Chronic infection with hepatitis G virus in relation to hepatocellular carcinoma among non-Asians in Los Angeles County, California

Expression of the lysyl oxidase propeptide in hepatocellular carcinoma and its clinical relevance

Lysyl oxidase is an important extracellular matrix remodeling enzyme and plays critical roles in tumor progression and development. Its tumor-suppressor activity has been shown to depend on the propeptide region. Previous studies have reported that the expression levels of lysyl oxidase propeptide (LOX-PP) are associated with cancer of the breast, pancreas, lung, prostate and gastrointestinal system. However, to date, the exact effects and molecular mechanisms of LOX-PP in hepatocellular carcinoma progression are still unclear. The present study aimed to investigate the expression and clinical significance of LOX-PP in human hepatocellular carcinoma. First, 42 cases of hepatocellular carcinoma and corresponding adjacent non-cancerous tissues (ANCTs) were collected, and the expression of LOX-PP in these samples was assessed by immunohistochemistry (IHC). The clinicopathological characteristics of all patients were recorded. Next, in in vitro studies, recombinant adenovirus LOX (ad-LOX-PP) was used to infect hepatocellular carcinoma cell lines to determine the function of LOX-PP. To determine whether ad-LOX-PP affects hepatocellular carcinoma cell survival, cell viability was examined by CCK-8 assay, and cell cycle progression was assessed by flow cytometry. We also investigated the effects of LOX-PP on the expression of cell cycle regulators (cyclin D1 and cyclin E) by western blot analysis. The migration and invasion capacities of hepatocellular carcinoma cells were observed by wound-healing and tranwell invasion assays. To further investigate how LOX-PP affects migration levels of matrix metallopeptidase (MMP)-2 and MMP-9 were assessed by western blot analysis. Additionally, markers of the PI3K and MAPK signaling pathway were detected to further confirm the mechanisms of LOX-PP. As a result, reduced expression of LOX-PP was found in hepatocellular carcinoma tissues, when compared with that in the ANCTs (15 vs. 83%, P<0.01), and its expression was associated with tumor stage and distant metastasis (each P<0.05). Proliferation in hepatocellular carcinoma cells was significantly decreased in the ad-LOX-PP group as indicated by CCK-8 assay. LOX-PP significantly reduced the expression of Ki-67, while prominent increases in the rate of apoptosis and cell cycle arrest were observed. Similarly, cell migration was significantly inhibited in the ad-LOX-PP group as evidenced by transwell invasion and wound-healing assays. The expression levels of MMP-2 and MMP-9 were attenuated in the ad-LOX-PP group, suggesting that LOX-PP inhibits hepatocellular carcinoma cell migration via down-regulation of MMPs expression. When LOX-PP expression was potentiated by an adenovirus containing LOX-PP, the expression of p-ERK was significantly downregulated, indicating that LOX-PP inhibits hepatocellular carcinoma cell proliferation and induces its apoptosis probably through downregulation of the MAPK/ERK pathway.

Hepatitis viruses (other than hepatitis B and C viruses) as causes of hepatocellular carcinoma: an update

Chronic hepatitis B and C virus infections are universally accepted as causes of hepatocellular carcinoma in humans. Hepatitis A and E viruses cause only acute self-limiting infections of the liver. Of the remaining hepatitis viruses - Delta hepatitis, hepatitis G (GB-C), TT and SEN - all have at some time been incriminated as causes of hepatocellular carcinoma. Delta hepatitis virus requires helper functions from hepatitis B virus to become invasive. Chronic Delta/hepatitis B viral co-infection runs a more severe course than that resulting from chronic hepatitis B virus infection alone, with progression to cirrhosis being more likely and more rapid. A substantial majority of the early studies did not find an increased incidence of hepatocellular carcinoma in co-infected individuals. But more recently, an increased incidence of the tumour has been recorded more often than no increase. Further studies are needed to draw a firm conclusion with regard to the hepatocarcinogenic effect of dual Delta/hepatitis B virus co-infection. With one exception, no published study (of 13) has incriminated chronic infection with hepatitis G virus as a cause of hepatocellular carcinoma. The dissenting study, published in 1999, was the only one performed in the United States. Fewer studies of the hepatocarcinogenic effect of TT virus have been performed. Apart from one study, published in 1999, no convincing evidence is available that supports a causal role for TT virus in hepatocarcinogenesis. The exception was in Japanese patients with high hepatitis C viral loads but independent of chronic hepatitis C virus infection. No evidence has been produced to indicate that SEN virus causes hepatocellular carcinoma.

