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)

It was previously shown that the potent new DNA-binding antibiotic, CC-1065, prolonged life span, but was not curative, when administered to mice bearing a variety of transplantable tumors. In this paper we show results of preliminary studies indicating that CC-1065 caused lethal delayed hepatotoxicity at therapeutic antineoplastic doses. In non-tumor-bearing mice toxic deaths were delayed ca 50 days after a single iv dose of 12.5 micrograms/kg and as much as 70 days after 10 micrograms/kg was given ip. Intravenous mouse LD50's were 9 micrograms/kg, single dose, and 0.3 microgram/kg/day, five daily doses. Intraperitoneal LD50's were 0.53 approximately 6.90 micrograms/kg, single dose, and 0.14 microgram/kg/day, five daily doses. Mice treated with high doses iv died within 12 days with frank hepatic necrosis, whereas delayed deaths at lower doses were associated with changes in hepatic mitochondrial morphology. This suggested that separate mechanisms of hepatotoxicity were operative at high and low dose ranges. Attempts to prevent the delayed toxicity of CC-1065 in the mouse by treatment with WR-2721, N-acetylcysteine, phenobarbital, Aroclor 1254, and 3-methylcholanthrene were unsuccessful; no effect on the LD50 or the times of death was observed. Lethal doses in the rabbit were similar on a body surface area basis to those in the mouse; evidence of hepatotoxicity was also observed in the rabbit.
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PMID:Preliminary toxicity studies with the DNA-binding antibiotic, CC-1065. 669 88

This study was undertaken to investigate the effect of exogenous sulfhydryl compound administration on the toxicity of doxorubicin in mice. Pretreatment of CDF1 mice with a pharmacologic dose (2,000 mg/kg) of n-acetyl-l-cysteine 1 h before doxorubicin (20 mg/kg, i.p.) decreased lethality from 100% (n = 44) to 37.7% (n = 53), P less than 0.001. Variation in the timing and dose of n-acetylcysteine significantly diminished its protective activity. Pretreatment with n-acetylcysteine also significantly reduced long-term mortality in animals receiving multiple doses of doxorubicin; 10 wk after the third of three doxorubicin doses (5 mg/kg, i.p.) administered at 2-wk intervals, survival in the n-acetylcysteine pretreated group was 51.4% (n = 35) compared with 16.7% (n = 30) for animals receiving saline before doxorubicin, P less than 0.01. In this experiment, n-acetylcysteine pretreatment also diminished doxorubicin-related losses in total body weight and heart wet weight by 55.2% (P less than 0.05), and 60.9% (P less than 0.02), respectively, compared with animals pretreated with saline. N-acetylcysteine pretreatment also ablated electron microscopic evidence of doxorubicin cardiomyopathy without alleviating morphological features of its toxic effects on the liver or small intestinal mucosa. The cardioprotective action of n-acetylcysteine may be partially explained by the 429 +/- 60% increase in cardiac nonprotein sulfhydryl content (P less than 0.01) that was measured one hour after n-acetylcysteine administration; nonprotein sulfhydryl concentration in the liver at the same time was insignificantly different from control levels. Treatment with n-acetylcysteine also increased the nonprotein sulfhydryl content of P388 leukemia cells nearly threefold; however, it did not after the chemotherapeutic activity of doxorubicin against this murine tumor. Whereas n-acetylcysteine blocked doxorubicin cardiac toxicity, it did not affect the uptake or metabolism of doxorubicin in the heart or liver. These results suggest that the concentration of free sulfhydryl groups in the heart may play a role in the development of doxorubicin cardiac toxicity and that augmenting cardiac nonprotein sulfhydryl group content with n-acetylcysteine may provide a means to enhance the chemotherapeutic index of doxorubicin.
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PMID:Prevention of doxorubicin cardiac toxicity in the mouse by N-acetylcysteine. 728 1

