Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: B0001 .4
 471,332 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two recently established human ovarian carcinoma cell lines (JA-T and TR175) have been used to study the effects of aphidicolin glycinate (APG), a specific competitive inhibitor of DNA polymerase alpha (Ikegani et al. (1978) Nature, 275, 458-460), on the formation and removal of four platinum-DNA adducts. Logarithmically-growing cells were exposed to cis-diamminedichloroplatinum (II) (cisplatin) (10 micrograms, 33.4 microM) in the presence or absence of APG (5 or 50 micrograms/ml, 11.6 or 116 microM). Platinum-DNA adducts were quantitated using a competitive ELISA technique. No differences were observed between the initial levels of total DNA platination and of specific DNA adducts formed in the presence or absence of APG in either cell line. Following 18 h posttreatment incubation both lines showed some ability to remove each of the three main platinum-DNA lesions (Pt-GMP, Pt-AG and Pt-GG). However, the levels of these specific DNA adducts decreased over this time period, by similar rates with or without APG addition. It was also shown that the APG concentrations used had minimal inhibitory effects alone on growth or DNA synthesis during this 18 h posttreatment incubation period. Furthermore its addition did not significantly modify cisplatin-induced cytotoxicity, as judged by inhibition of growth or DNA synthesis over this time period. We therefore conclude that under these experimental conditions APG does not modulate 'repair' of cisplatin-induced DNA damage in logarithmically-growing cultures of these two apparently 'repair-proficient' human ovarian tumour cell lines.
Carcinogenesis 1991 Mar
PMID:Lack of significant modulation of the formation and removal of platinum-DNA adducts by aphidicolin glycinate in two logarithmically-growing ovarian tumour cell lines in vitro. 190 Dec 53

A single dose of 1-ethynylpyrene (EP), 1-vinylpyrene (VP) or 2-ethynylnaphthalene (EN) was applied to the skin of SENCAR mice 5 min before an initiating dose of 7,12-dimethylbenz[a]anthracene (DMBA) or benzo[a]pyrene (B[a]P) and the development of skin tumors then promoted with biweekly topical applications of 12-O-tetradecanoylphorbol-13-acetate (TPA). The application of EP strongly inhibited the formation of skin tumors initiated by either DMBA or B[a]P in a dose-dependent manner. Application of 44 pmol of EP inhibited tumor initiation by 10 nmol of DMBA approximately 25%; application of 440 nmol of EP inhibited tumor initiation by 200 nmol of B[a]P approximately 51%. A high single dose of EP (4.4-44 mumol) nearly eliminated skin tumor initiation by either 10 nmol of DMBA or 200 nmol of B[a]P. Application of VP also inhibited the formation of skin tumors initiated by either DMBA or B[a]P in a dose-dependent manner, but higher doses of VP than of EP were required to produce comparable inhibitions. Application of 44 nmol of VP inhibited tumor initiation by 10 nmol of DMBA approximately 30%; application of 4.4 mumol of VP inhibited tumor initiation by 200 nmol of B[a]P approximately 56%. Application of EN yielded contrasting results. EN inhibited the formation of skin tumors initiated by 10 nmol of DMBA, but the observed dose-dependence was minimal; tumors were decreased about 40% by 3.3 mumol of EN and only about 65% by 132 mumol of EN. A high single dose of EN (132 mumol) increased both the mean number of tumors per mouse and the percentage of mice that developed tumors after initiation by 200 nmol of B[a]P. Topical application of 4.4 mumol of EP, 22 mumol of VP or 33 mumol of EN to the skin of SENCAR mice 5 min before a single initiation dose of 2.5 mumol of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) had a minimal inhibitory effect (14-28%) on the development of skin tumors produced by subsequent biweekly promotion with TPA. A single dose of 44 mumol of EP or 132 mumol of EN followed by biweekly applications of TPA did not produce skin tumors; however, a dose of 44 mumol of VP followed by promotion with TPA produced a low but significant number of skin tumors.(ABSTRACT TRUNCATED AT 400 WORDS)
Carcinogenesis 1991 Jul
PMID:Potent inhibitory effects of suicide inhibitors of P450 isozymes on 7,12-dimethylbenz[a]anthracene and benzo[a]pyrene initiated skin tumors. 190 78

