Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

AIM:To study hepatocarcinogenesis of hepatitis C virus (HCV).METHODS: Expression of HCV antigens (CP10, NS3 and NS5) and several cancer-associated gene products (ras p21, c-myc, c-erbB-2, mutated p53 and p16 protein) in the tissues of hepatocellular carcinoma (HCC, n = 46) and its surrounding liver tissue were studied by the ABC(avidin-biotin complex) immunohistochemical method. The effect of HCV infection on expression of those gene products in HCC was analyzed by comparing HCV antigen positive group with HCV antigen negative group.RESULTS:Positive immunostaining with one, two or three HCV antigens was found in 20 (43.5%) cases,with either of two or three HCV antigens in 16 (34.8%) cases, and with three HCV antigens in 9 (19.6%) cases.Deletion rate of p16 protein expression in HCC with positive HCV antigen (80%, 16/20)was significantly higher than that in HCC with negative HCV antigen. Whereas no significant difference of the other gene product expression was observed between the two groups.CONCLUSION:HCV appears related to about one third of cases of HCC in Chongqing, the southwest of China, and it may be involved in hepatocarcinogenesis by inhibi ting the function of p16 gene, which acts as a negative regulator of cell cycle.
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PMID:Effect of HCV infection on expression of several cancer-associated gene products in HCC. 1181 78

Hepatitis C virus (HCV) infects more than 180 million of the world's population and causes a persistent infection that over decades can result in cirrhosis and hepatocellular carcinoma. Treatment is only partially effective and control is likely only with the development of effective vaccines. Currently, only chimpanzees can be infected with HCV and alternative animal and tissue culture models are badly needed. We have used mice transgenic for HLA-DR and human CD4 to analyse the specificity of murine responses to the HCV NS3 antigen in an effort to determine whether the epitopes recognized correspond to those recognized by human T cells. Indeed, determinants mapped in transgenic mice overlap with those in a patient exposed to HCV through infection. This result provides hope that such an animal model may be a useful tool with which to analyse particular aspects of immune responses to HCV in vivo.
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PMID:Epitopes of the NS3 protein of hepatitis C virus: recognition in HLA-DR4 transgenic mice. 1186 68

The nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) has been shown to interact with a variety of cellular proteins and implicated in the regulation of cell growth, interferon resistance, and other cellular signaling pathways, but the role of NS5A in HCV pathogenesis has not been firmly established. To further characterize this multifunctional protein, we instigated the studies of the subcellular localization of NS5A in a hepatoma cell line. NS5A was localized to the perinuclear membrane structures, including the endoplasmic reticulum (ER) and the Golgi apparatus, by immunofluorescence staining and confocal microscopy. In addition, it was also associated with the surface of cytoplasmic globular structures when expressed alone or as a part of the NS3-5B polyprotein. Oil red O staining revealed that these globular structures were lipid droplets, where the HCV core protein was also localized. The association of NS5A with intracellular membrane was further confirmed by membrane flotation analysis. To determine whether NS5A interacts with any cellular lipid-binding protein, we performed yeast two-hybrid screening in both HepG2 and human liver cDNA libraries. Apolipoprotein A1 (apoA1), one of the protein components of high-density lipoprotein (HDL) particles, was identified by two independent screening processes. The interaction between NS5A and apoA1 was confirmed by both in vitro pull-down and in vivo coimmunoprecipitation experiments. Immunofluorescence staining revealed a significant colocalization of NS5A and apoA1 in the Golgi apparatus. Our results established an association of NS5A with lipid droplets and apoA1, suggesting that NS5A, together with the core protein, may play a role in the pathogenesis of the derangement of lipid metabolism, contributing to liver steatosis commonly observed in hepatitis C.
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PMID:Hepatitis C virus NS5A colocalizes with the core protein on lipid droplets and interacts with apolipoproteins. 1187 23

Our objective was to verify the presence of prostaglandin-producing suppressor cells in response to hepatitis C virus antigens in peripheral blood mononuclear cells proliferation. Standard proliferation tests were performed in 31 patients: 20 with chronic hepatitis C after antiviral treatment [7 long-term responders (LTR), 7 relapsers (RR), 6 nonresponders (NR)], 7 with HCV infection with persistently normal aminotransferase levels (PNAL), and 4 with hepatocellular carcinoma. Six antigens were used from the core and NS3 regions. A modified proliferation assay consisting of the addition of indomethacin was also done. Lymphoproliferative responses to the HCV antigens were detectable in 27% (11/41) of test points of LTR, 10% (3/31) of RR, 26% (9/35) of NR, and 18% (7/39) of patients with PNAL. Indomethacin only had effect in PNAL patients, by increasing the frequency of reactivity from 18% (7/39) to 36% (14/39) tests points (P = 0.037); also, in three of these patients (43%) indomethacin strongly modified proliferation to core 31-50 and NS3 1248-1261 antigens, increasing both the frequency and stimulation index from 33% (6/18) to 72% (13/18) (chi2 = 5.43, P = 0.019) and 1.89 +/- 0.43 to 6.18 +/- 4.74 (P = 0.028), respectively. These results suggest that prostaglandin-producing suppressor may play a role in chronic HCV infection by inhibiting cellular immune responses in patients with persistently normal ALT.
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PMID:Evidence for prostaglandin-producing supressor cells in HCV patients with normal ALT. 1191 41

