Diminished expression of integrin adhesion molecules

Integrins are transmembrane molecules that mediate celi-celi and cell-substratum adhesion. Because alterations in the adhesive properties oftumour cells are thought to influence tumour cell invasion, the expression of integrin a and j3 chains in 19 human colorectal carcinomas, eight adenomas, and eight normal colon tissues was examined immunohistochemically using an indirect immunofluorescent technique. Normal colonic epithelial celis were found to express the integrin a3, as, a6, 1 , and 4 chains, whereas the a2 chain was expressed only on epithelial cells lining the base of the crypts and was absent from cells lining the mouth of the crypts or the surface epithelium. No epithelial staining of the ac, a4, 12, and 13 chains was observed. A progressive reduction of all normally expressed a and 1B chains was associated with increasing neoplastic transformation. The expression of the a3 and a5 chains was already noticeably reduced in adenomas, and was completely absent in most colonic carcinomas. In contrast, a6, P3I, and 4 expression was maintained in adenomas, whereas the transformation from benign to malignant neoplasms associated with infiltrative growth was characterised by diminished or lost expression of a6, 1I, and 1 chains. Thus, the decreased expression of integrins in human colon carcinomas may contribute to the altered adhesion and migration properties of these