LAMININ RECEPTOR EXPRESSION AND FUNCTION IN SMALL-CELL LUNG-CARCINOMA

Interactions between tumor cells and laminin or other components of th e extracellular matrix are thought to play a role in tumor invasion an d metastasis. To analyze these interactions, we examined the expressio n of 5 types of laminin receptors on II cell lines derived from the hi ghly malignant and metastatic tumor small-cell lung cancer (SCLC). The integrins VLA-1, VLA-3, VLA-6 and the 67 KDa monomeric receptor were expressed at various levels, whereas the VLA-2 receptor was absent on the cell lines. Only one cell line expressed none of these laminin rec eptors. All cell lines co-expressed alpha(6) beta(1) (VLA-6) and the 6 7-kDa molecule, the only receptors specific for laminin. Analysis of t he ability of SCLC cells to bind radiolabeled laminin and to adhere to laminin substrata revealed a correlation between these 2 parameters a nd the expression of VLA-L and the 67-kDa monomeric receptor. Cell adh esion was mediated by alpha(6) beta(1), as indicated by inhibition of adhesion using an anti-VLA-6 monoclonal antibody (MAb). Both VLA-6 and the monomeric receptor were up-regulated in vitro by laminin. (C) 199 4 Wiley-Liss, Inc.