title: Endothelial deletion of Sag/Rbx2/Roc2 E3 ubiquitin ligase causes embryonic lethality and blocks tumor angiogenesis.
abstract: SAG (Sensitive to Apoptosis Gene), also known as RBX2 or ROC2, is a RING protein required for the activity of Cullin-RING ligase (CRL). Our recent study showed that Sag total knockout caused embryonic lethality at E11.5-12.5 days with associated defects in vasculogenesis. Whether Sag is required for de novo vasculogenesis in embryos and angiogenesis in tumors is totally unknown. Here, we report that Sag endothelial deletion also causes embryonic lethality at E15.5 with poor vasculogenesis. Sag deletion in primary endothelial cells (ECs) or knockdown in MS-1 ECs inhibits migration, proliferation and tube formation, with p27 accumulation being responsible for the suppression of migration and proliferation. Furthermore, Sag deletion significantly inhibits angiogenesis in an in vivo Matrigel plug assay, and tumor angiogenesis and tumorigenesis in a B16F10 melanoma model. Finally, MLN4924, an investigational small molecule inhibitor of NEDD8-activating enzyme (NAE) that inhibits CRL, suppresses in vitro migration, proliferation and tube formation, as well as in vivo angiogenesis and tumorigenesis. Taken together, our study, using both genetic and pharmaceutical approaches, demonstrates that Sag is essential for embryonic vasculogenesis and tumor angiogenesis, and provides the proof-of-concept evidence that targeting Sag E3 ubiquitin ligase may have clinical value for anti-angiogenesis therapy of human cancer.
authors.affiliation: Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tan
authors.affiliation: Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: H
authors.initials: H
authors.lastname: Li
authors.affiliation: Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology; D020964:Embryo Loss / Q000235:genetics*; D042783:Endothelial Cells / Q000473:pathology; D017353:Gene Deletion; D055785:Gene Knockdown Techniques; D008546:Melanoma, Experimental / Q000188:drug therapy / Q000473:pathology; D018345:Mice, Knockout; D000075687:NEDD8 Protein; D009389:Neovascularization, Pathologic / Q000235:genetics*; D011743:Pyrimidines / Q000494:pharmacology; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D014452:Ubiquitins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; C493961:Cdkn1b protein, mouse; D003517:Cyclopentanes; D000075687:NEDD8 Protein; C513172:Nedd8 protein, mouse; D011743:Pyrimidines; C573100:SAG protein, mouse; D014452:Ubiquitins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D044767:Ubiquitin-Protein Ligases; C539933:pevonedistat