Expression and Distribution Patterns of Spermine, Spermidine, and Putrescine in Rat Hair Follicle

The study tested whether suppressing ornithine decarboxylase (ODC) activity could block skin tumor promotion in mice with activated MEK mutations. By crossing these mice with those overexpressing antizyme (AZ), which degrades ODC, researchers found that AZ expression significantly delayed tumor development and reduced tumor numbers. This effect was most pronounced in MEK/K6-AZ mice, which had fewer than one tumor per mouse after 8 weeks, compared to over 13 tumors in MEK-only mice. The study suggested that AZ primarily inhibited putrescine accumulation, slowing cell growth by increasing G2/M transit time, without inducing apoptosis.

The study demonstrated that ornithine decarboxylase (ODC) played a significant role in hair follicle development and hair growth by being associated with cell proliferation and commitment. ODC was expressed in embryonic epidermis at sites of follicle development and persisted in proliferating bulb cells of anagen follicles, except at the base of the bulb. Its expression decreased as follicles entered catagen and resumed with new follicle initiation. In vibrissae, ODC showed a complex expression pattern, being present in both the bulb and hair shaft, and in outer root sheath cells near the follicle bulge, suggesting a link to hair follicle stem cells.

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.