Cepharanthine, isolated from Stephania cepharantha, is one of the bisbenzylisoquinoline-type alkaloids. We have found that it inhibits tumor promotion after topical application in two-stage carcinogenesis in mouse skin. Epidermal ornithine decarboxylase activities inhibited by topical application of cepharanthine, with an 5 micrograms/mouse) and mezerein (5 micrograms/mouse) were found to be inhibited by topical application of cepharanthine, with a ED50 of 1.2 mumol and 1.4 mumol respectively. These inhibitory effects of cepharanthine are considered to be related to its antitumor activity in two-stage carcinogenesis in mouse skin. Cell-mediated immunosuppression by TPA was unaffected by topical application of cepharanthine. A diet containing 0.005% cepharanthine (about 0.5 mg mouse-1 day-1) slightly suppressed the two-stage promotion of skin tumors by twice-weekly applications of 2.5 micrograms TPA for 2 weeks (first stage) followed by twice-weekly applications of 2.5 micrograms mezerein for 23 weeks (second stage) in ICR mice following initiation by 50 micrograms 7,12-dimethylbenz[a]anthracene. Oral administration of cepharanthine inhibits the tumor promotion in two-stage carcinogenesis in mouse skin.
 ...
PMID:Cepharanthine inhibits two-stage tumor promotion by 12-O-tetradecanoylphorbol 13-acetate and mezerein on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene. 190 98

Epidermal papillomas were induced in CD-1 mice by a single topical application of 7,12-dimethylbenzanthracene (DMBA) followed by twice weekly applications of 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in acetone. Control groups consisted of mice treated singly or chronically with acetone or TPA. TPA induced a rapid, yet transient 500- to 1000-fold increase in ornithine decarboxylase (ODC) activity which resulted in a 2- to 8.4-fold elevation of putrescine in both singly or chronically TPA-treated mouse epidermis 4-6 h after its application. After 24 h, levels of spermidine, but not spermine, were also elevated. The ODC and arginase activities in the 11 individual papillomas studied averaged 400- and 26-fold higher respectively than basal levels in epidermis. The activity of ODC in most papillomas, unlike ODC in epidermis, could be stimulated by guanosine 5'-triphosphate (GTP). Putrescine and spermidine levels in papillomas, especially those exhibiting highly GTP-stimulated ODC, were substantially higher compared to either normal or TPA-treated epidermis. Although epidermis contains a relatively high ornithine content, its level is even further elevated in papillomas, in some cases as much as 70-fold. The consequences of the constitutively elevated polyamine levels in papillomas caused by the loss of control over the normally tightly regulated polyamine biosynthetic pathway are not known, but could be important in regulating the balance between proliferation and differentiation in this self-renewing epithelial tissue.
Carcinogenesis 1991 Sep
PMID:Constitutively elevated levels of ornithine and polyamines in mouse epidermal papillomas. 190 38

The mutagenic heterocyclic amine 2-amino-3-methylimidazo[4,5-f] quinoline (IQ) is carcinogenic in the Fischer-344 rat, affecting the liver and small and large intestines, as well as several other organs. In male animals the incidences of tumors in the liver, small intestine, and large intestine were reported to be 67.5, 30.0, and 62.5%, respectively. Using 32P-postlabeling assays, the formation and persistence of IQ-DNA adducts in the liver and small and large intestines were studied in male Fischer-344 rats. Young, adult animals were either given a single p.o. dose (5, 25, or 50 mg/kg) of IQ and were killed 24 h later or were given a single p.o. or i.p. dose (50 mg/kg) of IQ and were killed at different time points, from 6 h to 31 days after p.o. treatment and from 6 h to 6 days after i.p. treatment, to follow adduct persistence. Up to five specific adducts could be isolated, and adduct formation was dose related in all three organs. Adduct 1, previously shown to be N-(hydroxyguanosin-8-yl)-IQ, was the major adduct in all cases, comprising up to 78% of the total. After p.o. administration (6-24 h) adduct levels in the liver were 3- to 4-fold higher than after i.p. administration, while levels in the intestines during this time period were independent of the route of administration. At 24 h after p.o. administration total adduct levels in the liver were 13.5-41.4 and 9.2-18.4 times higher than those in the small intestine and large intestine, respectively. Maximum adduct levels were observed between 6 and 24 h after administration, and from 1 to 6 days later, rates of removal from the liver were 7-fold and 2-fold slower, respectively, than from the small and large intestine. Rates of adduct removal from the intestines after i.p. administration were similar to those after p.o. administration. Beyond day 15 adduct levels in all organs constituted less than 12% of those on day 1, and low levels of adducts persisted for up to 31 days. In all cases there was no preferential loss or persistence of any of the adducts. It is concluded that total adduct levels and persistence in target organs may, in part, be related to susceptibility to IQ-induced carcinogenesis in the Fischer-344 rat.
 ...
PMID:Formation and persistence of DNA adducts of 2-amino-3-methylimidazo[4,5-f] quinoline in male Fischer-344 rats. 191 81

