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 weakly acidic fraction (WAF) of cigarette smoke particulate matter was fractioned by silica get chromatography. We assayed the various primary subfractions for potential tumor-promoting activity by measuring the incorporation of tritiated thymidine into mouse epidermal DNA as induced by these subfractions. Based on these results and on chemical composition, the primary subfractions, were then combined into four major subfractions and tested on initiated mouse skin for tumor-promoting activity by long-term application. Two of these subfractions (40% of WAF) were inactive, whereas the other two (18 and 35% of WAF) showed tumor-promoting activity. The two active portions were then further chromatographed and tested by the short-term bioassay. Some major components of the resulting active fractions included alkyl-2-cyclopenten-2-ol-1-ones, catechols, hydroquinone, fatty acids, and 3-hydroxypyridines. Among these components, catechol, hydroquinone, 3-hydroxypyridine, 6-methyl-3-hydroxypyridine, linolenic acid, and linoleic acid were inactive as tumor promoters in the experimental animal. The activity of the alkyl-2-cyclopenten-2-ol-1-ones is unknown. Other components remain to be identified.
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PMID:A study of tobacco carcinogenesis. XIII. Tumor-promoting subfractions of the weakly acidic fraction. 0 47

Malignant neoplasms of endocrine tissues represent almost half of the cancers diagnosed clinically in the United States, and many of these respond to hormonal therapies. Estrogen-induced testicular Leydig cell tumors in the mouse would seem to represent a realistic model for the laboratory investigation of this significant group of cancers. Data accumulated over the past few years clearly show that the Leydig cell is a target tissue for estrogens. Administering large doses of estrogen results in a reduction of enzymes converting progesterone to testosterone and induces a transient, but quantitatively very significant, synthesis of DNA in the Leydig cells of tumor-susceptible strains of mice. Neither of these actions of estrogen is mediated via the hypophysis. It has been demonstrated that the Leydig cells have specific protein receptors in their cytoplasm that bind estrogens and transport them to the nucleus where they are also bound. The genetic composition of the Leydig cells themselves is extremely important for the development of tumors. An adequately functioning pituitary gland is also essential for tumor formation. Confining the testes to the abdomen results in enzyme changes similar to those produced by estrogen administration and significantly augments the development of Leydig cell tumors. Once tumors form they frequently are dependent for their continued growth on estrogenic stimulation and/or on a functioning hypothysis. Regressed tumors may remain dormant for many months only to resume progressive growth when placed in and adequate hormone environment.
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PMID:Estrogen-induced Leydig cell tumor in the mouse: a model system for the study of carcinogenesis and hormone dependency. 1 51

The mode of generation of free radicals of daunomycin, adriamycin, and carboquone in the NADPH-rat liver microsome system was studied at room temperature by electron spin resonance (ESR) spectroscopy. ESR signals of all these quinoid anticancer chemicals were detected when dissolved oxygen in the reaction mixture was consumed since the radicals are easilyaut oxidizable. All the radicals had an appreciable lifetime under anaerobic conditions. However, there were differences in the mode of their generation between daunomycin and adriamycin, on the one hand, and carboquone, on the other, with respect to the lag time and the effect of the amount of chemicals, pH of the medium, kind of electron donors, NADPH and NADH, and the presence of excess of DNA. Especially, ESR signal reappeared after the first signal had decreased considerably, in the case of daunomycin and adriamycin but not in carboquone. Intact Ehrlich ascites tumor cells also gave rise to an ESR signal of adriamycin and carboquone, but the former signal was prevented from appearing in the presence of glucose.
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PMID:Electron spin resonance study on the mode of generation of free radicals of daunomycin, adriamycin, and carboquone in NAD(P)H-microsome system. 2 73

