In vivoadhesion of malignant B cells to bone marrow microvasculature is regulated by a4ß1 cytoplasmic-binding proteins

Autor: Martínez-Moreno, M, Leiva, M, Aguilera-Montilla, N, Sevilla-Movilla, S, Isern de Val, S, Arellano-Sánchez, N, Gutiérrez, N C, Maldonado, R, Martínez-López, J, Buño, I, García-Marco, J A, Sánchez-Mateos, P, Hidalgo, A, García-Pardo, A, Teixidó, J
Zdroj: Leukemia; April 2016, Vol. 30 Issue: 4 p861-872, 12p
Abstrakt: Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) cells must attach to the bone marrow (BM) microvasculature before lodging in the BM microenvironment. Using intravital microscopy (IVM) of the BM calvariae we demonstrate that the a4ß1 integrin is required for MM and CLL cell firm arrest onto the BM microvasculature, while endothelial P-selectin and E-selectin mediate cell rolling. Talin, kindlin-3 and ICAP-1 are ß1-integrin-binding partners that regulate ß1-mediated cell adhesion. We show that talin and kindlin-3 cooperatively stimulate high affinity and strength of a4ß1-dependent MM and CLL cell attachment, whereas ICAP-1 negatively regulates this adhesion. A functional connection between talin/kindlin-3 and Rac1 was found to be required for MM cell attachment mediated by a4ß1. Importantly, IVM analyses with talin- and kindlin-3-silenced MM cells indicate that these proteins are needed for cell arrest on the BM microvasculature. Instead, MM cell arrest is repressed by ICAP-1. Moreover, MM cells silenced for talin and kindlin-3, and cultured on a4ß1 ligands showed higher susceptibility to bortezomib-mediated cell apoptosis. Our results highlight the requirement of a4ß1 and selectins for the in vivoattachment of MM and CLL cells to the BM microvasculature, and indicate that talin, kindlin-3 and ICAP-1 differentially control physiological adhesion by regulating a4ß1 activity.
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