Differential expression of c-myc and H-ras oncogenes in Barrett's epithelium. A study using colorimetric in situ hybridization.

To determine the role of c-myc and H-ras in progressive, dysplastic Barrett's mucosa (BM), and the usefulness of these oncogenes as markers for dysplastic lesions at high risk for malignant transformation, sequential formaldehyde solution-fixed, paraffin-embedded biopsy specimens that were obtained from 12 patients with BM were evaluated by in situ hybridization with the use of biotinylated complimentary DNA probes. Nine of the patients were taken from a previous prospective study. Four of these nine patients had dysplasia, and adenocarcinoma had developed in two of them; five had nondysplastic BM only. Two additional patients had adenocarcinoma, but their initial biopsy specimens had revealed dysplasia. One additional patient had intermediate-grade dysplasia. The intensity of oncogene expression was quantified by computerized color-image analysis. Enhanced c-myc expression of approximately equal intensity was consistently observed in all grades of dysplasia and carcinoma. H-ras was also consistently expressed in higher grades of dysplasia and carcinoma but not in low-grade dysplasia. Neither c-myc nor H-ras expression was detected in nondysplastic BM. The expression of H-ras in dysplastic BM appears to be a helpful marker for identifying which dysplastic lesions will progress to carcinoma.