Kocher H M, Sandle J, Mirza T A, Li N F, Hart I R
Centre for Tumour Biology, Institute of Cancer and CR-UK Clinical Centre, Barts & The London School of Medicine & Dentistry, John Vane Science Centre, London, UK.
Gut. 2009 Feb;58(2):271-84. doi: 10.1136/gut.2008.159871. Epub 2008 Oct 13.
Pancreatic cancer is a highly invasive malignancy. Ezrin, a plasma membrane-cytoskeletal linker protein, is associated with the invasive behaviour of cancers. The purpose of this study was to elucidate a possible molecular mechanism for the invasive phenotype.
Using a combination of techniques, such as western blotting, co-immunoprecipitation, confocal and light microscopy, invasion and adhesion assays, organotypic cultures and human samples as well as RNA interference (RNAi) and expression of various mutant ezrin constructs, the dynamic molecular nature of podosomes in pancreatic cancer was dissected out.
Podosome and podosomal rosette formation in pancreatic carcinoma (PaCa3) cells is ezrin dependent and associated with adhesion to fibronectin with subsequent digestion of this substrate. Ezrin binds to increasing amounts of cortactin during formation of the podosomal rosette, with the C-terminal region, specifically the actin-binding domain, mediating this molecular linkage. Further, it is shown that phosphorylation of Tyr353 and Thr567 sites on ezrin (conventionally shown to translocate ezrin to the plasma membrane) is not required for podosome formation. The podosomal rosette is revealed to be a highly dynamic and transient structure, which can metamorphose into other cellular processes, such as filopodia or lamellipodia, and thereby enable epithelial cancer cells to "palpate" the underlying substrate and modify their cytoskeletal behaviour accordingly. In human tumour tissues and organotypic cultures, specific subcellular expression of ezrin (basal membranous; cellular processes invading stroma) in pancreatic cancer cells can be correlated with tumour progression and disease-free survival (log-rank test (Mantel-Cox), p = 0.019).
Podosomes and their rosettes are driven by ezrin-cortactin interaction and this plays a role in pancreatic cancer invasion.
胰腺癌是一种具有高度侵袭性的恶性肿瘤。埃兹蛋白是一种质膜 - 细胞骨架连接蛋白，与癌症的侵袭行为相关。本研究的目的是阐明侵袭表型可能的分子机制。
运用多种技术相结合，如蛋白质免疫印迹法、免疫共沉淀法、共聚焦和光学显微镜观察、侵袭与黏附实验、器官型培养及人体样本检测，以及RNA干扰（RNAi）和各种突变型埃兹蛋白构建体的表达，剖析胰腺癌中足体的动态分子特性。
胰腺癌（PaCa3）细胞中足体和足体玫瑰花结的形成依赖于埃兹蛋白，且与黏附于纤连蛋白并随后降解该底物有关。在足体玫瑰花结形成过程中，埃兹蛋白与越来越多的皮层肌动蛋白结合，其C末端区域，特别是肌动蛋白结合结构域介导了这种分子连接。此外，研究表明埃兹蛋白上Tyr353和Thr567位点的磷酸化（传统上认为可使埃兹蛋白转位至质膜）并非足体形成所必需。足体玫瑰花结是一种高度动态和短暂的结构，它可以转变为其他细胞过程，如丝状伪足或片状伪足，从而使上皮癌细胞能够“感知”下层底物并相应地改变其细胞骨架行为。在人类肿瘤组织和器官型培养中，胰腺癌细胞中埃兹蛋白的特定亚细胞表达（基底膜；侵入基质的细胞突起）与肿瘤进展和无病生存期相关（对数秩检验（曼特尔 - 考克斯），p = 0.019）。
足体及其玫瑰花结由埃兹蛋白 - 皮层肌动蛋白相互作用驱动，这在胰腺癌侵袭中发挥作用。
