Liver X receptor activation reduces angiogenesis by impairing lipid raft localization and signaling of vascular endothelial growth factor receptor-2.
OBJECTIVE
Liver X receptors (LXRα, LXRβ) are master regulators of cholesterol homeostasis. In the endothelium, perturbations of cell cholesterol have an impact on fundamental processes. We, therefore, assessed the effects of LXR activation on endothelial functions related to angiogenesis in vitro and in vivo.


RESULTS
LXR agonists (T0901317, GW3965) blunted migration, tubulogenesis, and proliferation of human umbilical vein endothelial cells. By affecting endothelial cholesterol homeostasis, LXR activation impaired the compartmentation of vascular endothelial growth factor receptor-2 in lipid rafts/caveolae and led to defective phosphorylation and downstream signaling of vascular endothelial growth factor receptor-2 upon vascular endothelial growth factor-A stimulation. Consistently, the antiangiogenic actions of LXR agonists could be prevented by coadministration of exogenous cholesterol. LXR agonists reduced endothelial sprouting from wild-type but not from LXRα(-/-)/LXRβ(-/-) knockout aortas and blunted the vascularization of implanted angioreactors in vivo. Furthermore, T0901317 reduced the growth of Lewis lung carcinoma grafts in mice by impairing angiogenesis.


CONCLUSIONS
Pharmacological activation of endothelial LXRs reduces angiogenesis by restraining cholesterol-dependent vascular endothelial growth factor receptor-2 compartmentation and signaling. Thus, administration of LXR agonists could exert therapeutic effects in pathological conditions characterized by uncontrolled angiogenesis.
Institute for Cancer Research and Treatment (IRCC), Candiolo, Italy.
Alessio
A
Noghero
Alessia
A
Perino
Giorgio
G
Seano
Elisa
E
Saglio
Giuseppe
G
Lo Sasso
Franco
F
Veglio
Luca
L
Primo
Emilio
E
Hirsch
Federico
F
Bussolino
Fulvio
F
Morello
D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001565:Benzoates / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D018827:Carcinoma, Lewis Lung / Q000098:blood supply / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology; D000071518:Liver X Receptors; D021962:Membrane Microdomains / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D057093:Orphan Nuclear Receptors / Q000819:agonists* / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects*; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D005466:Fluorocarbons; D000096926:Benzenesulfonamides
D020533:Angiogenesis Inhibitors; D001565:Benzoates; D001596:Benzylamines; D002784:Cholesterol; D006845:Hydrocarbons, Fluorinated; D000071518:Liver X Receptors; D057093:Orphan Nuclear Receptors; D013449:Sulfonamides; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; C473027:GW 3965; C000605213:NR1H3 protein, human; C000605214:Nr1h3 protein, mouse; C423915:T0901317; D005466:Fluorocarbons; D000096926:Benzenesulfonamides; C467484:VEGFA protein, human