We have recently described the presence of a guanylate cyclase [GTP pyrophosphate-lyase (cyclizing), EC 4.6.1.2] inhibitor (GCI) in an aqueous extract of the balsam pear (Momordica charantia abbreviata). Because the guanylate cyclase-cyclic GMP system is though to be involved in cell growth, DNA and RNA synthesis, and possible malignant transformation, we examined the effect of the aqueous extract containing GCI on an undifferentiated adenocarcinoma of the rat prostate and concanavalin-A-stimulated [3H]thymidine incorporation into cultured splenic lymphocytes, a process thought to be mediated by cyclic GMP. The results demonstrate that the extract of the balsam pear blocks both the growth of the rat prostatic adencarcinoma in vitro and [3H]thymidine incorporation into DNA. DNA histograms from flow cytometry indicated that the extract containing GCI inhibited in the G2 + M phase of the cell cycle, a presumed locus of cyclic GMP effects. In addition, guanylate cyclase activity was significantly greater in the tumor than normal prostate tissue and was decreased by the extract containing GCI. Cyclic GMP levels in the tumor in culture wer also decreased by addition of the extract. It remains to be determined whether or not the anti-tumor agent and GCI are the same substance.
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PMID:Inhibition of growth and guanylate cyclase activity of an undifferentiated prostate adenocarcinoma by an extract of the balsam pear (Momordica charantia abbreviata). 2 47

The interaction of analogs of L-aspartic acid with adenylosuccinic acid synthetase, L-asparagine synthetase, and L-aspartic acid transcarbamylase is discussed. Each of these enzymes is of critical importance in the economy of certain types of tumor cells. L-Alanosine, a new antitumor antibiotic, is shown to be accepted as a substrate by the enzymes of de novo purine biosynthesis which ordinarily use L-aspartic acid as a substrate; as a consequence of this interaction, an anabolite is thought to be produced which impairs the formation of adenine nucleotides by inhibiting adenylosuccinate synthetase, leading to an interruption in DNA synthesis. Homoserine-beta-adenylate, guanidinosuccinic acid, and PA2LA [3-(phosphonacetylamido)-L-alanine] are shown to be inhibitors of L-asparagine synthetase from murine lymphoblasts; each of these analogs of L-aspartic acid exhibits novel structural properties which can be used by synthetic chemists in the design of molecules with an even greater ability to block the biosynthesis of L-asparagine. Certain aspects of the mechanism of action of PALA (N-phosphonacetyl-L-aspartic acid) were examined. This agent, which is a potent inhibitor of mammalian L-aspartic acid transcarbamylase, is capable of stimulating the homologous enzyme from Escherichia coli under certain circumstances. In vivo the duration of inhibition produced by this agent is shown to be unusually protracted; for example, L-aspartic acid transcarbamylase in mouse liver remains at 30% of treatment levels for greater than or equal to 20 days after a single therapeutic dose of PALA. This long-lasting effect reflects either sluggish synthesis of new enzyme molecules in this organ or shuttling of the inhibitor from old to new molecules. It is suggested that new and still more potent analogs of L-aspartic acid be sought, and that they be screened, inter alia, against these target enzymes.
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PMID:Analogs of L-aspartic acid in chemotherapy for cancer. 3 3

Tissue analyses and tumour regression studies using the oncolytic antibiotic, adriamycin (14-hydroxydaunomycin), and its DNA complex at adriamycin dosages of 5 mg/kg and 10 mg/kg were made on C3H mice with transplanted mammary adenocarcinoma. Chemical analysis indicated a significantly lower (P < 0.05) uptake of adriamycin into cardiac tissue for the adriamycin-DNA complex. Tumour regression was comparable for both the complex and free adriamycin. Results suggest an advantageous role for the adriamycin DNA complex in the chemotherapy of metastatic breast carcinoma.
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PMID:The comparative toxicity and therapeutic efficacy of adriamycin and the adriamycin-DNA complex in the chemotherapy of C3H mice with transplanted mammary adenocarcinoma. 4 24

