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)

The activity of the mitochondrial glycerol phosphate dehydrogenase (EC 1.1.99.5), the enzyme unique to the glycerol phosphate hydrogen shuttle, was measured in normal human tissues and tumors and compared with the activity of succinate dehydrogenase, another enzyme that transfers electrons to ubiquinone at site II of the electron transport chain. Six of 7 insulinomas and 10 of 12 carcinoid tumors showed high glycerol phosphate dehydrogenase activity. The activity was also increased in 3 of 4 gastrinomas, 2 paraganglionomas, 1 of 4 thyroid nodules, and 1 parathyroid tumor. These tissues belong to the amine precursor uptake decarboxylation system. The activity of glycerol phosphate dehydrogenase was generally unremarkable in non-amine precursor uptake decarboxylation system tumors and in normal tissues studied. However, 1 of 2 breast carcinomas, 1 submandibular tumor, and 2 of 3 melanomas were enriched in glycerol phosphate dehydrogenase activity. In general, succinate dehydrogenase activity exceeded that of glycerol phosphate dehydrogenase in all tissues except some of the tissues in which glycerol phosphate dehydrogenase activity was high. Normal tissues, such as the pancreatic beta-cell, which aerobically metabolize glucose rapidly utilize the glycerol phosphate shuttle to oxidize the large amount of NADH formed from glucose metabolism in the cytosol. Whether this is the reason for the enriched activity of the glycerol phosphate dehydrogenase in certain amine precursor uptake decarboxylation system tumors is unknown.
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PMID:High activity of mitochondrial glycerol phosphate dehydrogenase in insulinomas and carcinoid and other tumors of the amine precursor uptake decarboxylation system. 197 16

The tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) can enhance or inhibit lymphocyte proliferation. Enhancement correlated with increased interleukin 2 (IL-2) production and activation of protein kinase C while inhibition correlated with decreased IL-2 and downregulation of protein kinase C activity (D.S. Grove and A.M. Mastro, Cancer Res. 51, 82-88). In this study, various activators and inhibitors of protein kinase C were used in order to try to separate the effects of TPA on this enzyme from its effects on IL-2 production and determine if protein kinase C activity was directly or indirectly related to IL-2 production. 1,2-Dioctanoylglycerol, 1-oleoyl-2-acetyl-glycerol, phospholipase C, and two "rationally designed" activators, 6-(N-decylamino)-4-hydroxy-methylindole and 3-(N-acetylamino)-5-(N-decyl-N-methylamino)-benzyl alcohol, were tested. Some activators enhanced proliferation in the presence of a Ca2+ ionophore, ionomycin, but not concanavalin A. Some activators suppressed proliferation and downregulated protein kinase C. Others neither downregulated protein kinase C nor inhibited IL-2 production and proliferation. However, inhibition or downregulation of protein kinase C activity always correlated with decreased IL-2 and depressed proliferation. Thus, the evidence in this and the previous study suggests that activation of protein kinase C is directly related to IL-2 production in activated T cells.
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PMID:Differential activation and inhibition of lymphocyte proliferation by modulators of protein kinase C: diacylglycerols, "rationally designed" activators and inhibitors of protein kinase C. 199 92

Protein kinase C is physiologically activated by 1,2-diacyl-sn-glycerol in the S configuration. The enzyme is also powerfully activated by structurally diverse tumor promotors. A model has been developed that demonstrates how the various tumor promotors and diacylglycerols can all be accommodated by the same binding site of the kinase. One prediction of this model concerns the structural nature of the pharmacophore in the tumor promotor debromoaplysiatoxin. This prediction is realized by synthesizing the analogs with the deduced pharmacophore and demonstrating that they are potent activators of protein kinase C. These findings provide strong experimental support for our structural model of protein kinase C activation.
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PMID:The pharmacophore of debromoaplysiatoxin responsible for protein kinase C activation. 200 Apr 1

To determine the predictive value of the IgG anti-cardiolipin antibody test for malignant tumor, two groups of the patients of Kurume and Kyushu University Hospitals were examined by quantitative enzyme linked immunoadsorbent assay (ELISA) for their serum anti-cardiolipin antibodies. With the first group of the patients consisting of a mixture of benign diseases and malignant tumors, the antibody was positive at 57% (39/72). With the second, malignant tumor group, 38% (19/50) was positive for the antibody. When examined for the specificity of the antibodies by a binding inhibition assay, it was shown that the antibodies in the tumor patients were less specific to cardiolipin: antibodies to cardiolipin in tumor patients were blocked by the specific antigen, cardiolipin, in a lesser degree than those in the control syphilis patients, and highly cross-reacted with 2 related phospholipids, i.e., phosphatidyl glycerol and phosphatidic acid. These findings obtained in this study suggest that ELISA for cardiolipin has the value for the tumor diagnosis, supplementing already established assays.
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PMID:[The predictive value of the anti-cardiolipin antibody test for malignant tumors]. 201 79

