Petri M K, Brobeil A, Planz J, Bräuninger A, Gattenlöhner S, Nestler U, Stenzinger A, Paradowska A, Wimmer M
Institute of Anatomy and Cell Biology, Justus-Liebig-University, 35385, Giessen, Germany,
J Neurooncol. 2015 May;123(1):15-25. doi: 10.1007/s11060-015-1763-8. Epub 2015 Apr 11.
Protein tyrosine phosphatase interacting protein 51 (PTPIP51) is upregulated in glioblastoma multiforme (GBM) and expression levels correlate with the grade of malignancy in gliomas. A similar correlation was reported for its interacting partner 14-3-3β, which has been shown to facilitate the interaction of PTPIP51 with cRAF (Raf1). Since the interaction of these signalling partners stimulates growth factor signalling downstream of the epidermal growth factor receptor (EGFR), a major drug target in GBM, we here investigated the impact of EGFR inhibition by small molecule inhibitors or monoclonal antibody on PTPIP51. The effect of EGFR inhibition on PTPIP51 mRNA, protein expression and its interaction profile in GBM was analyzed using the U87 cell line as model system. The transferability of the results to in vivo conditions was evaluated in cultured tumour cells from GBM patients. Cells were treated either to the small molecule tyrosine kinase inhibitor of EGFR Gefitinib or the monoclonal antibody Cetuximab in a time and dose dependent manner. Gefitinib treatment decreased the proliferation rate and induced apoptosis in U87 and primary tumour cells. The PTPIP51 interaction profile changed in correlation to the applied Gefitinib. Despite unchanged mRNA levels PTPIP51 protein was reduced. In contrast, treatment with Cetuximab had no effects on PTPIP51 expression. In conclusion, our results demonstrate the impact of EGFR inhibition by Gefitinib on PTPIP51 protein expression, a downstream regulator of MAPK signalling. These data will serve as a basis to unravel the precise role of PTPIP51-mediated signalling in GBM and its potential implications for Gefitinib-mediated therapy in future studies.
蛋白酪氨酸磷酸酶相互作用蛋白51（PTPIP51）在多形性胶质母细胞瘤（GBM）中上调，其表达水平与胶质瘤的恶性程度相关。据报道，其相互作用伴侣14-3-3β也有类似的相关性，14-3-3β已被证明可促进PTPIP51与cRAF（Raf1）的相互作用。由于这些信号伴侣的相互作用会刺激表皮生长因子受体（EGFR）下游的生长因子信号传导，而EGFR是GBM中的一个主要药物靶点，因此我们在此研究了小分子抑制剂或单克隆抗体对EGFR的抑制作用对PTPIP51的影响。以U87细胞系为模型系统，分析了EGFR抑制对GBM中PTPIP51 mRNA、蛋白表达及其相互作用谱的影响。在GBM患者的培养肿瘤细胞中评估了结果向体内条件的可转移性。细胞以时间和剂量依赖性方式分别用EGFR的小分子酪氨酸激酶抑制剂吉非替尼或单克隆抗体西妥昔单抗处理。吉非替尼处理降低了U87细胞和原代肿瘤细胞的增殖率并诱导了细胞凋亡。PTPIP51的相互作用谱随所用吉非替尼的变化而改变。尽管mRNA水平未变，但PTPIP51蛋白减少。相比之下，西妥昔单抗处理对PTPIP51表达没有影响。总之，我们的结果证明了吉非替尼对EGFR的抑制作用对PTPIP51蛋白表达的影响，PTPIP51是MAPK信号传导的下游调节因子。这些数据将作为基础，在未来的研究中揭示PTPIP51介导的信号传导在GBM中的精确作用及其对吉非替尼介导治疗的潜在影响。
