Wong Lee Lee, Chang Chan Fong, Koay Evelyn S C, Zhang Daohai
Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119074.
Int J Oncol. 2009 May;34(5):1291-301.
Activation of HER-2/neu leads to multiple signalling cascades and plays a vital role in cell survival and growth. We used a signal transduction antibody array to characterize the tyrosine phosphorylation profiles in heregulin (HRG alpha1)-treated BT474 breast cancer cells, and identified a group of 80 molecules in which tyrosine phosphorylation was highly regulated by HRG-enhanced HER-2/neu signalling. These phosphoproteins included many known HER-2/neu-regulated molecules (e.g., SHC, Akt, Syk and Stat1) and proteins that had not been previously linked to HER-2/neu signalling, such as Fas-associated death domain protein (FADD), apoptosis repressor with CARD domain (ARC), and the tumour suppressor, protein phosphatase type 2A (PP2A). Pharmacological inhibition with HER-2 inhibitor AG825, PI3K inhibitor LY294002, MEK1/2 inhibitor PD98095, and p38MAPK inhibitor SB203580 confirmed that PP2A phosphorylation was modulated by the complicated, HER-2/neu-driven downstream signal network, with the PI3K and MEK1/2 positively, while the p38MAPK negatively regulating its tyrosine phosphorylation. In breast tumour specimens, expression of tyrosine-phosphorylated PP2A (pY307-PP2A) was highly increased in the HER-2/neu positive breast tumours, and significantly correlated to tumour progression, thus enhancing its potential prognostic value. Our data provide meaningful information in the elucidation of the HER-2-driven tyrosine phosphorylation network, and in the development of phosphopeptide-related targets as prognostication indicators.
HER-2/neu的激活会引发多个信号级联反应，并在细胞存活和生长中发挥至关重要的作用。我们使用信号转导抗体阵列来表征在heregulin（HRGα1）处理的BT474乳腺癌细胞中的酪氨酸磷酸化谱，并鉴定出一组80个分子，其中酪氨酸磷酸化受到HRG增强的HER-2/neu信号的高度调控。这些磷酸化蛋白包括许多已知的HER-2/neu调控分子（如SHC、Akt、Syk和Stat1）以及先前未与HER-2/neu信号相关联的蛋白质，如Fas相关死亡结构域蛋白（FADD）、含CARD结构域的凋亡抑制因子（ARC）和肿瘤抑制因子2A型蛋白磷酸酶（PP2A）。用HER-2抑制剂AG825、PI3K抑制剂LY294002、MEK1/2抑制剂PD98095和p38MAPK抑制剂SB203580进行药理学抑制证实，PP2A的磷酸化受到复杂的、HER-2/neu驱动的下游信号网络的调节，其中PI3K和MEK1/2正向调节，而p38MAPK负向调节其酪氨酸磷酸化。在乳腺肿瘤标本中，酪氨酸磷酸化的PP2A（pY307-PP2A）在HER-2/neu阳性乳腺肿瘤中表达高度增加，且与肿瘤进展显著相关，从而增强了其潜在的预后价值。我们的数据为阐明HER-2驱动的酪氨酸磷酸化网络以及开发磷酸肽相关靶点作为预后指标提供了有意义的信息。