Mitoxantrone (MTO) was incorporated into small unilamellar liposomes by formation of a complex between the anticancer drug and negatively charged lipids. The complex was formed at a 2:1 molar ratio between the lipids and MTO, with phosphatidic acid (PA) being the strongest complex-forming lipid. Weaker complexes and lower incorporation rates of MTO resulted when liposomes containing dicetylphosphate, phosphatidyl inositol, phosphatidyl serine, phosphatidyl glycerol, oleic acid, and tridecylphosphate were used. Thus, all further experiments were performed with PA-MTO liposomes that contained 0.1-3 mg MTO/ml and had mean vesicle sizes of 40-150 nm, depending on the drug concentration and the method of liposome preparation. In vitro incubations of free and liposomal MTO with human plasma showed that the drug is slowly transferred from the liposome membranes to the plasma proteins. For liposomal MTO a transfer rate of 48% was determined, whereas 75.8% of free MTO was bound to the plasma proteins. The organ distribution of the two preparations in mice showed that higher and longer-lasting concentrations of liposomal MTO were found in the liver and spleen. The terminal elimination halflives in the liver were 77 h for liposomal MTO and 14.4 h for free MTO. In the blood, slightly higher concentrations were detected for liposomal MTO, which also had slower biphasic elimination kinetics as compared with the free drug. Drug distribution in the heart was not significantly different from that in the kidneys. The LD25 of PA-MTO liposomes in mice was 19.6 mg/kg and that of free MTO was 7.7 mg/kg. The antitumor effects of PA-MTO liposomes were evaluated in murine L1210 leukemia, in various xenografted human tumors, and in methylnitrosourea-induced rat mammary carcinoma. Generally, the liposomal application form was more effective and less toxic than the free drug. The cytostatic effects were dependent on the tumor model, the application schedule, and the drug concentration. At doses that were toxic when free MTO was used, the liposomal preparation produced strong antitumor effects in some cases. In summary, the incorporation of MTO into liposomes changes the drug's plasma-binding properties, alters its organ distribution, reduces its acute toxicity, and increases its cytostatic efficiency in various tumor models. The liposomal PA-MTO complex represents a new application form of MTO that has advantageous properties.
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PMID:Evaluation of incorporation characteristics of mitoxantrone into unilamellar liposomes and analysis of their pharmacokinetic properties, acute toxicity, and antitumor efficacy. 201 13

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates a rapid increase in ornithine decarboxylase (EC 4.1.1.17; ODC) activity in target cells. Here we demonstrate that this process involves a rapid accumulation of ODC mRNA, which is maximal 3 h after treatment (three- to eightfold greater than control cells) and decays to control levels within 18 h. Stimulation of ODC mRNA by TPA is blocked by phorbol dibutyrate down-regulation of protein kinase C (PKC). ODC mRNA was also induced by the PKC activators, phospholipase C and 1-oleoyl-2-acetyl-rac-glycerol, and blocked by kinase inhibitors (trifluoroperazine, H7, and palmitoyl-L-carnitine), consistent with a requirement for PKC activation in the induction mechanism. However, the non-PKC-specific protein kinase inhibitor HA1004 also suppressed expression of ODC mRNA in response to TPA, under conditions where it did not inhibit PKC, suggesting that additional kinases may be involved in the intracellular signalling process. The stability of the ODC mRNA (control value = 6.2 +/- 1.6 h) is not significantly changed by either TPA (5.7 +/- 0.8 h) or by cycloheximide (6.0 h). These results are inconsistent with any contribution from altered mRNA half-life towards the accumulation of ODC mRNA following treatment with phorbol ester tumor promoters.
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PMID:Involvement of protein kinase C in the regulation of ornithine decarboxylase mRNA by phorbol esters in rat hepatoma cells. 201 52

Mitogenicity, lethal toxicity, induction of tumor necrotizing factor (TNF), and antitumor activity against Meth A fibrosarcoma of four chemically synthesized lipopentapeptide analogs, S-[2,3-bis(palmitoyloxy)-2R (designated as KAB-1), -2S(KAB-3)-propyl]-N-palmitoyl-(R)-cysteinyl-(S)-seryl- (S)-seryl-(S)-asparaginyl-(S)-alanine, S-[2,3-bis(palmitoyloxy)-2R(KAB-2), and -2S(KAB-4)-propyl]-N-[(2,2,2)-trichloroethoxycarbonyl]-(R)- cysteinyl-(S)-seryl-(S)-seryl-(S)-asparaginyl-(S)-alanine, of bacterial lipoprotein were investigated. These four analogs, as well as bacterial lipopolysaccharide (LPS) or synthetic Escherichia coli-type lipid A (506), were capable of increasing of [3H]thymidine into splenocytes of C3H/He mice. Although LPS and 506 did not exhibit the mitogenic activity in C3H/HeJ mice, KAB compounds showed remarkable mitogenicity. These analogs did not show the lethal toxicity at a high dose of 50 micrograms/mouse in galactosamine-loaded C57BL/6 mice. Peritoneal macrophages, stimulated with four analogs, caused the production of TNF which induces the L929 cell lysis in vitro. Twice, intravenous injections of 50 micrograms/mouse of these analogs showed weak growth inhibition of Meth A fibrosarcoma in BALB/c mice. The inhibitory effect of KAB-2 compound, which caused the strong TNF-induction among the four analogs, was the most potent. These results indicate that the biological activity of KAB-2 (R-configuration of the C-2 position in glycerol moiety with dipalmitoyl) is stronger than that of the other three analogs.
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PMID:Comparison of biologic activities of synthetic lipopentapeptide analogs of bacterial lipoprotein in mice. 206 59

