Selectivity of the collagen-binding integrin inhibitors, TC-I-15 and obtustatin

Emma J Hunter,Samir W Hamaia,Donald Gullberg,Jean-Daniel Malcor,Richard W Farndale

doi:10.1016/j.taap.2021.115669

Emma J Hunter, Samir W Hamaia + Show 3 more

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https://doi.org/10.1016/j.taap.2021.115669

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Abstract

Integrins are a family of 24 adhesion receptors which are both widely-expressed and important in many pathophysiological cellular processes, from embryonic development to cancer metastasis. Hence, integrin inhibitors are valuable research tools which may have promising therapeutic uses. Here, we focus on the four collagen-binding integrins α1β1, α2β1, α10β1 and α11β1. TC-I-15 is a small molecule inhibitor of α2β1 that inhibits platelet adhesion to collagen and thrombus deposition, and obtustatin is an α1β1-specific disintegrin that inhibits angiogenesis. Both inhibitors were applied in cellular adhesion studies, using synthetic collagen peptide coatings with selective affinity for the different collagen-binding integrins and testing the adhesion of C2C12 cells transfected with each. Obtustatin was found to be specific for α1β1, as described, whereas TC-I-15 is shown to be non-specific, since it inhibits both α1β1 and α11β1 as well as α2β1. TC-I-15 was 100-fold more potent against α2β1 binding to a lower-affinity collagen peptide, suggestive of a competitive mechanism. These results caution against the use of integrin inhibitors in a therapeutic or research setting without testing for cross-reactivity.

Highlights

Integrins are a family of glycoprotein transmembrane cell adhesion receptors that exist as α/β heterodimers
Integrin αI-domain adhesion to collagen peptides is unaffected by TCI-15 and Obtustatin
To confirm that these inhibitors have no effect on isolated αI-do mains, GST-tagged αI-domains were tested in static adhesion assays where plates had been coated with either GLOGEN or GFOGER in the presence or absence of the in hibitors obtustatin, 6F1 and TC-I-15

Summary

Introduction

Integrins are a family of glycoprotein transmembrane cell adhesion receptors that exist as α/β heterodimers. It is thought that cells express an excess of β-subunits and the expression of α-subunits determines surface receptor expression (Santala and Heino, 1991) They play essential roles in embryonic development, cell migration, proliferation and angiogenesis, and have been implicated in tumorigenesis and inflammation (Santala and Heino, 1991; Arnaout, 2016; van der Flier et al, 2010; San Antonio et al, 2009; Pozzi et al, 1998; Zhang et al, 2008; Senger et al, 2002; da Silva et al, 2010; Sottnik et al, 2013; Alique et al, 2014). Many cell types must adhere to the matrix through integrins to survive (Schwartz and Assoian, 2001; Assoian, 1997)

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