Mapping proteolytic cancer cell-extracellular matrix interfaces

Abstract

For cancer progression and metastatic dissemination, cancer cells migrate and penetrate through extracellular tissues. Cancer invasion is frequently facilitated by proteolytic processing of components of the extracellular matrix (ECM). The cellular regions mediating proteolysis are diverse and depend upon the physical structure, composition, and dimensionality of the ECM contacted by the cell surface. Cancer cells migrating across 2D substrate contain proteolytic structures such as lamellipodia, invadopodia, and the trailing edge. Likewise, invasive mesenchymal migration through 3D fibrillar ECM, as monitored for HT1080 fibrosarcoma and MDA-MB-231 breast carcinoma cells by submicron-resolved imaging, is mediated by several types of proteolytic structures rich in filamentous actin, ß1 integrin, and MT1-MMP with distinct location and function. These comprise (i) anterior pseudopod bifurcataions and the nucleus corresponding to zones of local cell compression by constraining collagen fibers, (ii) lateral small spikes that protrude into the ECM and cause small spot-like proteolytic foci, and (iii) a strongly proteolytic trailing edge sliding along reorganized ECM fibers. Through their combined action these proteolytic surface structures cleave, remove, and realign ECM barriers, support rear end retraction, generate tube-like matrix defects and laterally widen existing tracks during 3D tissue invasion.

Invadosomes at a glance

“…These extensions might be the 3D equivalent of invadopodia that are observed in 2D cell culture. Image reproduced from Wolf and Friedl (Wolf and Friedl, 2009) …”

“…Also, leukocytes undergoing transendothelial diapedesis have been shown to form protrusions that resemble invadosomes (Carman et al, 2007;Carman, 2009), although their relationship to podosomes and invadopodia is unclear. Finally, fibrosarcoma cells migrating through a fibrillar matrix form numerous lateral spikes, which contact matrix fibers and are enriched in MT1-MMP-GFP (Wolf and Friedl, 2009), making them good candidates for in vivo counterparts of invadopodia.…”

An agarose-based microfluidic platform with a gradient buffer for 3D chemotaxis studies

“…In a 3D microenvironment, cells need to either degrade the extracellular matrix (ECM) or squeeze through small pores in amoeboid fashion (Wolf and Friedl 2008), and they may experience chemokine gradients differently, since many are matrix-binding (Patel et al 2001). As a result, cells behave very differently in 3D vs. 2D environments (Behnsen et al 2007;Cukierman et al 2001;Griffith and Swartz 2006;Pedersen and Swartz 2005).…”

Measuring dynamic cell–material interactions and remodeling during 3D human mesenchymal stem cell migration in hydrogels

“…These processes are important during development, wound regeneration, and pathophysiological states facilitated by proteolytic events via cellular protease secretion. Previous work has begun to elucidate the length scales and spatial effects of secreted proteases in relation to migrating tumor cells during collagen matrix remodeling (17)(18)(19). For example, Packard et al (20) used matrix metalloproteinase (MMP)-sensitive biosensors to visualize protease activity in the pericellular region of migrating tumor cells in collagen, finding increased activity at the polarized leading edge.…”