IngentaConnect The involvement of osteopontin and its receptors in multiple myel...

Authors: Caers, Jo¹; Günthert, Ursula²; Raeve, Hendrik³; Valckenborgh, Els Van¹; Menu, Eline¹; Riet, Ivan Van¹; Camp, Benjamin Van¹; Vanderkerken, Karin¹

Source: British Journal of Haematology, Volume 132, Number 4, February 2006 , pp. 469-477(9)

Publisher: Blackwell Publishing

Abstract:

Multiple myeloma (MM) is a malignancy characterised by the accumulation of monoclonal plasma cells in the bone marrow. Different reports indicate the expression of CD44 variant isoforms (CD44v) by MM cells. Osteopontin (OPN), which is expressed by MM cells, is known to be a ligand for CD44v6. In this study, we investigated the role of OPN with emphasis on a functional correlation between OPN and CD44v in the 5T33MM model. Our group reported the expression of CD44v by 5T33MM cells. Using this model, we have demonstrated the secretion of OPN by 5T33MM cells. OPN affected 5T33MM cell survival by increasing proliferation and inhibiting apoptosis. OPN also stimulated 5T33MM cell migration, transendothelial migration and matrix metalloproteinase-9 activity. We confirmed the proliferative and migratory effects of OPN on human MM cells. By applying inhibiting anti-CD44v6 antibodies, we found that OPN stimulated cell proliferation by engaging this isoform. Anti-CD44v antibodies and RGD peptides both inhibited cell migration, suggesting an involvement of both, CD44v isoforms and integrins. In conclusion, OPN may act as a mediator of MM cell survival by engaging CD44v. The protein is further involved in migration and invasion of MM cells through the activation of either αvβ3 integrin or CD44v isoforms.

Keywords: multiple myeloma; osteopontin; CD44 variants; survival; invasion

Document Type: Research article

DOI: 10.1111/j.1365-2141.2005.05886.x

Affiliations: 1: Department of Haematology and Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium 2: Department Clinical and Biological Sciences, Institute for Medical Microbiology, University of Basel, Basel, Switzerland 3: Department of Pathology, University of Antwerp, Antwerp, Belgium

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The involvement of osteopontin and its receptors in multiple myeloma cell survival, migration and invasion in the murine 5T33MM model