Leveraging Gα12 signaling to treat glioblastoma

摘要 多形性胶质母细胞瘤是最具侵袭性的原发脑肿瘤之一，其临床表现令人沮丧。 尽管在过去的几十年里治疗取得了进步，但预后。患者存活率低的原因是 病情缓解一段时间后复发。基底细胞瘤是一种高度侵袭性的肿瘤，它使 外科手术的经济衰退很困难。G蛋白偶联受体因其功能而日益为人们所认识 来调节肿瘤的生长。这些受体中的许多通过与阿尔法受体的偶联来传递信号 异源三聚体G蛋白GA12的亚基。癌组织中基底膜的电子显微镜检查 基因组图谱显示编码G⍺12的基因GNA12显著上调 通过这种G蛋白传递信号的G蛋白偶联受体(GPCRs)的过度表达。 我们最近确定靶向人脑胶质瘤干细胞(GSCs)中的G⍺12可以抑制肿瘤 细胞自我更新、干细胞基因表达和侵袭。一致的G⍺12击倒 (KD)减少体内原位移植的GSC细胞对肿瘤的侵袭。反过来， G-⍺-12的化学激活增加了侵袭力。G-⍺12kD肿瘤的核糖核酸序列分析 显示细胞黏附和迁移基因的表达减少，以及增加 原神经基因的表达。观察到的迁移行为和基因表达的变化 提示G-⍺-12信号通路促进原神经向间充质转化。有证据表明 G⍺12信号调节GSCs识别的干性和侵袭性的转录程序 这是一个潜在的信号节点，用于治疗干预。手术后进行放射治疗 治疗是治疗基底膜的标准。干性和侵袭性的降低，相关 神经状态越好，对放射治疗的敏感度就越高 可以反过来改善疾病的复发和对健康脑组织的损害。我们的短期计划 目的是为缺乏GSC的细胞对放射治疗的敏感性增强提供证据 G⍺12信令。我们将在细胞培养和荷瘤中使用GSCs的单剂量照射 使用图像引导照射的小鼠。我们的创新方法利用了新发现的 G-⍺-12在肿瘤生长和侵袭性中的作用评估能力 通过阻断G⍺12信号在人类患者来源的胶质瘤细胞中引发的放射增敏， 使用图像引导照射与精确医学方法是一致的。因此，我们的 这些发现可能会影响耐药肿瘤的放射治疗，并提高GBM患者的存活率。 如果成功，我们的研究将第一次证明靶向G⍺12信号的好处 联合放射治疗基底膜并将涉及G-⍺12偶联受体及其受体 转录调控的基因靶点作为潜在的治疗干预点。

Abstract Glioblastoma multiforme, one of the most aggressive primary brain tumors, has a dismal prognosis despite treatment advancements in the past decades. Low patient survival is driven by disease recurrency after a period of remission. GBM is a highly invasive tumor, which makes surgical recession difficult. G-protein coupled receptors are increasingly recognized for their ability to regulate tumor growth. Many of these receptors signal through their coupling to the alpha subunit of the heterotrimeric G-protein Ga12. In silico interrogation of GBM in The Cancer Genome Atlas reveals marked upregulation of GNA12, the gene encoding G⍺12, concomitant with overexpression of G-protein coupled receptors (GPCRs) that signal through this G-protein. We recently determined that targeting G⍺12 in human glioma stem cells (GSCs) attenuates tumor cell self-renewal, expression of stem cell genes, and invasion. Concordantly G⍺12 knockdown (KD) reduced invasion of tumors from orthotopically engrafted GSC cells in vivo. Reciprocally, chemogenetic activation of G⍺12 increased invasion. G⍺12 KD tumors assessed by RNA seq showed reduced expression of cell adhesion and migration genes, as well as increased expression of proneural genes. The observed changes in migratory behavior and gene expression suggest that G⍺12 signaling promotes a proneural-to-mesenchymal transition. The evidence that G⍺12 signaling regulates transcriptional programs for stemness and invasion of GSCs identifies this as a potential signaling node for therapeutic intervention. Surgery followed by radiation therapy is the standard of care for GBM. Decreases in stemness and invasiveness, associated with a more proneural state, would be predictive of improved sensitivity to radiation therapy which could in turn ameliorate disease recurrence and damage to healthy brain tissue. Our short-term goal is to provide evidence for enhanced GSC susceptibility to radiation treatment in cells lacking G⍺12 signaling. We will use single dose irradiation of GSCs in cell culture and in tumor bearing mice using image-guided irradiation. Our innovative approach leverages the newly discovered role of G⍺12 on tumor growth and invasiveness to improve GBM treatment. The ability to evaluate radiosensitization, elicited by blockade of G⍺12 signals, in human patient derived glioma cells, using image-guided irradiation is consistent with precision medicine approaches. Thus, our findings could impact radiation treatment of resistant tumors and improve GBM patient survival. If successful, our studies will be the first to demonstrate the benefit of targeting G⍺12 signaling in association with radiation to treat GBM and will implicate G⍺12-coupled receptors and their transcriptionally regulated gene targets as potential points of therapeutic intervention.