title: Soft matrices downregulate FAK activity to promote growth of tumor-repopulating cells.
abstract: Tumor-repopulating cells (TRCs) are a tumorigenic sub-population of cancer cells that drives tumorigenesis. We have recently reported that soft fibrin matrices maintain TRC growth by promoting histone 3 lysine 9 (H3K9) demethylation and Sox2 expression and that Cdc42 expression influences H3K9 methylation. However, the underlying mechanisms of how soft matrices induce H3K9 demethylation remain elusive. Here we find that TRCs exhibit lower focal adhesion kinase (FAK) and H3K9 methylation levels in soft fibrin matrices than control melanoma cells on 2D rigid substrates. Silencing FAK in control melanoma cells decreases H3K9 methylation, whereas overexpressing FAK in tumor-repopulating cells enhances H3K9 methylation. Overexpressing Cdc42 or RhoA in the presence of FAK knockdown restores H3K9 methylation levels. Importantly, silencing FAK, Cdc42, or RhoA promotes Sox2 expression and proliferation of control melanoma cells in stiff fibrin matrices, whereas overexpressing each gene suppresses Sox2 expression and reduces growth of TRCs in soft but not in stiff fibrin matrices. Our findings suggest that low FAK mediated by soft fibrin matrices downregulates H3K9 methylation through reduction of Cdc42 and RhoA and promotes TRC growth.
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hunghom, Kowloon, Hong Kong SAR, China.
authors.forename: Youhua
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Adam Richard
authors.initials: AR
authors.lastname: Wood
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Qiong
authors.initials: Q
authors.lastname: Jia
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Junyu
authors.initials: J
authors.lastname: Luo
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Junwei
authors.initials: J
authors.lastname: Chen
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China.
authors.forename: Junjian
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.affiliation: Center for Neuro-Medicine, Brain Science Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 136-791, South Korea.
authors.forename: Jihye
authors.initials: J
authors.lastname: Seong
authors.affiliation: Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Arash
authors.initials: A
authors.lastname: Tajik
authors.affiliation: Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
authors.forename: Rishi
authors.initials: R
authors.lastname: Singh
authors.affiliation: Laboratory for Cell Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, 430074, China; Department of Mechanical Science and Engineering, College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. Electronic address: nwangrw@illinois.edu.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D006657:Histones; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008545:Melanoma / Q000378:metabolism / Q000473:pathology; D008745:Methylation; D051379:Mice; D055748:SOXB1 Transcription Factors / Q000378:metabolism; D014410:Tumor Stem Cell Assay / Q000379:methods; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D006657:Histones; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; C066737:RHOA protein, human; D051417:Focal Adhesion Kinase 1; C496050:PTK2 protein, human; C496051:Ptk2 protein, mouse; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein; D008239:Lysine
keywords: Cancer; Focal adhesion kinase; Growth; Matrix stiffness; Tumor repopulating cell