Interactions between
cancer cells and
laminin, a major component of basement membranes, play a critical role at several steps of the complex process of
tumor invasion and
metastasis. These interactions are mediated through a large variety of
cell surface proteins designated as
laminin receptors and/or
laminin-
binding proteins. The growing number of identified
laminin binding proteins and domains of this
glycoprotein that are biologically active illustrate the complexity of cellular interactions with
laminin. The 67-kD
laminin receptor (67 LR) was the first
protein identified in 1983 as a high-affinity
laminin receptor, and its expression is dramatically increased in a large variety of
cancer cells. The 67 LR is the subject of several controversies and
confusion generated mainly by two events. First, the identification of several new
laminin-
binding proteins has raised the difficult task of attributing specific functions to specific receptors in contrast to initial beliefs that all cellular
laminin-driven
biological activities were mediated through the 67 LR. The second source of controversy is the large molecular-weight discrepancy between the 37-kD
polypeptide encoded by the 67 LR
cDNA clone and the mature 67 LR. In this manuscript, a critical and extensive review of the data accumulated on the 67 LR is presented regarding both its molecular structure and its role during
tumor invasion and
metastasis. A hypothetical model of the 67 LR is also proposed. Since the first identification of the 67 LR, at least 14 other cell surface molecules have been reported to be potential
laminin receptors or
laminin-
binding proteins. These include members of the
beta-galactoside-binding lectin family, seven members of the
integrin family, the
galactosyltransferase and some not yet fully characterized cell surface molecules. These
laminin receptors and
laminin-
binding proteins are also described and their functions are also discussed with a particular emphasis on their participation in the constitution of the invasive phenotype.