Matrix density-induced mechanoregulation of breast cell phenotype, signaling and gene expression through a FAK-ERK linkage

Oncogene (2009) 28, 43264343

& 2009 Macmillan Publishers Limited All rights reserved 0950-9232/09 $32.00 http://www.nature.com/onc

Web End =www.nature.com/onc

ORIGINAL ARTICLE

Matrix density-induced mechanoregulation of breast cell phenotype, signaling and gene expression through a FAKERK linkage

PP Provenzano1,2,3,4, DR Inman1,4, KW Eliceiri2,3 and PJ Keely1,2,3,4

1Department of Pharmacology, University of Wisconsin, Madison, WI, USA; 2Department of Biomedical Engineering, University of Wisconsin, Madison, WI, USA; 3Laboratory for Optical and Computational Instrumentation, University of Wisconsin, Madison, WI, USA and 4University of Wisconsin Paul P. Carbone Comprehensive Cancer Center, University of Wisconsin, Madison, WI, USA

Mammographically dense breast tissue is one of the greatest risk factors for developing breast carcinoma, yet the associated molecular mechanisms remain largely unknown.Importantly, regions of high breast density are associated with increased stromal collagen and epithelial cell content.We set out to determine whether increased collagen-matrix density, in the absence of stromal cells, was sufcient to promote proliferation and invasion characteristic of a malignant phenotype in non-transformed mammary epithelial cells. We demonstrate that increased collagen-matrix density increases matrix stiffness to promote an invasive phenotype. High matrix stiffness resulted in increased formation of activated three-dimensional (3D)-matrix adhesions and a chronically elevated outside-in/inside-out focal adhesion (FA) kinase (FAK)Rho signaling loop, which was necessary to generate and maintain the invasive phenotype. Moreover, this signaling network resulted in hyperactivation of the Rasmitogen-activated protein kinase (MAPK) pathway, which promoted growth of mammary epithelial cells in vitro and in vivo and activated a clinically relevant proliferation signature that predicts patient outcome. Hence, the current data provide compelling evidence for the importance of the mechanical features of the microenvironment, and suggest that mechanotransduction in these cells occurs through a FAKRhoERK signaling network with extracellular signal-regulated kinase (ERK) as a bottleneck through which much of the response to mechanical stimuli is regulated. As such, we propose that increased matrix stiffness explains part of the mechanism behind increased epithelial proliferation and cancer risk in human patients with high breast tissue density.

Oncogene (2009) 28, 43264343; doi:http://dx.doi.org/10.1038/onc.2009.299

Web End =10.1038/onc.2009.299 ; published online 12 October 2009

Keywords: epithelial morphogenesis; breast cancer; breast tissue density; cellextracellular matrix interaction; mechanotransduction; 3D matrix/focal adhesion

Introduction

Mammographically dense breast tissue is correlated with a greater than four-fold increased risk for developing breast carcinoma (Boyd et al., 1998, 2001; McCormack...