title: Rapamycin inhibits lymphatic endothelial cell tube formation by downregulating vascular endothelial growth factor receptor 3 protein expression.
abstract: Mammalian target of rapamycin (mTOR) controls lymphangiogenesis. However, the underlying mechanism is not clear. Here we show that rapamycin suppressed insulin-like growth factor 1 (IGF-1)- or fetal bovine serum (FBS)-stimulated lymphatic endothelial cell (LEC) tube formation, an in vitro model of lymphangiogenesis. Expression of a rapamycin-resistant and kinase-active mTOR (S2035T, mTOR-T), but not a rapamycin-resistant and kinase-dead mTOR (S2035T/D2357E, mTOR-TE), conferred resistance to rapamycin inhibition of LEC tube formation, suggesting that rapamycin inhibition of LEC tube formation is mTOR kinase activity dependent. Also, rapamycin inhibited proliferation and motility in the LECs. Furthermore, we found that rapamycin inhibited protein expression of VEGF receptor 3 (VEGFR-3) by inhibiting protein synthesis and promoting protein degradation of VEGFR-3 in the cells. Down-regulation of VEGFR-3 mimicked the effect of rapamycin, inhibiting IGF-1- or FBS-stimulated tube formation, whereas over-expression of VEGFR-3 conferred high resistance to rapamycin inhibition of LEC tube formation. The results indicate that rapamycin inhibits LEC tube formation at least in part by downregulating VEGFR-3 protein expression.
authors.affiliation: State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.forename: Donna
authors.initials: D
authors.lastname: Rogers
authors.forename: Wei
authors.initials: W
authors.lastname: Su
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Odaka
authors.forename: Hongyu
authors.initials: H
authors.lastname: Zhou
authors.forename: Wenxing
authors.initials: W
authors.lastname: Chen
authors.forename: Tao
authors.initials: T
authors.lastname: Shen
authors.forename: J Steven
authors.initials: JS
authors.lastname: Alexander
authors.forename: Shile
authors.initials: S
authors.lastname: Huang
mesh_terms: D000818:Animals; D002460:Cell Line; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D014176:Protein Biosynthesis / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000235:genetics / Q000378:metabolism*
chemical_list: D007334:Insulin-Like Growth Factor I; D040321:Vascular Endothelial Growth Factor Receptor-3; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus