Angiogenic sprouting is regulated by endothelial cell expression of Slug

Katrina M Welch-Reardon,Andrew C Newman,Kehui Wang,Steven C George,Christopher C W Hughes,Robert A Edwards,Ashley H Fong,Nan Wu,Monica Romero-Lopez,Seema M Ehsan

doi:10.1242/dev.112474

Katrina M Welch-Reardon, Andrew C Newman + Show 8 more

Open Access

https://doi.org/10.1242/dev.112474

Copy DOI

Abstract

The Snail family of zinc-finger transcription factors are evolutionarily conserved proteins that control processes requiring cell movement. Specifically, they regulate epithelial-to-mesenchymal transitions (EMT) where an epithelial cell severs intercellular junctions, degrades basement membrane and becomes a migratory, mesenchymal-like cell. Interestingly, Slug expression has been observed in angiogenic endothelial cells (EC) in vivo, suggesting that angiogenic sprouting may share common attributes with EMT. Here, we demonstrate that sprouting EC in vitro express both Slug and Snail, and that siRNA-mediated knockdown of either inhibits sprouting and migration in multiple in vitro angiogenesis assays. We find that expression of MT1-MMP, but not of VE-Cadherin, is regulated by Slug and that loss of sprouting as a consequence of reduced Slug expression can be reversed by lentiviral-mediated re-expression of MT1-MMP. Activity of MMP2 and MMP9 are also affected by Slug expression, likely through MT1-MMP. Importantly, we find enhanced expression of Slug in EC in human colorectal cancer samples compared with normal colon tissue, suggesting a role for Slug in pathological angiogenesis. In summary, these data implicate Slug as an important regulator of sprouting angiogenesis, particularly in pathological settings.

Highlights

Angiogenesis is a multi-step, tightly regulated process that plays a crucial role during embryogenesis and wound healing, as well as in pathological conditions such as tumor growth (Conway et al, 2001; Folkman, 1985; Risau, 1997)
Gene expression profiles reveal tip cells to be highly enriched in vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) (Gerhardt et al, 2003; Jakobsson et al, 2010; Ribatti and Crivellato, 2012; Sainson et al, 2008), platelet-derived growth factor B (PDGFB) (Ribatti and Crivellato, 2012; Sainson et al, 2008), neuropilin receptor 2 (NRP2) (Sainson et al, 2008), Jagged 1 (Jag1) (Johnston et al, 2009; Sainson et al, 2008), membrane type 1 matrix metalloproteinase (MT1-MMP), and delta-like 4 (Dll4) (Hellstrom et al, 2007; Suchting et al, 2007)
In recent years there has been a dramatic increase in our understanding of the growth factors and receptors that drive angiogenesis, and a growing appreciation of the signaling pathways downstream of these receptors

Summary

Introduction

Angiogenesis is a multi-step, tightly regulated process that plays a crucial role during embryogenesis and wound healing, as well as in pathological conditions such as tumor growth (Conway et al, 2001; Folkman, 1985; Risau, 1997). Expression of tip cell genes and induction of angiogenic sprouting are stimulated and regulated by pro-angiogenic cytokines including VEGF (Conway et al, 2001; Ribatti and Crivellato, 2012), tumor necrosis factor a (TNFa) (Otrock et al, 2007; Sainson et al, 2008), transforming growth factor b (TGFb) (Otrock et al, 2007), fibroblast growth factor (FGF) (Conway et al, 2001; Otrock et al, 2007) and hepatocyte growth factor (HGF) (Sengupta et al, 2003) During pathological events such as inflammation and tumor growth, several of these growth factors induce expression of the transcription factor Slug (Snai2), and expression of this gene in tumor cells contributes to invasion and to metastasis (Barrallo-Gimeno and Nieto, 2005; Romano and Runyan, 2000; Thiery, 2002)

Methods

Results

Conclusion