Genotypic Interactions in Brain Cancer Heterogeneity

项目摘要 IDHwt胶质母细胞瘤（GBM）患者12 - 15个月中位生存期的微小改善， 尽管神经外科、放射治疗和新疗法的临床试验取得了进展，但仍发生了这种情况。中央 这种侵袭性肿瘤的异质性是成功治疗的一个难题。多组学 分析提供了GBM细胞组成的粒度，说明这些恶性肿瘤可以是 分为三种分子亚型-经典型（CL）、间质型（MES）和前神经型（PN）， 个体肿瘤通常具有所有三种亚型的混合物。因此，多个空间上不同的， GBM内存在异型群体，使得任何病变或途径特异性治疗效果较差。而 相当大的努力已经放在理解细胞内在机制赋予治疗 然而，关于异型GBM细胞之间的相互作用， 无节制的天性。60%的GBM病例中存在的标志性突变是GBM基因的扩增和突变。 表皮生长因子受体（EGFR）。最常见的EGFR改变，EGFRvIII，是由结构性改变引起的。 在其细胞外结构域（ECD）内的缺失产生组成型活性受体，该受体传递肿瘤 增强和抗治疗作用。此外，表达EGFRvIII的细胞可以传递这些特性， 通过促生存、旁分泌因子1（类似于TNF α炎症信号传导）对扩增的EGFRwt细胞产生影响。像 TNF α、EGFRvIII活性，特别是在PTEN失活的情况下，导致NF-κ B RelA/p65核表达。 定位，与乙酰化赖氨酸结合BET的成员（溴结构域和额外末端）的缔合 结构域）家族增强子蛋白，以及炎症转录的激活。 BET溴结构域相互作用的K310乙酰化（acK310-RelA）2和NF-κ B在驱动PN/CL中的中心作用 到MES表型转换（MESt），3我们假设RelA K310乙酰化作为调节开关 控制MESt和与富含MES基因特征的肿瘤相关的治疗抗性。 这个更新项目的总体目标是剖析和靶向机制，从而GBM PN或EGFR驱动的 CL肿瘤转变为MES基因表达（在此统称为MES转变（MESt））并获得 通过激活acK310-RelA/BET介导的炎性基因表达产生治疗抗性。的 将采用以下实验路线：1）PTEN信号传导途径的生物化学询问 为了确定介导RelA K310乙酰化和相关MESt的效应物， 和巨噬细胞，以及对DNA损伤的抗性; 2）BET家族成员，BRD 2，3和 4、通过诱导蛋白降解、基因编辑、溴结构域（BD1、BD2）药理学靶向，以及 评估与acK310-RelA/BET增强子景观重新布线偶联的转录;以及3） PTEN/RelA/BET轴的药理学研究作为克服补救抗性的手段 复发性GBM患者的放射治疗。 1

Project Summary Minimal improvement in the 12-15-month median survival of patients with IDHwt glioblastoma (GBM) has occurred despite advances in neurosurgery, radiation therapy, and clinical trials for novel therapeutics. A central issue confounding successful treatment is the heterogeneous nature of this aggressive tumor. Multi-omics analyses have provided granularity into GBM cellular composition, illustrating that these malignancies can be classified into three molecular subtypes - classical (CL), mesenchymal (MES), and proneural (PN) - with individual tumors typically harboring mixtures of all three subtypes. As a result, multiple spatially distinct, heterotypic populations exist within GBM, making any lesion- or pathway-specific therapy less effective. While considerable effort has been placed on understanding cell intrinsic mechanisms conferring therapeutic resistance, much less is known about interactions between heterotypic GBM cells that contribute to its recalcitrant nature. A hallmark mutation present in 60% of GBM cases is amplification and mutation of the epidermal growth factor receptor (EGFR). The most common EGFR alteration, EGFRvIII, results from structural deletion within its extracellular domain (ECD) yielding a constitutively active receptor which conveys tumor enhancing and therapy resisting functions. Furthermore, EGFRvIII-expressing cells can transmit these properties to amplified EGFRwt cells through pro-survival, paracrine factors,1 akin to TNFα inflammatory signaling. Like TNFα, EGFRvIII activity, specifically in the context of PTEN inactivation, results in NF-κB RelA/p65 nuclear localization, association with members of the acetylated lysine-binding BET (bromodomain and extra terminal domain) family of enhancer proteins, and activation of inflammatory transcription.1 Given the requirement of RelA K310 acetylation (acK310-RelA) for BET bromodomain interactions2 and central role of NF-κB in driving a PN/CL to MES phenotype transition (MESt),3 we postulate that RelA K310 acetylation acts as a regulatory switch controlling MESt and therapy resistance associated with tumors enriched for MES gene signatures.4 The overall goal of this renewal project is to dissect and target mechanisms whereby GBM PN or EGFR-driven CL tumors transition to MES gene expression (collectively referred to here as MES transition (MESt)) and acquire therapeutic resistance through activation of acK310-RelA/BET-mediated inflammatory gene expression. The following lines of experimentation will be employed: 1) biochemical interrogation of the PTEN signaling pathway to determine effectors mediating RelA K310 acetylation and associated MESt, tumor abundance of microglia and macrophages, and resistance to DNA damage; 2) functional analysis of BET family members, BRD2, 3 and 4, through inducible protein degradation, gene editing, bromodomain (BD1, BD2) pharmacological targeting, and assessment of transcription coupled with acK310-RelA/BET enhancer landscape rewiring; and 3) pharmacological interrogation of the PTEN/RelA/BET axis as a means to overcome resistance to salvage radiation therapy in recurrent GBM patients. 1