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)

Prenatal exposure to a single dose of diethylstilbestrol (DES) produced a significant increase in carcinogenic response of hamster progeny that were subsequently subjected to the carcinogenic stimulus of 7,12-dimethylbenz(a)anthracene (DMBA) during postnatal life. The compounds were administered according to the following schedules. The pregnant animals (second group) received a single dose of DES, 10 mg/kg, on Day 14 of gestation. Postnatally, at 6 weeks of age, the progeny were given DMBA, 25 mg/kg p.o., twice weekly for 8 weeks. The first group received DMBA at 6 weeks of age, 30 mg/kg p.o., twice weekly for 18 weeks. The progeny exposed to DES prenatally and DMBA postnatally (DES-DMBA-exposed progeny) developed a greater multiplicity of tumors per tumor-bearing animal (p less than 0.001) and higher rates of neoplasms of the reproductive tract, e.g., ovarian and uterine tumors, mammary gland and forestomach tumors, and dermal melanomas. The prenatally DES-exposed progeny also had significantly higher incidences of malignant tumors, e.g., carcinomas of the mammary gland (p less than 0.001) and carcinomas of the forestomach (p less than 0.001), than did the hamsters given DMBA alone during postnatal life. Endocrine imbalance produced by exposure in utero may heighten the sensitivity of the progeny to development of neoplasms after a challenge with carcinogenic stimuli in adult life. The significance of these experimental data to the human situation is discussed.
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PMID:Effects of transplacental exposure to diethylstilbestrol on carcinogenic susceptibility during postnatal life in hamster progeny. 11 77

The effect of 1,3,5(10)-estratriene-3, 16 alpha, 17 beta-triol (estriol), 1, 3, 5(10)-estratriene-2,3-diol-17-one (2-hydroxyestrone), and 1,3,5(10)-estratriene-2,3,17 beta-triol (2-hydroxyestradiol) on the growth of dimethylbenz(a)anthracene-induced mammary tumor and of R3230AC-transplantable mammary tumor was compared with that produced by estradiol benzoate treatment. Estriol showed minimal inhibition of tumor growth in dimethylbenz(a)anthracene-induced tumor and no effect on R3230AC tumor while 2-hydroxyestrone showed no effect of tumor inhibition. On the other hand, 2-hydroxyestradiol showed appreciable inhibition of tumor growth in both tumors studied. That 2-hydroxyestradiol has been found to bind to estrogen receptors in mammary tumors and is uterotropic suggests that the inhibition of tumor growth by 2-hydroxyestradiol may be similar to the mechanism of inhibition of mammary tumors by high concentrations of estradiol.
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PMID:Effect of catechol estrogens on rat mammary tumors. 11 83

The enzymes responsible for the activation, transfer and hydrolysis of sialic acids were investigated in female rats with mammary adenocarcinomas induced by administration of a single oral dose (10 mg) of 7,12-dimethylbenz[alpha]anthracene. The carcinogenic process was modulated by the levels and degree of unsaturation of the dietary lipids. Tumor incidence was highest in rats fed a diet containing 20% corn oil, intermediate with 18% coconut oil plus 2% linoleic acid, and lowest in the group receiving a diet with 2% linoleic acid. Sialyltransferase and CMP-N-acetylneuraminic acid synthetase activities were higher in tumors than in control mammary glands. Neuraminidase activity, on the other hand, was higher in control tissue than in tumors. In addition to these tumor-related effects, comparison of the enzyme levels in mammary tissues from control animals of the 3 dietary groups revealed the presence of diet-related effects on sialic acid metabolism. In the livers of tumor-bearing rats, only minor changes of enzyme activities were detected.
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PMID:Sialic acid metabolism in rats undergoing chemically-induced mammary gland carcinogenesis in specific dietary states. 11 65

