Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0029463 (osteosarcoma)
 16,637 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An autopsy case of a 67 year old man with primary osteosarcoma arising in cirrhotic liver is reported. His son had von Recklinghausen disease and he had had a history of hepatitis C virus infection for 10 years. A large tumor, about 10 cm in diameter, was found in the right liver lobe. This tumor showed marked central necrosis and hemorrhage, and histologically diffuse sarcomatous cell proliferation associated with extensive osteoid formation and calcification of the periphery. Examination of the whole tumor and the cirrhotic liver (155 tissue blocks) showed that the tumor consisted of sarcoma cells mixed with osteoid with no region resembling hepatocellular carcinoma or hepatoblastoma. Minute hepatocellular carcinomas were found in the cirrhotic liver distant from the sarcomatous area. On immunohistochemical examination, the main tumor gave a distinct positive reaction for vimentin, but not for keratin or other epithelial markers. These findings indicate that the tumor was a true primary osteosarcoma, not an osteoid metaplasia of hepatocellular carcinoma.
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PMID:Primary osteosarcoma arising from cirrhotic liver. 755 Oct 4

The hepatitis C virus (HCV) nonstructural 5A (NS5A) protein has been implicated in the inherent resistance of HCV to interferon (IFN) antiviral therapy in clinical studies. Biochemical studies have demonstrated that NS5A interacts in vitro with and inhibits the IFN-induced, RNA-dependent protein kinase, PKR, and that NS5A interacts with at least one other cellular kinase. The present study describes the establishment and characterization of various stable NS5A-expressing human cell lines, and the development of a cell culture-based assay for determining the inherent IFN resistance of clinical NS5A isolates. Human epithelioid (Hela) and osteosarcoma (U2-OS) cell lines were generated that express NS5A under tight regulation by the tetracycline-dependent promoter. Maximal expression of NS5A occurred at 48 hours following the removal of tetracycline from the culture medium. The half-life of NS5A in these cell lines was between 4 to 6 hours. NS5A protein expression was localized cytoplasmically, with a staining pattern consistent with the location of the Golgi apparatus and endoplasmic reticulum. In the majority of cell lines, no obvious phenotypic changes were observed. However, three genotype 1b NS5A-expressing osteosarcoma cell lines exhibited cytopathic effect and severely reduced proliferation as a result of high-level NS5A expression. Full-length NS5A protein isolated from a genotype 1b IFN-nonresponsive patient (NS5A-1b) was capable of rescuing encephalomyocardititis virus replication during IFN challenge up to 40-fold, whereas a full-length NS5A-1a and an interferon sensitivity determining region (ISDR) deletion mutant (NS5A-1a-triangle upISDR) isolated from a genotype 1a IFN-nonresponsive patient showed no rescue activity. The NS5A-1b and NS5A-1a proteins also rescued vesicular stomatitis virus replication during IFN treatment by two- to threefold. These data cummulatively suggest that NS5A expression alone can render cells partially resistant to the effects of IFN against IFN-sensitive viruses, and that in some systems, these effects may be independent of the putative ISDR. A scenario is discussed in which the NS5A protein may employ multiple strategies contributing to IFN resistance during HCV infection.
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PMID:Characterization of the effects of hepatitis C virus nonstructural 5A protein expression in human cell lines and on interferon-sensitive virus replication. 1009 74

The nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is an RNA-dependent RNA polymerase (RdRp) which plays an essential role in viral RNA replication. Antibodies that specifically recognize NS5B will have utilities in monitoring NS5B production and subcellular localization, as well as in structure-function studies. In this report, three mouse monoclonal antibodies (mAbs), 16A9C9, 16D9A4 and 20A12C7, against a recombinant NS5B protein (genotype 1a, H-77 strain) were produced. These mAbs specifically recognize HCV NS5B, but not RdRps of polivirus (PV), bovine viral diarrhea virus (BVDV) or GB virus B (GBV-B). The mAbs can readily detect NS5B in cellular lysates of human osteosarcoma Saos2 cells constitutively expressing the nonstructural region of HCV (NS3-NS4A-NS4B-NS5A-NS5B). NS5B proteins of different HCV genotypes/subtypes (1a, 1b, 2a, 2c, 5a) showed varied affinity for these mAbs. Interestingly, the epitopes for the mAbs were mapped to the palm subdomain (amino acid 188-370) of the HCV RdRp as determined by immunoblotting analysis of a panel of HCV/GBV-B chimeric NS5B proteins. The binding site was mapped between amino acid 231 and 267 of NS5B for 16A9C9, and between 282 and 372 for 16D9A4 and 20A12C7. Furthermore, these mAbs showed no inhibitory effect on the NS5B polymerase activity in vitro.
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PMID:Characterization of monoclonal antibodies that specifically recognize the palm subdomain of hepatitis C virus nonstructural protein 5B polymerase. 1132 72

