Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Arginase activity was studied in the brain and other tissues of the rat at the different periods of neurinoma growth. The activity of the enzyme was considerably activated in the affected hemisphere on the 4th day, in the skin of the head and thigh on the 6th day after tumor transplantation. Elevation in arginase activity in the neoplasm itself was recorded on the 16th day. The data obtained point to the physiological significance of arginase during neurinoma growth.
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PMID:[Changes in arginase activity during neurinoma growth]. 402 73

Activity of arginase and of its isoenzymes was studied in rat brain tissue and in neurinoma tissue (strain 10-13-3) at the period of growth of the tumor in trigeminal nerve. Within the fourth day after the tumor transplantation the total activity of arginase was increased in brain and distinct alterations were found in the isoenzyme spectrum, mainly in the impaired hemisphere. The enzymatic activity was increased in the tumoral tissue within 16 days; the activation was localized in the malignant tissue and did not extent into surrounding nerves. In all the samples studied the positively charged isoenzyme I was activated, whereas the activity of the isoenzyme II was altered only slightly and usually tended to decrease. It was the activity of the isoenzyme I, which appeared to be altered in the growing tumor.
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PMID:[Brain arginase isoenzyme activity during the growth of neurinomas]. 409 Mar 69

We studied arginase activity in human prostatic tissue in 15 patients with benign hyperplasia and 27 patients with prostatic carcinoma. Arginase specific activity is greater (p less than 0.0001) in prostatic carcinomas than in hyperplastic prostates. Arginase specific activity is correlated inversely (p less than 0.0001) with the histological grade of the tumor.
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PMID:Arginase activity in prostatic tissue of patients with benign prostatic hyperplasia and prostatic carcinoma. 618 88

The levels of the five enzymes of the urea cycle were measured in normal 5-week-old rats, in a transplantable hepatoma, and in the livers of tumor-bearing rats (host livers). The levels of all five enzymes were much lower in the hepatoma, although there was no exact correlation of the decrease in levels. In host livers, the levels were higher than in the tumors, but lower than in normal liver. The levels of all five urea cycle enzymes were positively correlated with dietary protein content in normal livers, in hepatomas, and in host livers. In fact, the hepatomas showed the greatest changes in response to diet. On all diets, the levels in host liver remained below those in normal liver, indicating that the decreased level was probably not due to preferential utilization of nutrients by the tumor. The levels of urea cycle enzymes in normal liver were not altered by a single injection of glucocorticoid, glucagon, or dibutyryl cyclic adenosine 3':5'-monophosphate. By contrast, in hepatoma, the levels were usually significantly elevated by the same treatment. In addition, the levels in host livers were always significantly elevated and were usually above those in normal animals, whether the latter were hormone treated or not. Injection of plasma from tumor-bearing rats into normal animals produced a decrease in the levels of all five enzymes; if glucagon was injected together with the plasma, large increases in levels were observed. This result supports the concept of a humoral factor produced by the tumor which affects the levels and the inducibility of urea cycle enzymes in host livers. Autopsied human primary hepatomas also showed levels of urea cycle enzymes below those in normal livers with host livers having intermediate values. A cell line derived from a human hepatoma showed induction of arginase by glucocorticoid in culture; in this, it resembled a cell line of the rat hepatoma. Tyrosine aminotransferase in human hepatoma cells was not induced by glucocorticoid; in this, it differed from the rat hepatoma cells where induction of this enzyme was observed.
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PMID:Regulation of urea cycle enzymes in transplantable hepatomas and in the livers of tumor-bearing rats and humans. 626 64

Monomethoxypolyethylene glycol (PEG) was attached covalently to arginase. PEG-arginase was effective in prolonging the survival times of mice injected with the Taper liver tumor, whereas unmodified arginase was ineffective. PEG-arginase was more effective than arginase in the in vitro destruction of L5178Y mouse leukemia. However, neither PEG-arginase nor arginase inhibited the in vivo growth of this tumor.
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PMID:Cancer therapy with chemically modified enzymes. II. The therapeutic effectiveness of arginase, and arginase modified by the covalent attachment of polyethylene glycol, on the taper liver tumor and the L5178Y murine leukemia. 648 53

Macrophage arginine metabolism via nitric oxide (NO) synthase and arginase pathways reduces and enhances tumor cell proliferation, respectively. Transforming growth factor-beta (TGF-beta) has been shown to down-regulate the NO synthase pathway. The present study describes the effect of TGF-beta on the arginase pathway. TGF-beta up-regulated arginase activity in rat peritoneal macrophages as assessed by measuring the generation of [14C]urea from [14C]-L-arginine in the presence of NG-monomethyl-L-arginine (L-NMMA). The stimulation, which reached fivefold after a 48-h exposure of macrophages to 10 ng/ml TGF-beta, was due to reduction in Km value of arginase. TGF-beta-induced up-regulation of arginase activity led to the release of more polyamines, mainly putrescine. The role of this up-regulation on macrophage cytotoxicity toward L-929 tumor cells was analyzed in coculture experiments. Macrophages blunted DNA synthesis by L-929 cells as assessed by measuring the incorporation of [3H]TdR into the cells and the proportion of cells in the G2 phase. Addition of TGF-beta in the presence of L-NMMA permitted L-929 cells cocultured with macrophages to resume DNA synthesis. The mechanism responsible for this restoration was the up-regulation of arginase activity rather than the down-regulation of NO synthase activity since TGF-beta in the presence of L-NMMA failed to further reduce NO synthase activity whereas it still enhanced arginase activity; synthetic putrescine (1-10 microM) also blunted macrophage cytotoxicity toward L-929 cells. This is the first evidence that TGF-beta up-regulates arginase activity in macrophages and, hence, limits macrophage-dependent cytostasis.
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PMID:Transforming growth factor-beta stimulates arginase activity in macrophages. Implications for the regulation of macrophage cytotoxicity. 763 58

