Human α1 type IV collagen NC1 domain exhibits distinct antiangiogenic activity mediated by α1β1 integrin
Akulapalli Sudhakar, … , Dominic Cosgrove, Raghu Kalluri
Akulapalli Sudhakar, … , Dominic Cosgrove, Raghu Kalluri
Published October 3, 2005
Citation Information: J Clin Invest. 2005;115(10):2801-2810. https://doi.org/10.1172/JCI24813.
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Research Article Angiogenesis

Human α1 type IV collagen NC1 domain exhibits distinct antiangiogenic activity mediated by α1β1 integrin

Abstract

Human noncollagenous domain 1 of the α1 chain of type IV collagen [α1(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 α1(IV)NC1 binds to α1β1 integrin, competes with type IV collagen binding to α1β1 integrin, and inhibits migration, proliferation, and tube formation by ECs. Also, α1(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, α1(IV)NC1 did not affect proliferation, migration, or the activation of FAK/c-Raf/MEK1/2/p38/ERK1 MAPK pathway in α1 integrin receptor knockout ECs. Consistent with this, α1(IV)NC1 elicited significant antiangiogenic effects and tumor growth inhibition in vivo but failed to do the same in α1 integrin receptor knockout mice. This suggests a highly specific, α1β1 integrin–dependent antiangiogenic activity of α1(IV)NC1. In addition, α1(IV)NC1 inhibited hypoxia-induced expression of hypoxia-inducible factor 1α and VEGF in ECs cultured on type IV collagen by inhibiting ERK1/2 and p38 activation. This unravels a hitherto unknown function of human α1(IV)NC1 and suggests a critical role for integrins in hypoxia and hypoxia-induced angiogenesis. Collectively, the above data indicate that α1(IV)NC1 is a potential therapeutic candidate for targeting tumor angiogenesis.

Authors

Akulapalli Sudhakar, Pia Nyberg, Venkateshwar G. Keshamouni, Arjuna P. Mannam, Jian Li, Hikaru Sugimoto, Dominic Cosgrove, Raghu Kalluri

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Figure 4

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Effect of α1(IV)NC1 on ERK and p38 MAPK signal transduction pathways. Se...
Effect of α1(IV)NC1 on ERK and p38 MAPK signal transduction pathways. Serum-starved WT MLECs were pretreated 10 minutes with α1(IV)NC1, plated on type IV collagen–coated plates in incomplete medium, and lysed at the indicated times (0–60 minutes). The levels of phosphorylated proteins after incubation with α1(IV)NC1 (middle panels) were compared with untreated control (top panels) and the total signaling protein levels in α1(IV)NC1-treated WT MLECs (bottom panels) by immunoblot. (A) Raf phosphorylation. Immunoblots for phospho-Raf indicate that sustained phosphorylation of Raf (A, top panel) was inhibited by treatment with α1(IV)NC1 (A, middle panel) and total Raf protein (A, bottom panel). (B) MEK1/2 phosphorylation. Immunoblots for phospho-MEK1/2 indicate that sustained phosphorylation of MEK (B, top panel) was inhibited by treatment with α1(IV)NC1 (B, middle panel) and total MEK1/2 protein (B, bottom panel). (C) ERK1/2 phosphorylation. Immunoblots for phospho-ERK1/2 indicate that sustained phosphorylation of ERK (C, top panel) was inhibited by treatment with α1(IV)NC1 (C, middle panel) and total ERK1/2 protein (C, bottom panel). Treatment with α1(IV)NC1 inhibited phosphorylation of ERK1 but had no significant effect on ERK2 phosphorylation (C, middle panel). (D) p38 phosphorylation. Immunoblots for phospho-p38 indicate that sustained phosphorylation of p38 (D, top panel) was inhibited by treatment with α1(IV)NC1 (D, middle panel) and total p38 protein (D, bottom panel).