Gene-environment interactions in the stomach: role of mucins in Helicobacter pylori adhesion to normal and metaplastic mucosa of the stomach

Abstract

L David, A Teixeira, C Reis, A Peixoto, F Carvalho, F Santos Silva, M Sobrinho-Simões Institute of Molecular Pathology and Immunology of the University of Porto – IPATIMUP, Rua Dr. Roberto Frias, 4200 Porto, Portugal. Correspondence to: L David. (+351) 22 5570 799. E-mail: [email protected] *This paper was an invited presentation at the 18 th Annual Symposium of European Cancer Prevention Organisation (ECP): Precancerous lesions of the digestive tract held in Maastricht, The Netherlands, 12–14 October, 2000 Mucins are glycoproteins of the mucous gel that protects mucosas from environmental aggressions. The core protein backbone of mucins is heavily O -glycosylated in the numerous serine or threonine residues. Activation of genes coding for the apomucin and for individual glycosyltransferases, with unique donor–substrate specificity, are responsible for the large diversity of the final end-product. Inter-individual diversity of mucins is determined by the polymorphic nature of mucin genes and by the ABO histo-blood group and secretor genes. Further intra-individual tissue-specific diversity is dependent upon the activation of different mucin and glycosyltransferase genes. Our group has recently explored two different approaches to the potential relationship between mucin constitution/expression and the outcome of Helicobacter pylori infection: a. The relationship between constitutional MUC1 mucin gene polymorphism and different lesions in the gastric carcinogenesis pathway. Our data show that individuals with a small number of tandem repeats, with smaller glycoprotein products, have an increased risk for the development of chronic atrophic gastritis, incomplete intestinal metaplasia and gastric carcinoma (Carvalho F (1997) Glycoconj J14: 107; Garcia E (1997) Cancer Epidemiol Biomarkers Prev6: 1071). b. The relationship between the pattern of mucin expression and H. pylori colonization of intestinal metaplasia. Our results show that H. pylori colonizes rare cases of incomplete intestinal metaplasia that do not express the intestinal mucin MUC2, thus suggesting that absence of MUC2 is a prerequisite for H. pylori adhesion to metaplastic mucosa (Reis CA (1999) Cancer Res59: 1003).