Correlation between sequence variation of hepatitis C virus (HCV) and development of hepatocellular carcinoma (HCC) has not yet been demonstrated. In the present study, we analyzed sequence diversity of the NS3 protein of HCV and its possible correlation with HCC. On the basis of secondary structure of an amino-terminal portion of NS3, HCV subtype lb (HCV-1b) isolates were classified into two groups, A and B. Group A isolates were found in 4 (11%) of 36 patients with HCC, and 22 (63%) of 35 patients without HCC. On the other hand, group B isolates were found in 32 (89%) of 36 patients with HCC, and 12 (34%) of 35 patients without HCC. The distribution patterns of those groups were significantly different between patients with and without HCC (P< 0.001). HCV isolates of group B were found in both tumor and adjacent non-tumor tissues obtained from patients with HCC, suggesting that the emergence of group B isolates was not a result of, but rather a possible causative factor for development of HCC. Taken together, our present results suggest that HCV-lb strains of group B are highly associated with HCC and that the secondary structure analysis of NS3 would be useful to predict high risk for development of HCC in HCV-lb-infected patients.
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PMID:Correlation between secondary structure of an amino-terminal portion of the nonstructural protein 3 (NS3) of hepatitis C virus and development of hepatocellular carcinoma. 1236 18

Hepatitis C virus (HCV) infection is a major worldwide health problem, causing chronic hepatitis, liver cirrhosis and primary liver cancer (Hepatocellular carcinoma). HCV encodes a precursor polyprotein that is enzymatically cleaved to release the individual viral proteins. The viral non-structural proteins are cleaved by the HCV NS3 serine protease. NS3 is regarded currently as a potential target for anti-viral drugs thus specific inhibitors of its enzymatic activity should be of importance. A prime requisite for detailed biochemical studies of the protease and its potential inhibitors is the availability of a rapid reliable in vitro assay of enzyme activity. A novel assay for measurement of HCV NS3 serine protease activity was developed for screening of HCV NS3 serine protease potential inhibitors. Recombinant NS3 serine protease was isolated and purified, and a fluorometric assay for NS3 proteolytic activity was developed. As an NS3 substrate we engineered a recombinant fusion protein where a green fluorescent protein is linked to a cellulose-binding domain via the NS5A/B site that is cleavable by NS3. Cleavage of this substrate by NS3 results in emission of fluorescent light that is easily detected and quantitated by fluorometry. Using our system we identified NS3 serine protease inhibitors from extracts obtained from natural Indian Siddha medicinal plants. Our unique fluorometric assay is very sensitive and has a high throughput capacity making it suitable for screening of potential NS3 serine protease inhibitors.
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PMID:A novel high throughput screening assay for HCV NS3 serine protease inhibitors. 1250 40

Hepatitis C virus (HCV) is a major cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. Studies of HCV replication and pathogenesis have so far been hampered by the lack of an efficient tissue culture system for propagating HCV in vitro. Although HCV is primarily a hepatotropic virus, an increasing body of evidence suggests that HCV also replicates in extrahepatic tissues in natural infection. In this study, we established a B-cell line (SB) from an HCV-infected non-Hodgkin's B-cell lymphoma. HCV RNA and proteins were detectable by RNase protection assay and immunoblotting. The cell line continuously produces infectious HCV virions in culture. The virus particles produced from the culture had a buoyant density of 1.13 to 1.15 g/ml in sucrose and could infect primary human hepatocytes, peripheral blood mononuclear cells (PBMCs), and an established B-cell line (Raji cells) in vitro. The virus from SB cells belongs to genotype 2b. Single-stranded conformational polymorphism and sequence analysis of the viral RNA quasispecies indicated that the virus present in SB cells most likely originated from the patient's spleen and had an HCV RNA quasispecies pattern distinct from that in the serum. The virus production from the infected primary hepatocytes showed cyclic variations. In addition, we have succeeded in establishing several Epstein-Barr virus-immortalized B-cell lines from PBMCs of HCV-positive patients. Two of these cell lines are positive for HCV RNA as detected by reverse transcriptase PCR and for the nonstructural protein NS3 by immunofluorescence staining. These observations unequivocally establish that HCV infects B cells in vivo and in vitro. HCV-infected cell lines show significantly enhanced apoptosis. These B-cell lines provide a reproducible cell culture system for studying the complete replication cycle and biology of HCV infections.
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PMID:Establishment of B-cell lymphoma cell lines persistently infected with hepatitis C virus in vivo and in vitro: the apoptotic effects of virus infection. 1252 48

