title: Prognostic value and in vitro biological relevance of Neuropilin 1 and Neuropilin 2 in osteosarcoma.
abstract: Neoadjuvant chemotherapy in osteosarcoma increased the long-term survival of patients with localized disease considerably but metastasizing osteosarcoma remained largely treatment resistant. Neuropilins, transmembrane glycoproteins, are important receptors for VEGF dependent hyper-vascularization in tumor angiogenesis and their aberrant expression promotes tumorigenesis and metastasis in many solid tumors. Our analysis of Neuropilin-1 (NRP1) and Neuropilin-2 (NRP2) immunostaining in a tissue microarray of 66 osteosarcoma patients identified NRP2 as an indicator of poor overall, metastasis-free and progression free survival while NRP1 had no predictive value. Patients with tumors that expressed NRP2 in the absence of NRP1 had a significantly worse prognosis than NRP1(-)/NRP2(-), NRP1(+) or NRP1(+)/NRP2(+) tumors. Moreover, patients with overt metastases and with NRP2-positive primary tumors had a significantly shorter survival rate than patients with metastases but NRP2-negative tumors. Furthermore, the expression of both NRP1 and NRP2 in osteosarcoma cell lines correlated to a variable degree with the metastatic potential of the respective cell line. To address the functional relevance of Neuropilins for VEGF signaling we used shRNA mediated down-regulation and blocking antibodies of NRP1 and NRP2 in the metastatic 143B and HuO9-M132 cell lines. In 143B cells, VEGFA signaling monitored by AKT phosphorylation was more inhibited by blocking of NRP1, whereas in HuO9-M132 cells NRP2 blocking was more effective indicating that NRP1 and NRP2 can substitute each other in the functional interaction with VEGFR1. Altogether, these data point to NRP2 as a powerful prognostic marker in osteosarcoma and together with NRP1 as a novel target for tumor-suppressive therapy.
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Boro
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Matthias Je
authors.initials: MJ
authors.lastname: Arlt
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Harald
authors.initials: H
authors.lastname: Lengnick
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Robl
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Maren
authors.initials: M
authors.lastname: Husmann
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Josefine
authors.initials: J
authors.lastname: Bertz
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Walter
authors.initials: W
authors.lastname: Born
authors.affiliation: Laboratory for Orthopedic Research, Department of Orthopedics, Balgrist University Hospital, University of Zurich Forchstrasse 340, 8008 Zurich, Switzerland.
authors.forename: Bruno
authors.initials: B
authors.lastname: Fuchs
keywords: Neuropilin; Osteosarcoma; VEGF; tissue microarray