Integrins and their extracellular matrix ligands in gastric cancer

Extracellular matrix (ECM) proteins and their specific cellular receptors, play an important role in the regulation of epithelial, morphogenesis and differentiation. Alterations in their expression and function have been found in a number of malignant tumours and these changes may help to explain their dedifferentiation and altered behaviour. this study we have investigated expression and distribution of the epithelial β1 integrins (α2β1, α3β1 and α6β1) and their ECM ligands (fibronectin, tenascin and laminin) in normal and neoplastic gastric tissue. An up-regulation of two isoforms of fibronectin, and tenascin was seen in tumour associated matrix compared to normal stroma. Loss or down regulation of a integrin chains was seen more frequently in poorly differentiated carcinomas (α2 p=0.002; α3 p=0.013; α(6 p=0.0012) irrespective of tumour type (diffuse or intestinal) than in well/moderately differentiated tumours. Cell adhesion assays revealed that the ability of gastric carcinoma cell lines to bind matrix glycoproteins correlated to their degree of differentiation. Furthermore, poorly differentiated cell lines showed a down-regulation of α2 and α6 integrin expression. These data indicate that architectural and cytological differentiation in gastric carcinoma relates to altered patterns of expression of matrix glycoproteins and their receptors. The traditional Lauren classification seems to reflect these differences in cell-matrix interactions. Differing patterns of expression of those molecules involved in cellmatrix interactions may prove to be a more objective and biologically more relevant means of classifying gastric cancer.