title: Tissue stiffness regulates serine/arginine-rich protein-mediated splicing of the extra domain B-fibronectin isoform in tumors.
abstract: Alternative splicing of proteins gives rise to different isoforms that play a crucial role in regulating several cellular processes. Notably, splicing profiles are altered in several cancer types, and these profiles are believed to be involved in driving the oncogenic process. Although the importance of alternative splicing alterations occurring during cancer is increasingly appreciated, the underlying regulatory mechanisms remain poorly understood. In this study, we use both biochemical and physical tools coupled with engineered models, patient samples, and a murine model to investigate the role of the mechanical properties of the tumor microenvironment in regulating the production of the extra domain-B (EDB) splice variant of fibronectin (FN), a hallmark of tumor angiogenesis. Specifically, we show that the amount of EDB-FN produced by endothelial cells increases with matrix stiffness both in vitro and within mouse mammary tumors. Matrix stiffness regulates splicing through the activation of serine/arginine rich (SR) proteins, the splicing factors involved in the production of FN isoforms. Activation of the SR proteins by matrix stiffness and the subsequent production of EDB-FN are dependent on intracellular contractility and PI3K-AKT signaling. Notably, matrix stiffness-mediated splicing is not limited to EDB-FN, but also affects splicing in the production of PKC βII and the VEGF 165b splice variant. Together, these results demonstrate that the mechanical properties of the microenvironment regulate alternative splicing and establish a previously unidentified mechanism by which cells can adapt to their microenvironment.
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853;
authors.forename: Francois
authors.initials: F
authors.lastname: Bordeleau
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853;
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Califano
authors.affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853;
authors.forename: Yashira L
authors.initials: YL
authors.lastname: Negrón Abril
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853;
authors.forename: Brooke N
authors.initials: BN
authors.lastname: Mason
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853;
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: LaValley
authors.affiliation: Department of Pathology and Laboratory Medicine, The New York Presbyterian Hospital-Weill Cornell Medical College, New York, NY 10065.
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shin
authors.affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853;
authors.forename: Robert S
authors.initials: RS
authors.lastname: Weiss
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853; cak57@cornell.edu.
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Reinhart-King
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D001696:Biomechanical Phenomena; D015153:Blotting, Western; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism; D005109:Extracellular Matrix / Q000737:chemistry / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D009369:Neoplasms / Q000098:blood supply / Q000235:genetics* / Q000378:metabolism; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D059016:Tumor Microenvironment / Q000235:genetics*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D005353:Fibronectins; D020033:Protein Isoforms; D042461:Vascular Endothelial Growth Factor A; D012694:Serine; D001120:Arginine; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D054460:rho-Associated Kinases
keywords: alternative splicing; angiogenesis; cancer progression; extracellular matrix; matrix stiffness