Dynamic Expression of Ornithine Decarboxylase in Hair Growth

In this study, researchers investigated whether overexpression of ornithine decarboxylase (ODC) was sufficient for tumor promotion in mouse skin. They used transgenic mice with high ODC expression in epidermal keratinocytes and found that these mice were more sensitive to carcinogen initiation compared to controls. Notably, mice with ODC overexpression in hair follicle keratinocytes developed tumors without the need for additional tumor promoters. The study concluded that ODC overexpression was sufficient to activate target cells in hair follicles, leading to clonal expansion and epidermal tumor formation, indicating that hair follicles are key sites for chemical carcinogen targeting in the skin.

The study investigated the role of ornithine decarboxylase (ODC) in hair follicle function using transgenic mice that overexpressed a mutated ODC transgene in hair follicle keratinocytes. These mice experienced normal initial hair growth but lost their hair completely 2-3 weeks after birth, coinciding with the onset of ODC overexpression and the development of follicular cysts. The study found that the ODC inhibitor 2-difluoromethylornithine could prevent hair loss and partially restore normal skin histology if administered early, and it could also reactivate hair growth in mice with complete hair loss. The results suggested that ODC played a crucial regulatory role in mouse hair follicles.

The study investigated the role of polyamines in hair follicle function and fiber composition in sheep. It found that inhibiting ornithine decarboxylase with alpha difluoromethylornithine altered fiber characteristics but did not inhibit wool follicle growth in culture. Conversely, inhibiting S-adenosylmethionine decarboxylase with methylglyoxal (bis)guanylhydrazone completely inhibited fiber growth, which could be reversed by adding spermidine, but not spermine. The study concluded that polyamines, particularly spermidine, were crucial for hair growth, as evidenced by the ability of spermidine to partially counteract growth depression in methionine-deficient conditions.

The study investigated the expression patterns of ornithine decarboxylase (ODC) and keratins in early papillomas in SENCAR mice to identify markers for early skin tumorigenesis. Tumors were induced using 7,12-dimethylbenzanthracene and promoted with 12-O-tetradecanoylphorbol-13-acetate. In early papillomas, keratin K1 showed patchy staining, while K10 was minimally expressed, contrasting with their normal expression in mildly hyperplastic epidermis. ODC expression was intense and diffuse in suprabasal cells of papillomas, correlating with decreased K1 and K10 expression, indicating altered differentiation. These findings suggested that high ODC expression and reduced K1 and K10 could serve as markers for early tumorigenesis in mouse skin.