Melanoma antigen genes 1 and 2 are differentially expressed in human gastric and cardial carcinomas

MAGE genes encode for tumor-rejection antigens and are expressed in tumors of different histologic types but not in normal tissues, with the exception of testis and placenta. The aim of this study was to evaluate the frequency of MAGE-1 and -2 expression in gastric and in cardial carcinomas; these conditions have been described as two distinct diseases, having different etiologies, epidemiologic patterns, and gene mutations.

Two groups of patients were studied: patients with distal gastric carcinoma and patients with carcinoma of the cardia. A group of patients with intestinal metaplasia in the gastric mucosa and controls were also included. All of them underwent upper GI endoscopy. Paired biopsy specimens were taken for routine histology and for RNA extraction, to study the expression of MAGE-1 and -2 genes.

None of the intestinal metaplastic samples or controls expressed MAGE-1 and -2 at detectable levels. Whereas 40% of the gastric cancer patients expressed either MAGE-1 or -2, 26.6% transcribed both. In the cardial cancer group, 20% of the cases expressed at least one MAGE, and only 6.6% expressed both genes. These results might reinforce the concept that cancer of the cardia is a distinct neoplastic disease with regard to esophageal and gastric (distal) carcinomas.

Here we show that MAGE gene expression occurs in advanced stages of gastric and cardial cancer and therefore appears to be a late event. This might point to a reconsideration of their potential role in cancer immunotherapy.