The preparation and properties of an antiserum to human DNA polymerase I (6 to 8 S) are described. Care was taken in the purification of the antigen to remove certain other DNA polymerases found in human cells. An incubation of antigen and antiserum lasting about 48 hours is necessary to achieve maximal inhibition. About 1 mug of the antipolymerase immunoglobulin G, prepared in rats, neutralizes 60% of the activity present in 54 ng of the enzyme. Tritrations varying both antiserum and enzyme demonstrate clear regions of antigen and antibody excess. Inhibition of enzyme activity is about the same whether the templateprimer is (dA)n-(dT)12-18, or partially digested DNA. An assay was developed which measures the remaining activity in the supernatant after precipitation of enzyme-antibody complexes with goat anti-rat immunoglobulin G. In this assay, 2.2 mug of the antipolymerase immunoglobulin G quantitatively bind 33 ng of DNA polymerase I. With use of the direct neutralization assay and the immuno-precipitation test, we found little, if any, antigenic relationship between DNA polymerase I and DNA polymerase II (3.4 S). Similarly, little, if any, relationship was found to the DNA polymerases from five RNA tumor viruses. The activities of RNA-directed DNA polymerases from the blood leukocytes of two patients with acute myelogenous leukemia and from the placentas of rhesus monkeys were not inhibited in neutralization assays which were shortened because these enzymes were thermolabile. In identically shortened neutralization assays, the antipolymerase immunoglobulin G neutralized up to 76% of the activity of DNA polymerase I. In addition to its utility in distinguishing cellular DNA polymerases, the rat antiserum should be useful reagent for testing of novel DNA polymerases isolated in small quantities from human tumors for contamination with DNA polymerase I. This enzyme is present in abundance in proliferating tissue and often confuses the biochemical characterization of these novel enzymes.
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PMID:Serological analysis of human deoxyribonucleic acid polymerases. Preparation and properties of antiserum to deoxyribonucleic acid polymerase I from human lymphoid cells. 4 29

The RNA-dependent DNA polymerase present in intracisternal A-type particles from mouse myeloma tumor cells has been studied. This polymerase can use either endogenous A particle RNA or an exogenous synthetic polynucleotide [poly (rA)] as a template. The DNA reaction product is small (4S-10S) and over 90% of it hybridizes to A particle RNA, whereas up to 50% of it hybridizes to murine sarcoma-leukemia virus RNAs. The RNA isolated from purified A particles is generally of low molecular weight (5S-15S) but contains small amount of 70S and 35S components. These results suggest that A-type particles may be related to C-type oncornaviruses.
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PMID:Characterization of DNA polymerase and RNA associated with A-type particles from murine myeloma cells. 4 84

A new method for the analysis and purification of the RNA-directed DNA polymerase of RNA tumor viruses has been developed. This nucleic acid affinity chromatography system utilizes an immobilized oligo (dT) moiety annealed with poly (A). The alpha and alphabeta DNA polymerases of avain myeloblastosis virus bound effectively to poly (A) oligo (dT)-cellulose. Alpha DNA polymerase did not bind effectively to poly (A) oligo (dT)-cellulose, poly (A)-cellulose, or to cellulose. Alphabeta bound to oligo (dT)-cellulose and cellulose at the same extent (approximately 30%), indicating that this enzyme did not bind specifically to the oligo (DT) moiety only. However, alphabeta bound to poly (A)-cellulose two to three times better than to cellulose itself, showing that alphabeta could bind to poly (A) without a primer. Alphabeta DNA polymerase also bound to poly (C)-cellulose, whereas alpha did not. These data show that the alpha DNA polymerase is defective in binding to nucleic acids if the beta subunit is not present. Data is presented which demonstrates that the alphabeta DNA polymerase bound tighter to poly (A). oligo (DT)-cellulose and to calf thymus DNA-cellulose than the alpha DNA polymerase, suggesting that the beta subunit or, at least part of it is responsible for this tighter binding. In addition, alphabeta DNA polymerase is able to reversibly transcribe avian myeloblastosis virus 70S RNA approximately fivefold faster than alpha DNA polymerase in the presence of Mg2+ and equally efficient in the presence of Mn2+. alpha DNA polymerase transcribed 9S globin m RNA slightly better than alphabeta with either metal ion.
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PMID:Binding properties of avian myeloblastosis virus DNA polymerases to nucleic acid affinity columns. 4 87

To estimate the influence of topical treatment with DMBA and induced tumors on delayed hypersensitivity, the response of spleen lymphocytes to PHA in vitro and macrophage migration inhibition with PHA were studied in DMBA-treated hairless mice. DNA synthesis and blastic transformation of cultured lymphocytes decreased after 6-12 weeks of DMBA application. Lymphocyte response to PHA gradually diminished during the experiment, as compared with control animals. Since the malignant transformation of skin tumors was not observed before 16 weeks of DMBA carcinogenesis, it seems that derangements in cellular immunity preceded the malignant proliferation. The increase in spleen weight and the absence of PHA-induced inhibition of macrophage migration in hairless mice with malignant tumors may also be related to the influence of the tumor itself on the lymphatic system of experimental animals.
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PMID:Immunological phenomena in harmless mice during experimental carcinogenesis induced with long-term topical application of 7, 12-dimethylbenzanthracene (DMBA). 4 67


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