P53 PROTEIN ACCUMULATION IN ESOPHAGEAL SQUAMOUS-CELL CARCINOMAS AND PRECANCEROUS LESIONS

Aims-To investigate the immunohistochemical expression of p53 protein in oesophageal squamous cell carcinomas and in dysplastic areas of the oesophageal mucosa surrounding the tumours. Methods-Biopsy samples we re obtained from 20 patients with an oesophageal squamous cell carcino ma. Blocks of the tumours and of the surrounding mucosa were immunosta ined with the monoclonal antibody DO-7. Results-Fourteen of the 20 car cinomas were positive for p53 (70%). The frequency of p53 overexpressi on increased with the differentiation of the tumour. Nine out of 13 dy splastic specimens were positive for p53 (69%): eight cases with sever e dysplasia and one case with moderate dysplasia. No p53 immunostainin g was detected in normal oesophageal epithelium. All p53 positive dysp lastic specimens were taken from the mucosa adjacent to tumours that w ere also immunostained. In moderate dysplastic mucosa the p53 positive cells were located in the proliferative basal zone, whereas in severe dysplasia the immunostained cells increased in number and spread to u pper cell layers of the epithelium. Conclusion-This study supports the hypothesis that TP53 gene is frequently involved in the development o f oesophageal squamous cell carcinoma and that p53 protein accumulatio n is an early event in human oesophageal carcinogenesis.