Abstract 4414: Neuropilin2 is a novel target gene of Wnt signaling pathway regulating angiogenesis, metastasis and growth of osteosarcoma

Abstract

Abstract Objective: Multivascularity of osteosarcoma (OS) rendered the anti-angiogenesis is a promising therapeutics. Neuropilin 2 (NRP2), a coreceptor of vascular endothelial growth factor (VEGF), has been implicated in tumor angiogenesis, growth, and metastasis of many cancers. Its act in osteosarcoma still remains poorly understood. In order to explore the role of NRP2 in modulating tumor growth, angiogenesis, invasion, and lung metastasis of osteosarcoma, we conduct the current study. Methods: Cell culture, RNA interference, stable transfection, real time PCR, western blot, motility and invasion assay, in vivo tumorigenesis model, tube formation assay, ChIP. Results: By microtissue array assay, the expression of NRP2 is implicated in metastasis and poor prognosis of osteosarcoma patients. The in vitro data showed NRP2 knockdown has an inhibitory effect on OS tumor cell growth, both anchoragedependent and anchorageindependent way. Xenograft model showed silencing of NRP2 expression in OS cells has an extraordinary inhibitory effect. Both migration and invasion were significantly impaired in two NRP2 knockdown OS cell lines in vitro. Again, a lung metastasis mice model was used to verify the antimetastasis effect after NRP2 silencing and the results showed metastasis was inhibited. The blood vessels and capillaries in the xenograft samples were evaluated by immunohistochemistry staining for CD31. The capillaries in NRP2 knockdown tumors were rarely seen compared with the intact capillaries in control tumors. In order to explore the mechanism underlying the anti angiogenesis effect, we conducted the coculture of tumor cells and HUVEC cells in both contact and noncontact way. The ability of recruiting HUVEC cells by OS cells were dramatically inhibited by NRP2 knockdown. Also NRP2 silencing caused the tumor cells to behave less involved in tube formation. ChIP assay revealed TCF4, wnt effector, bound all the five binding sites in NRP2 promoter region. Conclusion: We demonstrated that NRP2 plays an important role in modulating tumor growth, angiogenesis, invasion, and lung metastasis of osteosarcoma. Citation Format: Tao Ji, Yi Guo, Carol Lin, Cheng-Fong Chen, Xiaolin Zi, Bang H. Hoang. Neuropilin2 is a novel target gene of Wnt signaling pathway regulating angiogenesis, metastasis and growth of osteosarcoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4414. doi:10.1158/1538-7445.AM2014-4414