Using 4 McAbs to HCV-C, E, NS3 and NS4 regions' antigens and PcAb to HBsAg, 59 cases of hepatocellular carcinoma(HCC) and 35 cases of liver cirrhosis(LC) were tested by immunohistochemistry technique. Positive reactions for hepatitis C virus were mainly present in the cytoplasm of hepatocytes and tumor cells with fine granules. The positive rates of HCV were 17.2% in HCC(29 cases) of Beijing, 26.7% in HCC(30 cases) of Shenyang and 14.3% in LC(35 cases) of Shenyang. C region's McAb had the highest positive rate of detection, which suggested that C region's protein had a high level expression. The positive rates of hepatitis B virus surface antigen were 63.0% in HCC(29 cases) of Beijing, 73.3% in HCC(30 cases) of Shenyang and 54.3% in LC(35 cases) of Shenyang, all of which were higher than their positive rate for HCV detected. In HCC and LC, HBV and HCV inclined to suppress the opposite side.
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PMID:[Detection of hepatitis C virus-C, E, NS3 and NS4 regions' antigens in hepatocellular carcinoma and liver cirrhosis]. 1252 45

Studies on the replication of hepatitis C virus (HCV) have been facilitated by the development of selectable subgenomic replicons replicating in the human hepatoma cell line Huh-7 at a surprisingly high level. Analysis of the replicon population in selected cells revealed the occurrence of cell culture-adaptive mutations that enhance RNA replication substantially. To gain a better understanding of HCV cell culture adaptation, we characterized conserved mutations identified by sequence analysis of 26 independent replicon cell clones for their effect on RNA replication. Mutations enhancing replication were found in nearly every nonstructural (NS) protein, and they could be subdivided into at least two groups by their effect on replication efficiency and cooperativity: (i). mutations in NS3 with a low impact on replication but that enhanced replication cooperatively when combined with highly adaptive mutations and (ii). mutations in NS4B, -5A, and -5B, causing a strong increase in replication but being incompatible with each other. In addition to adaptive mutations, we found that the host cell plays an equally important role for efficient RNA replication. We tested several passages of the same Huh-7 cell line and found up to 100-fold differences in their ability to support replicon amplification. These differences were not due to variations in internal ribosome entry site-dependent translation or RNA degradation. In a search for cellular factor(s) that might be responsible for the different levels of permissiveness of Huh-7 cells, we found that replication efficiency decreased with increasing amounts of transfected replicon RNA, indicating that viral RNA or proteins are cytopathic or that host cell factors in Huh-7 cells limit RNA amplification. In summary, these data show that the efficiency of HCV replication in cell culture is determined both by adaptation of the viral sequence and by the host cell itself.
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PMID:Viral and cellular determinants of hepatitis C virus RNA replication in cell culture. 1258 26

Hepatitis C virus (HCV) genotype 1 (subtypes 1a and 1b) is responsible for the majority of treatment-resistant liver disease worldwide. Thus far, efficient HCV RNA replication has been observed only for subgenomic and full-length RNAs derived from genotype 1b isolates. Here, we report the establishment of efficient RNA replication systems for genotype 1a strain H77. Replication of subgenomic and full-length H77 1a RNAs required the highly permissive Huh-7.5 hepatoma subline and adaptive amino acid substitutions in both NS3 and NS5A. Replication could be detected by RNA quantification, fluorescence-activated cell sorting, and metabolic labeling of HCV-specific proteins. Replication efficiencies were similar for subgenomic and full-length RNAs and were most efficient for HCV RNAs lacking heterologous RNA elements. Interestingly, both subtype 1a and 1b NS3 adaptive mutations are surface exposed and present on only one face of the NS3 structure. The cell culture-adapted subtype 1a replicons should be useful for basic replication studies and for antiviral development. These results are also encouraging for the development of adapted replicons for the remaining HCV genotypes.
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PMID:Efficient replication of hepatitis C virus genotype 1a RNAs in cell culture. 1258 42


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