Deciphering the role of Microglia in Glioblastoma

胶质母细胞瘤是最常见的原发性恶性脑肿瘤。神经外科全切除术 胶质母细胞瘤是不可能的，并且即使在切除、化疗和放疗后肿瘤也总是复发。 尽管对胶质母细胞瘤的生物学进行了广泛的研究，但护理标准没有改变 大约20年，从诊断到死亡的中位寿命仍然很低，大约15个月。这 强调了需要确定治疗这些破坏性肿瘤的新靶点。 胶质母细胞瘤的特征是小胶质细胞的广泛浸润;主要的固有免疫反应是免疫球蛋白。 脑细胞。然而，尽管小胶质细胞大量存在，但它们无法控制肿瘤， 促进肿瘤生长。小胶质细胞促肿瘤作用的确切机制仍不完全 明白使用一种方法，使我们能够选择性地识别和分离小胶质细胞存在于 肿瘤（与那些在同一个大脑，但在肿瘤外），我们确定了这些转录组 在胶质母细胞瘤的鼠模型中通过RNASeq的胶质母细胞瘤相关小胶质细胞（GAMi）。我们发现 胶质母细胞瘤通过下调可能参与小胶质细胞转录网络的途径来重编程， 识别并杀死肿瘤细胞。具体地说，我们发现，GAMi下调：（a）基因可能 参与胶质母细胞瘤细胞的免疫感应和吞噬作用，以及（B）可能参与 直接杀死肿瘤。我们还发现，在GAMi中观察到的大多数变化可能是由小胶质细胞驱动的。 具体途径。当我们分析来自人类胶质母细胞瘤患者的数据集时，我们获得了类似的发现。 在本申请中，我们建议测试这些小胶质细胞的转录变化是功能性的， 使用三种临床前小鼠胶质母细胞瘤模型和共培养模型调节肿瘤生长的重要性 患者来源的人胶质母细胞瘤和iPSC来源的小胶质细胞。我们还将识别出 调节这些过程的途径。为此，我们提出了三个具体目标。在目标1中， 确定GAMi识别和吞噬肿瘤细胞的功能能力是否降低，以及 这种降低的肿瘤生长能力。在目标2中，我们将确定GAMi是否具有降低的功能能力， 杀死肿瘤细胞，以及这种能力降低对肿瘤生长的影响。在目标3中，我们确定具体的 调节小胶质细胞感应和胶质母细胞瘤细胞吞噬作用的小胶质细胞通路，直接杀死肿瘤 细胞以及靶向这种途径是否会调节整体肿瘤生长。我们的研究可以证明 这些途径可以作为治疗这种毁灭性肿瘤的潜在有效靶点。

Glioblastomas are the most common primary malignant brain tumors. Total neurosurgical resection of glioblastomas is not possible, and tumors invariably recur even following resection, chemo- and radiotherapy. Despite extensive research into the biology of glioblastomas, there has been no change in the standard of care for ~20 years and the median lifespan from time of diagnosis to death remains dismal at ~15 months. This highlights the need for identifying new targets for therapy of these devastating tumors. Glioblastomas are characterized by extensive infiltration of microglia; the main resident innate immune cells of the brain. Yet, despite their large presence, microglia fail to keep the tumor in check and appear to promote tumor growth. The exact mechanism(s) of this pro-tumor role of microglia remain incompletely understood. Using an approach that allows us to selectively identify and isolate microglia present within the tumor (vs. those in the same brain but outside the tumor), we determined the transcriptomes of these Glioblastoma Associated Microglia (GAMi) by RNASeq in a murine model of glioblastoma. We found that glioblastomas reprogram microglial transcriptional networks by downregulating pathways potentially involved in recognizing and killing tumor cells. Specifically, we found that GAMi have downregulated: (a) genes potentially involved in immune sensing and phagocytosis of glioblastoma cells and (b) transcripts potentially involved in direct tumor killing. We also found that most of the changes observed in GAMi may be driven by a microglia specific pathway. We obtained similar findings when we analyzed datasets from human glioblastoma patients. In this application, we propose to test which of these microglial transcriptional changes are functionally important in regulating tumor growth using three preclinical mouse glioblastoma models and a co-culture model of patient-derived human glioblastoma and iPSC-derived microglia. We will also identify the precise microglial pathway that regulates these processes. To achieve this, we propose three specific aims. In aim 1, we will determine if GAMi have reduced functional capacity to recognize and phagocytose tumor cells, and the effect of such reduced capacity on tumor growth. In aim 2, we will determine if GAMi have reduced functional capacity to kill tumor cells, and the effect of such reduced capacity on tumor growth. In aim 3, we determine the specific microglial pathway that regulates microglial sensing and phagocytosis of glioblastoma cells, direct killing of tumor cells and whether targeting such pathway will regulate overall tumor growth. Our studies would provide proof of concept that these pathways can be used as potential effective targets for therapy of this devastating tumor.