Quantitative phase imaging reveals matrix stiffness-dependent growth and migration of cancer cells

Gabriel Popescu,Kristopher A Kilian,Michael J Fanous,Yanfen Li

doi:10.1038/s41598-018-36551-5

Abstract

Cancer progression involves complex signals within the tumor microenvironment that orchestrate proliferation and invasive processes. The mechanical properties of the extracellular matrix (ECM) within this microenvironment has been demonstrated to influence growth and the migratory phenotype that precedes invasion. Here we present the integration of a label-free quantitative phase imaging technique, spatial light interference microscopy (SLIM)—with protein-conjugated hydrogel substrates—to explore how the stiffness of the ECM influences melanoma cells of varying metastatic potential. Melanoma cells of high metastatic potential demonstrate increased growth and velocity characteristics relative to cells of low metastatic potential. Cell velocity in the highly metastatic population shows a relative stability at higher matrix stiffness suggesting adoption of migratory routines that are independent of mechanics to facilitate invasion. The use of SLIM and engineered substrates provides a new approach to characterize the invasive properties of live cells as a function of microenvironment parameters. This work provides fundamental insight into the relationship between growth, migration and metastatic potential, and provides a new tool for profiling cancer cells for clinical grading and development of patient-specific therapeutic regimens.

Highlights

Cancer progression involves complex signals within the tumor microenvironment that orchestrate proliferation and invasive processes
A hallmark of cancer is the excess production of extracellular matrix (ECM) proteins including collagen I, II, III, V, and IX, which leads to tissue fibrosis[13,14,15,16,17]
This in turn increases the stiffness of the tumor microenvironment as compared to the surrounding tissue, which further enhances cancer progression via reducing levels of tumor suppressors PTEN and HOXA9 in cancer cells[17,18]

Summary

Introduction

Cancer progression involves complex signals within the tumor microenvironment that orchestrate proliferation and invasive processes. The extracellular matrix (ECM) is an important component of the microenvironment and consists of proteins, glycoproteins, proteoglycans, polysaccharides, and other biochemically distinct components[2,3] This ordered structure contains unique chemical, physical, and mechanical properties which are essential in numerous physiological processes including homeostasis[4], differentiation[5,6] and migration[7,8]. Weaver and colleagues demonstrated how breast adenocarcinoma cells will secrete lysyl oxidase which crosslinks ECM proteins, leading to additional stiffening to facilitate invasion[19] This increase in stiffness impacts surrounding cells including creation of cancer-associated fibroblasts[20] and tumor-activated macrophages[21]. While considerable work has led to the identification of processes underlying cancer cell invasiveness, no technique can simultaneously probe the interdependence of matrix parameters on multiple complex functions, i.e. migration and growth, which are critical aspects of invasion

Methods

Results

Conclusion