Knockdown of neuropilin-1 suppresses invasion, angiogenesis, and increases the chemosensitivity to doxorubicin in osteosarcoma cells - an in vitro study.

OBJECTIVES: Neuropilin-1 (NRP- 1) is a novel co-receptor for vascular endothelial growth factor (VEGF). NRP-1 expression in os - teosarcoma tissues was significantly higher, and high NRP-1 expression was more frequently oc - curred in osteosarcoma tissues with advanced clinical stage, positive distant metastasis and poor response to chemotherapy. We tested a hy - pothesis that the NRP-1 gene plays a role in the invasiveness, angiogenesis and chemoresis - tance of human OS. MATERIALS AND METHODS: To determine the role of NRP-1 in OS, NRP-1 was stably transfected into the human OS cell line MG-63 to increase the NPR-1 level, and NRP-1 siRNA was stably transfected into the human OS cell line SaOS-2 to knockdown of NRP-1. The effect of NRP-1 on invasion and angiogenesis was as - sessed by Matrigel invasion assay and in vitro angiogenesis assay. Chemosensitivity to dox - orubicin was assessed by MTT assay in the MG-63 and SaOS-2 cells following NRP-1 over - ex pression or siRNA-induced downregulation of NRP-1. RESULTS: The NRP-1 transfected MG-63 cells showed a markedly higher level of invasion in Matrigel invasion assay. The capillary-like struc - ture formation of endothelial cells was also in - creased by coculture with the NRP-1 transfected MG-63 cells. On the contrary, the NRP-1 siRNA transfected SaOS-2 cells showed a markedly lower level of invasion in Matrigel invasion as - say. The capillary-like structure formation of en - dothelial cells was also repressed by coculture with the NRP-1 siRNA transfected SaOS-2 cells. NRP-1 overexpression in MG-63 cells increased survival of cells after exposure to doxorubicin. In contrast, downregulation of NRP-1 expression in SaOS-2 cells markedly increased chemosensitiv - ity after exposure to doxorubicin. CONCLUSIONS: We suggest that NRP-1 could be used as a biomarker for OS progression and a novel therapeutic or chemopreventive target for human OS treatment.