K-ras codon 12 mutations of the super-minute dysplasia in Barrett's esophagus by DNA extraction using a microdissection method.

The aim of this study was to clarify the histogenesis of Barrett's cancer. First, 28 lesions of the super-minute dysplasia <or= 1 mm in diameter were detected by pathological examinations for Barrett's esophagus. Secondly, the K-ras codon 12 mutations in these super-minute neoplasias of the Barrett's esophagus were examined by DNA extraction using a microdissection. It was found that seven of 28 (25%) super-minute dysplasia lesions in the Barrett's esophagus showed K-ras mutation, and were a single mutation, with AGT being detected in three lesions and GAT being detected in four lesions. Also, these dysplasia lesions could be divided into two groups according to p53-LI. Two among three lesions with p53-LI over 90%, which were considered to be morphologically high grade dysplasia or intramucosal adenocarcinoma, showed K-ras mutations (both lesions: GGT-->AGT), and 5 among 25 lesions with an average p53-LI of 58%, which were considered to be morphologically low grade dysplasia, showed K-ras mutation (four lesions: GGT-->GAT, 1 lesion: GGT-->AGT). This current study shows that some dysplasia lesions have K-ras mutations in their initial condition, whether these atypical tubule lesions are low grade dysplasia or high grade dysplasia (intramucosal adenocarcinoma), and supports the dysplasia-carcinoma sequence in the histogenesis of Barrett's cancer and synchronously suggests that there is a different route to it.