Identification of beta1 integrin as mediator of melanoma cell adhesion to lumican.

Lumican is a small leucine-rich proteoglycan (SLRP) present in the dermal extracellular matrix. Previous data from our laboratory demonstrated that lumican decreases melanoma progression in vivo. Here, we show that melanoma cell migration is decreased by lumican and that this effect is due to an enhanced cell adhesion. The adhesion of A375 human melanoma cells on lumican was dose-dependent and required Mg2+ and Mn2+ divalent cations. Using a panel of monoclonal antibodies directed against integrin subunits, we showed that A375 cells can bind to recombinant lumican through beta1 type integrins. Moreover, the use of rhodocetin, an inhibitor of alpha2 integrin, suggested that this particular subunit might also be involved in the interaction with lumican. The increased beta1 integrin-mediated adhesion of melanoma cells to lumican might explain, at least in part, the anti-invasive effect of this SLRP.