Gkretsi Vasiliki, Stylianou Andreas, Stylianopoulos Triantafyllos
Cancer Biophysics Laboratory, Department of Mechanical and Manufacturing Engineering, University of Cyprus, Cyprus.
Cancer Biophysics Laboratory, Department of Mechanical and Manufacturing Engineering, University of Cyprus, Cyprus.
Exp Cell Res. 2017 Mar 15;352(2):281-292. doi: 10.1016/j.yexcr.2017.02.019. Epub 2017 Feb 14.
A hallmark of cancer cells is their ability to invade surrounding tissues and form metastases. Cell-extracellular matrix (ECM)-adhesion proteins are crucial in metastasis, connecting tumor ECM with actin cytoskeleton thus enabling cells to respond to mechanical cues. Vasodilator-stimulated phosphoprotein (VASP) is an actin-polymerization regulator which interacts with cell-ECM adhesion protein Migfilin, and regulates cell migration. We compared VASP expression in MCF-7 and MDA-MB-231 breast cancer (BC) cells and found that more invasive MDA-MB-231 cells overexpress VASP. We then utilized a 3-dimensional (3D) approach to study metastasis in MDA-MB-231 cells using a system that considers mechanical forces exerted by the ECM. We prepared 3D collagen I gels of increasing concentration, imaged them by atomic force microscopy, and used them to either embed cells or tumor spheroids, in the presence or absence of VASP. We show, for the first time, that VASP silencing downregulated Migfilin, β-catenin and urokinase plasminogen activator both in 2D and 3D, suggesting a matrix-independent mechanism. Tumor spheroids lacking VASP demonstrated impaired invasion, indicating VASP's involvement in metastasis, which was corroborated by Kaplan-Meier plotter showing high VASP expression to be associated with poor remission-free survival in lymph node-positive BC patients. Hence, VASP may be a novel BC metastasis biomarker.
癌细胞的一个标志是它们侵袭周围组织并形成转移灶的能力。细胞-细胞外基质（ECM）黏附蛋白在转移过程中至关重要，它将肿瘤ECM与肌动蛋白细胞骨架相连，从而使细胞能够对机械信号作出反应。血管舒张刺激磷蛋白（VASP）是一种肌动蛋白聚合调节剂，它与细胞-ECM黏附蛋白Migfilin相互作用，并调节细胞迁移。我们比较了MCF-7和MDA-MB-231乳腺癌（BC）细胞中VASP的表达情况，发现侵袭性更强的MDA-MB-231细胞过表达VASP。然后，我们采用三维（3D）方法，利用一个考虑了ECM施加的机械力的系统来研究MDA-MB-231细胞的转移。我们制备了浓度递增的3D I型胶原蛋白凝胶，用原子力显微镜对其成像，并在有或没有VASP的情况下，将细胞或肿瘤球体嵌入其中。我们首次表明，VASP沉默在二维和三维条件下均下调了Migfilin、β-连环蛋白和尿激酶型纤溶酶原激活剂，提示存在一种不依赖基质的机制。缺乏VASP的肿瘤球体侵袭能力受损，表明VASP参与转移，这一点得到了Kaplan-Meier绘图仪的证实，该绘图仪显示高VASP表达与淋巴结阳性BC患者无缓解生存期差有关。因此，VASP可能是一种新型的BC转移生物标志物。
