Somatic alterations of the DPC4 gene in human colorectal cancers in vivo.

Abstract

The chromosome region 18q21 has been shown to be frequently deleted in colorectal cancers, and such frequent allelic loss is a hallmark of the presence of a tumor-suppressor gene. The DPC4 gene, which is located at 18q21, has been identified as a tumor-suppressor gene from examination of pancreatic cancers. The aim of the present study was to determine if it might also be altered in colorectal cancers. Mutation analyses of the DPC4 gene were performed on complementary DNA samples from 31 primary colorectal cancer specimens using a combination of polymerase chain reaction, single-strand conformation polymorphism, and DNA sequencing. Four missense mutations producing amino acid substitutions and a somatic 12-base pair deletion in the coding region of the DPC4 gene were detected in the 31 cancers (16%; 5 of 31). The DPC4 gene may play a role as a tumor-suppressor gene in a fraction of colorectal cancers; however, while allelic loss at 18q21 is very often seen in colorectal cancers, only a minority show DPC4 mutations, suggesting that there might be another tumor-suppressor gene in this chromosome region.