Patients with AIDS have decreased levels of the intracellular antioxidant, glutathione, in their circulating lymphocytes and plasma. N-acetylcysteine (NAC) increases intracellular stores of glutathione and has direct antioxidant properties. In this study, the effects of glutathione and NAC on the cytotoxicity of neutrophils and mononuclear cells were tested using cells from healthy controls and human immunodeficiency virus (HIV)-infected patients. NAC (1 and 5 mM) enhanced the antibody-dependent cellular cytotoxicity (ADCC) of neutrophils from healthy adult controls and HIV-infected adults and children. The antineoplastic drug, 1,3 bis(2-chloroethyl)-1-nitrosourea (BCNU), which depletes intracellular glutathione, inhibited the ADCC of neutrophils; the addition of NAC partially reversed this inhibition. Similar effects of BCNU and NAC were seen when the cytotoxicity of mononuclear cells was tested using CEM tumor cells bearing the HIV gp120 antigen as targets. Thus, NAC enhances various forms of cytotoxicity and may be beneficial to AIDS patients whose defects in leukocyte cytotoxicity may be due to glutathione depletion.
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PMID:N-acetylcysteine enhances antibody-dependent cellular cytotoxicity in neutrophils and mononuclear cells from healthy adults and human immunodeficiency virus-infected patients. 759 8

This overview of the potential mechanisms of chemopreventive activity will provide the conceptual groundwork for chemopreventive drug discovery, leading to structure-activity and mechanistic studies that identify and evaluate new agents. Possible mechanisms of chemopreventive activity with examples of promising agents include carcinogen blocking activities such as inhibition of carcinogen uptake (calcium), inhibition of formation or activation of carcinogen (arylalkyl isothiocyanates, DHEA, NSAIDs, polyphenols), deactivation or detoxification of carcinogen (oltipraz, other GSH-enhancing agents), preventing carcinogen binding to DNA (oltipraz, polyphenols), and enhancing the level or fidelity of DNA repair (NAC, protease inhibitors). Chemopreventive antioxidant activities include scavenging reactive electrophiles (GSH-enhancing agents), scavenging oxygen radicals (polyphenols, vitamin E), and inhibiting arachidonic acid metabolism (glycyrrhetinic acid, NAC, NSAIDs, polyphenols, tamoxifen). Antiproliferation/antiprogression activities include modulation of signal transduction (glycyrrhetinic acid, NSAIDs, polyphenols, retinoids, tamoxifen), modulation of hormonal and growth factor activity (NSAIDs, retinoids, tamoxifen), inhibition of aberrant oncogene activity (genistein, NSAIDs, monoterpenes), inhibition of polyamine metabolism (DFMO, retinoids, tamoxifen), induction of terminal differentiation (calcium, retinoids, vitamin D3), restoration of immune response (NSAIDs, selenium, vitamin E), enhancing intercellular communication (carotenoids, retinoids), restoration of tumor suppressor function, induction of programmed cell death (apoptosis) (butyric acid, genistein, retinoids, tamoxifen), correction of DNA methylation imbalances (folic acid), inhibition of angiogenesis (genistein, retinoids, tamoxifen), inhibition of basement membrane degradation (protease inhibitors), and activation of antimetastasis genes. A systematic drug development program for chemopreventive agents is only possible with continuing research into mechanisms of action and thoughtful application of the mechanisms to new drug design and discovery. One approach is to construct pharmacological activity profiles for promising agents. These profiles are compared among the promising agents and with untested compounds to identify similarities. Classical structure-activity studies are used to find optimal agents (high efficacy with low toxicity) based on good lead agents. Studies evaluating tissue-specific and pharmacokinetic parameters are very important. A final approach is design of mechanism-based assays and identification of mechanism-based intermediate biomarkers for evaluation of chemopreventive efficacy.
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PMID:Mechanistic considerations in chemopreventive drug development. 761 36

Chymotrypsin activity is rapidly inactivated by the N-mustard anti-tumor drug, chlorambucil. Since mustards react with thiols, amines, carboxyls, imidazoles, and sulfide sites on proteins, N-acetylcysteine, 2 proprietary protein hydrolyzates, beta-mercaptoethanol, ethanolamine, and sodium lactate were tested for their capacity to protect chymotrypsin from inactivation by the mustard. In each instance, protection was afforded to chymotrypsin. In as much as N-acetylcysteine protected chymotrypsin from inactivation by chlorambucil, it is suggested that this thiol compound may serve as a detoxication agent and may not require prior transformation into glutathione by cells in order to reduce mustard levels within the cells, as suggested by Smith and Gross (Proceedings of the NATO Panel VIII meeting, Grenoble, France, 1991.) It is further suggested that amino acids present as biosynthetic and degradative components of cells may detoxify mustards.
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PMID:Protection of chymotrypsin from inactivation by a N-mustard analog. 770 11