The potential effects of arginine depletion on promotion of hepatocarcinogenesis and the proliferation of hepatoma cells was investigated. A promotional effect of an arginine-free diet on tumor incidence in liver and kidney was not detected in rats and mice treated with N-nitrosodimethylamine. Inhibitory effects of an arginine-deficient diet on the growth of transplanted hepatomas were observed. Relative to the effect on body weight, the inhibition was greater in mice than rats. The inhibitory effects of an arginine-deficient diet were not correlated with the arginase activity in the tumors. Studies with hepatoma cells treated with polyethyleneglycol-modified arginase indicated that the inhibitory effects of arginine-deprivation on DNA synthesis need not be related to depletion of polyamine precursors.
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PMID:Inhibitory effect of arginine restriction on hepatoma growth. 811 29

Human liver arginase has many biological effects on lymphocytes, macrophages, liver cells, and tumor cells, in addition to its major role in the liver urea cycle. We have developed a sandwich enzyme-linked immunosorbent assay (ELISA) method to quantitate arginase concentrations in plasma that can be applied to various body fluids. The sensitivity was 2.5 ng/mL. The coefficients of variation were good both in intra- and inter-assay. Using this method to study the stability of an arginase preparation, we found that plasma arginase was stable for only 1 or 2 days even at temperatures as low as 4 degrees C. The mean plasma level was 41.0 +/- 3.3 ng/mL (mean +/- SE) in 143 normal subjects. There was no age difference in the general population and in the male group. However, in the female group, the plasma arginase level increased with age (p = 0.05). Its biological significance was unclear. As a whole, the ELISA method for the measurement of arginase concentration in the body fluid is convenient and reliable.
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PMID:Plasma arginase concentration measured by an enzyme-linked immunosorbent assay (ELISA) in normal adult population. 812 60

Amino acid-degrading enzymes are known to inhibit the growth of tumor cells in culture by depleting amino acids in the medium. Here we demonstrate that arginine deiminase (EC 3.5.3.6) from Mycoplasma arginini had stronger growth-inhibitory activity against all 4 kinds of tumor cell lines tested than L-asparaginase and arginase, which are well-known anti-tumor enzymes. Next, chemical modification of the arginine deiminase molecule with polyethylene glycol was shown to enhance its potency as an anti-tumor enzyme. The percentage of modified amino groups per molecule was estimated to be 51% of the total amino groups, and the average molecular weight was estimated to be about 400,000 by gel-filtration HPLC. The enzymic activity of the modified enzyme was 25.5 units/mg protein, which was equivalent to 57% of that of the native enzyme. The modified enzyme strongly inhibited growth of a mouse hepatoma cell line, MH134, at a concentration of more than 10 ng/ml, showing almost the same dose-response curve as the native enzyme. When a bolus of 5 units of the modified enzyme was intravenously injected into male BDF1 mice, L-arginine in the blood completely disappeared within 5 min, and remained undetectable for more than 8 days. On the other hand, in the case of bolus injection of the same number of units of native enzyme, the plasma L-arginine level recovered up to 66% of the control level at 8 days. These results suggest that this modified enzyme has a longer plasma clearance time and may be more effective as a new anti-tumor agent than the native enzyme.
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PMID:Chemical modification by polyethylene glycol of the anti-tumor enzyme arginine deiminase from Mycoplasma arginini. 827 24

The present investigations were undertaken to study whether the macrophages associated with Dalton's lymphoma (DLAM), a spontaneous T-cell lymphoma, are modulated for the secretion of tumor growth-promoting factors in ascites. The DL ascitic fluid (DLAF) and the culture supernatants of DLAM harvested from mid and late tumor-bearing stages, but not early tumor-bearing stage, enhanced the proliferation of DL cells in vitro. These observations indicate that DLAF contains certain DL growth-promoting substances and at least some of them are secreted by DLAM. The DLAM obtained from mid and late tumor-bearing stages showed enhanced IL-1 production and arginase activity, with a concomitant decline in the RNI production, which could be implicated in the DLAM-mediated promotion of tumor growth.
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PMID:Alteration in IL-1 and arginase activity of tumor-associated macrophages: a role in the promotion of tumor growth. 894 21


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