title: The differential roles of Slit2-exon 15 splicing variants in angiogenesis and HUVEC permeability.
abstract: 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.
authors.affiliation: Department of Pulmonary Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung, Taiwan, ROC.
authors.forename: Yun-Chiu
authors.initials: YC
authors.lastname: Yang
authors.forename: Pei-Ni
authors.initials: PN
authors.lastname: Chen
authors.forename: Siou-Yu
authors.initials: SY
authors.lastname: Wang
authors.forename: Chen-Yi
authors.initials: CY
authors.lastname: Liao
authors.forename: Yu-Ying
authors.initials: YY
authors.lastname: Lin
authors.forename: Shih-Rhong
authors.initials: SR
authors.lastname: Sun
authors.forename: Chun-Ling
authors.initials: CL
authors.lastname: Chiu
authors.forename: Yih-Shou
authors.initials: YS
authors.lastname: Hsieh
authors.forename: Jia-Ching
authors.initials: JC
authors.lastname: Shieh
authors.forename: Jinghua Tsai
authors.initials: JT
authors.lastname: Chang
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D002465:Cell Movement; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000378:metabolism; D017077:Culture Media, Conditioned; D005091:Exons; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D009389:Neovascularization, Pathologic; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D010539:Permeability; D011956:Receptors, Cell Surface / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism; D015398:Signal Transduction; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D017077:Culture Media, Conditioned; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C462951:ROBO4 protein, human