7,12-Dimethylbenz[a]anthracene

About: 7,12-Dimethylbenz[a]anthracene is a research topic. Over the lifetime, 1717 publications have been published within this topic receiving 40892 citations.

Long-term effect of Spirulina platensis extract on DMBA-induced hamster buccal pouch carcinogenesis (immunohistochemical study)

Abstract: In cancer research, the use of complementary and alternative medicine has increased over the past decade. In this study, 80 male golden Syrian hamsters were divided into four equal groups; the right buccal pouches of the hamster rats in group 1 were painted with 0.5% solution of 7, 12-dimethylbenz[a]anthracene (DMBA), three times a week for 32 weeks. The same pouches of group 2 were subjected to the same DMBA painting; but at the same time, the animals received 10 mg/daily Spirulina platensis extract for the same period. In group 3, the same regimen of DMBA painting was done but for 24 weeks only and the daily systemically S. platensis was received for the 32 weeks. In group 4, neither DMBA painting nor S. platensis administration was done but pouches were painted with saline and served as a control one. Five rats from each group were sacrificed at 12, 24, 28, and 32 weeks, respectively. The required pouches were excised, fixed, and embedded in paraffin to be immunostained with proliferating cell nuclear antigen (PCNA). The results showed that increased PCNA expression was directly related to the severity of pathological alterations from normal epithelium to dysplasia and from dysplasia to squamous cell carcinoma (SCC) in the study groups at the different extended periods of DMBA application and S. platensis extract administration. Analysis of variance and Duncan’s multiple-range test for PCNA labeling index were proved a high significant difference (P < 0.01) between the different groups. From the pervious results, it can be concluded that S. platensis extract has a beneficial role in regression of cancer progression.

Antitumor effects of SEF19, a new nonsteroidal aromatase inhibitor, on 7,12-dimethylbenz[a] anthracene-induced mammary tumors in rats

Abstract: The antitumor and endocrine effects of a new nonsteroidal aromatase inhibitor, 2-(imidazol-1-yl)-4,6-dimorphorino-l, 3, 5-triazine (SEF19) were examined in female Sprague-Dawley rats bearing estrogen dependent 7,12-dimethylbenz[a]anthracene(DMBA)-induced mammary tumors, and the effects were compared with those of CGS20267. The rats bearing DMBA-induced mammary tumors within 6-15 weeks after the DMBA administration were divided into the treatment groups once a week every week, and they were treated with SEF19, CGS20267 and vehicle for 4 weeks. One hundred rats were sacrificed 4 hours after the last administration, and the remaining 60 rats were sacrificed after a 4-week recovery period. During the treatment and recovery period, the tumor size was generally smaller in the SEF19 and CGS20267-treated subgroups than in the control subgroup. Tumor sizes in the subgroups treated with high doses of SEF19 (25 mg/kg/day and 50 mg/kg/2 days) were reduced to the size of the CGS20267-treated subgroup. The CGS20267-treated rats showed decrease in the serum estradiol level and an increase in the serum testosterone level. Their uterine weights were reduced. SEF19 treatment failed to show any effect on the serum levels of estrone, estradiol, testosterone and androstenedione, but it suppressed uterine weight in a dose-dependent manner. After the recovery period, no effect was detected in the serum concentrations of steroid hormones and the weight of the organs. At every dose used in the present study the aromatase inhibitory activity of SEF19 was weaker than that of CGS20267, but the inhibitory effect on mammary tumor growth of SEF19 at high doses was comparable to that of CGS20267. We conclude that the antitumor effect of SEF19 is not due to aromatase inhibition but mainly to its direct cytotoxicity.

Protective Effect of Benzoflavone and Estrogen against 7,12-Dimethylbenz(a)anthracene- and Aflatoxin-induced Cytotoxicity in Cultured Liver Cells

Abstract: 7,8-Benzoflavone, a competitive inhibitor of polycyclic hydrocarbon hydroxylation, protects cultured liver cells against the cytotoxicity of aflatoxin B1 and sterigmatocystin. Estrogenic steroids, which have previously been shown to protect against the cytotoxic effect of 7,12-dimethylbenz(a)anthracene, also protect against the cytotoxic effect of aflatoxin B1. The possible relationship of this protective effect of estrogens to human clinical and epidemiological data is discussed.

Photodynamic cytotoxicity of mammalian cells exposed to sunlight-simulating near ultraviolet light in the presence of the carcinogen 7,12-dimethylbenz(a)anthracene.

Abstract: — The coal-derived carcinogen 7,12-dimethylbenz(a)anthracene (DMBA), added to cultures of V79 Chinese hamster, C3H mouse 10T1/2, and human HeLa cells, enhances photolethality induced by the sunlight-simulating emission from Westinghouse Sun Lamps (- 29˜100 nm) but only in the presence of O2. Treatment of cells with DMBA after irradiation is without lethal effect; the endoperoxide of DMBA is ineffective both before as well as after irradiation, and DMBA incubation before far-UV exposure (254 nm) is protective. Cells rendered photosensitive by incubation with DMBA rapidly lose their sensitivity (in < 10 min, 37°C) if incubated in a DMBA-free solution containing serum, but maintain their sensitivity at least for several hours if a serum-free solution is used. Although DMBA enhances light-induced killing of cells in all phases of the cycle, those undergoing DNA syntheses are preferentially sensitized. The data support photodynamic lethality due to one or both of the following: (1) the reaction with DNA of either DMBA radicals followed by oxidation, or DMBA-produced singlet oxygen; or (2) the peroxidation of lysosomal membranes followed by the release of hydrolases including DNAses. As a model system of the combined effects of a fossil-fuel derived polycyclic aromatic hydrocarbon and sunlight, the results with DMBA + near-UV are discussed in the context of altered cell properties (e.g. neoplastic transformation) in sublethally affected cells.