Bagci T, Wu J K, Pfannl R, Ilag L L, Jay D G
Department of Neuroscience, Tufts University School of Medicine, Boston, MA 2111, USA.
Oncogene. 2009 Oct 8;28(40):3537-50. doi: 10.1038/onc.2009.204. Epub 2009 Aug 17.
Glioblastoma multiforme (GBM) is the most malignant glioma type with diffuse borders due to extensive tumor cell infiltration. Therefore, understanding the mechanism of GBM cell dispersal is critical for developing effective therapies to limit infiltration. We identified neuropilin-1 as a mediator of cancer cell invasion by a functional proteomic screen and showed its role in GBM cells. Neuropilin-1 is a receptor for semaphorin3A (Sema3A), a secreted chemorepellent that facilitates axon guidance during neural development. Although neuropilin-1 expression in GBMs was previously shown, its role as a Sema3A receptor remained elusive. Using fluorophore-assisted light inactivation and RNA interference , we showed that neuropilin-1 is required for GBM cell migration. We also showed that GBM cells secrete Sema3A endogenously, and RNA interference-mediated downregulation of Sema3A inhibits migration and alters cell morphology that is dependent on Rac1 activity. Sema3A depletion also reduces dispersal, which is recovered by supplying Sema3A exogenously. Extracellular application of Sema3A decreases cell-substrate adhesion in a neuropilin-1-dependent manner. Using immunohistochemistry, we showed that Sema3A is overexpressed in a subset of human GBMs compared with the non-neoplastic brain. Together, these findings implicate Sema3A as an autocrine signal for neuropilin-1 to promote GBM dispersal by modulating substrate adhesion and suggest that targeting Sema3A-neuropilin-1 signaling may limit GBM infiltration.
多形性胶质母细胞瘤（GBM）是最恶性的胶质瘤类型，由于肿瘤细胞广泛浸润，边界呈弥漫性。因此，了解GBM细胞扩散的机制对于开发限制浸润的有效疗法至关重要。我们通过功能蛋白质组学筛选确定神经纤毛蛋白-1为癌细胞侵袭的介质，并展示了其在GBM细胞中的作用。神经纤毛蛋白-1是信号素3A（Sema3A）的受体，Sema3A是一种分泌型化学排斥因子，在神经发育过程中促进轴突导向。尽管先前已显示GBM中神经纤毛蛋白-1的表达，但其作为Sema3A受体的作用仍不清楚。使用荧光团辅助光灭活和RNA干扰，我们表明神经纤毛蛋白-1是GBM细胞迁移所必需的。我们还表明GBM细胞内源性分泌Sema3A，RNA干扰介导的Sema3A下调抑制迁移并改变依赖于Rac1活性的细胞形态。Sema3A的缺失也减少了扩散，通过外源性提供Sema3A可恢复。细胞外应用Sema3A以神经纤毛蛋白-1依赖的方式降低细胞与底物的粘附。使用免疫组织化学，我们表明与非肿瘤性脑相比，Sema3A在一部分人类GBM中过表达。总之，这些发现表明Sema3A作为神经纤毛蛋白-1的自分泌信号，通过调节底物粘附促进GBM扩散，并表明靶向Sema3A-神经纤毛蛋白-1信号传导可能限制GBM浸润。
