Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Short-term cultures of cells from human rain tumours have been reported to synthesise RNA particles of density in the range characteristic of C type RNA retroviruses, with associated DNA polymerase activity. Fresh tumour cells obtained from 6 children with astrocytoma and 7 children with medulloblastoma, together with one sample of normal brain tissue and normal leukocytes from brain tumour patients were assayed by several characteristics for the primate retrovirus. 1 or 6 (17%) astrocytomas and 4 of 7 (57%) medulloblastomas released RNA particles which banded in sucrose gradients at a density of 1.16-1.18 g/cm3 together with a short segment of DNA, which was eliminated by prior ribonuclease treatment and two proteins of 28k and 16k daltons. These findings were compatible with the presence of a primate retrovirus. Immune coprecipitation of 125I-labelled proteins from the 1.16-1.18 g/cm3 gradient region failed to show any reactivity with antisera to p28 core antigens or the p70 reverse transcriptase antigens of simian sarcoma virus, baboon endogenous virus or Mason Pfizer virus. Assays for DNA polymerase activity in culture supernatant fluid showed only a low amount of activity with template preferences not characteristic of the retroviral reverse transcriptase enzyme.
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PMID:Children's brain tumour cells produce RNA particles with incomplete retrovirus characteristics. 628 9

The Turcot syndrome (TS) is a rare, probably autosomal recessive, disorder characterized by development of primary neuroepithelial tumors of the central nervous system (CNS) and numerous adenomatous colorectal polyps. To examine the possible involvement of mutations of the APC gene, which is responsible for familial adenomatous polyposis (FAP), in Turcot syndrome, we examined DNAs from TS patients for alterations in this gene by means of ribonuclease protection analysis. Germ-line APC mutations were detected in each of three unrelated cases of TS, and additional (somatic) mutations were observed in colonic adenomas that had developed in one of these patients. However, no somatic mutations in APC were found among 91 neuroepithelial tumors (medulloblastoma, glioblastoma, astrocytoma, and oligodendroglioma), whether sporadic or associated with TS. These results suggest that the APC gene is associated with pathogenesis of one feature of TS, but that at least one other gene is responsible for the genesis of neuroepithelial tumors in the CNS.
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PMID:Germ-line and somatic mutations of the APC gene in patients with Turcot syndrome and analysis of APC mutations in brain tumors. 751 58

Matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that function in the turnover of extracellular matrix components during development. In addition, MMPs also contribute to pathological conditions associated with inflammation, angiogenesis, and tumor invasion. A 72-kDa type IV collagenase, also referred to as gelatinase A or MMP-2, has been proposed to potentiate the invasion and metastasis of malignant tumors. In particular, MMP-2 activity has been shown to constitute an important component of human astroglioma invasion. We investigated the influence of various cytokines, both proinflammatory and immunosuppressive, on MMP-2 gene expression in two human astroglioma cell lines (U251-MG and CRT). Our results indicate that the cell lines constitutively express high levels of MMP-2 mRNA, protein, and bioactivity as assessed by ribonuclease protection assay, immunoblotting, and zymography assays, respectively. The proinflammatory cytokines TNF-alpha and IFN-gamma individually can inhibit constitutive MMP-2 expression, and function in an additive manner for near-complete inhibition of MMP-2 expression. Inhibition of MMP-2 mRNA levels by TNF-alpha and IFN-gamma is not due to destabilization of the MMP-2 message; rather, inhibition is mediated at the transcriptional level. Furthermore, TNF-alpha/IFN-gamma inhibition of MMP-2 expression results in decreased invasiveness of the human astroglioma cells through an extracellular matrix. These results raise the possibility that TNF-alpha and IFN-gamma may have beneficial effects in attenuating astroglioma invasive properties.
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PMID:Transcriptional suppression of matrix metalloproteinase-2 gene expression in human astroglioma cells by TNF-alpha and IFN-gamma. 986 95

The aim of this study was to evaluate the clinical value of assessing epidermal growth factor receptor (EGFR) amplification and the common 5' rearrangement of EGFR resulting in the EGFRvIII transcript in astrocytic gliomas. Data from 221 tumours were correlated with patient survival. The majority of previous studies evaluated amplification alone and provided contradictory results. Amplification was analysed by a densitometry of Southern blot analysis or quantitative polymerase chain reaction (PCR). EGFR transcripts were examined by reverse transcription PCR and subsequent sequencing. A ribonuclease (RNase) protection assay was carried out on a subgroup to confirm PCR results. Amplification of EGFR was found in 41% (65/160) of glioblastomas (GBs) and 10% (4/41) of anaplastic astrocytomas (AAs). The EGFRvIII rearrangement was identified in 54% (35/65) of GBs and 75% (3/4) of AAs with amplification, as well as in 8% (8/95) of GBs and 5% (2/37) of AAs without amplification (confirmed by RNase protection assay). There were no abnormalities of the EFGR or its transcript in grade II astrocytoma (AII). We found no significant association between EGFR amplification or rearrangement, and age or survival in the 160 GB patients. We noted a tendency towards decreased survival with any EGFR abnormality in the 41 patients with AAs. This was most marked in the five cases with the EGFRvIII transcript (p=0.069), but these were significantly older than those without (p=0.023). No abnormalities of EGFR were identified in AII patients. We conclude that neither EGFR amplification nor the presence of the EGFRvIII transcript predicts patient outcome in conventionally treated GBs. However, in AAs, although uncommon, EGFR aberrations appear to be associated with shorter survival.
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PMID:Clinical significance of EGFR amplification and the aberrant EGFRvIII transcript in conventionally treated astrocytic gliomas. 1613 18