Enhancing Treatment Response by Leveraging STAT5-OLIG2 signaling in GBM

项目摘要 胶质母细胞瘤（GBM）是所有人类癌症中最具治疗抗性和致命性的。有效GBM 肿瘤细胞侵入周围健康脑组织， 导致肿瘤复发。因此，针对浸润性残留细胞的治疗方法的发展 为了提高GBM患者的存活率，我们之前报道过， TNF受体超家族成员Fn 14的表达在浸润性神经胶质瘤细胞中是高的。增加 Fn 14信号转导促进体外GBM细胞迁移/侵袭和化疗耐药性，而Fn 14缺失 在颅内异种移植模型中增加对替莫唑胺（TMZ）的敏感性和存活率。FN 14是一种 可被组成型活性受体酪氨酸激酶激活的诱导蛋白 EGFR及其活性突变体EGFRvIII。EGFR vIII诱导的Fn 14上调主要由STAT 5驱动 促进胶质瘤侵袭和治疗抗性的活性。值得注意的是，Fn 14表达和STAT 5 在选择替莫唑胺（TMZ）的GBM患者来源的异种移植物（PDX）系中， 阻力在表达EGFRvIII的GBM细胞中抑制JAK 1/2表达/活性并不影响细胞的增殖。 STAT 5磷酸化（pSTAT 5），这是其激活所必需的，或Fn 14表达，表明 STAT 5的激活不依赖于JAK 1/2。有趣的是，我们发现关键细胞OLIG 2的表达 命运因子对胶质瘤干细胞（GSC）的致瘤潜力很重要，影响STAT 5的活化 Fn 14的表达。在GSC中，STAT 5与OLIG 2相互作用，并且用STAT 5抑制剂治疗， 匹莫齐特导致Fn 14表达和GSC侵袭降低。上游分子 JAK非依赖性激活STAT 5和下游信号通路的机制 必须鉴定由OLIG 2-STAT 5复合物调节的细胞以最终靶向侵袭性GSC。我们 假设STAT 5/OLIG 2/Fn 14信号通路是侵袭性， 残留的GBM细胞和靶向该途径将降低治疗抗性并增加存活率 在PDX模型中。在目标1中，我们将确定STAT 5信号转导诱导Fn 14的机制。 在EGFRvIII下游表达，以增强GBM细胞侵袭和治疗抗性。目标2将 鉴定参与OLIG 2介导的STAT 5-Fn 14表达调节的分子机制， 全球供应链。在目的3中，我们将确定STAT 5抑制与TMZ和IR组合对GBM的影响。 颅内异种移植物和同基因免疫活性 GBM的小鼠模型。该提案的成功将识别、验证并纳入临床有意义的 将STAT 5/OLIG 2/Fn 14信号通路作为浸润细胞的治疗靶标， 导致GBM死亡

Project Summary Glioblastoma (GBM) is among the most treatment resistant and lethal of all human cancers. Effective GBM treatment is hindered by aggressive tumor cell invasion into surrounding healthy brain tissue that invariably leads to tumor recurrence. Therefore, the development of therapies that target the infiltrative, residual cells are greatly needed in order to improve the survival of GBM patients. We previously reported that the expression of the TNF receptor superfamily member Fn14 is high in infiltrating glioma cells. Increased Fn14 signaling promotes GBM cell migration/invasion and chemoresistance in vitro while Fn14 depletion increases sensitivity to temozolomide (TMZ) and survival in an intracranial xenograft model. Fn14 is an inducible protein that can be activated by constitutively active receptor tyrosine kinases such as amplified EGFR and its active mutant EGFRvIII. EGFRvIII-induced Fn14 upregulation is mainly driven by STAT5 activity to promote glioma invasion and therapeutic resistance. Notably, both Fn14 expression and STAT5 activation are elevated in GBM patient-derived xenograft (PDX) lines selected for temozolomide (TMZ) resistance. Inhibition of JAK1/2 expression/activity in EGFRvIII expressing GBM cells did not affect the phosphorylation of STAT5 (pSTAT5), which is essential for its activation, or Fn14 expression suggesting that STAT5 activation is independent of JAK1/2. Intriguingly, we find that expression of OLIG2, a key cell fate factor important for the tumorigenic potential of glioma stem cells (GSCs), affects STAT5 activation and Fn14 expression. In GSCs, STAT5 interacts with OLIG2 and treatment with the STAT5 inhibitor, pimozide results in decreased Fn14 expression and invasion of GSCs. The upstream molecular mechanisms involved in JAK-independent activation of STAT5 and downstream signaling pathway(s) regulated by OLIG2-STAT5 complex must be identified to ultimately target invasive GSCs. We hypothesize that the STAT5/OLIG2/Fn14 signaling pathway is a node of vulnerability in the invasive, residual GBM cells and targeting this pathway will decrease therapeutic resistance and increase survival in PDX models. In Aim 1, we will determine the mechanism(s) by which STAT5 signaling induces Fn14 expression downstream of EGFRvIII to enhance GBM cell invasion and therapeutic resistance. Aim 2 will identify the molecular mechanism(s) involved in OLIG2-mediated regulation of STAT5-Fn14 expression in GSCs. In Aim 3 we will determine the impact of STAT5 inhibition in combination with TMZ and IR on GBM tumor growth and therapeutic resistance in intracranial xenografts and syngeneic immunocompetent mouse models of GBM. Success of the proposal will identify, validate, and place into a clinically meaningful context the STAT5/OLIG2/Fn14 signaling pathway as a therapeutic target for infiltrating cells that commonly underlie GBM fatality.