Cell-matrix interactions contribute to regulating the adhesion, growth, migration, and differentiation of epithelial intestinal cells. Alterations in matrix components and their cellular receptors have been found in tumours but their specific roles remain unclear. The tissue patterns of
laminin-5 and alpha 3, beta 3 and gamma 2 subunits, as well as those of the alpha 3, alpha 6, beta 1, and beta 4
integrin chains, were determined by immunofluorescence on frozen sections of 12 colorectal mucosal samples from four patients, 15
adenomas, 29
adenocarcinomas, and eight
metastases. Distinct patterns of
laminin-5 and
integrin expression were found along the mucosa-
adenoma, and
adenoma-
carcinoma transitions. Expression of basement membrane
laminin-5 and subunits was continuous and gradient-like in normal mucosa, enhanced at the periphery of
adenomas, and discontinuous in places in
carcinomas and
metastases. Decrease of the
alpha 3 integrin chain was found in
adenomas, together with that of alpha 6 and beta 4 chains in
carcinomas. A subpopulation of
carcinoma cells dissociating (budding) from neoplastic tubules was found to accumulate the
laminin-5 beta 3 gamma 2 heterodimer in the cytoplasm, with progressive loss of surface
integrin expression. These results suggest that in
colorectal cancer, an abnormal expression of
laminin-5 subunits and
integrin chains may identify a subset of
carcinoma cells prone to invade focally and to contribute to disease aggressiveness.