Glioblastoma (GBM, WHO grade IV glioma) is the most common and lethal malignant brain tumor in adults with a dismal prognosis. The extracellular matrix (ECM) supports GBM progression by promoting tumor cell proliferation, migration, and immune escape. Uridine diphosphate (UDP)-glucose 6-dehydrogenase (UGDH) is the rate-limiting enzyme that catalyzes the biosynthesis of glycosaminoglycans that are the principal component of the CNS ECM. We investigated how targeting UGDH in GBM influences the GBM immune microenvironment, including tumor-associated microglia/macrophages (TAMs) and T cells. TAMs are the main immune effector cells in GBM and can directly target tumor cells if properly activated. In co-cultures of GBM cells and human primary macrophages, UGDH knockdown in GBM cells promoted macrophage phagocytosis and M1-like polarization. In orthotropic human GBM xenografts and syngeneic mouse glioma models, targeting UGDH decreased ECM deposition, increased TAM phagocytosis marker expression, reduced M2-like TAMs and inhibited tumor growth. UGDH knockdown in GBM cells also promoted cytotoxic T cell infiltration and activation in orthotopic syngeneic mouse glioma models. The potent and in-human-use small molecule GAG synthesis inhibitor 4-methylumbelliferone (4-MU) was found to inhibit GBM cell proliferation and migration in vitro, mimic the macrophage and T-cell responses to UGDH knockdown in vitro and in vivo and inhibit growth of orthotopic murine GBM. Our study shows that UGDH supports GBM growth through multiple mechanisms and supports the development of ECM-based therapeutic strategies to simultaneously target tumor cells and their microenvironment.

胶质母细胞瘤（GBM，WHO IV 级胶质瘤）是成人中最常见和致命的恶性脑肿瘤，预后不佳。细胞外基质 (ECM) 通过促进肿瘤细胞增殖、迁移和免疫逃逸来支持 GBM 进展。尿苷二磷酸 (UDP)-葡萄糖 6-脱氢酶 (UGDH) 是催化糖胺聚糖生物合成的限速酶，糖胺聚糖是 CNS ECM 的主要成分。我们研究了在 GBM 中靶向 UGDH 如何影响 GBM 免疫微环境，包括肿瘤相关的小胶质细胞/巨噬细胞 (TAM) 和 T 细胞。TAM 是 GBM 中的主要免疫效应细胞，如果激活得当，可以直接靶向肿瘤细胞。在 GBM 细胞和人类原代巨噬细胞的共培养物中，GBM 细胞中的 UGDH 敲低促进了巨噬细胞的吞噬作用和 M1 样极化。在正交各向异性人 GBM 异种移植物和同系小鼠神经胶质瘤模型中，靶向 UGDH 可减少 ECM 沉积，增加 TAM 吞噬标志物表达，减少 M2 样 TAM 并抑制肿瘤生长。GBM 细胞中的 UGDH 敲低还促进了原位同基因小鼠神经胶质瘤模型中的细胞毒性 T 细胞浸润和活化。发现有效且在人体内使用的小分子 GAG 合成抑制剂 4-甲基伞形酮 (4-MU) 可抑制 GBM 细胞增殖和迁移在体外，在体外和体内模拟巨噬细胞和 T 细胞对 UGDH 敲低的反应，并抑制原位鼠 GBM 的生长。我们的研究表明，UGDH 通过多种机制支持 GBM 生长，并支持开发基于 ECM 的治疗策略，以同时靶向肿瘤细胞及其微环境。