GENE-EXPRESSION OF MARKERS ASSOCIATED WITH PROLIFERATION AND DIFFERENTIATION IN HUMAN KERATINOCYTES CULTURED FROM EPIDERMIS AND FROM BUCCALMUCOSA

Normal keratinocytes from epidermis and from buccal mucosa underwent d issimilar stages of differentiation in the same culture medium and res ponded differently to changes in the composition of the medium. Manife stations of these variations were examined in terms of the expression at the mRNA level (as measured by reverse transcriptase-polymerase cha in reaction) of three regulatory genes (cdc2, c-myc, and p53) and five genes that encode structural proteins (keratins K5, K10 and K13, invo lucrin, and filaggrin), in three growth-medium formulations. The cultu re conditions enhanced or retarded maturation; the observed alteration s in gene expression correlated with these changes. Except for the pro liferation genes, the non-keratinizing buccal mucosa generally respond ed more weakly than the orthokeratotic epidermis to culture-medium sup plementation favouring differentiation. Gene expression in cultured ke ratinocytes reflected their ability to differentiate in vivo; genes we re expressed even when the corresponding protein was not seen in vitro . Although keratin K10 is not prevalent in the buccal mucosa nor kerat in K13 in the epidermis, the genes for both were found to be expressed in both tissues.