Statistical methods are discussed for application in animal carcinogenesis bioassays that test a general null hypothesis that response frequencies are independent of the treatment level for all tumor endpoints, sexes, and species considered in the bioassay, conditional on survival. These methods are similar to those proposed earlier by Farrar and Crump (1988, Fundam, Appl. Toxicol. 11, 652-663) which involve test statistics that are functions of p values from multiple standard statistical hypothesis tests, and evaluation of significance using randomization. Refinements include the introduction of an exact incidental tumor test analogous to the asymptotic test of Hoel and Walburg (1972, J. Natl. Cancer Inst. 49, 361-372), which takes into account the possibility that any differences among treatment groups in response rates result from differences in survival that is independent of tumors. Additional consideration is given to selection of test statistics, and a test is proposed that is sensitive specifically to cases where the same tumor endpoints are affected in multiple sexes and species. Applications of the procedures to results of National Toxicology Program (NTP) bioassays concerning decabromodiphenyl oxide and iodinated glycerol illustrate the sensitivity of tests based on different test statistics to distinct alternative hypotheses. When compared with the qualitative conclusions of the NTP regarding the strength of evidence for a carcinogenic effect in the same bioassays, the results presented suggest that the methods can be useful in clarifying otherwise equivocal evidence for carcinogenicity. Various difficulties are discussed relevant to the construction of exact combined fatal and incidental tumor tests analogous to the tests of Peto et al. (1980, IARC Monogr. Suppl. 2).
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PMID:Exact statistical tests for any carcinogenic effect in animal bioassays. II. Age-adjusted tests. 208 15

M5076, a tumorigenic murine macrophage cell line, demonstrates diverse proliferative responses to a panel of protein kinase C activators. Thus, the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate and mezerein potently inhibit cellular proliferation (by greater than 90%), whereas the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol markedly stimulates proliferation of serum-starved, quiescent M5076 cells. Another DG analogue, 1,2-dioctanoyl-sn-glycerol, has no effect on growth. However, all of these agents induce expression of c-fos oncogene mRNA levels to a similar magnitude and activate protein kinase C as determined by Mr 80,000 phosphorylation. Levels of c-fos protein induced by these treatments were markedly different with the antiproliferative agents producing greater c-fos protein levels.
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PMID:Protein kinase C-induced stimulation or inhibition of cellular proliferation in a murine macrophage tumor cell line. 210 88

The mature product of the c-met proto-oncogene is a putative tyrosine kinase receptor of 190 kd with an alpha beta heterodimeric structure. The c-met protein is phosphorylated in vivo on the beta subunit in the gastric carcinoma cell line GTL-16 (Giordano et al., 1988). Western blots with phosphotyrosine antibodies show that tyrosine phosphorylation of the beta subunit is reduced by treatment of GTL-16 cells with protein kinase C activators (tumor promoting phorbol esters such as phorbol 12-myristate 13-acetate, TPA, and beta-phorbol 12,13-dibutyrate, PdBu, or membrane permeable synthetic diacylglycerol 1-oleyl-2-acetyl-sn-glycerol, OAG). The inactive analog alpha-phorbol 12,13-didecanoate has no effect. The inhibition induced by TPA is dose dependent and maximal after 1 h. Depletion of protein kinase-C by prolonged treatment with TPA (18-48 h) increases the phosphorylation on tyrosine of the beta subunit. Phospho-amino acid analysis of the c-met protein immunoprecipitated from [32P]orthophosphate-labelled GTL-16 cells shows that protein kinase-C activation leads to an increase in serine phosphorylation and to concomitant decrease in tyrosine phosphorylation. These results suggest that, similar to the EGF and insulin receptor, the putative receptor encoded by the c-met proto-oncogene may be negatively modulated by protein kinase-C phosphorylation.
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PMID:Protein kinase-c activation inhibits tyrosine phosphorylation of the c-met protein. 211 5


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