 
         
         Summary
         
         The expression/function of vascular endothelial growth factor (VEGF) and its receptor
            2 (VEGFR-2/KDR) in multiple myeloma (MM)-associated angiogenesis is under scrutiny.
            We show here that bone marrow endothelial cells (EC) from 16 patients with MM (MMEC)
            highly expressed VEGF-A (the main VEGF isoform) and VEGFR-2 at both mRNA and protein
            level, whereas EC from 14 patients with monoclonal gammopathy unassociated/unattributable
            (MG[u]) (MG[u]EC) and 12 human umbilical veins (HUVEC) expressed very low mRNAs and/or
            proteins. MMEC showed constitutive autophosphorylation in both VEGFR-2 and the associated
            extracellular signal-regulated kinase-2 (ERK-2), whereas this was marginal in MG[u]EC
            and HUVEC. MMEC proliferated rapidly and formed a closely-knit capillary meshwork
            on Matrigel. These cell functions were reduced in the other EC. Autophosphorylation,
            proliferation and capillarogenesis were prevented by a neutralizing antiVEGF-A antibody,
            and more efficaciously by an anti-VEGFR-2 antibody. Both antibodies had no effect
            or were poorly effective on the other EC. These findings as a whole suggest the existence
            of an autocrine loop of VEGF in MMEC. Since this is very likely a mechanism for the
            amplification of VEGF activity in neovascularization, it would constitute an appropriate
            target for antiangiogenic management in MM.
         
         Keywords
Angiogenesis - autocrine growth - endothelial cells - multiple myeloma - VEGF