新型EGFRvIII抑制剂对EGFRvIII+/PTEN null神经胶质瘤的抗肿瘤作用及机制研究

Glioblastoma multiforme (GBM, WHO grade IV glioma) is the most common form of malignant brain cancers in adults and one of the most lethal human cancers. Affected patients have a uniformly poor prognosis with a median survival of only 12-15 months. Epidermal growth factor receptor (EGFR) gene amplification and mutation are frequently observed in primary GBM. The constitutive activated deletion variant EGFRvIII, which is found in almost half of GBMs with EGFR applification, and PTEN, the deficiency is also frequently observed in primary GBM, are tightly associated with oncogenesis and malignance. The clinic available EGFR monoantibodies and inhibitors have thus far failed to deliver significant responses in GBM patients. Identification of EGFRvIII specific inhibitor has important implication for the development and treatment of GBM. Here, we got several EGFRvIII specific inhibitor candidates through the high-through screening strategy. To gain insight into the structural moiety that is essential for EGFRvIII inhibition, we will conduct a structure-activity relationship (SAR) study by analyzing a panel of interesting candidate derivatives with various substituent groups to get the most potent inhibitor. Then, the molecular and cellular mechanisms of EGFRvIII inhibitor’s action will be explored in vitro and in vivo through the binding assay, kinase activity inhibition and signal pathway study. Finally, the EGFRvIII inhibitor’s anti-tumor effects and mechanisms will be studied in human GBM cell lines (EGFRvIII+/PTEN-deficient or intact) and the mouse subcutaneous and intracranial U87MG-EGFRvIII (PTEN-deficientl) xenograft models. Accomplishment of the proposed aims will allow us to get interesting EGFRvIII inhibitors, which can block GBM, and to better develop clinic therapeutic drugs for GBM patients.

多形性胶质母细胞瘤（Glioblastoma multiforme, GBM）是WHO分级中恶性度最高最常见的一类胶质瘤，手术切除结合放疗化疗仅存活12-15个月。表皮生长因子受体突变体EGFRvIII高表达和PTEN缺失与GBM发生及恶性度密切相关，目前临床可用的EGFR抗体和抑制剂对GBM基本没有疗效，EGFRvIII靶向抗肿瘤药物研究意义突出。本项目对新获得EGFRvIII抑制剂进行构效关系分析，通过结合实验、激酶活性检测及信号通路研究阐明抑制剂的特异性及作用机制，分析PTEN对抑制剂作用的影响，采用细胞和移植性肿瘤小鼠模型研究抑制剂对EGFRvIII+/PTEN null GBM的抗肿瘤效果及机制。最终获得高特异性和低毒性EGFRvIII抑制剂，有效抑制恶性度极高的EGFRvIII+/PTEN null GBM生长，延长存活期，促进具有自主知识产权的分子靶向抗肿瘤药物研发。

多形性胶质母细胞瘤（Glioblastoma multiforme, GBM）是WHO分级中恶性度最高最常见的一类胶质瘤，手术切除结合放疗化疗仅存活12-15个月。常伴随表皮生长因子受体EGFR及其突变体III的高表达和PTEN缺失，尚缺乏有效的治疗手段。本研究获得了两个针对EGFR阳性PTEN缺失恶性GBM的有效抗肿瘤化合物，其中一个化合物C9直接作用于EGFR抑制EGFR及其下游信号分子从而抑制细胞增殖实现抗肿瘤作用；另一个化合物B8则是来源于传统中药蟾酥的抗肿瘤活性单体华蟾酥毒基，该化合物不直接抑制EGFR活性，但较C9更高效特异抑制EGFR阳性PTEN缺失GBM的细胞增殖，通过结合SH3BGRL3影响SH3BGRL3-EGFR的相互作用，抑制EGFR及其下游的信号分子抑制细胞增殖，并诱导细胞凋亡和细胞毒性，对正常细胞基本没有影响，B8在体内能有效抑制GMB肿瘤移植小鼠脑内的肿瘤生长并延长小鼠生存期。该项目的执行发现了两个有效的抗肿瘤化合物，其作用靶点及效果比较明确，为临床药物研发提供了备选化合物，也为传统中药作用的物质基础研究建立了有效的策略和技术体系。