IDENTIFICATION OF P53-GENE MUTATIONS IN GASTROINTESTINAL AND PANCREATIC CARCINOIDS BY NONRADIOISOTOPIC SSCA

A nonisotopic screening method based on single-strand DNA conformation analysis (SSCA) was established for the identification of p53 gene al terations in archived tissue samples. The sensitivity of this approach was validated by testing mutations previously identified by direct se quencing. Applying this assay, 40 samples of formalin-fixed, paraffin- embedded tumors, including 33 gastrointestinal carcinoids and seven en docrine pancreatic tumors, were screened. Only one mutation (codon 283 , CGC to CCC) was identified in a single clinically benign rectal carc inoid. This mutation occurred during the development of the tumor and was accompanied by loss of the wild-type gene. Our data indicate, that , in contrast to gastrointestinal carcinomas, alterations of the p53 g ene are infrequent events in the development of gastrointestinal and p ancreatic carcinoids. In addition, there was no evidence for the invol vement of p53 in the malignant metastatic progression of carcinoids.