Since the 1960s, the loss of sulfomucin from colonic epithelium has been considered to be an indicator of an early stage of carcinogenesis; yet, the biochemical basis for this phenomenon has never been elucidated. We recently prepared a monoclonal antibody (mAb) 91.9H that immunoprecipitates the normal colonic mucins metabolically incorporating [35S]-sulfate. This mouse IgG1 antibody did not cross-react with colon carcinoma mucins that lack sulfate groups. Using normal colonic epithelia unlabeled or radiolabeled with [35S]sulfate and [3H]glucosamine, we purified a high molecular weight glycoprotein that reacts with mAb 91.9H. This was achieved by a combination of DEAE-cellulose anion-exchange chromatography, consecutive treatments with chondroitinase ABC plus heparitinase and with sodium dodecyl sulfate plus 2-mercaptoethanol, and gel filtration on Sepharose CL-2B in the presence of 8 M urea. Antibody reactivity was found in acidic but not neutral high molecular weight glycoproteins. After Sepharose CL-2B fractionation, the mAb 91.9H-reactive fractions consisted of a component with an approximate molecular weight of 500,000-900,000. A purified sulfomucin contained protein, neutral sugar, amino sugar, sialic acid, and sulfate in an approximate ratio of 2.5:1.0:1.1:0.4:0.5. The polypeptide portion was rich in hydrophilic amino acids, particularly threonine. Binding of mAb 91.9H in solid-phase assays was inhibited to 50% by purified normal colon acidic mucin at doses of 5-50 micrograms/ml, depending on different preparations. Various glycosaminoglycans or sulfatides did not show inhibitory activity. Sulfomucin reactivity with mAb 91.9H, as determined by solid-phase-binding inhibition and by dot blot assays, was significantly reduced by chemical desulfation of sulfomucins with anhydrous hydrochloric acid, suggesting that sulfate groups served as a portion of the immunochemical determinant for this antibody. Sulfate residues were apparently linked to alkaline-sensitive carbohydrate chains, but alkaline-released carbohydrate chains did not react with mAb 91.9H. Immunohistochemical examinations showed that mAb 91.9H bound normal colonic epithelial cells, which also stained with high-iron diamine, more strongly than it bound colon carcinoma cells.
 ...
PMID:Human colonic sulfomucin identified by a specific monoclonal antibody. 191 91

The risks of total-body irradiation with large doses of X rays (average dose 6.7 Gy) and fission neutrons (average dose 3.4 Gy) were investigated by keeping a group of long-term surviving monkeys from an experiment on acute effects under continuous observation. On the basis of the number of animals developing tumors in each group as a function of the total observation period and the average absorbed dose, relative biological effectiveness (RBE) values between 4 and 5 have been derived at these high dose levels. In experiments on mammary carcinogenesis in rats the highest RBE values are observed for neutrons with energies of 0.43 to 1 MeV as produced by the p + T reaction or by the fission process. Based upon linear dose-response curves for neutrons and X rays, a maximum RBE value of 15 was observed for induction of adenocarcinomas in WAG/Rij rats. Appreciably higher RBE values would be obtained if the results of the gamma-ray exposure, indicating a nearly quadratic dose-response relationship, were used as a baseline. For radiation protection applications it should be realized, however, that such an increase will be caused by the lower efficiency of low-linear-energy-transfer radiation rather than by an increase in efficiency of the neutron irradiation at low doses.
 ...
PMID:Relative biological effectiveness for neutron carcinogenesis in monkeys and rats. 192 39

