Seton-Rogers Sarah E, Lu Yu, Hines Lisa M, Koundinya Malvika, LaBaer Joshua, Muthuswamy Senthil K, Brugge Joan S
Department of Cell Biology and Harvard Institute of Proteomics, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 2004 Feb 3;101(5):1257-62. doi: 10.1073/pnas.0308090100. Epub 2004 Jan 22.
MCF10A mammary epithelial cells form growth-arrested structures when cultured in three-dimensional basement membrane gels. Activation of the receptor tyrosine kinase ErbB2 induces formation of proliferative structures that share properties with noninvasive early stage lesions. We conducted a genetic screen to identify cDNAs that can cooperate with ErbB2 to induce migration in these cells, with the hypothesis that they would represent candidate "second hits" in the development of invasive breast carcinomas. We found that expression of transforming growth factor (TGF)beta1 and TGFbeta3 in cells expressing activated ErbB2 induces migration in transwell chambers and invasive behavior in both basement membrane cultures and invasion chambers. The ability of ErbB2 to cooperate with TGFbeta correlated with sustained, elevated activation of extracellular signal-regulated kinase (Erk)-mitogen-activated protein kinase. Pharmacological reduction of Erk activity inhibited the cooperative effect of TGFbeta and ErbB2 on migration and expression of activated Erk kinase was sufficient to cooperate with TGFbeta to induce migration and invasion, suggesting that sustained Erk activation is critical for ErbB2/TGFbeta cooperation. In addition, we show that costimulation of ErbB2 and TGFbeta induces autocrine secretion of factors that are sufficient to induce migration, but not invasion, by means of both epidermal growth factor receptor-dependent and -independent processes. These results support the role of TGFbeta as a pro-invasion factor in the progression of breast cancers with activated ErbB2 and suggest that activation of the Erk and epidermal growth factor receptor pathways are key in mediating these events.
MCF10A乳腺上皮细胞在三维基底膜凝胶中培养时会形成生长停滞的结构。受体酪氨酸激酶ErbB2的激活会诱导增殖性结构的形成，这些结构与非侵袭性早期病变具有共同特征。我们进行了一项基因筛选，以鉴定能够与ErbB2协同作用诱导这些细胞迁移的cDNA，假设它们可能代表侵袭性乳腺癌发展过程中的候选“二次打击”。我们发现，在表达活化ErbB2的细胞中，转化生长因子（TGF）β1和TGFβ3的表达会诱导细胞在Transwell小室中迁移，并在基底膜培养物和侵袭小室中表现出侵袭行为。ErbB2与TGFβ协同作用的能力与细胞外信号调节激酶（Erk）-丝裂原活化蛋白激酶的持续、升高的激活相关。药理学方法降低Erk活性可抑制TGFβ和ErbB2对迁移的协同作用，而活化的Erk激酶的表达足以与TGFβ协同诱导迁移和侵袭，这表明持续的Erk激活对于ErbB2/TGFβ的协同作用至关重要。此外，我们表明，ErbB2和TGFβ的共刺激会诱导自分泌因子，这些因子足以通过表皮生长因子受体依赖性和非依赖性过程诱导迁移，但不能诱导侵袭。这些结果支持TGFβ在具有活化ErbB2的乳腺癌进展中作为促侵袭因子的作用，并表明Erk和表皮生长因子受体途径的激活是介导这些事件的关键。
