve as potential therapeutic targets in liver cancer among certain important pro-carcinogenic signaling pathways. The strategies of how to investigate and analyze the protein-protein interactions are also included in this review. A survey of these protein interactions may provide alternative therapeutic targets in liver cancer.

Association of Ghrelin Gene Polymorphisms and Serum Ghrelin Levels with the Risk of Hepatitis B Virus-Related Liver Diseases in a Chinese Population

Background

The functions of ghrelin (GHRL) include anti-inflammatory effects, reduction of the fibrogenic response, protection of liver tissue, and regulation of cell proliferation. Genetic variations in the GHRL gene may play an important role in the development of chronic hepatitis B (CHB), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). Therefore, we investigated whether GHRL gene polymorphisms and its serum levels are associated with hepatitis B virus (HBV)-related diseases risk in a Chinese population.

Methods

176 patients with CHB, 106 patients with HBV-related LC, 151 patients with HBV-related HCC, and 167 healthy controls were recruited in the study. Genotyping of GHRL rs26311, rs27647, rs696217, and rs34911341 polymorphisms were determined with the polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) and DNA sequencing. The serum GHRL concentrations were determined using enzyme-linked immunosorbent assay (ELISA).

Results

Binary logistic regression analyses adjusting for gender and age revealed that a significant increased risk of LC was found in the GHRL rs26311 GC genotype and combined GC+CC genotypes when compared with the GG genotype (GC vs. GG: OR = 1.671, 95% CI = 1.013–2.757, P = 0.044; GC+CC vs. GG: OR = 1.674, 95% CI = 1.040–2.696, P = 0.034). In subgroup analysis by gender, binary logistic regression analyses adjusting for age showed that the GHRL rs26311 C allele and combined GC+CC genotypes were associated with a significantly increased risk to LC in males (C vs. G OR = 1.416, 95% CI = 1.017–1.972, P = 0.040; GC+CC vs. GG: OR = 1.729, 95% CI = 1.019–2.933, P = 0.042). In addition, we found significant decreased serum GHRL levels in LC patients compared with the healthy controls. However, there was no significant association of the GHRL rs26311 polymorphism with serum GHRL levels in LC patients.

Conclusions

These observations suggest that the GHRL rs26311 polymorphism is associated with an increased risk to HBV-related LC, especially in men. We also found an inverse association of serum GHRL levels with LC.

CUL4A facilitates hepatocarcinogenesis by promoting cell cycle progression and epithelial-mesenchymal transition

CUL4A, a member of the CULLIN family, functions as a scaffold protein for an E3 ubiquitin ligase. It was reported that the CUL4A gene showed amplification in some human primary hepatocellular carcinomas (HCC). However, the exact role of CUL4A in HCC remains unknown. Here, we aimed to investigate the expression and function of CUL4A in HCC development. Through immunohistochemistry study, we showed increased CUL4A expression in HCC tissues. Statistical analysis disclosed an inverse correlation between CUL4A expression and tumor differentiation grade, and patient survival, but a positive correlation with hepatocyte proliferation as well as lymphatic and venous invasion. CUL4A expression in HCC tissues was associated with HBeAg status in patients and upregulated by HBV in HCC cell lines. Further functional assay showed that CUL4A overexpression significantly promoted growth of H22 tumor homografts in BALB/c mice. Consistently, CUL4A knockdown inhibited the proliferation of established HCC cells, accompanied by S-phase reduction and Cyclin A and Cyclin B1 repression. Furthermore, CUL4A siRNA ameliorated the motility of HCC cell lines with altered expression of epithelial-mesenchymal transition (EMT)-associated molecules. Taken together, our findings indicate that CUL4A plays a pivotal role in HCC progression and may serve as a potential marker for clinical diagnosis and target for therapy.

Neuropilin-2 induced by transforming growth factor-β augments migration of hepatocellular carcinoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common form of liver cancer and the third most lethal cancer worldwide. The epithelial to mesenchymal transition (EMT) describes the transformation of well-differentiated epithelial cells to a de-differentiated phenotype and plays a central role in the invasion and intrahepatic metastasis of HCC cells. Modulation of the transforming growth factor-β (TGF-β) signaling is known to induce various tumor-promoting and EMT-inducing pathways in HCC. The meta-analysis of a panel of EMT gene expression studies revealed that neuropilin 2 (NRP2) is significantly upregulated in cells that have undergone EMT induced by TGF-β. In this study we assessed the functional role of NRP2 in epithelial and mesenchymal-like HCC cells and focused on the molecular interplay between NRP2 and TGF-β/Smad signaling.

