ANALYSIS OF BCL-2 EXPRESSION IN NORMAL, INFLAMED, DYSPLASTIC NASOPHARYNGEAL EPITHELIA, AND NASOPHARYNGEAL CARCINOMA - ASSOCIATION WITH P53 EXPRESSION

To further characterize bcl-2 expression in nasopharyngeal carcinoma ( NPC), the authors analyzed bcl-2 expression immunohistochemically in b iopsy specimens from 101 cases of NPC, of which 65 had the component o f normal nasopharyngeal epithelium (NPE), 24 with dysplastic lesions a djacent to carcinoma, and 14 with both primary and metastatic lesions. An additional 25 nasopharyngeal biopsies of NPE from patients with ch ronic inflammation of nasopharynx were also included. The percentage o f detectable bcl-2 expression shown in NPC (80%) and adjacent dysplast ic lesions (71%) was significantly higher than in adjacent NPE (37%) a nd NPE from patients with chronic inflammation of the nasopharynx (30% ) (P < .05). In both normal and inflamed NPE, the detectable bcl-2 exp ression was restricted to the basal cells; however, in dysplastic lesi ons; the bcl-2 staining distribution was increased with the dysplastic cell layers, and in entire layers of epithelium in severe dysplasia o r carcinoma in situ. In addition, the staining intensity of bcl-2 in c arcinomas and adjacent dysplastic lesions was generally stronger than that of adjacent NPE. These observations suggest that the expression o f bcl-2 in dysplasia and carcinoma is enhanced relative to that of adj acent NPE, Enhanced bcl-2 expression to prevent apoptosis seems to occ ur from the early stages and may play an important role in the carcino genesis of NPC. Furthermore, up to 77% of NPC with the coexpression of bcl-2 and p53 was observed and suggested that the association of bcl- 2 and p53 expression seems to occur from the early stages of the devel opment of NPC. The overexpression of p53 protein in NPC suggests that the mutation of p53 gene or altered function of wild-type p53 protein map contribute to the pathogenesis. It is conceivable that the presenc e of both enhanced bcl-2 expression and altered p53 functions may play a crucial synergistic effect in the carcinogenesis of NPC. Copyright (C) 1997 by W.B. Saunders Company.