title: Stiffening and unfolding of early deposited-fibronectin increase proangiogenic factor secretion by breast cancer-associated stromal cells.
abstract: Fibronectin (Fn) forms a fibrillar network that controls cell behavior in both physiological and diseased conditions including cancer. Indeed, breast cancer-associated stromal cells not only increase the quantity of deposited Fn but also modify its conformation. However, (i) the interplay between mechanical and conformational properties of early tumor-associated Fn networks and (ii) its effect on tumor vascularization remain unclear. Here, we first used the Surface Forces Apparatus to reveal that 3T3-L1 preadipocytes exposed to tumor-secreted factors generate a stiffer Fn matrix relative to control cells. We then show that this early matrix stiffening correlates with increased molecular unfolding in Fn fibers, as determined by Förster Resonance Energy Transfer. Finally, we assessed the resulting changes in adhesion and proangiogenic factor (VEGF) secretion of newly seeded 3T3-L1s, and we examined altered integrin specificity as a potential mechanism of modified cell-matrix interactions through integrin blockers. Our data indicate that tumor-conditioned Fn decreases adhesion while enhancing VEGF secretion by preadipocytes, and that an integrin switch is responsible for such changes. Collectively, our findings suggest that simultaneous stiffening and unfolding of initially deposited tumor-conditioned Fn alters both adhesion and proangiogenic behavior of surrounding stromal cells, likely promoting vascularization and growth of the breast tumor. This work enhances our knowledge of cell - Fn matrix interactions that may be exploited for other biomaterials-based applications, including advanced tissue engineering approaches.
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA; Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Karin
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Andresen Eguiluz
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Fei
authors.initials: F
authors.lastname: Wu
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Bo Ri
authors.initials: BR
authors.lastname: Seo
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA; Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fischbach
authors.affiliation: Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA; Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA. Electronic address: dg434@cornell.edu.
authors.forename: Delphine
authors.initials: D
authors.lastname: Gourdon
mesh_terms: D041721:3T3-L1 Cells; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000556:secondary*; D045744:Cell Line, Tumor; D055119:Elastic Modulus; D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D040542:Mechanotransduction, Cellular; D051379:Mice; D009389:Neovascularization, Pathologic / Q000378:metabolism*; D011489:Protein Denaturation; D017510:Protein Folding; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D042461:Vascular Endothelial Growth Factor A
keywords: Integrin switch; Matrix stiffness; Molecular unfolding; Proangiogenic factor secretion; Tumor-conditioned fibronectin