Previous studies appeared to indicate that CYP1B1 was not constitutively expressed in mouse liver. In our laboratory, we demonstrated using aromatic hydrocarbon-responsive receptor knock-out (AHR --/-) mice that both piperonyl butoxide (PBO) and acenaphtyhlene (ACN) are AHR-independent inducers of m
Induction of metallothionein mRNA by tumor promoters in mouse skin and its constitutive expression in papillomas
โ Scribed by Hiroki Hashiba; Junichi Hosoi; Mika Karasawa; Shuhei Yamada; Kiyoshi Nose; Toshio Kuroki
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 566 KB
- Volume
- 2
- Category
- Article
- ISSN
- 0899-1987
No coin nor oath required. For personal study only.
โฆ Synopsis
A single topical application of 12-O-tetradecanoylphorbol-13-acetate (TPA) was found to induce mRNA of a metallothionein (MT) gene or genes in the skin of Sencar mice, and papillomas produced by repeated applications of TPA were shown to have elevated levels of MT mRNA. Induction of MT mRNA was maximal 4-8 h after application of TPA and returned to the control level 24 h later. A dose-dependent increase of MT mRNA was observed with doses of TPA of 1-5 micrograms. Of the other promoters tested, phorbol-12, 13-didecanoate, mezerein, and the ionophore A23187 also induced MT mRNA, but 4-O-methyl-TPA and benzoyl peroxide did not. Phorbol and 4 alpha-phorbol-12,13-didecanoate, which are not promoters, also did not induce MT mRNA. Retinoic acid and 1 alpha, 25-dihydroxyvitamin D3, inhibitors of tumor promotion, did not induce MT mRNA themselves or inhibit the induction of MT mRNA by TPA. In C57BL/6 promotion-resistant mice, TPA caused only slight induction of MT mRNA. These data suggest a correlation between induction of MT mRNA and epidermal hyperplasia. The constitutive elevation of MT mRNA levels in papillomas may be due to the loss, during the process of tumor promotion, of some mechanism regulating MT gene expression.
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