Expression and Clinical Significance of Neuropilin-1 in Patients With Multiple Myeloma

BACKGROUND: Neuropilin-1 (NRP1) is a receptor for vascular endothelial growth factor A (VEGFA), and has been reported to be overexpressed in several malignancies. Since angiogenesis plays an important role in pathogenesis of multiple myeloma (MM) and the role of NRP1 in MM has not been studied yet, we characterized the expression of NRP1 in this disease. MATERIALS AND METHODS: The expression level of NRP1 was measured in 140 patients newly diagnosed with MM and 28 healthy controls by flow cytometry and quantitative reverse transcriptase polymerase chain reaction. RESULTS: Expression of NRP1 was significantly reduced on plasma cells (median=2.05%) compared to that on B-cells (median=10.05%, p<0.0001) in bone marrow of patients with MM. In MM, the expression of NRP1 was high on plasmacytoid dendritic cells (median=85.85%) and low on regulatory T-cells (median=0.6%). CONCLUSION: In MM, NRP1 is regulated differentially as compared to other B-cell malignancies at both the RNA and protein level.