title: Epithelial-mesenchymal transition enhances nanoscale actin filament dynamics of ovarian cancer cells.
abstract: Epithelial ovarian cancer cells enhance their ability to migrate and invade through the epithelial-mesenchymal transition (EMT), resulting in cell seeding and metastasis in the peritoneal cavity and onto adjacent organ surfaces. It has been speculated that cytoskeletal dynamics, such as those of the actin filament, play a role in enhanced cell motility; however, direct evidence has not been provided. Herein, we have directly measured pico- to nanonewton-scale mechanical forces generated by actin dynamics of ovarian cancer SKOV-3 cells upon binding of integrin α5β1 to fibronectin (FN), i.e., formation of a focal adhesion, using real-time atomic force microscopy (AFM) in a force spectroscopy mode. The dendrimer surface chemistry through which FN was immobilized on the AFM probe surfaces further enhanced the sensitivity of the force measurement by 1.5-fold. Post-EMT SKOV-3 cells, induced by transforming growth factor-β, generated larger focal adhesion mechanical forces (17 and 41 nN before and after EMT, respectively) with migration faster than that of pre-EMT cells. Importantly, 22% of the forces transmitted through a single FN-integrin α5β1 pair from post-EMT cells were shown to be sufficient to rupture the binding between FN and integrin α5β1 on the cells, a result which is not observed on pre-EMT cells. This implies that post-EMT cells, by generating forces strong enough to break the FN-integrin binding, migrate and metastasize beyond the ovary, whereas pre-EMT cancer cells are confined in the ovary without such force generation. These results demonstrate quantitative and direct evidence for the role of actin dynamics in the enhanced motility of post-EMT ovarian cancer cells, providing a fundamental insight into the mechanism of ovarian cancer metastasis.
authors.affiliation: Elmhurst Hospital Center, Icahn School of Medicine at Mount Sinai, Elmhurst, NY 11373.
authors.forename: Sunyoung
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Biopharmaceutical Sciences, University of Illinois, Chicago, IL 60612.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Science, Icahn School of Medicine at Mount Sinai, New York, NY 10029.
authors.forename: David
authors.initials: D
authors.lastname: Fishman
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Banaszak Holl
authors.affiliation: Department of Biopharmaceutical Sciences, University of Illinois, Chicago, IL 60612.
authors.forename: Seungpyo
authors.initials: S
authors.lastname: Hong
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D045744:Cell Line, Tumor; D002465:Cell Movement; D004338:Drug Combinations; D058750:Epithelial-Mesenchymal Transition; D005260:Female; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D039081:Integrin alpha5beta1 / Q000737:chemistry / Q000378:metabolism; D018625:Microscopy, Atomic Force; D010051:Ovarian Neoplasms / Q000378:metabolism / Q000473:pathology; D011412:Propanolamines / Q000737:chemistry; D011485:Protein Binding; D013806:Theophylline / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D000199:Actins; D004338:Drug Combinations; D005353:Fibronectins; D039081:Integrin alpha5beta1; D011412:Propanolamines; D013806:Theophylline; C069987:pamabrom