METHODS

NRP2 expression was analyzed in human HCC cell lines and tissue arrays comprising 133 HCC samples. Cell migration was examined by wound healing and Transwell assays in the presence and absence of siRNA against NRP2. NRP2 and TGF-β signaling were analyzed by Western blotting and confocal immunofluorescence microscopy.

RESULTS

We show that NRP2 is particularly expressed in HCC cell lines with a dedifferentiated, mesenchymal-like phenotype. NRP2 expression is upregulated by the canonical TGF-β/Smad signaling while NRP2 expression has no impact on TGF-β signaling in HCC cells. Reduced expression of NRP2 by knock-down or inhibition of TGF-β signaling resulted in diminished cell migration independently of each other, suggesting that NRP2 fails to collaborate with TGF-β signaling in cell movement. In accordance with these data, elevated levels of NRP2 correlated with a higher tumor grade and less differentiation in a large collection of human HCC specimens.

CONCLUSIONS

These data suggest that NRP2 associates with a less differentiated, mesenchymal-like HCC phenotype and that NRP2 plays an important role in tumor cell migration upon TGF-β-dependent HCC progression.

Rapid and quantitative detection of hepatitis B virus

Despite availability of a universal vaccine, hepatitis B virus (HBV) infection has a huge impact on public health worldwide. Accurate and timely diagnosis of HBV infection is needed. Rapid developments have been made in the diagnostic and monitoring methods for HBV infection, including serological and molecular assays. In clinical practice, qualitative hepatitis B surface antigen (HBsAg) testing has long served as a diagnostic marker for individuals infected with HBV. More recently, HBsAg level has been used to predict treatment outcome when determined early during treatment or at baseline. However, identification of HBV DNA positive cases that do not have detectable HBsAg has encouraged the application of molecular tests. Hence, combination of quantitative detection of HBV DNA and HBsAg can be used to discriminate patients during the course of HBV infection and to monitor therapy. This article reviews the most commonly used quantitative methods for HBsAg and HBV DNA.

Full-length single-cell RNA-seq applied to a viral human cancer: applications to HPV expression and splicing analysis in HeLa S3 cells

Background

Viral infection causes multiple forms of human cancer, and HPV infection is the primary factor in cervical carcinomas. Recent single-cell RNA-seq studies highlight the tumor heterogeneity present in most cancers, but virally induced tumors have not been studied. HeLa is a well characterized HPV+ cervical cancer cell line.

Result

We developed a new high throughput platform to prepare single-cell RNA on a nanoliter scale based on a customized microwell chip. Using this method, we successfully amplified full-length transcripts of 669 single HeLa S3 cells and 40 of them were randomly selected to perform single-cell RNA sequencing. Based on these data, we obtained a comprehensive understanding of the heterogeneity of HeLa S3 cells in gene expression, alternative splicing and fusions. Furthermore, we identified a high diversity of HPV-18 expression and splicing at the single-cell level. By co-expression analysis we identified 283 E6, E7 co-regulated genes, including CDC25, PCNA, PLK4, BUB1B and IRF1 known to interact with HPV viral proteins.

Conclusion

Our results reveal the heterogeneity of a virus-infected cell line. It not only provides a transcriptome characterization of HeLa S3 cells at the single cell level, but is a demonstration of the power of single cell RNA-seq analysis of virally infected cells and cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13742-015-0091-4) contains supplementary material, which is available to authorized users.

The emerging role of nuclear viral DNA sensors

Detecting pathogenic DNA by intracellular receptors termed "sensors" is critical toward galvanizing host immune responses and eliminating microbial infections. Emerging evidence has challenged the dogma that sensing of viral DNA occurs exclusively in sub-cellular compartments normally devoid of cellular DNA. The interferon-inducible protein IFI16 was shown to bind nuclear viral DNA and initiate immune signaling, culminating in antiviral cytokine secretion. Here, we review the newly characterized nucleus-originating immune signaling pathways, their links to other crucial host defenses, and unique mechanisms by which viruses suppress their functions. We frame these findings in the context of human pathologies associated with nuclear replicating DNA viruses.

