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)

Diets with partial replacement of sulfur amino acids by thiazolidine-4-carboxylate or 2-phenylthiazolidine-4-carboxylate were fed to normal and to rhabdomyosarcoma-bearing rats (methionine-dependent tumor) to evaluate their efficacy as cysteine precursors and as antitumor agents. Food intake, weight gain, food efficiency and plasma albumin and plasma sulfur amino acid concentrations were not different when these diets were compared with isosulfurous diets containing either methionine or N-acetylcysteine. 2-Phenylthiazolidine-4-carboxylate induced a lower plasma glutathione (GSH) level than the latter diets. Tumor-bearing rats had lower plasma GSH concentration. A negative linear relationship was found between plasma GSH levels and tumor weight and also the tumor weight: body weight ratio. This could mean that the tumor becomes the most important organ in the uptake of GSH. However, there was also a significant positive correlation between plasma GSH and albumin, suggesting a reduced GSH hepatic synthesis due to amino acid uptake by the tumor. There were no differences in tumor growth among rats receiving diets containing N-acetylcysteine, thiazolidine-4-carboxylate or 2-phenylthiazolidine-4-carboxylate.
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PMID:Thiazolidine-4-carboxylate and 2-phenylthiazolidine-4-carboxylate are active as cysteine precursors but have no effect on growth of a methionine-dependent tumor in rats. 172 69

The effect of Adriamycin on the invasive capacity of rat ascites hepatoma cells, W1, was studied. The invasive capacity of W1 cells was estimated in vitro by counting the number of penetrated single tumor cells and tumor cell colonies formed from the penetrated cells underneath a cultured mesothelial cell monolayer (H. Akedo et al., Cancer Res., 46: 2416-2422, 1986). A considerable increment of the invasive capacity was observed when the tumor cells had been treated with 1.0 to 20.0 microM Adriamycin. This augmentation of invasive capacity of tumor cells was partially inhibited by 60 microM N-acetylcysteine, a scavenger of free radicals. On the other hand, 60 microM N-acetylcysteine did not impair the cytotoxicity of Adriamycin for W1 cells measured by an in vitro tetrazolium-based colorimetric assay for cytotoxicity.
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PMID:Potentiation of invasive capacity of rat ascites hepatoma cells by adriamycin. 231 90

Mitomycin C (MC) activation to a reactive species was studied in nuclei isolated from rat liver and EMT6 tumor cells. Both preparations were similar in the rate of 4-(p-nitrobenzyl)pyridine (NBP) alkylation by MC and the levels of NADPH-cytochrome P-450 reductase. MC activation by both hepatic and EMT6 cell nuclei was inhibited by the presence of O2 and by heat inactivation. NADPH was preferred over NADH as the source of reducing equivalents by both types of isolated nuclei. MC activation to alkylating metabolites was not affected when EDTA or diethylenetriaminepentaacetic acid, two Fe2+ chelating agents, was present in the incubation system with either preparation of isolated nuclei. Glutathione (1 and 5 mM) and N-acetylcysteine (1 and 10 mM) both inhibited MC alkylation of NBP in nuclear preparations from rat liver and EMT6 tumor cells by 50-60%. Ethylxanthate (1 mM) effectively inhibited the MC alkylation of NBP by hepatic nuclei but was unable to inhibit MC alkylation of NBP by tumor cell nuclei. At 100 mM, ethylxanthate produced a slight stimulation in the rate of MC alkylation of NBP. These data are consistent with the hypothesis that MC activation in EMT6 tumor cells proceeds via a one electron reduction pathway which is inhibitable by glutathione but not inhibitable by ethylxanthate. Hepatic nuclei are apparently able to activate MC by either a one- or two-electron pathway.
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PMID:Effects of glutathione and ethylxanthate on mitomycin C activation by isolated rat hepatic or EMT6 mouse mammary tumor nuclei. 241 96

