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.

Fluorescence spectroscopic identffication of 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis

Abstract: An attempt was made to study whether light-induced fluorescence spectroscopy could be exploited to discriminate premalignant and malignant tissues of hamster buccal pouch carcinogenesis from normal tissues during a 16 week regimen of tri-weekly topical application of 7,12-dimethylbenz[a]anthracene (DMBA) in liquid paraffin. Histologically, the DMBA-treated buccal mucosa showed hyperplastic changes at 4-6 weeks, papillomas at 8-10 weeks, early invasive carcinomas at 11-13 weeks and finally well-differentiated squamous cell carcinomas at 14-16 weeks of treatment. Acetone extracts of these different staged tissues with age matched control tissues were excited at 405 and 420 nm and the emissions were scanned from 430 and 440 to 700 nm respectively. The spectral profiles of control and transformed tissues were found to be different, each displaying their own characteristic prominent maxima and other spectral marks. The spectra of transformed tissues showed characteristic peaks around 620-630 nm which did not appear in control tissues and the fluorescent intensities at 630 nm [FI(630)nm] were significantly increased from early stages onwards when compared to controls. The spectra of DMBA carcinomas developed at the 18th week after withdrawal of DMBA application at the 10th week and carcinoma extract spiked with DMBA confirmed the peak around 620-630 could be attributed only to porphyrin compounds accumulated in transformed tissues. Furthermore, the ratios of FI(520)nm/FI(630)nm of transformed tissues were also significantly decreased when compared to control tissues. This diagnostic test had a very close resemblance with respect to histological studies. These results suggest that this technique using conventional light-induced fluorescence spectroscopy may be useful for early diagnosis of premalignant and malignant lesions of oral cavity.

Influence of Dietary Retinyl Acetate on Normal Rat Mammary Gland Development and on the Enhancement of 7,12-Dimethylbenz[a]anthracene-Induced Rat Mammary Tumorigenesis by High Levels of Dietary Fat

Abstract: The effect of high levels of dietary fat and retinyl acetate (ROA) on 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumor development and growth was examined. Female Sprague-Dawley rats, 51-53 days of age, were treated ig with 5 mg DMBA. At 55-57 days of age, the animals were divided into the following dietary treatment groups: A) 4.5% fat [control fat (CF)]; B) CF + 1.0 mmol ROA/kg diet (CF + ROA); C) 20.0% fat [high fat (HF)]; and D) HF + ROA. HF diets significantly increased mammary tumor multiplicity, with or without ROA, but did not significantly influence mammary tumor growth. ROA treatment reduced mammary tumor multiplicity regardless of the level of dietary fat and inhibited mammary tumor growth in the presence of normal levels of dietary fat. High levels of dietary fat did not significantly influence normal mammary gland growth and development. ROA significantly decreased normal mammary gland growth and development regardless of the level of dietary fat. Blood retinoids in rats fed ROA were primarily in the form of retinyl esters, i.e., retinyl linoleate, retinyl palmitate-oleate, and retinyl stearate. Free retinol levels in blood were not significantly influenced by ROA feeding. Blood retinyl ester levels were lower in rats fed the HF + ROA diet as compared to rats fed the CF + ROA diet.