Abstract
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 α4β1 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 β1-integrin-binding partners that regulate β1-mediated cell adhesion. We show that talin and kindlin-3 cooperatively stimulate high affinity and strength of α4β1-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 α4β1. 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 α4β1 ligands showed higher susceptibility to bortezomib-mediated cell apoptosis. Our results highlight the requirement of α4β1 and selectins for the in vivo attachment of MM and CLL cells to the BM microvasculature, and indicate that talin, kindlin-3 and ICAP-1 differentially control physiological adhesion by regulating α4β1 activity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Animals
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Apoptosis
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Blotting, Western
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Bone Marrow / metabolism
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Bone Marrow / pathology*
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Cell Adhesion*
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Cell Movement
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Cell Proliferation
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Cytoplasm / metabolism
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E-Selectin / genetics
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E-Selectin / metabolism
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Endothelium, Vascular / metabolism
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Endothelium, Vascular / pathology*
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Flow Cytometry
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Humans
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Integrin alpha4beta1 / genetics
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Integrin alpha4beta1 / metabolism*
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism
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Intravital Microscopy
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Leukemia, Lymphocytic, Chronic, B-Cell / genetics
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Leukemia, Lymphocytic, Chronic, B-Cell / metabolism
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Leukemia, Lymphocytic, Chronic, B-Cell / pathology*
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Membrane Proteins / genetics
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Membrane Proteins / metabolism
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Mice
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Mice, Inbred NOD
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Mice, SCID
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Microvessels
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Multiple Myeloma / genetics
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Multiple Myeloma / metabolism
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Multiple Myeloma / pathology*
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism
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P-Selectin / genetics
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P-Selectin / metabolism
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RNA, Messenger / genetics
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Real-Time Polymerase Chain Reaction
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Reverse Transcriptase Polymerase Chain Reaction
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Talin / genetics
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Talin / metabolism
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Tumor Cells, Cultured
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Xenograft Model Antitumor Assays
Substances
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Adaptor Proteins, Signal Transducing
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E-Selectin
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FERMT3 protein, human
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ITGB1BP1 protein, human
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Integrin alpha4beta1
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Neoplasm Proteins
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P-Selectin
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RNA, Messenger
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SELE protein, human
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SELP protein, human
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TLN1 protein, human
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Talin