Growth pattern and expressions of cell cycle regulator proteins p53 and p21WAF1/CIP1 in early gastric carcinoma

BACKGROUND. The growth pattern of early gastric carcinoma, as based on a volumetric analysis, reflects the biologic characteristics of a tumor. The penetrating growth (Pen) type tumor has an unfavorable prognosis, compared with the case of a superficially spreading (Super) type. The wild-type of the p53 protein plays an important role in cell growth regulation and apoptosis. 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 submucosal invasion, expressions of p53 and p21 proteins were studied immunohistochemically, and the relation between growth pattern and expressions was analyzed. RESULTS. Early gastric carcinomas were grouped into the superficially spreading (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 tumors 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 expression (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 the Super type. CONCLUSIONS. Thus, deregulation of the cell cycle by p53 and p21 in this study was shown to play an important role in progression of Pen-A type early gastric carcinoma.