The IFN-induced double-stranded RNA (dsRNA)-activated protein kinase PKR is one of the key molecules in the antiviral effects of IFN. To clarify the effects of hepatitis C virus nonstructural protein 5A (NS5A) on antiviral activity of IFN, in particular on PKR kinase activity, in mammalian cells, we established inducible NS5A-expressing cell lines derived from human osteosarcoma (Saos-2). The cells expressing NS5A derived from an IFN-resistant clone (NS5A-lb) that interacted with endogenous PKR in vitro, showed a suppressive effect on IFN function as determined by interference with vesicular stomatitis virus (VSV) infection, whereas NS5A (NS5A-2a) from an IFN-sensitive clone did not block the antiviral effect of IFN. A mutant with deletion of the IFN sensitivity determining region (ISDR) in NS5A-1b (NS5A-AISDR) also interacted with PKR and suppressed its activity in vitro. However, neither NS5A-2a nor the C-terminal truncated mutant of NS5A-1b (NS5A-deltaC) blocked PKR activity. These observations confirmed the previous report that the inhibitory effect of NS5A on IFN activity is mediated at least in part by the repression of PKR. In addition, we showed that IFN sensitivity was determined not only by the ISDR but that the involvement of the C-terminal region of NS5A-1b is important for the suppression of PKR activity.
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PMID:Effects of mutation in hepatitis C virus nonstructural protein 5A on interferon resistance mediated by inhibition of PKR kinase activity in mammalian cells. 1183

Hepatitis C virus (HCV), especially the genotype 1, is naturally resistant to the antiviral effects of interferon-alpha (IFN-alpha). Expression of the whole HCV genome and the NS5A protein has been suggested to interfere with the antiviral activity of IFN-alpha. Here we have analyzed the effect of individual or various combinations of HCV proteins on IFN-alpha-mediated antiviral effect against vesicular stomatitis virus (VSV). When the structural proteins (core-E1-E2) of HCV genotype 1 were expressed in human osteosarcoma cells in a tetracycline-regulated manner, partial VSV resistance to IFN-alpha was established. This was seen as an enhancement of both viral protein synthesis and production of infectious virus. Priming of core-E1-E2-expressing cells with low doses of IFN-gamma (10 IU/ml) partially restored the antiviral activity of IFN-alpha. The core (high-level expression) and NS4B protein expression also showed some rescue of VSV replication. In this model cell system NS3A-NS4A complex and NS5A showed no inhibition of IFN-alpha-induced antiviral activity. Our results indicate that the expression of structural proteins of HCV may impair the antiviral activity of IFNs.
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PMID:Expression of HCV structural proteins impairs IFN-mediated antiviral response. 1220 19

The core protein of Hepatitis C virus affects several biological functions of the host cells such as cellular growth and apoptosis. The core was shown to interact with 53BP2/Bbp/ASPP2, a p53-binding protein, in a yeast two-hybrid assay. The core competed with p53 in binding to ASPP2 in vitro. In an apoptosis assay using human osteosarcoma Saos-2 cells or hepatocellular carcinoma HepG2 cells, ectopic expression of p53 induced apoptosis and ASPP2 enhanced this p53-induced apoptosis. However, coexpression of the core with p53 and ASPP2 increased the number of surviving cells. In a reporter assay, neither ASPP2 nor the core with ASPP2 affected the transcriptional activity of p53 on the promoters of Bax and p21, major p53 target genes. These findings suggest that the core inhibits p53-mediated apoptosis by blocking the interaction between p53 and ASPP2, without modulating the transcriptional activity of p53, which plays a role in oncogenesis of hepatocellular carcinoma.
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PMID:Hepatitis C virus core protein interacts with p53-binding protein, 53BP2/Bbp/ASPP2, and inhibits p53-mediated apoptosis. 1498 81

