The mechanical microenvironment regulates ovarian cancer cell morphology, migration, and spheroid disaggregation

Andrew J Mckenzie,Zöe L Edmunds,Stephanie R Hicks,Hannah Naughton,Kathryn V Svec,Alan K Howe

doi:10.1038/s41598-018-25589-0

Andrew J Mckenzie, Zöe L Edmunds + Show 4 more

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https://doi.org/10.1038/s41598-018-25589-0

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Journal: Scientific Reports	Publication Date: May 8, 2018
Citations: 133	License type: open-access

Affiliation: University of Vermont

Abstract

There is growing appreciation of the importance of the mechanical properties of the tumor microenvironment on disease progression. However, the role of extracellular matrix (ECM) stiffness and cellular mechanotransduction in epithelial ovarian cancer (EOC) is largely unknown. Here, we investigated the effect of substrate rigidity on various aspects of SKOV3 human EOC cell morphology and migration. Young’s modulus values of normal mouse peritoneum, a principal target tissue for EOC metastasis, were determined by atomic force microscopy (AFM) and hydrogels were fabricated to mimic these values. We find that cell spreading, focal adhesion formation, myosin light chain phosphorylation, and cellular traction forces all increase on stiffer matrices. Substrate rigidity also positively regulates random cell migration and, importantly, directional increases in matrix tension promote SKOV3 cell durotaxis. Matrix rigidity also promotes nuclear translocation of YAP1, an oncogenic transcription factor associated with aggressive metastatic EOC. Furthermore, disaggregation of multicellular EOC spheroids, a behavior associated with dissemination and metastasis, is enhanced by matrix stiffness through a mechanotransduction pathway involving ROCK, actomyosin contractility, and FAK. Finally, this pattern of mechanosensitivity is maintained in highly metastatic SKOV3ip.1 cells. These results establish that the mechanical properties of the tumor microenvironment may play a role in EOC metastasis.

Highlights

Cells interpret and respond to the mechanical properties of the extracellular matrix (ECM) by exerting contractile force and sensing counter-tension through mechanocellular systems[1]
Spheroids formed from highly-invasive epithelial ovarian cancer (EOC) cells show increased expression of both lysyl oxidase 1 (LOX1), a collagen-crosslinking enzyme crucial for promoting matrix stiffness and invasion in breast cancer[10], and tissue transglutaminase (TG2), which promotes ECM polymerization and cross-linking[26,27]
We show that cell morphology, focal adhesion and cytoskeletal organization, and actomyosin contractility of SKOV-3 human EOC cells all positively correlate with substrate stiffness

Summary

Introduction

Cells interpret and respond to the mechanical properties (e.g. stiffness and topology) of the extracellular matrix (ECM) by exerting contractile force and sensing counter-tension through mechanocellular systems[1]. The minimal metastatic unit of EOC is thought to be a multi-cellular aggregate, or spheroid, that exfoliates from the primary tumor and moves throughout the peritoneal cavity by normal peritoneal fluid flow[17,20,24] These spheroids have been shown to use myosin-generated force to clear the mesothelium of peritoneal organs and attach to the submesothelial connective tissue[25]. Increasing matrix rigidity decreases expression of the Wnt pathway inhibitor DKK1, promoting increased Wnt signaling enhanced MT1-MMP expression and increased matrix invasion[30] While these observations strongly implicate a role for the mechanical microenvironment in the pathogenesis of EOC, the effects of matrix rigidity on the morphological and migratory aspects of EOC cells remain largely unexplored.

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