SITE-SPECIFIC COMPARISON OF P53 IMMUNOSTAINING IN SQUAMOUS-CELL CARCINOMAS

The p53 tamer suppressor gene is believed to be the most commonly muta ted gene in human cancer, p53 is thought to function as a negative reg ulator of the cell cycle, arresting cells in the G1 phase, This study examined the effects of different mutagenic environments on the incide nce of p53 overexpression in squamous cell carcinomas (SCCs) from sun exposed and non-sun exposed squamous epithelium, An immunohistochemica l analysis was undertaken in an attempt to assay SSC for p53 overexpre ssion, an indirect measure of missense mutant p53. Positive nuclear st aining for p53 was observed in 14 of 21 sun exposed SCCs, two of 19 vu lvar/perianal SCCs, and 15 of 20 oral cavity SCCs. The number of posit ive anogenital tumors was low compared with that of both sun exposed ( chi-squared, 1 df, P = .0004) and oral (chi-squared, 1 df, P < .0001) sites. It was concluded that p53 protein accumulation is common in sun -exposed cutaneous SCC and oral SCC compared with anogenital SCC, and thus it is hypothesized that the nature of the mutagenic environment i n which SCC develops directly affects the incidence of immunohistochem ically detectable p53-positive cells. Copyright (C) 1995 by W.B. Saund ers Company