The morphological and numerical changes in the epidermal melanocyte system of the tail of C57BL mice were studied after exposure to 7, 12 dimethylbenz(alpha)anthracene (DMBA) followed by UVB irradiation. The dorsal aspect of the tail was exposed for 5 days per week, for a total duration of 10 weeks, to a daily dosage of 0.1 J/cm2 UVB (peak 310 nm). Once a week, 0.2 ml of 0.15% DMBA in acetone was locally applied to the irradiated areas. Biopsies were studied by the combined skin-splitting DOPA and electron microscopic techniques. After 10 weeks of DMBA treatment the following changes were observed: DMBA treatment the following changes were observed: the original brick-like arrangement of melanocytes became confluent, melanocytes were irregularly shaped, dendrites shortened and clumped together, and the outer root sheaths of the hair follicles became covered with melanocytes. There was a significant increase in the number of DOPA positive melanocytes at the end of the first week in DMBA and DMBA + UVB treated skin. Ultrastructurally, an increase in melanosome formation in melanocytes and transfer into keratinocytes was found, as well as redistribution of melanosomes from singlets and doublets into larger groups. Damage of melanocytes by the DMBA treatment was seen, but no inflammation or tumor formation was observed.
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PMID:The effects of UVB and 7, 12, dimethylbenz(alpha)anthracene (DMBA) on epidermal melanocytes of the tail in C57BL mice. 11 59

Biological characteristics of nodule-like alveolar lesions (NLAL) induced by 7,12-dimethylbenz[a]anthracene (DMBA) in organ culture of whole mammary gland (BALB/c female mice) were assessed after transplantation into gland-free mammary fat pads of syngeneic virgin mice. (i) Tissue-fragment explants from NLAL areas of the gland produced abnormal lobuloalveolar (LA) outgrowths in 3 of 10 fat pads. (ii) Transplantation of dissociated cells of NLAL-derived LA outgrowths into 36 fat pads showed 100% LA outgrowths and 3 (8%) of these 36 outgrowths produced mammary carcinomas. (iii) The explants of dissociated cells from whole mammary glands treated with DMBA in culture produced full or partial LA structures in 2 of 56 outgrowths. (iv) The explants of dissociated cells prepared from outgrowths derived from outgrowths derived from explants as in iii produced 9 LA outgrowths in 16 instances; mammary tumor incidence in these outgrowths was 3 of 16 (18%). (v) The explants of tissue fragments from LA outgrowths as in iv produced LA outgrowths in 20 of 20 fat pads; mammary carcinomas appeared in 16 of 20 (80%) of these outgrowths. No NLAL was detectable in control glands treated with dimethyl sulfoxide (solvent for DMBA); explants of the control glands consistently produced ductal outgrowths and no tumor. This accomplishment of chemical carcinogen-induced neoplastic transformation of epithelial cells in vitro provides a model for studying carcinogenesis in an entire isolated organ.
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PMID:Neoplastic transformation of epithelial cells in whole mammary gland in vitro. 11 56

In noninbred rats chloramphenicol and its optical isomer dextramycin diminished the blastomogenic effect of 7,12-dimethylbenz(a)anthracene on mammary glands. The protective effect was shown by a decreased tumor incidence at all periods of observation and an increase in the life span of rats and in the case of dextramycin this action consisted in a prolongation of the latent period of tumor emergence.
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PMID:[Chloramphenicol and dextramycin, inhibitors of mammary carcinogenesis induced by 7,12-dimethylbenz(a)anthracene]. 12 Feb 6

Prolactin binding activity was studied in suspensions of cells which had been enzymatically dissociated from R3230AC mammary tumors, 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors and lactating rat mammary glands. Prolactin bound specifically with high affinity (apparent binding affinity = 4.0 X 10(9) M-1) to R3230AC tumor cells. Hormone binding at room temperature was proportional to cell number and increased with time of incubation up to 120-180 min. Prolactin binding to R3230AC tumor cells from diabetic animals was reduced by about 50%. Specific prolactin binding activity was also demonstrated in preparations of cells from DMBA-induced tumors and lactating mammary gland. The levels of hormone binding in both dissociated cells and subcellular particles prepared from these tissues varied as follows: DMBA-induced tumors > lactating mammary gland > R3230AC mammary adenocarcinoma.
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PMID:Prolactin binding to dissociated cells from rat mammary tumors and mammary gland. 12 22

