title: Human alpha1 type IV collagen NC1 domain exhibits distinct antiangiogenic activity mediated by alpha1beta1 integrin.
abstract: Human noncollagenous domain 1 of the alpha1 chain of type IV collagen [alpha1(IV)NC1], or arresten, is derived from the carboxy terminal of type IV collagen. It was shown to inhibit angiogenesis and tumor growth in vivo; however, the mechanisms involved are not known. In the present study we demonstrate that human alpha1(IV)NC1 binds to alpha1beta1 integrin, competes with type IV collagen binding to alpha1beta1 integrin, and inhibits migration, proliferation, and tube formation by ECs. Also, alpha1(IV)NC1 pretreatment inhibited FAK/c-Raf/MEK/ERK1/2/p38 MAPK activation in ECs but had no effect on the PI3K/Akt pathway. In contrast, alpha1(IV)NC1 did not affect proliferation, migration, or the activation of FAK/c-Raf/MEK1/2/p38/ERK1 MAPK pathway in alpha1 integrin receptor knockout ECs. Consistent with this, alpha1(IV)NC1 elicited significant antiangiogenic effects and tumor growth inhibition in vivo but failed to do the same in alpha1 integrin receptor knockout mice. This suggests a highly specific, alpha1beta1 integrin-dependent antiangiogenic activity of alpha1(IV)NC1. In addition, alpha1(IV)NC1 inhibited hypoxia-induced expression of hypoxia-inducible factor 1alpha and VEGF in ECs cultured on type IV collagen by inhibiting ERK1/2 and p38 activation. This unravels a hitherto unknown function of human alpha1(IV)NC1 and suggests a critical role for integrins in hypoxia and hypoxia-induced angiogenesis. Collectively, the above data indicate that alpha1(IV)NC1 is a potential therapeutic candidate for targeting tumor angiogenesis.
authors.affiliation: Cell Signaling and Angiogenesis Laboratory, Department of Genetics, Boys Town National Research Hospital, Omaha, Nebraska 68131, USA. akulapallis@boystown.org
authors.forename: Akulapalli
authors.initials: A
authors.lastname: Sudhakar
authors.forename: Pia
authors.initials: P
authors.lastname: Nyberg
authors.forename: Venkateshwar G
authors.initials: VG
authors.lastname: Keshamouni
authors.forename: Arjuna P
authors.initials: AP
authors.lastname: Mannam
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Hikaru
authors.initials: H
authors.lastname: Sugimoto
authors.forename: Dominic
authors.initials: D
authors.lastname: Cosgrove
authors.forename: Raghu
authors.initials: R
authors.lastname: Kalluri
mesh_terms: D020533:Angiogenesis Inhibitors / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects; D024141:Collagen Type IV / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004789:Enzyme Activation; D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism*; D017353:Gene Deletion; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis; D039222:Integrin alpha1beta1 / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009369:Neoplasms / Q000098:blood supply / Q000188:drug therapy / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000188:drug therapy / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis
chemical_list: D020533:Angiogenesis Inhibitors; D024141:Collagen Type IV; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D039222:Integrin alpha1beta1; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D011494:Protein Kinases