Amsellem Valérie, Kryszke Marie-Hélène, Hervy Martial, Subra Frédéric, Athman Rafika, Leh Hervé, Brachet-Ducos Corinne, Auclair Christian
Laboratoire de Biotechnologie et Pharmacologie génétique appliquée, CNRS UMR 8113, Ecole Normale Supérieure de Cachan, 61 avenue du Président Wilson, 94230 Cachan, France.
Exp Cell Res. 2005 Apr 1;304(2):443-56. doi: 10.1016/j.yexcr.2004.10.035. Epub 2004 Dec 13.
Changes in cell architecture, essentially linked to profound cytoskeleton rearrangements, are common features accompanying cell transformation. Supporting the involvement of the microfilament network in tumor cell behavior, several actin-binding proteins, including zyxin, a potential regulator of actin polymerization, may play a role in oncogenesis. In this work, we investigate the status of zyxin in Ewing tumors, a family of pediatric malignancies of bone and soft tissues, which are mainly associated with a t(11;22) chromosomal translocation encoding the EWS-FLI1 oncoprotein. We observe that EWS-FLI1-transformed murine fibroblasts, as well as human Ewing tumor-derived SK-N-MC cells, exhibit a complete disruption of their actin cytoskeleton, retaining very few stress fibers, focal adhesions and cell-to-cell contacts. We show that within these cells, zyxin is expressed at very low levels and remains diffusely distributed throughout the cytoplasm, instead of concentrating in actin-rich dynamic structures. We demonstrate that zyxin gene transfer into EWS-FLI1-transformed fibroblasts elicits reconstitution of zyxin-rich focal adhesions and intercellular junctions, dramatic reorganization of the actin cytoskeleton, decreased cell motility, inhibition of anchorage-independent growth and impairment of tumor formation in athymic mice. We observe similar phenotypic changes after zyxin gene transfer in SK-N-MC cells, suggesting that zyxin has tumor suppressor activity in Ewing tumor cells.
细胞结构的变化与深刻的细胞骨架重排密切相关，是细胞转化过程中的常见特征。有几种肌动蛋白结合蛋白，包括锌指蛋白（一种肌动蛋白聚合的潜在调节因子），支持微丝网络参与肿瘤细胞行为，它们可能在肿瘤发生过程中发挥作用。在这项研究中，我们调查了锌指蛋白在尤因肿瘤中的状态，尤因肿瘤是一类儿童期骨和软组织恶性肿瘤，主要与编码EWS-FLI1癌蛋白的t(11;22)染色体易位有关。我们观察到，EWS-FLI1转化的小鼠成纤维细胞以及人尤因肿瘤来源的SK-N-MC细胞，其肌动蛋白细胞骨架完全破坏，仅保留极少的应力纤维、粘着斑和细胞间接触。我们发现，在这些细胞中，锌指蛋白表达水平极低，且在整个细胞质中呈弥散分布，而不是集中在富含肌动蛋白的动态结构中。我们证明，将锌指蛋白基因导入EWS-FLI1转化的成纤维细胞可引发富含锌指蛋白的粘着斑和细胞间连接的重建、肌动蛋白细胞骨架的显著重组、细胞运动性降低、非锚定依赖性生长的抑制以及无胸腺小鼠肿瘤形成的受损。在SK-N-MC细胞中进行锌指蛋白基因转移后，我们观察到了类似的表型变化，这表明锌指蛋白在尤因肿瘤细胞中具有肿瘤抑制活性。
