The percentage of dark basal keratinocytes was quantitatively assessed in normal epidermis of Sencar mice before and after birth and in adult epidermis after topical application of several compounds of varying promoting efficiency. The percentage of dark keratinocytes reached a maximum at the 19th day of gestation (~40%%) and fell abruptly after birth (~3%%). Old animals exhibited a very low number of dark basal cells (0.2%%). After topical application of the weak promoters resiniferotoxin, anthralin, ethylphenylpropiolate, and 12-deoxyphorbol–13–2,4,6-decatrienoate, the percentage of dark cells in young adult epidermis, did not differ markedly from that in control (acetone-treated) specimens. The strong first-stage promoters 4-O-methyl-12-O-tetradecanoylphorbol-13-acetate and calcium ionophore A 23187, as well as the strong complete promoter 12-deoxyphorbol-13-deoxyphorbol-13-decanoate, induced the appearance of large numbers of dark keratinocytes, in a percentage similar to that seen after 12-O-tetradecanoylphorbol-13-acetate application (~20%%). The similarities between the dark keratinocytes seen after topical application of 12-O-tetradecanoylphorbol-13-acetate or other strong promoters and the dark cells observed in the fetal epidermis before the onset of the adult type of epidermal keratinization indicate that potent and/or first stage tumorpromoters can be identified by their ability to induce cells resembling fetal-type dedifferentiated keratinocytes.
|Original language||English (US)|
|Number of pages||4|
|State||Published - Nov 1 1981|
ASJC Scopus subject areas
- Cancer Research