低氧诱导的小胶质细胞中 HIF-1alpha/IL-1beta 轴的激活通过 NF-κB 介导的乙酰肝素酶表达上调促进了神经胶质瘤的进展。

BACKGROUND: Glioma is a common tumor that occurs in the brain and spinal cord. Hypoxia is a crucial feature of the tumor microenvironment. Tumor-associated macrophages/microglia play a crucial role in the advancement of glioma. This study aims to illuminate the detailed mechanisms by which hypoxia regulates microglia and, consequently, influences the progression of glioma. METHODS: The glioma cell viability and proliferation were analyzed by cell counting kit-8 assay and 5-ethynyl-2'-deoxyuridine assay. Wound healing assay and transwell assay were implemented to detect glioma cell migration and invasion, respectively. Enzyme-linked immunosorbent assay was conducted to detect protein levels in cell culture medium. The protein levels in glioma cells and tumor tissues were evaluated using western blot analysis. The histological morphology of tumor tissue was determined by hematoxylin-eosin staining. The protein expression in tumor tissues was determined using immunohistochemistry. Human glioma xenograft in nude mice was employed to test the influence of hypoxic microglia-derived interleukin-1beta (IL-1β) and heparanase (HPSE) on glioma growth in vivo. RESULTS: Hypoxic HMC3 cells promoted proliferation, migration, and invasion abilities of U251 and U87 cells by secreting IL-1β, which was upregulated by hypoxia-induced activation of hypoxia inducible factor-1alpha (HIF-1α). Besides, IL-1β from HMC3 cells promoted glioma progression and caused activation of nuclear factor-κB (NF-κB) and upregulation of HPSE in vivo. We also confirmed that IL-1β facilitated HPSE expression in U251 and U87 cells by activating NF-κB. Hypoxic HMC3 cells-secreted IL-1β facilitated the proliferation, migration, and invasion of U251 and U87 cells via NF-κB-mediated upregulation of HPSE expression. Finally, we revealed that silencing HPSE curbed the proliferation and metastasis of glioma in mice. CONCLUSION: Hypoxia-induced activation of HIF-1α/IL-1β axis in microglia promoted glioma progression via NF-κB-mediated upregulation of HPSE expression.

背景：脑胶质瘤是一种常见的发生于脑和脊髓的肿瘤。缺氧是肿瘤微环境的一个关键特征。肿瘤相关巨噬细胞/小胶质细胞在胶质瘤的进展中起着至关重要的作用。本研究旨在阐明缺氧调节小胶质细胞的详细机制，以及其如何影响胶质瘤的进展。

方法：通过细胞计数试剂盒-8 检测和 5-乙炔基-2'-脱氧尿苷检测分析胶质瘤细胞的活力和增殖。实施划痕愈合实验和 Transwell 实验分别检测胶质瘤细胞的迁移和侵袭。酶联免疫吸附试验检测细胞培养上清液中的蛋白水平。通过 Western blot 分析评估胶质瘤细胞和肿瘤组织中的蛋白水平。通过苏木精-伊红染色确定肿瘤组织的组织学形态。通过免疫组织化学检测肿瘤组织中的蛋白表达。采用人胶质瘤异种移植裸鼠模型检测缺氧微胶质细胞衍生的白细胞介素-1β（IL-1β）和乙酰肝素酶（HPSE）对体内胶质瘤生长的影响。

结果：缺氧的 HMC3 细胞通过分泌白细胞介素-1β（IL-1β）促进 U251 和 U87 细胞的增殖、迁移和侵袭能力，IL-1β 由缺氧诱导的缺氧诱导因子-1α（HIF-1α）激活所上调。此外，HMC3 细胞中的 IL-1β在体内促进了神经胶质瘤的进展，并导致核因子-κB（NF-κB）的激活和 HPSE 的上调。我们还证实，IL-1β 通过激活 NF-κB 促进了 U251 和 U87 细胞中 HPSE 的表达。缺氧的 HMC3 细胞分泌的 IL-1β通过 NF-κB 介导的 HPSE 表达上调促进了 U251 和 U87 细胞的增殖、迁移和侵袭。最后，我们发现沉默 HPSE 可抑制小鼠神经胶质瘤的增殖和转移。

结论：微胶质细胞中缺氧诱导的 HIF-1α/IL-1β 轴的激活通过 NF-κB 介导的 HPSE 表达上调促进了胶质瘤的进展。