Zhang Libo, Fogg Darin K, Waisman David M
Cancer Biology Research Group, Departments of Biochemistry & Molecular Biology and Oncology, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
J Biol Chem. 2004 Jan 16;279(3):2053-62. doi: 10.1074/jbc.M310357200. Epub 2003 Oct 21.
S100A10 is a key plasminogen receptor of the extracellular cell surface that is overexpressed in many cancer cells. Typically, S100A10 is thought to be anchored to the plasma membrane via the phospholipid-binding sites of its binding partner, annexin A2. Here, using the potent and highly sequence-specific mechanism of RNA interference (RNAi), we have stably silenced the expression of the S100A10 gene in colorectal (CCL-222) cancer cells. We show that siRNA expression mediated by the pSUPER vector causes efficient, stable, and specific down-regulation of S100A10 gene expression. The siRNA-mediated down-regulation of S100A10 gene expression resulted in a major decrease in the appearance of extracellular S100A10 protein and correlated with a 45% loss of plasminogen binding, a 65% loss in cellular plasmin generation and a complete loss in plasminogen-dependent cellular invasiveness. We also observed that the CCL-222 cells do not express annexin A2 on their extracellular surface. Thus, the data show that annexin A2 is not required by S100A10 for its association with the plasma membrane, for its colocalization with uPAR, or for its binding and activation of plasminogen.
S100A10是细胞外细胞表面的一种关键纤溶酶原受体，在许多癌细胞中过表达。通常认为，S100A10通过其结合伴侣膜联蛋白A2的磷脂结合位点锚定在质膜上。在此，我们利用强大且高度序列特异性的RNA干扰（RNAi）机制，在结肠直肠癌（CCL - 222）细胞中稳定沉默了S100A10基因的表达。我们发现，由pSUPER载体介导的siRNA表达可有效、稳定且特异性地下调S100A10基因的表达。siRNA介导的S100A10基因表达下调导致细胞外S100A10蛋白的出现大幅减少，并且与纤溶酶原结合减少45%、细胞纤溶酶生成减少65%以及纤溶酶原依赖性细胞侵袭性完全丧失相关。我们还观察到，CCL - 222细胞在其细胞外表面不表达膜联蛋白A2。因此，数据表明，S100A10与质膜的结合、与尿激酶型纤溶酶原激活物受体（uPAR）的共定位以及与纤溶酶原的结合和激活并不需要膜联蛋白A2。
