title: Sunitinib inhibits lymphatic endothelial cell functions and lymph node metastasis in a breast cancer model through inhibition of vascular endothelial growth factor receptor 3.
abstract: BACKGROUND
  Metastasis is a common event and the main cause of death in cancer patients. Lymphangiogenesis refers to the formation of new lymphatic vessels and is thought to be involved in the development of metastasis. Sunitinib is a multi-kinase inhibitor that blocks receptor tyrosine kinase activity, including that of vascular endothelial growth factor receptors (VEGFRs). Although sunitinib is a clinically available angiogenesis inhibitor, its effects on lymphangiogenesis and lymph node metastasis remain unclear. The purpose of this study was to investigate the effects of sunitinib on vascular endothelial growth factor receptor 3 (VEGFR-3) and a related event, lymphangiogenesis.
  
  
  METHODS
  The effects of sunitinib on the degree of phosphorylation of VEGFR-2/3 and other signaling molecules was examined in lymphatic endothelial cells (LECs) treated with the drug; VEGF-induced LEC growth, migration, and tube formation were also examined. For the in vivo study, luciferase-expressing breast cancer cells were transplanted into mammary fat pads of mice; the microvessel and lymphatic vessel density was then measured after treatment with sunitinib and anti-VEGFR-2 antibody.
  
  
  RESULTS
  First, in human LECs, sunitinib blocked both VEGFR-2 and VEGFR-3 phosphorylation induced by VEGF-C or VEGF-D, and abrogated the activation of the downstream molecules extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt. Furthermore, sunitinib attenuated the cell-proliferation activity induced by VEGF-C/D and prevented VEGF-C-induced migration and tube formation of the LECs; however, anti-VEGFR2 treatment shows only a partial effect on the growth and functions of the LECs. We used a breast cancer cell line expressing luciferase as a metastatic cancer model. Sunitinib treatment (40 mg/kg/day) inhibited the growth of the primary tumor transplanted in the mammary fat pad of the mice and significantly reduced the number of blood and lymphatic vessels in the tumor. Furthermore, the development of axillary lymph node metastasis, detected by bioluminescent imaging, was markedly suppressed. This effect of sunitinib was more potent than that of DC101, an anti-mouse VEGFR-2 antibody.
  
  
  CONCLUSIONS
  The results suggest that sunitinib might be beneficial for the treatment of breast cancer by suppressing lymphangiogenesis and lymph node metastasis, through inhibition, particularly important, of VEGFR-3.
authors.affiliation: Shien-Lab, National Cancer Center Hospital, Chuo-ku, Tokyo, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kodera
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Katanasaka
authors.forename: Yuka
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tsuda
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nishio
authors.forename: Tomohide
authors.initials: T
authors.lastname: Tamura
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Koizumi
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology; D000818:Animals; D002465:Cell Movement; D042783:Endothelial Cells / Q000187:drug effects*; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D042583:Lymphangiogenesis / Q000187:drug effects*; D008207:Lymphatic Metastasis / Q000517:prevention & control*; D042601:Lymphatic Vessels / Q000187:drug effects / Q000473:pathology; D008325:Mammary Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D010766:Phosphorylation; D011758:Pyrroles / Q000494:pharmacology*; D000077210:Sunitinib; D042582:Vascular Endothelial Growth Factor C / Q000378:metabolism; D042643:Vascular Endothelial Growth Factor D / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D007211:Indoles; D011758:Pyrroles; D042582:Vascular Endothelial Growth Factor C; D042643:Vascular Endothelial Growth Factor D; D040301:Vascular Endothelial Growth Factor Receptor-2; D040321:Vascular Endothelial Growth Factor Receptor-3; D000077210:Sunitinib