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)

Recent evidence suggests that tumour necrosis factor alpha (TNF) is an autocrine growth factor for the chronic B-cell malignancies hairy cell leukaemia (HCL) and some cases of B-chronic lymphocytic leukaemia (B-CLL). Incubation with TNF in vitro has been shown to increase viability, DNA synthesis and the expression of the protooncogenes myc, fos and jun in the tumour cells from these patients. TNF in vitro also increases expression of TNF-mRNA, suggesting the existence of an autocrine growth loop for TNF in these cells. Current experiments are compatible with the hypothesis that interferon alpha (IFN) interferes with this autocrine growth loop in HCL and B-CLL by stimulating degradation of messenger RNAs (mRNAs) for a number of cytokines including that of TNF. This RNA degradation may be mediated through induction of the enzyme 2,5 oligo-A synthetase with consequent increased synthesis of 2,5 oligo-A which is known to stimulate the activity of a latent ribonuclease capable of degrading cytokine mRNAs. Circulating tumour-derived TNF may also contribute to the pancytopenia in HCL and B-CLL. Whether cytokine autocrine growth loops are important in other B-cell malignancies, e.g. myeloma and non-Hodgkin's lymphoma, and subject to IFN-stimulated breakdown needs further study.
 ...
PMID:Possible mechanism of action of interferon alpha in chronic B-cell malignancies. 193 2

Alkaline ribonuclease (RNase; EC 3.1.27.5) activities and 2',5'-oligoadenylate synthetase (2-5 AS; no EC no. assigned) activities in serum were measured in nine patients with hepatitis B e antigen-positive chronic hepatitis B before, during, and after treatment with recombinant human interferon alpha-2b for four weeks at daily doses ranging from 3 to 10 mega-units. Alkaline RNase activities in serum significantly increased from 65.8 +/- 9.5 units/L (mean +/- SD) to 84.3 +/- 11.9 units/L after the first week of therapy (P less than 0.001). (One unit of RNase activity is defined as that increasing the absorbance at 260 nm by 1.0 in 1 min). This increase persisted during and until two weeks after the end of the therapy, at which time the mean RNase activity in serum was still significantly increased (70.8 +/- 9.4 units/L, P less than 0.01). Before therapy, phosphocellulose chromatography of RNase showed five active peaks of enzyme activity, which were similar to that observed even when RNase activity increased immediately after therapy. There was a close correlation between RNase activities and the logarithm of 2-5 AS activities, measured simultaneously in each patient. We conclude that recombinant alpha-interferon therapy increases RNase activities in serum, associated with the increased 2-5 AS activities.
 ...
PMID:Effects of recombinant leukocyte interferon on ribonuclease activities in serum in chronic hepatitis B. 235 34