Growth pattern and expressions of cell cycle regulator proteins p53 and p21 WAF1/CIP1 in early gastric carcinoma

BACKGROUND. The growth pattern of early gastric carcinoma, as based on a vo lumetric analysis, reflects the biologic characteristics of a tumor. The pe netrating growth (Pen) type tumor has an unfavorable prognosis, compared wi th the case of a superficially spreading (Super) type. The wild-type of the p53 protein plays an important role in cell growth regulation and apoptosi s. The p21 protein, which is encoded by the WAF1/CIP1 gene, is a downstream target effector of wild-type p53 protein, and these proteins act as tumor suppressors in a negative cell-cycle regulation. METHODS. In 133 Japanese patients with early gastric carcinoma with submuco sal invasion, expressions of p53 and p21 proteins were studied immunohistoc hemically, and the relation between growth pattern and expressions was anal yzed. RESULTS. Early gastric carcinomas were grouped into the superficially sprea ding (Super) type 40 (30.1%) cases, expansively penetrating growth (Pen-A) type 28 (21.1%), infiltratively penetrating growth (Pen-B) type 20 (15.0%), small mucosal type 35 (26.3%), and mixed type 10 (7.5%). The Pen-A type tu mors were characterized by the highest incidence of p53 expression and loss of p21 expression, and the rate of p53-positive and/or p21-negative cases was 71.4%. There were significant differences in the incidence of the p53 e xpression (50.0% vs. 25.0%), the loss of p21 expression (53.6% vs. 27.5%), and the 5-year survival rate (83.2% vs. 97.2%) between the Pen-A type and t he Super type. CONCLUSIONS. Thus, deregulation of the cell cycle by p53 and p21 in this st udy was shown to play an important role in progression of Pen-A type early gastric carcinoma. (C) 2001 American Cancer Society.