N-Acetylcysteine is currently being considered as a possible selective protector against pulmonary toxicity resulting from X-rays or chemotherapeutic treatment, but its clinical application awaits evidence that it does not interfere with the efficient killing of tumor cells. The capacity of N-acetylcysteine to protect against the antitumor activity of X-rays and of bleomycin was evaluated in a clonogenic cell-survival assay using SW-1573 human squamous lung carcinoma cells as a tumor model. Using the highest non-toxic dose of N-acetylcysteine (incubation for 2 days in the continuous presence of 10 mM) no effect on clonogenic cell killing by X-rays or bleomycin treatment could be detected, even though a twofold enhancement of endogenous glutathione was effectuated. Our data thus indicate that clinically relevant concentrations of N-acetylcysteine are incapable of protecting tumor cells against clonogenic killing by X-rays and by bleomycin.
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PMID:Effect of N-acetylcysteine on the antiproliferative action of X-rays or bleomycin in cultured human lung tumor cells. 247 48

The systemic use of thiol-containing uroepithelial protecting agents, e.g., N-acetylcysteine (NAC) or mesna, in conjunction with the alkylating agent cyclophosphamide is predicated on the assumption that the toxic metabolic by-products will be consumed by thiol without diminishing the cytotoxicity of the active alkylating intermediate, phosphoramide mustard. Studies in murine tumor systems have been with either a single dose or two equally divided doses of thiol, administered within 30 min of the addition of cyclophosphamide, without an observed adverse effect on antitumor activity; however, the relatively short serum half-life of thiol relative to alkylating agent in humans weakens the clinical relevance of these results. This study presents a thermodynamic model for the chemical reaction of phosphoramide mustard with either NAC or mesna. The gas phase thermodynamic parameters for these reactions, enthalpy (H) and entropy (S), were calculated using the semiempirical quantum mechanical method AM1 and were used to predict the free energy (delta G) for these processes. For the reaction of phosphoramide mustard with NAC or mesna, delta G = +3.82 and 2.29 kcal/mol, respectively. In the absence of enzyme catalysis, these results suggest that such reactions are not favored. In order to assess the validity of this gas phase thermodynamic model, the cellular cytotoxicity of phosphoramide mustard in the presence or absence of either NAC or mesna was studied using CCRF-CEM cells in culture. In these experiments the 50% effective dose of phosphoramide mustard was 1.7 micrograms/ml; this result was unchanged in the presence of 10 micrograms/ml concentration of either thiol. This study supports the conclusion that phosphoramide mustard and protector thiols are compatible.
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PMID:Thermodynamic analysis of the reaction of phosphoramide mustard with protector thiols. 249 18

Cancerous involvement of the nipple and subareolar tissue (nipple and areolar complex, NAC) was confirmed histopathologically in 24 of 65 patients with gross tumors measuring 2.5 centimeters or less. Erosion of the nipple as a clinical manifestation of involvement of NAC was seen in only two patients. The other 22 were all subclinical. The histologic form of involvement of NAC included intraductal-1 in 19 patients, stromal in one patient, lymphatic in two patients and intraductal-1 as well as stromal in two. Stepcut and serial observation of the whole breast suggested that both intraductal spread and stromal invasion of carcinoma were continuous processes from the underlying tumor. Involvement of NAC was more frequent if the patient was aged 50 years or less and if the proximity of the tumor to the nipple was less than 4 centimeters, regardless of the size of the tumor.
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PMID:Involvement of the nipple in early carcinoma of the breast. 253 37

