D'Angelo Rosemarie Chirco, Liu Xu-Wen, Najy Abdo J, Jung Young Suk, Won Joshua, Chai Karl X, Fridman Rafael, Kim Hyeong-Reh Choi
Department of Pathology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan.
Department of Pathology, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan
Mol Cancer Res. 2014 Sep;12(9):1324-33. doi: 10.1158/1541-7786.MCR-14-0105. Epub 2014 Jun 3.
Tissue inhibitor of metalloproteinase-1 (TIMP-1) regulates intracellular signaling networks for inhibition of apoptosis. Tetraspanin (CD63), a cell surface binding partner for TIMP-1, was previously shown to regulate integrin-mediated survival pathways in the human breast epithelial cell line MCF10A. In the current study, we show that TIMP-1 expression induces phenotypic changes in cell morphology, cell adhesion, cytoskeletal remodeling, and motility, indicative of an epithelial-mesenchymal transition (EMT). This is evidenced by loss of the epithelial cell adhesion molecule E-cadherin with an increase in the mesenchymal markers vimentin, N-cadherin, and fibronectin. Signaling through TIMP-1, but not TIMP-2, induces the expression of TWIST1, an important EMT transcription factor known to suppress E-cadherin transcription, in a CD63-dependent manner. RNAi-mediated knockdown of TWIST1 rescued E-cadherin expression in TIMP-1-overexpressing cells, demonstrating a functional significance of TWIST1 in TIMP-1-mediated EMT. Furthermore, analysis of TIMP-1 structural mutants reveals that TIMP-1 interactions with CD63 that activate cell survival signaling and EMT do not require the matrix metalloproteinase (MMP)-inhibitory domain of TIMP-1. Taken together, these data demonstrate that TIMP-1 binding to CD63 activates intracellular signal transduction pathways, resulting in EMT-like changes in breast epithelial cells, independent of its MMP-inhibitory function.
TIMP-1's function as an endogenous inhibitor of MMP or as a "cytokine-like" signaling molecule may be a critical determinant for tumor cell behavior.
金属蛋白酶组织抑制剂-1（TIMP-1）调节细胞内信号网络以抑制细胞凋亡。四跨膜蛋白（CD63）是TIMP-1的细胞表面结合伴侣，先前已证明其可调节人乳腺上皮细胞系MCF10A中整合素介导的生存途径。在本研究中，我们表明TIMP-1表达诱导细胞形态、细胞粘附、细胞骨架重塑和运动性的表型变化，这表明上皮-间质转化（EMT）。上皮细胞粘附分子E-钙粘蛋白的丧失以及间充质标志物波形蛋白、N-钙粘蛋白和纤连蛋白的增加证明了这一点。通过TIMP-1而非TIMP-2发出的信号以CD63依赖的方式诱导TWIST1的表达，TWIST1是一种重要的EMT转录因子，已知可抑制E-钙粘蛋白转录。RNA干扰介导的TWIST1敲低挽救了TIMP-1过表达细胞中E-钙粘蛋白的表达，证明了TWIST1在TIMP-1介导的EMT中的功能重要性。此外，对TIMP-1结构突变体的分析表明，TIMP-1与CD63的相互作用激活细胞生存信号和EMT不需要TIMP-1的基质金属蛋白酶（MMP）抑制结构域。综上所述，这些数据表明TIMP-1与CD63的结合激活细胞内信号转导途径，导致乳腺上皮细胞发生类似EMT的变化，与其MMP抑制功能无关。
TIMP-1作为MMP的内源性抑制剂或作为“细胞因子样”信号分子的功能可能是肿瘤细胞行为的关键决定因素。
