Kaas. Warnakulasuriya et al., RELATIONSHIP OF P53 OVEREXPRESSION TO OTHER CELL-CYCLE REGULATORY PROTEINS IN ORAL SQUAMOUS-CELL CARCINOMA, Journal of oral pathology & medicine, 27(8), 1998, pp. 376-381
Aberrations of the p53 gene and the overexpression of its protein are
described in a variety of neoplasms, including oral and other head and
neck cancers. Here we report the association of p53 (over)expression
with a downstream cell cycle inhibitor p21/waf1 in oral squamous cell
carcinoma (SCC). The loss of expression of p16 and p27, two other cycl
in-dependent kinase (cdk) inhibitors, was also examined. In this panel
of tumours, 10/24 carcinomas were p53-immunopositive. Heterogeneous e
xpression of p21 and p27 was seen in 10/24 SCC and 9/16 SCC, respectiv
ely, and this was not correlated to p53 status. The expression of p21
and p27 in these SCCs suggests the existence of mechanisms by which so
me growing tumour cells may tolerate these cell cycle inhibitors; eigh
t SCCs lacked expression of both inhibitors but only two of these canc
ers overexpressed p53, suggesting that accumulation of p21/p27 can be
independent of the functional status of the p53 gene. Data do not supp
ort a clear example of a phenotype that shows an overexpression of p53
with downregulation of p21 or p27 leading to cell cycle alterations.
Furthermore, only three SCCs were p16-negative and p53-positive. This
suggests that these two tumour suppressors may act in separate pathway
s.