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Titolo:
Patterns of DNA adduct formation in liver and mammary epithelial cells of rats treated with 7,12-dimethylbenz(a)anthracene, and selective effects of chemopreventive agents
Autore:
Izzotti, A; Camoirano, A; Cartiglia, C; Grubbs, CJ; Lubet, RA; Kelloff, GJ; De Flora, S;
Indirizzi:
Univ Genoa, Dept Hlth Sci, Sect Hyg & Prevent Med, I-16132 Genoa, Italy Univ Genoa Genoa Italy I-16132 t Hyg & Prevent Med, I-16132 Genoa, Italy Univ Alabama, Chemoprevent Ctr, Birmingham, AL 35294 USA Univ Alabama Birmingham AL USA 35294 revent Ctr, Birmingham, AL 35294 USA NCI, Rockville, MD 20892 USA NCI Rockville MD USA 20892NCI, Rockville, MD 20892 USA
Titolo Testata:
CANCER RESEARCH
fascicolo: 17, volume: 59, anno: 1999,
pagine: 4285 - 4290
SICI:
0008-5472(19990901)59:17<4285:PODAFI>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
BUTYLATED HYDROXYTOLUENE; DIETARY SELENITE; INHIBITION; TUMORIGENESIS; INVIVO; 7,12-DIMETHYLBENZANTHRACENE; TUMORS; 7,12-DIMETHYLBENZANTHRACENE; CARCINOGENESIS; SENSITIVITY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Clinical Medicine
Life Sciences
Citazioni:
36
Recensione:
Indirizzi per estratti:
Indirizzo: De Flora, S Univ Genoa, Dept Hlth Sci, Sect Hyg & Prevent Med, Via A Pastore 1, I-16132 Genoa, Italy Univ Genoa Via A Pastore 1 Genoa Italy I-16132 2 Genoa, Italy
Citazione:
A. Izzotti et al., "Patterns of DNA adduct formation in liver and mammary epithelial cells of rats treated with 7,12-dimethylbenz(a)anthracene, and selective effects of chemopreventive agents", CANCER RES, 59(17), 1999, pp. 4285-4290

Abstract

7,12-Dimethylbenz(a)anthracene (DMBA) is a prototype carcinogen that induces a high yield of mammary tumors in rats after a single feeding. We investigated the induction and chemoprevention of DNA adducts in female Sprague Dawley rats receiving DMBA by gavage according to a variety of treatment schedules. The patterns of P-32-postlabeled DNA adducts in liver and mammary epithelial cells were similar to those produced by the ill vitro reaction ofmetabolically activated DMBA with calf thymus DNA. There was a high and statistically significant correlation between dose of DMBA administered to rats (0, 0.6, 2.4, and 12 mg/kg body weight) and levels of DNA adducts in both types of cells. The regression lines relating DMBA doses to total DNA adduct levels were significantly divergent and crossed at 1.5 mg/kg body weight, indicating that, at lower doses, the formation of DNA adducts is more intense in target mammary cells, whereas at higher doses, DNA adduct levels are more elevated in liver cells, presumably due to the greater metabolic capacity of this organ, When the rats were sacrificed 7 days rather than 2 days after DMBA administration, DNA adduct levels were approximately halved in both liver and mammary cells, The observed patterns can be interpreted based on toxicokinetic factors, local and distant metabolism, removal of DNA adducts by excision repair, and cell proliferation rate. Of three chemopreventive agents given with the diet to rats treated with 12 mg of DMBA, 5,6-benzoflavone (1650 ppm) was the most effective, inhibiting DNA adduct formation in liver and mammary cells by 96.5 and 83.5%, respectively. Feeding of 1,2-dithiole-3-thione (600 ppm) inhibited this biomarker by 68.5 and 50.2%,whereas butyl hydroxyanisole (BHA; 5000 ppm) showed a significant inhibition in the liver (46.5%) but: was ineffective in mammary cells (29.0%, not significant). These data correlate nicely with the results of a parallel study in which 5,6-benzoflavone, 1,2-dithiole-3-thione, and BHA inhibited formation of hemoglobin adducts by 80.0, 44.0, and 0%, respectively; the incidence of mammary tumors by 82.4, 47.1, and 5.9%, respectively; and their multiplicity by 92.6, 80.0, and 7.4%, respectively, Therefore, biomarkers of biologically effective dose are highly predictive of the efficacy of chemopreventive agents in the DMBA rat mammary model, The selective inhibition by BHA of DNA adducts in the liver but not in mammary cells is consistent with the finding that this phenolic antioxidant stimulated phase II activities in the liver but not in the mammary gland (L. L. Song et at, manuscript in preparation). In any case, the broad-spectrum inducer 5,6-BF appears to be more effective than the two monofunctional phase II inducers, presumably because an enhanced activation of DMBA to reactive metabolites is coordinated with their blocking, detoxification, and excretion.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 06/07/20 alle ore 08:12:35