Overexpression of S-adenosylhomocysteine hydrolase and down-regulation of prohibitin and c-Myc binding protein in the human esophageal squamous cell line HEEC exposed to N-nitrosomethylbenzylamine

Abstract

Numerous studies have shown that N-nitrosamines and their precursors are probable etiological factors for esophageal cancer. Certain N-nitrosamines have been shown to induce esophageal cancer in animal models. However, the molecular mechanisms by which N-nitrosamines promote esophageal carcinogenesis remain poorly understood. In this study, we compared the protein expression profiles of the human esophageal squamous cell line HEEC before and after treatment with various concentrations of N-nitrosomethylbenzylamine (NMBA). There were no marked changes in protein expression in HEEC cells exposed to 2 or 10 µg/ml NMBA. Twenty-eight differentially expressed protein spots were identified in HEEC cells exposed to 50 µg/ml NMBA. Two tumor suppressor proteins, prohibitin and c-Myc binding protein, were found to be down-regulated in NMBA-treated HEEC cells. S-adenosylhomocysteine hydrolase, a regulator of biological methylation, was found to be up-regulated in NMBA-treated HEEC cells. These findings may contribute to the further study of the molecular mechanism by which N-nitrosamines promote esophageal carcinogenesis.