Cowden Dahl Karen D, Symowicz Jaime, Ning Yan, Gutierrez Elisa, Fishman David A, Adley Brian P, Stack M Sharon, Hudson Laurie G
Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, Albuquerque, New Mexico, USA.
Cancer Res. 2008 Jun 15;68(12):4606-13. doi: 10.1158/0008-5472.CAN-07-5046.
Epidermal growth factor (EGF) receptor (EGFR) is frequently elevated in epithelial ovarian cancer, and E-cadherin expression is often reduced in advanced disease. In this study, we investigated a mechanism by which EGFR activation promotes disruption of adherens junctions through induction of matrix metalloproteinase 9 (MMP-9). We show that EGFR activation down-modulates E-cadherin, and broad spectrum MMP inhibition ameliorates EGF-stimulated junctional disruption and loss of E-cadherin protein. MMP-9 involvement in EGF-dependent down-regulation of E-cadherin was determined by siRNA specifically directed against MMP-9. Furthermore, treatment with recombinant MMP-9 or transient expression of MMP-9 is sufficient to reduce E-cadherin levels in differentiated ovarian tumor cells. Stable overexpression of MMP-9 led to a loss of E-cadherin and junctional integrity, and promoted a migratory and invasive phenotype. Thus, elevated MMP-9 protein expression is sufficient for junctional disruption and loss of E-cadherin in these cells. The associations between EGFR activation, MMP-9 expression, and E-cadherin were investigated in human ovarian tumors and paired peritoneal metastases wherein immunohistochemical staining for activated (phospho) EGFR and MMP-9 colocalized with regions of reduced E-cadherin. These data suggest that regulation of MMP-9 by EGFR may represent a novel mechanism for down-modulation of E-cadherin in ovarian cancer.
表皮生长因子（EGF）受体（EGFR）在上皮性卵巢癌中常常上调，而E-钙黏蛋白的表达在晚期疾病中常常降低。在本研究中，我们探究了一种机制，即EGFR激活通过诱导基质金属蛋白酶9（MMP-9）促进黏附连接的破坏。我们发现EGFR激活下调E-钙黏蛋白，而广谱MMP抑制可改善EGF刺激的连接破坏和E-钙黏蛋白的丢失。通过特异性针对MMP-9的siRNA确定了MMP-9参与EGF依赖性的E-钙黏蛋白下调。此外，用重组MMP-9处理或MMP-9的瞬时表达足以降低分化型卵巢肿瘤细胞中E-钙黏蛋白的水平。MMP-9的稳定过表达导致E-钙黏蛋白和连接完整性的丧失，并促进迁移和侵袭表型。因此，升高的MMP-9蛋白表达足以导致这些细胞中的连接破坏和E-钙黏蛋白的丢失。在人卵巢肿瘤和配对的腹膜转移瘤中研究了EGFR激活、MMP-9表达和E-钙黏蛋白之间的关联，其中活化（磷酸化）EGFR和MMP-9的免疫组织化学染色与E-钙黏蛋白减少的区域共定位。这些数据表明，EGFR对MMP-9的调节可能代表卵巢癌中E-钙黏蛋白下调的一种新机制。
