MT1-MMP directs force-producing proteolytic contacts that drive tumor cell invasion

GaëLle Martin,Robin Ferrari,Philippe Chavrier,Alessandra Cambi,StéPhane Vassilopoulos,Oya Tagit,RaphaëL Voituriez,Alan Guichard

doi:10.1038/s41467-019-12930-y

Abstract

Unraveling the mechanisms that govern the formation and function of invadopodia is essential towards the prevention of cancer spread. Here, we characterize the ultrastructural organization, dynamics and mechanical properties of collagenotytic invadopodia forming at the interface between breast cancer cells and a physiologic fibrillary type I collagen matrix. Our study highlights an uncovered role for MT1-MMP in directing invadopodia assembly independent of its proteolytic activity. Electron microscopy analysis reveals a polymerized Arp2/3 actin network at the concave side of the curved invadopodia in association with the collagen fibers. Actin polymerization is shown to produce pushing forces that repel the confining matrix fibers, and requires MT1-MMP matrix-degradative activity to widen the matrix pores and generate the invasive pathway. A theoretical model is proposed whereby pushing forces result from actin assembly and frictional forces in the actin meshwork due to the curved geometry of the matrix fibers that counterbalance resisting forces by the collagen fibers.

Highlights

Unraveling the mechanisms that govern the formation and function of invadopodia is essential towards the prevention of cancer spread
Proteolytic degradation is indispensable for the tissue-penetrating properties of cancer cells, largely due to the high degree of intra- and intermolecular covalent cross-links found in type I collagen, the dominant extracellular matrix (ECM) found in native tissues, that prevent the physical expansion of pre-existing pores to accommodate cell invasion[2,3,4]
The classical model of invadopodia that combines small actindriven plasma membrane protrusions with MMP activity is based mostly on the analysis of cancer cells that are plated on a gelatin monolayer as a substrate

Summary

Introduction

Unraveling the mechanisms that govern the formation and function of invadopodia is essential towards the prevention of cancer spread. We and others reported that cancer cells, which invade through the collagen gel with a nucleus-at-the-back configuration, preferentially form elongated invadopodia at the level of the advancing invasive protrusion ahead of the nucleus and degrade the matrix constricting fibers to support invasive path-generation[4,9,18] In addition to their ability to proteolytically remodel the ECM, tumor cells may utilize cellular force to mechanically reorganize the ECM as they migrate through tissue barriers[19,20,21]. Using a combination of platinum replica electron microscopy, type I collagen fiber tracking and laser-induced rupture of collagen fibrils, we have uncovered a proteaseindependent role for MT1-MMP in controlling actin polymerization and mechanical force production at the invadopodial front These data make a shift in the invadopodia paradigm wherein selfassembling, force-producing proteolytic cell–matrix contacts promote matrix pore enlargement to facilitate tumor-cell invasion

Methods

Results

Conclusion