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) inhibits growth and induces terminal squamous differentiation of normal human bronchial cells when added to the culture media [J. C. Willey, A. J. Saladino, C. Ozanne, J. F. Lechner, and C. C. Harris, Carcinogenesis (lond.), 5: 209-215, 1984]. We have investigated the possibility of oxygen free radicals being involved as intermediates in this process. Electron paramagnetic resonance measurements using the spin-trapping agent 5,5-dimethyl-1-pyrroline-1-oxide failed to detect oxygen free radicals in bronchial epithelial cells exposed to TPA, although oxy radicals were detected in bronchial epithelial cells after a nontoxic exposure to menadione, and in human neutrophils after exposure to TPA. Addition to the culture media of free radical scavenger, i.e., reduced glutathione, N-acetylcysteine, D-alpha-tocopherol, copper (II) (3,5-diisopropylsalicyclic acid)2, or the combination of superoxide dismutase and catalase did not affect the dose-dependent growth inhibition of TPA on the bronchial epithelial cells. Moreover, exposure of the bronchial epithelial cells to TPA did not result in increased DNA single strand breaks measured by alkaline elution, as would be expected with a free radical mediated mechanism. Thus, our results argue against the importance of oxygen free radicals in the inhibition of growth and the induction of squamous differentiation by TPA in normal human bronchial epithelial cells.
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PMID:Role of oxygen radicals in 12-O-tetradecanoylphorbol-13-acetate-induced squamous differentiation of cultured normal human bronchial epithelial cells. 282 86

N-Acetylcysteine (NAC) is a soluble nucleophile that has been shown to have antimutagenic activity towards various genotoxic agents including 1,2-dimethylhydrazine (DMH). The present report extends such observations by showing the protective effect of NAC against the carcinogenic activity of DMH. This thiol-containing molecule reduced the incidence of rat intestinal tumors. Moreover, it significantly lowered the colic tumor yield as expressed by the number of tumors per rat bearing tumors. With regard to localisation of colic carcinomas, NAC induced a shift from distal to more proximal sites.
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PMID:Anti-initiation activity of N-acetylcysteine in experimental colonic carcinogenesis. 374 38

Procarbazine causes dose-dependent decreases in sperm count after a single i.p. injection in (C57BL/6 X DBA/2)F1 male mice. Two antioxidants, N-acetylcysteine and sodium ascorbate, administered with equimolar doses of procarbazine decreased the spermatotoxicity of procarbazine. At the highest doses of procarbazine (400 mg/kg) that caused a 56% decrease in sperm count, equimolar doses of N-acetylcysteine coadministered with procarbazine caused only a 17% decrease in sperm count, and equimolar doses of ascorbate coadministered with procarbazine caused only a 13% decrease in sperm count. Thus, protection against the spermatotoxic effects of procarbazine was demonstrated with either antioxidant. The effect of the antioxidants on the chemotherapeutic efficacy of procarbazine against murine L1210 leukemia was also assessed. Procarbazine at the highest dose (600 mg/kg) increased mean survival time of mice inoculated i.p. with 1 X 10(5) L1210 leukemia cells by 31%. Simultaneous administration of equimolar doses of either N-acetylcysteine or ascorbate given with procarbazine caused no change in the increased mean survival time of tumor-bearing mice. These results indicate a decrease in the toxicity of procarbazine when coadministered with antioxidants, via decreased spermatotoxicity without changing anticancer efficacy. The results also indicate that different mechanisms are involved in the spermatotoxicity and anticancer activity of procarbazine.
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PMID:Separate mechanisms for procarbazine spermatotoxicity and anticancer activity. 381 55

This study investigated the effect of oxygen radical scavengers and iron chelating agents on the toxicity of doxorubicin for MCF-7 human breast cancer cells. Superoxide dismutase and catalase, but not the heat-inactivated enzymes, the hydroxyl radical scavenger N-acetylcysteine, and the organoselenium compound 2-phenyl-1-2-benzisoselenazol-3(2H)-one, which possesses glutathione peroxidase-like activity, significantly reduced or abolished tumor cell killing by doxorubicin. Similar protective activity was found only for those iron chelating agents capable of penetrating the tumor cell plasma membrane. These experiments suggest that an iron-dependent oxygen radical cascade contributes to the antineoplastic action of the anthracycline antibiotic doxorubicin.
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PMID:Prevention of doxorubicin-induced killing of MCF-7 human breast cancer cells by oxygen radical scavengers and iron chelating agents. 395 78


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