EB1 Restricts Breast Cancer Cell Invadopodia Formation and Matrix Proteolysis via FAK

Brice Chanez,Ali Badache,Kevin Ostacolo,Sylvie Thuault

doi:10.3390/cells10020388

Abstract

Regulation of microtubule dynamics by plus-end tracking proteins (+TIPs) plays an essential role in cancer cell migration. However, the role of +TIPs in cancer cell invasion has been poorly addressed. Invadopodia, actin-rich protrusions specialized in extracellular matrix degradation, are essential for cancer cell invasion and metastasis, the leading cause of death in breast cancer. We, therefore, investigated the role of the End Binding protein, EB1, a major hub of the +TIP network, in invadopodia functions. EB1 silencing increased matrix degradation by breast cancer cells. This was recapitulated by depletion of two additional +TIPs and EB1 partners, APC and ACF7, but not by the knockdown of other +TIPs, such as CLASP1/2 or CLIP170. The knockdown of Focal Adhesion Kinase (FAK) was previously proposed to similarly promote invadopodia formation as a consequence of a switch of the Src kinase from focal adhesions to invadopodia. Interestingly, EB1-, APC-, or ACF7-depleted cells had decreased expression/activation of FAK. Remarkably, overexpression of wild type FAK, but not of FAK mutated to prevent Src recruitment, prevented the increased degradative activity induced by EB1 depletion. Overall, we propose that EB1 restricts invadopodia formation through the control of FAK and, consequently, the spatial regulation of Src activity.

Highlights

Metastatic progression is the leading cause of mortality among breast cancer patients.In order to leave the primary tumor and reach distant organs, cancer cells need to migrate and degrade the surrounding extracellular matrix (ECM)
We investigated the contribution of EB1 to breast cancer cells ability to form invadopodia and degrade the ECM
Invasive MDA-MB-231 breast cancer cells transfected with either a control siRNA or siRNAs directed against EB1 were seeded on an artificial ECM composed of fluorescently-labeled gelatin for 4 h (Figure 1A)

Summary

Introduction

Metastatic progression is the leading cause of mortality among breast cancer patients.In order to leave the primary tumor and reach distant organs, cancer cells need to migrate and degrade the surrounding extracellular matrix (ECM). Metastatic progression is the leading cause of mortality among breast cancer patients. Invadopodia, which are dynamic actin-rich membrane protrusions developed by cancer cells, play a major role in ECM proteolysis [1,2,3]. Invadopodia formation is commonly initiated following Src kinase activation downstream of ligand-induced activation of receptor tyrosine kinases, such as EGF receptor. This leads to the recruitment and activation of signaling and structural factors implicated in actin reorganization, such as Cortactin, Arp2/3, N-WASP, Tks4/5, and the release of proteases such as MT1-MMP, involved in matrix proteolysis. Invadopodia appear as key structures involved in cancer cell invasion and metastatic progression [4,5]

Methods

Results

Conclusion