The study of underlying mechanism of EGFR-Ras signaling in glioblastoma

如果没有有效的治疗，高级别星形细胞瘤（HGA）仍然是致命的。通过诱导cred驱动的成人星形胶质细胞特异性系统，我们探索了人类胶质母细胞瘤（IV级；GBM）中受干扰的关键通路在HGA发生和发展中的相对作用。产生疾病的可能事件组合（工程化的和自发的）表明了每种畸变的等级特异性作用，并提出了特定的进展机制，从II级[仅由prb肿瘤抑制（TS）失活诱导]到III级（KrasG12D激活，p53因突变或错定位而自发失活），再到IV级[进一步增加PTEN失活（自发或工程化）]，没有IDH1突变。在从II级疾病向III级疾病过渡以及随后的KrasG12D激活过程中，Trp53错义突变与人类GBM突变一致。本研究强调了具有明显肿瘤异质性的随机事件的重要性，以便概括疾病特性。重要的是，小鼠GBM转录组显示与高度侵袭性的人间充质GBM亚类一致。为了确定EGFR是否在我们的rbb - ts失活和KrasG12D激活的星形细胞瘤小鼠模型（TR模型）中发挥肿瘤进展作用，我们对TR肿瘤进行了免疫组织化学（IHC）研究和FISH分析，发现EGFR被扩增/过表达。EGFR抑制剂厄洛替尼抑制EGFR在体内和体外对TR肿瘤显示出耐药性，这与人体临床数据一致。然而，这些肿瘤在体外对多种RTK抑制剂表现出敏感性，表明其他RTK可能补偿单一EGFR抑制。我们目前正在进行分子通路分析，剖析EGFR抑制的代偿机制。宋勇，张强，Bash R, Kutlu B, Difilippantonio S, Yin C, Gilbert D, Wang C, Yang C, Bullitt E, Kafri T, McCarthy K, Louis D, Hood L, Miller CR, Van Dyke T.胶质母细胞瘤的进化途径：来自工程小鼠的研究。（《癌症发现》正在审查中）

High grade astrocytomas (HGA) remain fatal without effective treatment. Using an inducible Cre-driven adult astrocyte-specific system, we explored the relative roles of key pathways perturbed in human glioblastomas (grade IV; GBM) in initiation and progression of HGA. The likely event combinations (engineered and spontaneous) yielding disease indicate grade-specific roles for each aberration and suggest specific progression mechanisms from grade II [induced only by pRb-tumor suppression (TS) inactivation] to III (addition of KrasG12D activation, with spontaneous inactivation of p53 by mutation or mislocalization), to Grade IV [further addition of PTEN inactivation (spontaneous or engineered)] without IDH1 mutation. In the transition from grade II to III disease and subsequent to KrasG12D activation, Trp53 missense mutations congruent with human GBM mutations. This study underscores the importance of stochastic events with evident tumor heterogeneity in order to recapitulate disease properties. Importantly, murine GBM transcriptomes showed concordance with the highly aggressive human mesenchymal GBM subclass.To determine whether EGFR played a role on tumor progression in our astrocytoma mouse model with inactivation of Rb-TS and activation of KrasG12D (TR model), we performed immunohistochemistry (IHC) study and FISH analysis on TR tumors, and found that EGFR was amplified/overexpressed. Inhibition of EGFR by EGFR inhibitor Erlotinib showed resistance in vivo and in vitro on TR tumors, which is consistent with the human clinical data. However, these tumors showed sensitivity to multiple RTK inhibitors in vitro, indicating that other RTKs may compensate for single EGFR inhibition. We are currently working on molecular pathway analysis to dissect the compensatory mechanism of EGFR inhibition. Song Y, Zhang Q, Bash R, Kutlu B, Difilippantonio S, Yin C, Gilbert D, Wang C, Yang C, Bullitt E, Kafri T, McCarthy K, Louis D, Hood L, Miller CR, Van Dyke T. An evolutionary path to glioblastoma: Insight into etiology from engineered mice. (Under review at Cancer Discovery)