RESUMO
Integrin-mediated interactions with collagen IV and its domains were examined in a human neuroblastoma cell line (SK-N-SH). By adhesion assays we demonstrated that neuroblastoma cells bound to solid-phase intact collagen IV and synthetic cell-binding peptide HEP-III, derived from the collagenous part of the molecule, but not to the main noncollagenous NC1 domain or to the synthetic cell-binding peptide HEP-I, derived from this domain. Monoclonal antibodies against beta1, alpha3, and alpha(v)beta3 integrins resulted in inhibition of cell binding to collagenous substrates by 95, 30, and 35%, respectively. By flow cytometry and immunoblotting it was shown that culture of SK-N-SH cells on collagen IV resulted in alteration in the expression of major neuroblastoma cell integrins. Binding to collagen IV induced the expression and activation of matrix metalloproteinases A and B (MMP-2, MMP-9), with a concomitant increase at the protein level of tissue-specific inhibitors of metalloproteinases (TIMP-1, TIMP-2). Finally, the expression of MMP-2 was significantly up-regulated by anti-alpha3beta1 antibodies, whereas ligation of anti-alpha(v)beta3 antibodies resulted in a modest down-regulation of MMP-2. Our results indicate that the presence of collagen IV modulates the expression of integrins, which are used for binding to this glycoprotein, and MMP-2 secreted by SK-N-SH cells.
