Bimodal EGFR signaling in glioblastoma

摘要 胶质母细胞瘤（GBM）是成人中最常见的原发性脑癌。EGFR在大多数人中表达， GBM和异常EGFR信号传导是恶性表型的主要驱动因素。尽管EGFR 被认为是GBM中的主要癌基因，TCGA分析表明，在EGFR扩增的GBM中，EGFR配体 是抑制肿瘤的。我们的初步数据还表明，配体激活的EGFR具有肿瘤抑制作用。 配体激活的EGFR的肿瘤抑制作用导致对侵袭的意想不到的抑制。 我们认为组成型和配体依赖性EGFR野生型信号传导触发不同的信号传导， 途径。因此，组成性EGFR信号传导促进侵袭，而配体激活的EGFR信号传导则转向 抑制增殖并阻止入侵。我们阐明了EGFR调节侵袭的潜在机制， 确定BIN 3，一种已知影响细胞骨架的蛋白质，作为GBM侵袭的关键抑制因子。我们也 探讨配体激活EGFR介导胶质瘤细胞的机制及生物学意义 增殖我们研究了增殖和侵袭对肿瘤大小和预后的相对影响， GBM。提高对GBM侵袭机制的理解对于改善治疗至关重要。 此外，我们确定托法替尼作为一种药物，可以激活EGFR的肿瘤抑制功能， 增加EGFR配体、上调BIN 3和抑制GBM侵袭。托法替尼是一种临床可用的 和FDA批准的药物。我们的模型适用于表达EGFR野生型或突变型的GBM EGFRvIII.在具体目标1中：我们阐明了RTK反式激活在驱动侵袭或增殖中的作用。 我们检验了这样一个假设，即组成型EGFR信号促进EGFR侵袭性，而配体诱导的EGFR信号促进EGFR侵袭性。 组成型EGFR信号传导导致Met的激活，从而增加 侵略性我们还鉴定了驱动GBM侵袭的TAB 1-TAK 1-NF- B通路。配体激活的 EGFR信号传导导致Axl活化和增殖以及GBM侵袭性降低。具体目标2： 我们揭示了EGFR抑制GBM细胞侵袭性的机制。我们检验了一个假设， BIN 3是入侵的主要负调节因子。配体诱导的EGFR活性上调BIN 3， 抑制入侵。我们研究了BIN 3、BIN 3伴侣、EGFR和其他RTK的表达模式。 GBM中的网络。在具体目标3中，我们研究了组成型与配体诱导的生物学效应。 在原位小鼠模型中EGFR-RTK-BIN 3信号传导对GBM侵袭的影响，并检查托法替尼作为一种免疫抑制剂的作用。 在配体缺乏的GBM中特异性抑制GBM侵袭的治疗。.

Abstract Glioblastoma (GBM) is the most common primary brain cancer in adults. EGFR is expressed in the majority of GBMs and aberrant EGFR signaling is a major driver of the malignant phenotype. Although the EGFR is considered a prime oncogene in GBM, TCGA analysis indicates that in EGFR amplified GBMs, EGFR ligands are tumor suppressive. Our preliminary data also suggest that ligand-activated EGFR is tumor suppressive. The tumor suppressive effects of ligand-activated EGFR result form an unexpected suppression of invasion. We propose that constitutive and ligand-dependent EGFR wild type signaling triggers distinct signaling pathways. Thus, constitutive EGFR signaling promotes invasion while ligand-activated EGFR signaling turns on proliferation and turns off invasion. We elucidate mechanisms underlying EGFR regulation of invasion and identify BIN3, a protein known to influence the cytoskeleton, as a key suppressor of GBM invasion. We also identify the mechanisms and biological significance of ligand-activated EGFR mediated glioma cell proliferation. We examine the relative contribution of proliferation and invasion to tumor size and prognosis in GBM. An improved understanding of mechanisms that drive GBM invasion is critical to improved treatment. Furthermore, we identify tofacitinib as a drug that can activate the tumor suppressor function of EGFR by increasing EGFR ligand, upregulating BIN3 and suppressing GBM invasion. Tofacitinib is a clinically available and FDA approved drug. Our model holds true for GBMs that express EGFR wild type or the mutant EGFRvIII. In Specific Aim 1: We elucidate the role of RTK transactivation in driving invasion or proliferation. We test the hypothesis that constitutive EGFR signaling promotes EGFR invasiveness whereas ligand-induced EGFR signaling blocks it. Constitutive EGFR signaling leads to activation of Met leading to increased invasiveness. We also identify a TAB1-TAK1-NF- B pathway that drives GBM invasion. Ligand-activated EGFR signaling leads to Axl activation and proliferation and decreased GBM invasiveness. In Specific Aim 2: we uncover mechanisms used by EGFR to suppress invasiveness of GBM cells. We test the hypothesis that BIN3 is a major negative regulator of invasion. Ligand-induced EGFR activity upregulates BIN3 and suppresses invasion. We examine the expression patterns of BIN3, BIN3 partners, EGFR and other RTKs networks in GBM. In Specific Aim 3 we examine the biological effects of constitutive vs. ligand induced EGFR–RTK-BIN3 signaling on GBM invasion in an orthotopic mouse model and examine tofacitinib as a treatment that specifically inhibits GBM invasion in ligand-poor GBMs. .