[Overexpression of p53 protein in human spontaneous esophageal carcinoma and fetal esophageal carcinoma induced by N-methyl-N-benzylnitrosamine (NMBzA)].

In normal cells, p53 protein is virtually undetectable by immunohistochemical methods. Mutation of p53 gene results in overexpression of the protein and thus levels of p53 detectable by immunohistochemistry may indicate expression of the mutant form of p53. Esophageal cancer (EC) samples obtained from patients who had undergone surgery were assayed for expression in p53 protein. Among 18 primary EC and their adjacent tissues, 7 cases of EC and 5 adjacent tissues overexpression of p53 protein was detected immunohistochemically. In cases with overexpression of the p53 in the adjacent tissues was detected 4 were also positive in the carcinomas. These results suggest that overexpression of p53 protein is a common molecular event in EC and may occur in the early stage of esophageal tumorigenesis. In addition, we found over expression of the p53 protein in the human fetal esophageal carcinoma induced by NMBzA, indicating that p53 gene mutation (s) might have occurred. The results provide further evidence that N-nitrosamine is a causative agent of human esophageal cancer.