title: Beta-carotene inhibition of 7,12-dimethylbenz[a]anthracene-induced transformation of murine mammary cells in vitro.
abstract: The chemopreventive action of beta-carotene during chemically-induced transformation of the epithelial cells in organ culture of the whole mammary glands from BALB/c female mice was studied. The mammary epithelial cells in the whole mammary organ in a hormone supplemented, serum-free medium were transformed after 24 h exposure to 7.8 microM 7,12-dimethylbenz[a]anthracene (DMBA) between 3rd and 4th day of a total 10 day culture period. The transformation process was associated with appearance of nodule-like alveolar lesions (NLAL) in glands in vitro. The epithelial cells transformed by DMBA are potentially neoplastic, and NLAL serves as a morphological marker of preneoplasia in the glands in vitro. Treatment with beta-carotene (10(-6) M) during DMBA exposure (3rd-4th day) caused 68% inhibition in the number of glands with incidence of NLAL. A 49% inhibition of NLAL was evident when the glands were incubated with beta-carotene (days 4-10) after exposure to DMBA. Results indicate that beta-carotene inhibits DMBA-induced transformation of the mammary glands in vitro acting both at the initiation and the promotional stages. This inhibitory effect is likely due to the action of beta-carotene itself since no accumulation of retinol, the metabolic derivative of the vitamin A precursor, was detectable in the mammary glands during the 10 day culture period.
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene; D000818:Animals; D002338:Carotenoids / Q000378:metabolism / Q000494:pharmacology*; D002471:Cell Transformation, Neoplastic / Q000187:drug effects*; D004848:Epithelium / Q000473:pathology; D005260:Female; D066298:In Vitro Techniques; D008321:Mammary Glands, Animal / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C; D019207:beta Carotene
chemical_list: D019207:beta Carotene; D002338:Carotenoids; D015127:9,10-Dimethyl-1,2-benzanthracene