Hepatitis G virus

A number of new hepatitis viruses (G, TT, SEN) were discovered late in the past century. We review the data available in the literature and our own findings suggesting that the new hepatitis G virus (HGV), disclosed in the late 1990s, has been rather well studied. Analysis of many studies dealing with HGV mainly suggests the lymphotropicity of this virus. HGV or GBV-C has been ascertained to influence course and prognosis in the HIV-infected patient. Until now, the frequent presence of GBV-C in coinfections, hematological diseases, and biliary pathology gives no grounds to determine it as an “accidental tourist” that is of no significance. The similarity in properties of GBV-C and hepatitis C virus (HCV) offers the possibility of using HGV, and its induced experimental infection, as a model to study hepatitis C and to develop a hepatitis C vaccine.

GB virus C/hepatitis G virus

GB virus C (GBV-C), or hepatitis G virus (HGV), is a recently discovered enveloped RNA virus belonging to the Flaviviridae family. GBV-C/HGV is transmitted by contaminated blood and/or blood products, intravenous drug use, from mother to child, sexually, and possibly through close social contacts. Several reports indicate a high prevalence of GBV-C/HGV viremia (1-4%) within healthy populations in Europe and North America, and an even higher prevalence (10-33%) among residents in South America and Africa. GBV-C/HGV has been suggested to be a causative agent for non-A-non-E hepatitis. However, several contradictory observations suggest that its ability to cause hepatitis is questionable. Taken together most data suggest that GBV-C/HGV is not a major cause of liver disease despite recent data indicating that it may infect and replicate in hepatocytes.

International trends and patterns of primary liver cancer

Primary liver cancer (PLC) is common in many areas of the developing world, but uncommon in most of the developed world. Some evidence suggests, however, that the global pattern of PLC may be changing. To clarify this issue, we examined incidence rates for PLC over the 15-year time period, 1978-92, in selected cancer registries around the world. With some exceptions, developed countries have experienced PLC increases in incidence whereas developing countries have experienced declines. Although the reasons for the trends are not entirely clear, the increased seroprevalence of HCV in the developed world and the elimination of HBV-cofactors in the developing world are likely to have contributed to the patterns. Further progress against PLC may be seen in the developing world once the HBV-vaccinated segment of the population reaches adulthood. Published 2001 Wiley-Liss, Inc.

Hepatocellular carcinoma--cause, treatment and metastasis

In the recent decades, the incidence of hepatocellular carcinoma (HCC) has been found to be increasing in males in some countries. In China, HCC ranked second of cancer mortality since 1990s. Hepatitis B and C viruses (HBV and HCV) and dietary aflatoxin intake remain the major causative factors of HCC. Surgery plays a major role in the treatment of HCC, particularly for small HCC. Down-staging unresectable huge HCC to smaller HCC and followed by resection will probably be a new approach for further study. Liver transplantation is indicated for small HCC, however, some issues remain to be solved. Different modes of regional cancer therapy for HCC have been tried. Systemic chemotherapy has been disappointing in the past but the future can be promising. Biotherapy, such as cytokines, differentiation inducers, anti-angiogenic agents, gene therapy and tumor vaccine will probably play a role, particularly in the prevention of tumor recurrence. HCC invasiveness is currently the major target of study. Tremendous works have been done at the molecular level, which will provide clues for biomarker of HCC progression as well as targets for intervention.

GB virus C/hepatitis G virus (GBV-C/HGV): still looking for a disease

GB Virus C and Hepatitis G Virus (GBV-C/HGV) are positive, single-stranded flaviviruses. GBV-C and HGV are independent isolates of the same virus. Transmission via the blood-borne route is the commonest mode, although vertical and sexual transmission is well documented. GBV-C/HGV is distributed globally; its prevalence in the general population is 10 fold higher in African countries than in non-African countries. High prevalences of GBV-C/HGV have been found in subjects with frequent parenteral exposure and in groups at high risk of exposure to blood and blood products. The clinical significance of human infection with GBV-C/HGV is currently unclear. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Only some 12-15% of chronic Non-A, B, C hepatitis cases are infected with GBV-C/HGV. A direct association with liver pathology is still lacking and it is not yet clear as to whether GBV-C/HGV is indeed a hepatotropic virus. Current evidence suggests that the spectrum of association of GBV-C/HGV infection with extrahepatic diseases ranges from haematalogical diseases, aplastic anaemia, human immunodeficiency virus (HIV)-positive idiopathic thrombocytopenia and thalassemia, through to common variable immune deficiency and cryoglobunemia.

Hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has ranked second in cancer mortality in China since the 1990s and is increasing in frequency among males in many countries. Hepatitis B and C viruses, aflatoxin and algal toxin in the contaminated drinking water remain major aetiological factors and hepatitis G virus and transfusion-transmitted virus can not be excluded. A prospective randomized control trial screening for HCC in a high-risk population using alpha fetoprotein (AFP) and ultrasonography has demonstrated a decrease in HCC mortality. Rapidly progressing medical imaging has continuously contributed to the improving treatment results. Surgical resection still plays a major role in influencing prognosis of HCC. Studies on recurrence and metastasis after curative resection have become a key issue for further improvement of the surgical outcome. Regional cancer therapies are progressing rapidly, based on the advances in early diagnosis. The advantages and disadvantages of these are noted. Multimodality combination and sequential treatment has been accepted as an important approach for unresectable HCC and cytoreduction and sequential resection have attracted attention. Conformal radiotherapy has shown important potential for HCC treatment. Intra-arterial chemotherapy has been repeatedly proved effective; however, systemic chemotherapy for HCC remains disappointing. The effects of tamoxifen are questionable, whereas alpha-interferon has been shown to have significant potential, particularly in prevention of recurrence. All of these treatments have resulted in continuing improvement of HCC prognosis in some centres.

GB virus C/hepatitis G virus (GBV-C/HGV): still looking for a disease

GB Virus C and Hepatitis G Virus (GBV-C/HGV) are positive, single-stranded flaviviruses. GBV-C and HGV are independent isolates of the same virus. Transmission via the blood-borne route is the commonest mode, although vertical and sexual transmission is well documented. GBV-C/HGV is distributed globally; its prevalence in the general population is 10 fold higher in African countries than in non-African countries. High prevalences of GBV-C/HGV have been found in subjects with frequent parenteral exposure and in groups at high risk of exposure to blood and blood products. The clinical significance of human infection with GBV-C/HGV is currently unclear. The virus can establish both acute and chronic infection and appears to be sensitive to interferon. Only some 12-15% of chronic Non-A, B, C hepatitis cases are infected with GBV-C/HGV. A direct association with liver pathology is still lacking and it is not yet clear as to whether GBV-C/HGV is indeed a hepatotropic virus. Current evidence suggests that the spectrum of association of GBV-C/HGV infection with extrahepatic diseases ranges from haematalogical diseases, aplastic anaemia, human immunodeficiency virus (HIV)-positive idiopathic thrombocytopenia and thalassemia, through to common variable immune deficiency and cryoglobunemia.

[Transfusion safety: emergent or hypothetical risks]

Three categories of emerging risks are studied: 1) A new variant of Creutzfeld-Jakob disease, different from its sporadic form; limited to the British isles (48 of 51 cases), it affects younger patients, and has a higher duration with a predominance of psychiatric symptoms. Environmental risk factors include a previous stay in the British isles and oral transmission via contaminated food. No link has been made evident between blood component (BC) transfusion and occurrence of the disease. A potential risk exists if its agent is found in blood and peripheral lymphoid tissues and if buffy coat from infected animals has been inoculated intracerebrally. Since 1993, prevention measures have been taken: exclusion of donors with a potential risk as well as transfused donors, systematic leukocyte reduction and implementation of disease surveillance. Excluding donors after a several month-stay in the British Isles is being discussed. 2) Novel hepatitis viruses. Hepatitis G virus (HGV) has been detected in 2-4% of blood donors. Ten percent of patients with chronic non-A-E hepatitis are HGV RNA positive. The incidence of HGV infection is higher than expected from PCR studies. HGV has a high prevalence in the world. Novel DNA non-enveloped virus (TTV) has a normal distribution. Its prevalence varies from 2 to 80%, depending on the country. Although it has not been shown to be aggressive for the liver, prolonged follow-up is required. 3) Human herpes virus 8 (HHV8) is associated with Kaposi's sarcoma in 80% of cases. Its prevalence (0-20%) varies depending on the country. Kaposi's sarcoma has never been reported after BC transfusion. PCR-based viral DNA searches have yielded negative results in 19 poly-transfused subjects. Continuous monitoring is required for recipients at risk (e.g., immunosuppressed). In response to a possible health risk, emerging risks govern the "Precaution Principle", so difficult to implement.