The differential roles of Slit2-exon 15 splicing variants in angiogenesis and HUVEC permeability

• Published in: Angiogenesis (London) Vol. 18; no. 3; pp. 301 - 312
• Main Authors: Yang, Yun-Chiu, Chen, Pei-Ni, Wang, Siou-Yu, Liao, Chen-Yi, Lin, Yu-Ying, Sun, Shih-Rhong, Chiu, Chun-Ling, Hsieh, Yih-Shou, Shieh, Jia-Ching, Chang, Jinghua Tsai
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.07.2015; Springer Nature B.V
• Subjects: Alternative Splicing; Animals; Biomedical and Life Sciences; Biomedicine; Cancer Research; Cardiology; Cell Biology; Cell Movement; Chick Embryo; Chorioallantoic Membrane - metabolism; Culture Media, Conditioned; Exons; Human Umbilical Vein Endothelial Cells; Humans; Intercellular Signaling Peptides and Proteins - genetics; Intercellular Signaling Peptides and Proteins - metabolism; Neovascularization, Pathologic; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Oncology; Ophthalmology; Original Paper; Permeability; Receptors, Cell Surface - metabolism; Receptors, Immunologic - metabolism; Roundabout Proteins; Signal Transduction; Robo1; Angiogenesis; Human umbilical vein endothelial cells; Chicken chorioallantoic membrane assay; Tube formation; Slit2 splicing variants; Permeability; Robo4
• ISSN: 0969-6970; 1573-7209; 1573-7209
• DOI: 10.1007/s10456-015-9467-4

Slit2, a secreted glycoprotein, is down-regulated in many cancers. Slit2/Robo signaling pathway plays an important, but controversial, role in angiogenesis. We identified splicing variants of Slit2 at exon 15, Slit2-WT and Slit2-ΔE15, with differential effects on proliferation and invasive capability of lung cancer cells. The aim of this study was to elucidate the differential roles of these exon 15 splicing variants in angiogenesis. Our results revealed that both Slit2-WT and Slit2-ΔE15 inhibit motility of human umbilical vein endothelial cells (HUVECs). The conditioned medium (CM) collected from CL1-5/VC or CL1-5/Slit2-WT lung adenocarcinoma cells blocked HUVEC tube formation and angiogenesis on chorioallantoic membrane (CAM) assay when compared with untreated HUVECs and CAM, respectively. However, CM of CL1-5/Slit2-ΔE15 restored the quality of tubes and the size of vessels. Although both Slit2-WT and Slit2-ΔE15 inhibited permeability induced by CM of cancer cells, Slit2-ΔE15 exhibited stronger effect. These results suggested that Slit2-ΔE15 plays important roles in normalization of blood vessels by enhancing tube quality and tightening endothelial cells, while Slit2-WT only enhances tightening of endothelial cells. It appears that Robo4 is responsible for Slit2 isoform-mediated inhibition of permeability, while neither Robo1 nor Robo4 is required for Slit2-ΔE15-enhanced tube quality. The results of this study suggest that Slit2-ΔE15 splicing form is a promising molecule for normalizing blood vessels around a tumor, which, in turn, may increase efficacy of chemotherapy and radiotherapy.