Oncogenic Neu/ErbB-2 increases ets, AP-1, and NF-kappa B-dependent gene expression, and inhibiting ets activation blocks neu-mediated cellular transformation
Oncogenic Neu/ErbB-2 increases ets, AP-1, and NF-kappa B-dependent gene expression, and inhibiting ets activation blocks neu-mediated cellular transformation
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DOI：
10.1074/jbc.271.14.7992
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发表时间：
1996-04-05
影响因子：
4.8
通讯作者：
Hauser, CA
中科院分区：
文献类型：
--
作者：
Galang, CK;GarciaRamirez, JJ;Hauser, CA
Neu (ErbB-2/HER2) 过度表达存在于约 20% 的乳腺肿瘤中。点突变 (Neu(T)) 激活 Neu 会导致该跨膜受体的组成型酪氨酸激酶活性和成纤维细胞中的转化活性。为了确定 Neu 的下游靶点，我们分析了 Neu 激活基因表达的能力。 Neu(T) 而非正常 Neu 的表达引起 Ets、AP-1 或 NF-kappa B 依赖性报告基因的转录激活。显性抑制性 Ras 或 Raf 突变体阻断了 Neu 介导的转录激活，证实了 Ras 信号通路是这种激活所必需的。对 Ets2 突变体的分析表明，Neu(T) 或致癌 Ras 介导的 Ets2 转录活性的激活需要相同 Ets2 残基苏氨酸 72 的磷酸化。显性抑制性 Ets2 突变体的共转染特异性阻断 Neu(T) 介导的 Ets 依赖性报告基因的激活。此外，在使用 NIH 3T3 细胞的病灶形成测定中，当 Neu(T) 与显性失活 Ets2 突变体共转染时，Neu(T) 的转化活性被抑制 5 倍。然而，平行集落形成测定表明，Ets2 显性失活突变体不会抑制正常细胞的生长。总之，这些数据表明 Neu(T) 通过 Ras 信号通路激活多种转录因子家族，并且 Ets 激活是 Neu(T) 介导的细胞转化所必需的。因此，Neu 的下游靶标，包括 Ets 转录因子，可能是 Neu/ErbB-2 相关癌症治疗干预的有用点。
Overexpression of Neu (ErbB-2/HER2) is found in similar to 20% of breast tumors. Activation of Neu by a point mutation (Neu(T)) causes constitutive tyrosine kinase activity of this transmembrane receptor and transforming activity in fibroblasts. To identify downstream targets of Neu, we have analyzed the ability of Neu to activate gene expression. Expression of Neu(T), but not normal Neu, caused transcriptional activation of Ets, AP-1, or NF-kappa B-dependent reporter genes. Dominant inhibitory Ras or Raf mutants blocked the Neu-mediated transcriptional activation, confirming that Ras signaling pathways were required for this activation. Analysis with Ets2 mutants indicated that activation of Ets2 transcriptional activity mediated by Neu(T) or oncogenic Ras required phosphorylation of the same Ets2 residue, threonine 72. Cotransfection of dominant inhibitory Ets2 mutants specifically blocked Neu(T)-mediated activation of Ets-dependent reporter genes. Furthermore, in focus formation assays using NIH 3T3 cells, the transforming activity of Neu(T) was inhibited 5-fold when Neu(T) was cotransfected with a dominant negative Ets2 mutant. However, parallel colony formation assays showed that the Ets2 dominant negative mutant did not inhibit the growth of normal cells. Together, these data show that Neu(T) activates a variety of transcription factor families via the Ras signaling pathway and that Ets activation is required for Neu(T)-mediated cellular transformation. Thus, downstream targets of Neu, including Ets transcription factors, may be useful points for therapeutic intervention in Neu/ErbB-2-associated cancers.