Dicistronic, subgenomic hepatitis C virus (HCV) replicons were constructed containing sequences from JFH1, a genotype 2a strain, that also incorporated the firefly luciferase gene under the control of the HCV internal ribosome entry site element. Luciferase activity in Huh-7 cell extracts containing in vitro-transcribed subgenomic JFH1 RNA was monitored over a 72 h period to examine early stages of HCV replication in the absence of any selective pressure. Enzyme activities produced by the replicon were almost 200-fold greater than those generated from corresponding genotype 1b replicons and correlated with an accumulation of NS5A protein and replicon RNA. Transient replication was sensitive to IFN treatment in a dose-dependent manner and, in addition to Huh-7 cells, the U2OS human osteosarcoma cell line supported efficient replication of the JFH1 replicon. Thus, this system based on JFH1 sequences offers improvements over prior genotype 1b replicons for quantitative measurement of viral RNA replication.
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PMID:Development and characterization of a transient-replication assay for the genotype 2a hepatitis C virus subgenomic replicon. 1622 30

Cancer therapy and supportive measures entail the risk of infection with hepatitis B (HBV), hepatitis C (HCV) or human immunodeficiency virus (HIV). The objective of this analysis was to establish the incidence of infections with these viruses during antineoplastic treatment in our paediatric sarcoma patients, who are being followed-up within the Late Effects Surveillance System (LESS), which prospectively registers sequelae of therapy for Ewing's-, soft tissue- and osteosarcoma in patients treated in Germany, Austria and Switzerland within the trials EICESS-92/EURO-E.W.I.N.G.-99, CWS-96/CWS-2002P and COSS-96. We studied 264 eligible relapse-free paediatric patients [median age at diagnosis 14.3 (IQR 11.1-16.4) years], treated from January 7, 1998 until April 24, 2004. According to the LESS protocol, serological examinations for HBV, HCV and HIV were scheduled 4 weeks and 6 months after cessation of antineoplastic treatment. The median follow-up was 20.6 (IQR 12.4-26) months. None of the patients was reported to have acquired HBV, HCV or HIV during antineoplastic treatment. Blood donor screening and prophylactic measures employed in Germany, Austria and Switzerland to prevent infections of cancer patients with HBV, HCV and HIV seem to be very effective, having fully prevented new infections in this large cohort of paediatric sarcoma patients.
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PMID:Prospective evaluation of hepatitis B, C and HIV infections as possible sequelae of antineoplastic treatment in paediatric sarcoma patients: a report from the Late Effects Surveillance System. 1646 31

The hepatitis C virus (HCV) non-structural (NS) 3/4A protein complex inhibits the retinoic acid inducible gene I (RIG-I) pathway by proteolytically cleaving mitochondria-associated CARD-containing adaptor protein Cardif, and this leads to reduced production of beta interferon (IFN-beta). This study examined the expression of CCL5 (regulated upon activation, normal T-cell expressed and secreted, or RANTES), CXCL8 (interleukin 8) and CXCL10 (IFN-gamma-activated protein 10, or IP-10) chemokine genes in osteosarcoma cell lines that inducibly expressed NS3/4A, NS4B, core-E1-E2-p7 and the entire HCV polyprotein. Sendai virus (SeV)-induced production of IFN-beta, CCL5, CXCL8 and CXCL10 was downregulated by the NS3/4A protein complex and by the full-length HCV polyprotein. Expression of NS3/4A and the HCV polyprotein reduced the binding of interferon regulatory factors (IRFs) 1 and 3 and, to a lesser extent, nuclear factor (NF)-kappaB (p65/p50) to their respective binding elements on the CXCL10 promoter during SeV infection. Furthermore, binding of IRF1 and IRF3 to the interferon-stimulated response element-like element, and of c-Jun and phosphorylated c-Jun to the activator protein 1 element of the CXCL8 promoter, was reduced when NS3/4A and the HCV polyprotein were expressed. In cell lines expressing NS3/4A and the HCV polyprotein, the subcellular localization of mitochondria was changed, and this was kinetically associated with the partial degradation of endogenous Cardif. These results indicate that NS3/4A alone or as part of the HCV polyprotein disturbs the expression of IRF1- and IRF3-regulated genes, as well as affecting mitogen-activated protein kinase kinase- and NF-kappaB-regulated genes.
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PMID:Hepatitis C virus proteins interfere with the activation of chemokine gene promoters and downregulate chemokine gene expression. 1819 74