The thiol N-acetylcysteine (NAC) is currently considered one of the most promising cancer chemopreventive agents by virtue of its multiple and coordinated mechanisms affecting the process of chemical carcinogenesis. Recent studies have shown that an unpaired cysteine residue in the propeptide plays a key role in inactivation of latent metastasis-associated metalloproteinases: the present study was designed to assess whether NAC could also affect tumor take, invasion and metastasis of malignant cells. As assessed by zymographic analysis, NAC completely inhibited the gelatinolytic activity of type-IV collagenases in the cells tested (gelatinases A and B). Moreover, NAC was efficient in inhibiting the chemotactic and invasive activities of tumor cells of human (A2058 melanoma) and murine origin (K1735 and B16-F10 melanoma cells as well as C87 Lewis lung carcinoma cells) in Boyden-chamber assays, which are predictive of the invasive and metastatic properties. Reduced glutathione (GSH) had a similar, although less effective activity. The number of lung metastases decreased sharply when B16-F10 murine melanoma cells, injected i.v. into nude mice, were pre-treated with NAC and resuspended in medium supplemented with 10 mM NAC. In other experiments NAC was given in drinking water, starting 48-72 hr before subcutaneous inoculation of either B16-F10 cells or of their highly metastatic variant B16-BL6, or intramuscular injection of LLC cells. In all experiments NAC treatment decreased the weight of the locally formed primary tumor and produced a dose-related delay in tumor formation. Spontaneous metastasis formation by B16-F10 and B16-BL6 tumors was slightly yet significantly reduced by oral administration of NAC. However, this was not observed for Lewis lung tumors. These data indicate that NAC affects the process of tumor-cell invasion and metastasis, probably due to inhibition of gelatinases by its sulfhydryl group, with the possible contribution of other mechanisms, including the potent antioxidant activity of this thiol.
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PMID:Inhibition of invasion, gelatinase activity, tumor take and metastasis of malignant cells by N-acetylcysteine. 770 24

We investigated the role of reactive oxygen intermediates and protein kinase C in the induction of expression of the c-jun gene in human ML-2 leukemic cells and normal human DET-551 fibroblasts by comparing the effects of exposure to either ionizing radiation or H2O2 in the presence or absence of appropriate inhibitors. In these cell types, the radiation- and H2O2-mediated increase in c-jun mRNA levels could be prevented by pretreatment of the cells with N-acetylcysteine, an antioxidant, or H7, an inhibitor of protein kinase C and protein kinase A, but not by HA1004, a specific inhibitor of protein kinase A and G. These results suggest a role for protein kinase C and reactive oxygen intermediates in the induction of c-jun gene expression in both normal and tumor cells. We also investigated potential differences in c-jun gene expression induced by radiation or H2O2 in normal and tumor cells by examining steady-state c-jun mRNA levels in a number of human fibroblast, leukemia, melanoma, sarcoma and carcinoma cell types. We observed heterogeneity in the steady-state level of c-jun mRNA in both the untreated normal and tumor cells and in such cells exposed to ionizing radiation or to H2O2. Exposure to radiation produced a varied response which ranged from little or no induction to an increase in the steady-state level of the c-jun mRNA of more than two orders of magnitude. Exposure to H2O2 gave a pattern similar to that of ionizing radiation. The basis for the differential induction in response to these agents may be attributable to either cell lineage or genetic heterogeneity or a combination of these two parameters.
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PMID:Heterogeneity in c-jun gene expression in normal and malignant cells exposed to either ionizing radiation or hydrogen peroxide. 772 34

