[Mutation and expression of Rb gene in human esophageal cancer]

The mutation and expression of Rb gene in human esophageal cancer (EC) were investigated by PCR-direct sequencing and Northern blot hybridization. In PCR amplification analysis, in one of 20 (5%) cases of EC was found to have Rb gene deletion in exon 17 and 21; in one of 6 cases of the adjacent non-tumours tissue was found to have deletion in exon 21. Esophageal carcinoma of human fetus induced by NMBzA had Rb gene deletion in exon 17 and 21 too. In PCR-direct sequencing analysis, four of 10 (40%) EC were found to contain Rb gene mutations in exon 17 and 21. In northern blot analysis, seven of 12 (58.3%) EC exhibited abnormal Rb gene expression, including inactivation in 6 abbreviated expression in one. The results suggest that Rb tumor suppressor gene might play an important role in carcinogenesis of EC. The mechanisms of Rb gene mutation, deletion or abnormal expression related to carcinogenic nitrosamine in the environment need further study.