<i>In vivo</i> DMBA induced mouse skin epithelial hypertrophy and associated molecular changes during various intervals within 24-hour of exposure and their prevention by natural agents

This in vivo study was conducted to determine the effects of a single exposure to 7,12-dimethylbenzo[a]anthracene (DMBA) on mouse skin at several end points throughout a 24-hour exposure period. The protective effects of calcium glucarate (CAG), butyric acid (BA), and nicotinamide (NA) were also assessed in terms of DNA synthesis, hypertrophy, and cell proliferation markers, including the expression of the inflammation-related gene cyclooxygenase-2 (Cox-2), proliferating cell nuclear antigen (PCNA), cellular myelocytomatosis oncogene (c-Myc), and ornithine decarboxylase (ODC). Briefly, mouse skin was topically treated with DMBA. Additionally, the DMBA-treated area received topical applications of BA, NA, or CAG, either separately or in combination. Mice were sacrificed at the end of 4, 8, 16 and 24 hours after DMBA treatment. To access DNA synthesis, the [methyl-3H] thymidine incorporation test was performed. Reverse transcription-PCR (RT-PCR) and Western blotting were employed to assess gene expression at the mRNA and protein levels. As early as 4 hours after exposure, DMBA caused increased DNA synthesis and consequent hypertrophy, which was followed by overexpression of ODC, c-Myc, PCNA, and Cox-2. It gradually decreases at the end of the 24-hour period following exposure to DMBA, after peaking at the end of the 16-hour period. It was identified that DMBA-induced alterations could be prevented by BA, NA, and CAG, but that their combination worked best. A novel and improved method of managing skin hypertrophy with natural agents is made possible by the combined enhanced preventative effects of BA, NA, and CAG.