title: Substrate stiffness promotes latent TGF-β1 activation in hepatocellular carcinoma.
abstract: Hepatocellular carcinoma (HCC) was usually coupled with increased stiffness of the extracellular matrix (ECM) and elevated level of transforming growth factor-β1 (TGF-β1). However, the mechanism by which substrate rigidity modulated TGF-β1 signaling transduction remained unknown. This paper investigated the molecular mechanism of how matrix stiffness regulating TGF-β1 signaling in HCC cells. By means of stiffness tunable collagen I-coated polyacrylamide (PA) gels, we found that the expressions of β1 integrin, p-FAKY397and p-Smad2 upregulated on stiffer gels as well as the content of TGF-β1 in culture media of HCC cells, which were inhibited by RGD blocking peptides, Y-27632 (ROCK inhibitor) or Blebbistatin (myosin II inhibitor). Cellular traction force was also significantly higher when plated on stiffer substrates but dramatically decreased after treatment with Y-27632 or Blebbistatin. Furthermore, the upregulation of p-Smad2 in the HCC cells on stiffer PA gels induced by exogenetic latent TGF-β1 was downregulated in the presence of RGD peptides. The nuclear translocation of Smad2 induced by latent TGF-β1 was inhibited by Y-27632 or Blebbistatin. Our results suggested that the extracellular matrix stiffness regulated latent TGF-β1 activation by cytoskeletal tension in HCC cells, showing that matrix stiffness was a key regulator involving the TGF-β1 activity in HCC cells. The current study presented a mechanism of how hepatocirrhosis developed into liver cancer.
authors.affiliation: Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Mingshu
authors.initials: M
authors.lastname: Pang
authors.affiliation: Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Teng
authors.affiliation: Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China; Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA. Electronic address: hjypku@gmail.com.
authors.forename: Jianyong
authors.initials: J
authors.lastname: Huang
authors.affiliation: College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai 201306, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.affiliation: Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China. Electronic address: cyxiong@pku.edu.cn.
authors.forename: Chunyang
authors.initials: C
authors.lastname: Xiong
mesh_terms: D000577:Amides / Q000737:chemistry; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D045744:Cell Line, Tumor; D003599:Cytoskeleton / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D056945:Hep G2 Cells; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry; D015398:Signal Transduction; D051899:Smad2 Protein / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation; D020741:rho GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000577:Amides; D006576:Heterocyclic Compounds, 4 or More Rings; D019012:Integrin beta1; D009842:Oligopeptides; D011725:Pyridines; C497782:SMAD2 protein, human; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; C108830:Y 27632; C472645:blebbistatin; C047981:arginyl-glycyl-aspartic acid; D051416:Focal Adhesion Protein-Tyrosine Kinases; D020741:rho GTP-Binding Proteins
keywords: Hepatocellular carcinoma; Substrate stiffness; Traction forces; Transforming growth factor β1; β1 integrin