The authors investigated the influences of recombinant human growth hormone (rh-GH) on rat urinary bladder carcinogenesis induced with N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Rats belonging to the control group (Group I, n = 19) were given 0.05% BBN in drinking water for 9 weeks, and the bladder was excised on the 22nd week after the initiation of BBN administration and inspected. All animals developed visible tumors in the bladder. The mean number of tumors per bladder was 11.26 +/- 5.21, and the mean total volume of tumors per bladder was 126.1 +/- 212.7 microliters. In all but one of the experimental groups (Group V) and in the control group, all animals developed visible tumors in the bladder. When 0.5 units of rh-GH was injected subcutaneously once a week from the week 1 through the week 6 (Group II; n = 20), the mean number of tumors and mean total volume of the tumors were 12.15 +/- 6.59 and 206.6 +/- 318.0 microliters, respectively. When the administration period of rh-GH was changed to between week 7 through the week 12 (Group III; n = 19), the mean number of tumors and mean total volume of the tumors were 16.95 +/- 7.07 and 204.5 +/- 317.7 microliters, respectively. When rh-GH was administered from the week 13 through the week 18 (Group IV; n = 19), the respective values were 16.79 +/- 10.75 and 213.4 +/- 274.6 microliters. In Group V (n = 19), which received only rh-GH from week 1 through the week 6, no tumors were detected. There were statistically significant differences in the mean tumor numbers between Groups I and III, Groups I and IV, and Groups II and III. The mean volume of individual tumor was the greatest in Group II, although the differences were not statistically significant in comparison with the other groups. Histologically, all tumors were transitional cell carcinoma in every group. There were no statistically significant differences in distributions of tumor stage and tumor grade between any groups. These findings suggest that rh-GH enhances the promotion of carcinogenesis of chemically induced rat urinary bladder cancer. It will be necessary to elucidate whether this effect of rh-GH is expressed by the somatostatin hypothesis of GH action, its direct action, or some other mechanisms.
 ...
PMID:Stimulatory effects of growth hormone on rat bladder carcinogenesis. 193 78

A carcinogenic heterocyclic amine, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), was measured in condensate of cigarette mainstream smoke by HPLC. PhIP was detected in all brands of filter-tipped cigarettes analyzed. The mean level of PhIP in the cigarette mainstream smoke was 16.4 ng/cig.
Carcinogenesis 1991 Oct
PMID:Detection of a carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), in cigarette smoke condensate. 193 75

The in vivo formation of specific 7,12-dimethylbenz[a]-anthracene (DMBA)-DNA adducts in the mammary gland of the female Sprague-Dawley rat was studied in response to dietary butylated hydroxytoluene (BHT). Dietary BHT concentrations of 0.4 and 0.8% significantly inhibited total DMBA-DNA binding by 41.5 and 35.6% respectively, as compared to controls. However, the decrease in total binding associated with intake of BHT was not due to a uniform inhibition in the formation of all individual adducts. The formation of two adducts resulting from the binding of the anti-dihydrodiolepoxide of DMBA to deoxyguanosine (anti-dGuo) was significantly decreased by a combined average of 51.5% for rats fed BHT-supplemented diets as compared to controls. However, syn-derived DMBA-DNA adducts were not consistently inhibited by dietary BHT. Adduct formation resulting from the binding of the syn-dihydrodiolepoxide of DMBA to deoxyadenosine (syn-dAdo) was significantly inhibited only for rats fed a diet supplemented with 0.4% BHT. The formation of the syn-dGuo adduct was not affected by the feeding of BHT-supplemented diets. These results suggest that in vivo inhibition by BHT of mammary DNA adducts formed from the anti-diastereomer of DMBA may be an important contribution to the inhibitory effect of BHT on the initiation stage of DMBA-induced mammary carcinogenesis.
Carcinogenesis 1991 Oct
PMID:Selective in vivo inhibition of rat mammary 7,12-dimethylbenz[a]anthracene-DNA adduct formation by dietary butylated hydroxytoluene. 193 80


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>