Diethyldithiocarbamate (DDTC) and N-acetylcysteine (NAC) are nucleophile sulfur-containing compounds which can protect the platinum-induced nephrotoxicity. Combinations of cis-diamminedichloroplatinum(II) (cis-DDP) and DDTC or NAC were tested on the leukemia L1210 and melanoma B 16 tumor models. Nephrotoxicity of cis-DDP alone and in combination with DDTC or NAC was evaluated. On both of the investigated tumor models clastogenic effects in bone marrow cells were detected. DNA synthetic and mitotic activity of L1210 cells in vivo were evaluated by 3H-thymidine incorporation and cytogenetic analysis. Amelioration of the platinum induced nephrotoxicity and preservation of the antitumor activity of cis-DDP through combined application with DDTC or NAC were obtained at the L1210 model. Maximal inhibition of the DNA synthesis in L1210 cells was detected with the cis-DDP treatment. The sulfurcontaining nucleophiles DDTC or NAC could modulate the inhibitory effect of cis-DDP on the incorporation of 3H-thymidine into the nuclei of L1210 cells. Enhanced mitotic activity was detected during cytotoxic therapy with cis-DDP. Cis-DDP alone and in combination with DDTC or NAC caused a significant growth inhibition on the s.c. tumor of the melanoma B16 bearing mice. Two times better therapeutic results at this model were obtained with cis-DDP alone (T/C = 234.09%, T/C = 136.36% for cis-DDP+DDTC and T/C = 151.14% for cis-DDP+NAC). The usefulness of DDTC or NAC as adjuvants in the platinum based chemotherapy of human cancers have been discussed. Clastogenic effect and antitumor activity are probably connected and it is supposed that the reduction of the genotoxicity could lead to a decreased antitumor activity of the platinum complex.
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PMID:Antitumor, nephrotoxic and clastogenic effect of cis-DDP with DDTC or NAC. 785 94

Mitomycin C (MC), a clinically used natural antitumor agent, was shown to form three monoconjugates (11a-13a) and two bisconjugates (14a, 15a) with GSH upon reductive activation by rat liver microsomes, purified NADPH-cytochrome c reductase, or NADH-cytochrome c reductase or chemical reduction using H2/PtO2. Rat liver cytosol/NADH activated MC only at acidic pH (5.8), resulting in the formation of a single GSH-MC monoconjugate, 13a. The reductase responsible for cytosolic activation of MC to form this conjugate was DT-diaphorase. GSH itself did not reduce MC, and unreduced MC did not form conjugates with GSH. A moderate catalytic effect by glutathione S-transferase was demonstrated on the cytosol-activated reaction. Mercaptoethanol and N-acetylcysteine gave analogous sets of five MC-thiol conjugates under cytochrome c reductase or H2/PtO2 activation conditions. The structures of all 15 MC-thiol conjugates (five each with GSH, mercaptoethanol, and N-acetylcysteine, respectively) were determined, using 1H-NMR, UV, and mass spectroscopies, combined with analytical chemical and radiolabeling methods. The mechanism of formation of the conjugates features SN2 displacement of the carbamate of the reduced MC by GS-. The MC-GSH conjugates were noncytotoxic to the tumor cells tested. The conjugation of GSH with activated MC is likely to represent detoxication in mammalian cells. As another effect, GSH accelerates the rate of reduction of MC by "slow" reducing agents such as cytochrome c reductases and H2/PtO2. A mechanism is proposed to explain this effect, which involves further reduction of the initially formed MC semiquinone free radical by GSH.
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PMID:Conjugation of glutathione and other thiols with bioreductively activated mitomycin C. Effect of thiols on the reductive activation rate. 807 71

Hemin, which is the mitogenic oxidizing agent, has immunostinulatory properties for murine splenocytes. We studied the anti-tumor effect of hemin with IL-2 by using murine renal cell carcinoma (Renca). Treatment of cells with hemin and IL-2 resulted in a marked enhancement of mitogenicity and generation of cytotoxicity in vitro. These enhancements were achieved at low dose of IL-2. Splenocytes isolated from mice that had been treated with hemin and IL-2 incorporated increased amounts of 3H-thymidine during 20 hours incubation in vitro. Treatment with the combination of hemin and IL-2 was more effective than either hemin or IL-2 alone. The combination of hemin and IL-2 was effective in inducing cytotoxicity for Renca. Induction of cytotoxicity was optimal at the hemin concentration of 10 microM, and higher concentrations were less effective. In vivo administration of hemin and IL-2 in Renca bearing mice resulted in a significant survival prolongation. IL-2 alone, at the dose used, was ineffective. The anti-tumor effect was enhanced by administration of N-acetylcysteine and by nephrectomy. Since hemin can safely be administered to patients, it may represent a new class of biologic response modifiers that could enhance IL-2 mediated anti-tumor effects.
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PMID:[Anti-tumor effect of IL-2 and hemin on murine renal cell carcinoma]. 818 58


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