title: Insulin-like growth factors 1 and 2 induce lymphangiogenesis in vivo.
abstract: Lymphangiogenesis is an important process that contributes to the spread of cancer. Here we show that insulin-like growth factors 1 (IGF-1) and 2 (IGF-2) induce lymphangiogenesis in vivo. In a mouse cornea assay, IGF-1 and IGF-2 induce lymphangiogenesis as detected with LYVE-1, a specific marker for lymphatic endothelium. Interestingly, IGF-1-induced lymphangiogenesis could not be blocked by a soluble vascular endothelial growth factor receptor 3, suggesting that the vascular endothelial growth factor receptor 3-signaling pathway is not required for IGF-induced lymphangiogenesis. In vitro, IGF-1 and IGF-2 significantly stimulated proliferation and migration of primary lymphatic endothelial cells. IGF-1 and IGF-2 induced phosphorylation of intracellular signaling components, such as Akt, Src, and extracellular signal-regulated kinase in lymphatic endothelial cells. Immunohistochemistry, RT-PCR, and Affymetrix GeneChip microarray analysis showed that the receptors for IGFs are present in lymphatic endothelium. Together, our findings suggest that IGFs might act as direct lymphangiogenic factors, although any indirect roles in the induction of lymphangiogenesis cannot be excluded. Because members of the IGF ligand and receptor families are widely expressed in various types of solid tumors, our findings suggest that these factors are likely to contribute to lymphatic metastasis.
authors.affiliation: Laboratory of Angiogenesis Research, Microbiology and Tumor Biology Center, Karolinska Institute, S-171 77 Stockholm, Sweden.
authors.forename: Meit
authors.initials: M
authors.lastname: Björndahl
authors.forename: Renhai
authors.initials: R
authors.lastname: Cao
authors.forename: L Johan
authors.initials: LJ
authors.lastname: Nissen
authors.forename: Steve
authors.initials: S
authors.lastname: Clasper
authors.forename: Louise A
authors.initials: LA
authors.lastname: Johnson
authors.forename: Yuan
authors.initials: Y
authors.lastname: Xue
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Zhou
authors.forename: David
authors.initials: D
authors.lastname: Jackson
authors.forename: Anker Jon
authors.initials: AJ
authors.lastname: Hansen
authors.forename: Yihai
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000818:Animals; D004729:Endothelium, Lymphatic / Q000187:drug effects / Q000502:physiology; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D042583:Lymphangiogenesis / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017526:Receptor, IGF Type 1 / Q000032:analysis; D017527:Receptor, IGF Type 2 / Q000032:analysis; D042582:Vascular Endothelial Growth Factor C / Q000502:physiology; D042643:Vascular Endothelial Growth Factor D / Q000502:physiology; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000502:physiology
chemical_list: D017527:Receptor, IGF Type 2; D042582:Vascular Endothelial Growth Factor C; D042643:Vascular Endothelial Growth Factor D; C467483:vascular endothelial growth factor C, mouse; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1; D040321:Vascular Endothelial Growth Factor Receptor-3