Experimental Molecular Pathology, Department of Pathology, Fondazione IRCCS Istituto Tumori Milano, Via G. Venezian 1, 20133 Milano, Italy.
Neuro Oncol. 2010 Aug;12(8):776-89. doi: 10.1093/neuonc/noq003. Epub 2010 Feb 17.
We have previously demonstrated that chordomas express activated platelet-derived growth factor receptor (PDGFRB) and that treatment with imatinib, which is capable of switching off the activation of various receptor tyrosine kinases (RTKs) including PDGFRB, benefits a number of patients. The aim of this study was to identify the possible presence of other activated RTKs and their downstream signaling effectors. Cryopreserved material from 22 naïve sporadic chordomas was investigated for the presence of activated RTKs and their cognate ligands and downstream signaling effectors by means of human phospho-RTK antibody arrays, Western blotting, and molecular analysis; immunohistochemistry and fluorescence in situ hybridization were used to analyze the corresponding formalin-fixed and paraffin-embedded samples. We detected activated PDGFRB, FLT3, and colony stimulating factor 1 receptor (CSF1R) of the PDGFR family and highly phosphorylated EGFR, HER2/neu, and (to a lesser extent) HER4 of the EGFR family. The detection of PDGFRB/PDGFB confirmed our previous data. The presence of activated EGFR was paralleled by the finding of high levels of epidermal growth factor (EGF) and transforming growth factor alpha (TGFalpha) and PDGFB co-expression and PDGFRB co-immunoprecipitation. Of the downstream effectors, the PI3K/AKT and RAS/MAPK pathways were both activated, thus leading to the phosphorylation of mammalian target of rapamycin (mTOR) and 4E-BP1 among the regulators involved in translational control. Taken together, our results (i) provide a rationale for tailored treatments targeting upstream activated receptors, including the PDGFR and EGFR families; (ii) support the idea that a combination of upstream antagonists and mTOR inhibitors enhances the control of tumor growth; and (iii) indicate that the 4E-BP1/eIF4E pathway is a major regulator of protein synthesis in chordoma.
我们之前已经证明，软骨肉瘤表达激活的血小板衍生生长因子受体（PDGFRB），并且用伊马替尼治疗，这能够关闭各种受体酪氨酸激酶（RTKs）的激活，包括 PDGFRB，使许多患者受益。本研究的目的是确定其他激活的 RTKs 及其下游信号效应物的可能存在。通过人磷酸化 RTK 抗体阵列、Western blot 和分子分析，对 22 例未经治疗的散发性软骨肉瘤的冷冻材料进行了激活的 RTKs 及其同源配体和下游信号效应物的检测；免疫组织化学和荧光原位杂交用于分析相应的福尔马林固定和石蜡包埋样本。我们检测到 PDGFR 家族的激活 PDGFRB、FLT3 和集落刺激因子 1 受体（CSF1R）以及 EGFR 家族的高度磷酸化 EGFR、HER2/neu 和（程度较低）HER4。PDGFRB/PDGFB 的检测证实了我们之前的数据。激活的 EGFR 的存在与高水平的表皮生长因子（EGF）和转化生长因子 alpha（TGFalpha）以及 PDGFB 共表达和 PDGFRB 共免疫沉淀相平行。在下游效应物中，PI3K/AKT 和 RAS/MAPK 途径都被激活，从而导致参与翻译控制的调节物中哺乳动物雷帕霉素靶蛋白（mTOR）和 4E-BP1 的磷酸化。总之，我们的结果（i）为针对上游激活受体（包括 PDGFR 和 EGFR 家族）的靶向治疗提供了依据；（ii）支持这样一种观点，即上游拮抗剂和 mTOR 抑制剂的联合使用增强了对肿瘤生长的控制；（iii）表明 4E-BP1/eIF4E 途径是软骨肉瘤中蛋白质合成的主要调节剂。
