Bcl-2 Expression Is Correlated with Low Apoptotic Index and Associated with Histopathological Grading in Esophageal Squamous Cell Carcinomas

The aim of this study was to examine the relationship between apoptosis, protein expression of apoptosis mediator and inhibitor genes p53 and bcl-2 and various histopathological grades of squamous cell carcinoma of the esophagus. Apoptotic index was evaluated in thirty human esophageal squamous cell carcinomas and adjoining normal tissue by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL). Protein expression of bcl-2 and p53 was measured by immunohistochemical staining of cryocut sections and Western blotting. Apoptototic cells were seen mainly around areas of keratinization and the apoptotic index was highest in well-differentiated squamous cell carcinomas. High Bcl-2 expression correlated inversely with the apoptotic index. p53 protein expression did not correlate with the grade of the tumor or the apoptotic index. We propose that deregulation of apoptosis contributes to the pathogenesis of esophageal squamous cell carcinoma.