.slit2/robo1 Function In Tumor Angiogenesis And Robo1 Function In The Transformation Process Of Normal Cells To Tumor Cells

Slit is a known secreted neuron guidance cue, and functions as the chemorepellent in axon guidance and neuronal migration, and as an inhibitor in leukocyte chemotaxis. Here our experiments showed Slit2 expressions in a large number of tumor cell lines and its receptor Robo1 expressions in human embryonic vein endothelial cells. Recombinant Slit2 protein attracted endothelial cells migration and promoted tube formation in a Robo1- and phosphatidylinositol kinase-dependent manner. In CAM assay, anti-Robo1 function-blocking mAb could inhibit capillary formation in the chicken allantoic membrane. In nude mice Xenograft assay, we found the tumor induced by Slit2/A375 cells, which overexpressed Slit2 protein, grew much faster, burdened more microvessel and bigger tumor mass than the control v/A375 cells. Both RoboN(Robo1 extracellular region) and anti-Robo1 function-blocking mAb could slower the growth rate of tumor induced by A375 cells, decrease the microvessel density and the tumor mass. All these findings demonstrate the angiogentic role of Slit2/Robo1 signal pathway in tumor and associated positive effect on tumor growth. In the research of Slit2/Robo1 signal-pathway, we also found Filamin-A, a cytoskeleton protein, and binding to Robo1 CC3 domain, had the possibility to take part in the signal-pathway downstream of Slit2/Robo1.Robo1 overexpression in human embryonic kidney 293 cell line could change the cell shape, increase the proliferation and migration ability of cell in vitro, and also induce normal cells transformation to tumor cells through down-regulation of E-cadherin. Robo1/293 cells could promote tumor and metastasis in lung and liver in null mice, which reveals the importance of Robo1 on cells transformation in the tumor progression.