Pang Mingshu, Teng Yao, Huang Jianyong, Yuan Yuan, Lin Feng, Xiong Chunyang
Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China; Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
Biochem Biophys Res Commun. 2017 Jan 29;483(1):553-558. doi: 10.1016/j.bbrc.2016.12.107. Epub 2016 Dec 24.
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-FAK and 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.
肝细胞癌（HCC）通常与细胞外基质（ECM）硬度增加和转化生长因子-β1（TGF-β1）水平升高相关。然而，底物硬度调节TGF-β1信号转导的机制尚不清楚。本文研究了基质硬度如何调节HCC细胞中TGF-β1信号的分子机制。通过使用硬度可调的I型胶原包被的聚丙烯酰胺（PA）凝胶，我们发现，在较硬的凝胶上，β1整合素、磷酸化粘着斑激酶（p-FAK）和磷酸化Smad2的表达上调，同时HCC细胞培养基中TGF-β1的含量也增加，而这些变化被RGD阻断肽、Y-27632（ROCK抑制剂）或Blebbistatin（肌球蛋白II抑制剂）所抑制。当接种在较硬的底物上时，细胞牵引力也显著更高，但在用Y-27632或Blebbistatin处理后显著降低。此外，在存在RGD肽的情况下，外源性潜伏TGF-β1诱导的较硬PA凝胶上HCC细胞中p-Smad2的上调被下调。潜伏TGF-β1诱导的Smad2核转位被Y-27632或Blebbistatin抑制。我们的结果表明，细胞外基质硬度通过HCC细胞中的细胞骨架张力调节潜伏TGF-β1的激活，表明基质硬度是涉及HCC细胞中TGF-β1活性的关键调节因子。本研究提出了肝硬化发展为肝癌的机制。
