Argonaute-2 Expression Is Regulated by Epidermal Growth Factor Receptor and Mitogen-Activated Protein Kinase Signaling and Correlates with a Transformed Phenotype in Breast Cancer Cells
Argonaute-2 Expression Is Regulated by Epidermal Growth Factor Receptor and Mitogen-Activated Protein Kinase Signaling and Correlates with a Transformed Phenotype in Breast Cancer Cells
复制标题
DOI：
10.1210/en.2008-0984
复制
发表时间：
2009-01-01
期刊：
影响因子：
4.8
通讯作者：
White, Bruce A.
中科院分区：
文献类型：
--
作者：
Adams, Brian D.;Claffey, Kevin P.;White, Bruce A.
Argonaute（Ago）2是哺乳动物RNA干扰的催化引擎，但关于Ago 2通过细胞信号传导途径的调节知之甚少。在这项研究中，我们发现，在雌激素受体（ER）α阴性（ER α（-））与ER α阳性（ER α（+））乳腺癌细胞系中，以及在ER α（-）乳腺肿瘤中，Ago 2的表达升高，而Ago 1、Ago 3或Ago 4则没有。在MCF-7细胞中，发现低水平的Ago 2依赖于活性ER α/雌激素信号传导。有趣的是，通过使用药理学MAPK激酶抑制剂U 0126或针对EGF受体的小干扰RNA抑制表皮生长因子（EGF）受体/MAPK信号通路，ER α（-）细胞中Ago 2的高表达被严重减弱。使用放线菌酮的半衰期研究表明，EGF增强，而U 0126降低，Ago 2蛋白的稳定性。此外，蛋白体抑制剂MG 132阻断Ago 2蛋白周转。通过用全长和截短形式的Ago 2稳定转染ER alpha（+）MCF-7细胞来检查Ago 2水平升高的功能后果。全长Ago 2转染子显示增殖增强，细胞间粘附减少，迁移能力增加，分别通过增殖，同型聚集和伤口愈合试验显示。全长Ago 2的过表达，而不是Ago 2的截短形式或空载体对照，降低了E-钙粘蛋白、β-连环蛋白和β-肌动蛋白的水平，以及增强了内源性miR-206活性。这些数据表明Ago 2在转录和翻译后水平都受到调节，并且还暗示Ago 2和增强的micro-RNA活性在乳腺癌细胞系的致瘤进展中。（内分泌学150：14-23，2009）
Argonaute (Ago) 2 is the catalytic engine of mammalian RNA interference, but little is known concerning the regulation of Ago2 by cell-signaling pathways. In this study we show that expression of Ago2, but not Ago1, Ago3, or Ago4, is elevated in estrogen receptor (ER) alpha-negative (ER alpha(-)) vs. ER alpha-positive (ER alpha(+)) breast cancer cell lines, and in ER alpha(-) breast tumors. In MCF-7 cells the low level of Ago2 was found to be dependent upon active ER alpha/estrogen signaling. Interestingly, the high expression of Ago2 in ER alpha(-) cells was severely blunted by inhibition of the epidermal growth factor (EGF) receptor/MAPK signaling pathway, using either a pharmacological MAPK kinase inhibitor, U0126, or a small interfering RNA directed against EGF receptor. Half-life studies using cycloheximide indicated that EGF enhanced, whereas U0126 decreased, Ago2 protein stability. Furthermore, a proteosome inhibitor, MG132, blocked Ago2 protein turnover. The functional consequences of elevated Ago2 levels were examined by stable transfection of ER alpha(+) MCF-7 cells with full-length and truncated forms of Ago2. The full-length Ago2 transfectants displayed enhanced proliferation, reduced cell-cell adhesion, and increased migratory ability, as shown by proliferation, homotypic aggregation, and wound healing assays, respectively. Overexpression of full-length Ago2, but not truncated forms of Ago2 or an empty vector control, reduced the levels of E-cadherin, beta-catenin, and beta-actin, as well as enhanced endogenous miR-206 activity. These data indicate that Ago2 is regulated at both the transcriptional and posttranslational level, and also implicate Ago2 and enhanced micro-RNA activity in the tumorigenic progression of breast cancer cell lines. (Endocrinology 150: 14-23, 2009)