Expression and function of protein phosphatase PP2A in malignant testicular germ cell tumours
Expression and function of protein phosphatase PP2A in malignant testicular germ cell tumours
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DOI：
10.1002/path.2203
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发表时间：
2007-09-01
影响因子：
7.3
通讯作者：
Fayyazi, A.
中科院分区：
文献类型：
--
作者：
Schweyer, S.;Bachem, A.;Fayyazi, A.
睾丸生殖细胞肿瘤（TGCT）是年轻男性中最常见的恶性肿瘤。我们以前报道过丝裂原活化蛋白激酶（MAPK）家族的两个原型成员，MAPK ERK激酶（MEK）和细胞外信号调节激酶（ERK），在恶性睾丸生殖细胞中是无活性的，并在药物刺激后变得活跃，导致肿瘤细胞凋亡。在这项研究中，我们问蛋白磷酸酶PP 2A，一种已知的MEK-ERK通路的抑制剂，是否参与原代TGCT（n = 48）以及两个TGCT细胞系（NTERA和NCCIT）的增殖和/或凋亡。定量RT-PCR、免疫组织化学、蛋白质印迹分析和磷酸酶测定表明，原代TGCT以及TGCT细胞系表达PP 2A，并且PP 2A在TGCT细胞系中具有活性。通过应用两种PP 2A抑制剂，藜芦酸（CA）和冈田酸（OA）来抑制PP 2A，导致半胱天冬酶-3介导的TGCT细胞系凋亡的显著增加。因此，PP 2A抑制伴随着MEK和ERK的磷酸化和活化。使用MEK抑制剂PD 98059的功能测定表明，NIEK和ERK的磷酸化是诱导caspase-3介导的恶性生殖细胞凋亡所必需的。因此，我们的数据表明，PP 2A的抑制介导其对TGCT的凋亡诱导作用，通过激活MEK-ERK信号通路，导致caspase-3介导的肿瘤细胞凋亡。此外，我们的结果支持以前的观察，PP 2A发挥抗恶性肿瘤细胞凋亡的影响。版权所有（c）2007大不列颠和爱尔兰病理学会。由John Wiley & Sons有限公司出版
Testicular germ cell tumours (TGCT) represent the most common malignancy in young males. We reported previously that two prototype members of the mitogen-activated protein kinase (MAPK) family, the MAPK ERK kinase (MEK) and extracellular signal-regulated kinase (ERK), are inactive in malignant testicular germ cells and become active after drug stimulation, leading to apoptosis of tumour cells. In this study, we asked whether the protein phosphatase PP2A, a known inhibitor of the MEK-ERK pathway, participates in the proliferation and/or apoptosis of primary TGCT (n = 48) as well as two TGCT cell lines (NTERA and NCCIT). Quantitative RT-PCR, immunohistochemistry, western blot analyses and phosphatase assay indicate that primary TGCT as well as TGCT cell lines express PP2A and that PP2A is active in TGCT cell lines. The inhibition of PP2A by application of two PP2A inhibitors, cantharidic acid (CA) and okadaic acid (OA), results in a significant increase in caspase-3-mediated apoptosis of TGCT cell lines. Thereby, PP2A inhibition was accompanied by phosphorylation and activation of MEK and ERK. Functional assays using the MEK inhibitor PD98059 demonstrated that the phosphorylation of NIEK and ERK was required for the induction of caspase-3-mediated apoptosis of malignant germ cells. Thus, our data suggest that inhibition of PP2A mediates its apoptosis-inducing effect on TGCT through activation of the MEK-ERK signalling pathway that leads to caspase-3-mediated apoptosis of tumour cells. In addition our results support previous observations that PP2A exerts an anti-apoptotic effect on malignant tumour cells. Copyright (c) 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.