Ectopic lymphoid structures function as microniches for tumor progenitor cells in hepatocellular carcinoma

Ectopic lymphoid-like structures (ELSs) are often observed in cancer, yet their function is obscure. Although ELSs signify good prognosis in certain malignancies, we found that hepatic ELSs indicated poor prognosis for hepatocellular carcinoma (HCC). We studied an HCC mouse model that displayed abundant ELSs and found that they constituted immunopathological microniches wherein malignant hepatocyte progenitor cells appeared and thrived in a complex cellular and cytokine milieu until gaining self-sufficiency. The egress of progenitor cells and tumor formation were associated with the autocrine production of cytokines previously provided by the niche. ELSs developed via cooperation between the innate immune system and adaptive immune system, an event facilitated by activation of the transcription factor NF-κB and abolished by depletion of T cells. Such aberrant immunological foci might represent new targets for cancer therapy.

Ectopic lymphoid structures function as microniches for tumor progenitor cells in hepatocellular carcinoma

Ectopic lymphoid-like structures (ELS) are often observed in cancer, yet their function is obscure. Although ELSs signify good prognosis in certain malignancies, we found that hepatic ELSs indicate poor prognosis in hepatocellular carcinoma (HCC). We studied an HCC mouse model, displaying abundant ELSs and found that they constitute immunopathological microniches, wherein progenitor malignant hepatocytes appear and thrive in a complex cellular and cytokine milieu until gaining self-sufficiency. Progenitor egression and tumor formation is associated with autocrine production of cytokines previously provided by the niche. ELSs develop upon cooperation between the innate and adaptive immune system which is facilitated by NF-κB activation and abolished by T cell depletion. These aberrant immune foci could be new targets for cancer therapy.

SIP1 is a downstream effector of GADD45G in senescence induction and growth inhibition of liver tumor cells

Cellular senescence evasion caused by the inactivation of tumor suppressive programs is implicated in tumor initiation and therapeutic resistance. Our previous study has shown that the downregulation of growth arrest and DNA damage 45G (GADD45G) contributes to senescence bypass in hepatocellular carcinoma (HCC). Here, we report that the Smad-interacting protein-1 (SIP1) is transcriptionally activated and functions critically in the GADD45G-induced tumor cell senescence. Knockdown of SIP1 significantly abrogates the suppressive effects of GADD45G on the growth of xenografted liver tumor in vivo. The essential role of SIP1 in GADD45G activities is further validated in the model of the proteasome inhibitor MG132-induced cell senescence. We further show that JNK but not p38 MAPK activation is involved in the GADD45G-mediated SIP1 upregulation, and that JNK inhibition counteracts the GADD45G-induced cellular senescence. More importantly, we show that GADD45G and SIP1 expression are coincidently downregulated in primary human HCC tissues. Together, our results establish that the dowregulation of GADD45G-SIP1 axis may contribute to cellular senescence evasion and HCC development.

The transcription factor c-JUN/AP-1 promotes HBV-related liver tumorigenesis in mice

Hepatocellular carcinoma (HCC) develops as a consequence of chronic inflammatory liver diseases such as chronic hepatitis B virus (HBV) infection. The transcription factor c-Jun/activator protein 1 (AP-1) is strongly expressed in response to inflammatory stimuli, promotes hepatocyte survival during acute hepatitis and acts as an oncogene during chemically induced liver carcinogenesis in mice. Here, we therefore aimed to characterize the functions of c-Jun during HBV-related liver tumorigenesis. To this end, transgenic mice expressing all HBV envelope proteins (HBV(+)), an established model of HBV-related HCC, were crossed with knockout mice lacking c-Jun specifically in hepatocytes and tumorigenesis was analyzed. Hepatic expression of c-Jun was strongly induced at several time points during tumorigenesis in HBV(+) mice, whereas expression of other AP-1 components remained unchanged. Importantly, formation of premalignant foci and tumors was strongly reduced in HBV(+) mice lacking c-Jun. This phenotype correlated with impaired hepatocyte proliferation and increased expression of the cell cycle inhibitor p21, whereas hepatocyte survival was not affected. Progression and prognosis of HBV-related HCC correlates with the expression of the cytokine osteopontin (Opn), an established AP-1 target gene. Opn expression was strongly reduced in HBV(+) livers and primary mouse hepatocytes lacking c-Jun, demonstrating that c-Jun regulates hepatic Opn expression in a cell-autonomous manner. These findings indicate that c-Jun has important functions during HBV-associated tumorigenesis by promoting hepatocyte proliferation as well as progression of dysplasia. Therefore, targeting c-Jun may be a useful strategy to prevent hepatitis-associated tumorigenesis.

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.