P53 has important regulatory functions in cell growth, differentiation and
apoptosis. Here we analyzed the effects of p53 on the growth response of or
al mucosal keratinocytes (OMKCs) using p53-deficient (p53-/-) mice. No morp
hological difference was found between p53-/- and wild-type (p53+/+) oral m
ucosa. In a long-term culture, p53-/- OMKCs continued to proliferate past t
he point at which p53 +/+ became senescent. The percentage of p53 -/- OMKCs
in the G(0)/G(1) phase was lower than that of p53 +/+ OMKCs. Proliferation
of cultured OMKCs induced by epidermal growth factor (EGF) and interleukin
(IL)-1 alpha was more strongly enhanced in p53-/- than in p53+/+ mice. Such
an enhanced response was not due to increased mRNA expression of growth fa
ctor receptors. These data suggest that p53 acts as a modulator of GI arres
t in OMKCs and is also involved in the regulation of responses to EGF and I
L-1 alpha without affecting the expression of their receptors.