Frequent K‐<i>ras</i> mutations and absence of p53 mutations in mucin‐producing tumors of the pancreas

Abstract

Mucin-producing tumors of the pancreas (MPT) are characterized by the production of much mucin and a benign course after surgical treatment. We examined 16 cases of MPT and 20 cases of "common" pancreatic duct cell carcinomas (DCC) in regard to K-ras and p53 mutations. The mutations were detected by constant denaturant gel electrophoresis in combination with other techniques using PCR products amplified from the samples microdissected from the tissue sections. K-ras codon 12 mutations were identified in all MPT and in 95% of DCC. On the other hand, p53 mutations were found in four of 20 (20%) DCC, and p53 was immunocytochemically overexpressed in 3 of the 4 mutated cases. However, no p53 mutations and no p53 overexpression were identified in the 16 MPT. These results indicate that, although the K-ras codon 12 mutations may be almost essential for the development of both MPT and DCC, p53 mutations seemed to be involved mainly to the latters.