The estrogen-binding capacity of mammary tumors induced by 7,12-dimethylbenz(a)anthracene was measured in lesions from animals after the ovariectomy, deprival of insulin (diabetes), or treatment with lergotrile mesylate to inhibit prolactin secretion. The average estrogen-binding capacity was 30 fmoles/mg cytosol protein in growing or static carcinomas from intact (control) animals. A significant reduction in estrogen-binding capacity was observed in regressing but not static mammary tumors from ovariectomized animals. In regressing and static tumors from diabetic rats, estrogen-binding capacity was significantly lower than in lesions from intact animals; this effect was not seen in growing tumors from diabetic rats. Tumors that were growing or static in lergotrile-treated animals showed reduced capacity to bind labeled estradiol. The effects of duration of hormone treatment or time of tissue storage on estrogen-binding capacity were examined and did not appear to be correlated with the decreased binding in tumors from treated animals. The results suggest that hormones capable of producing altered neoplastic growth may influence the level of estrogen receptors.
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PMID:Influence of hormonal alteration of host on estrogen-binding capacity in 7,12-dimethylbenz(a)anthracene-induced mammary tumors. 13 55

Ether-permeabilized (nucleotide-permeable) Escherichia coli cells exhibited DNA excision repair when exposed to the following carcinogenic K-region epoxides: 7-methyl- and 7,12-dimethyl-benz[a]anthracene-5,6-oxide, chrysene-5,6-oxide and benzo[a]pyrene-4,5-oxide. This DNA excision repair was missing in uvr A and uvr B mutant cells. The K-region epoxide phenanthrene-9,10-oxide was ineffective in all E. coli strains tested. In contrast to the K-region epoxides which where found active only in wild type cells, 1,2,3,4-diepoxybutane and the 6,7-epoxides of the tumor promoter TPA (12-O-tetradecanoyl-phorbol-13-acetate) elicited DNA repair in uvrA, uvrB mutant cells as well. Enzymic activities catalyzing particular repair steps were identified by determining a) repair polymerization and b) size reduction of denatured DNA. A) An easily quantifiable effect in E. coli wild type cells was epoxide-induced repair polymerization. None of the K-region epoxides tested stimulated DNA repair synthesis in uvrA, uvrB mutant cells, indicating that the uvrA-, uvrB-controlled UV-endonuclease initiated excision repair by cleaving epoxide-damaged DNA. 1,2,3,4-Diepoxybutane and the TPA-6,7-oxides induced DNA repair polymerization in uvr-deficient cells, although to a lesser extent than in wild type cells, suggesting the involvement of uvr-independent incision steps. None of the epoxides induced repair polymerization in a mutant (polA107) lacking the 5'--3'exonucleolytic activity of DNA polymerase I (exonuclease VI). The absence of any repair polymerization in the polA107 mutant indicates that the exonuclease VI plays a central role in removing epoxide-damaged nucleotides. As evidenced by greatly reduced levels of repair polymerization measured in polA1 cells, DNA polymerase I was the main polymerizing enzyme. b) As a consequence of treatment with 7-methyl-benz[a]anthracene-5,6-oxide, DNA from wild type cells, contrary to uvrA mutant cells, showed size reduction after denaturation and sedimentation in alkaline sucrose gradients. This is explained by repair-specific endonucleolytic cleavage of damaged DNA. The incision required the presence of ATP indicating that functional UV-endonuclease needs ATP as a cofactor.
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PMID:Carcinogen-induced DNA repair in nucleotide-permeable Escherichia coli cells. Analysis of DNA repair induced by carcinogenic K-region epoxides and 1,2,3,4-diepoxybutane. 15 97

Experiments were undertaken with 7,12-dimethylbenz(q)anthracene-induced mammary tumors of the rat to determine whether ovarian-dependent and ovarian-independent tumors could be distinguished on the basis of differences in the estrogen binding capacity of the tumors in vitro and in vivo. Our results confirm reports showing that ovarian-depentent tumors undergo interaction between ovarian-dependent tumors undergo interaction between 17beta-(3H)estradiol and specific estrogen binding components both in vivo and in vitro, as described for other estrogen target tissues. However, our results also demonstrated that certain 7,12-dimethylbenz(a)anthracene-induced tumors, which continue to grow after ovariectomy of the host, contained significant amounts of 17beta-(3H)estradiol bound to cytoplasmic as well as nuclear components. The sedimentation properties of these components were indistinguishable from those of either ovarian-dependent 7,12-dimethylbenz(a)anthracene-induced tumors or rat uterus. The cytoplasmic binding components of both classes of tumors exhibited similar specificities for estrogens. There did not appear to be an absolute correlation between estrogen-binding capacity of a tumor and its growth response to ovariectomy.
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PMID:Specific estrogen binding in rat mammary tumors induced by 7,12-dimethylbenz(a)anthracene. 16 81


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