肿瘤细胞通过选择性排除 miR-375 促进 CTGF-EGFR 通路激活进而促进胶质瘤进展。
Selective exosome exclusion of miR-375 by glioma cells promotes glioma progression by activating the CTGF-EGFR pathway.
机构信息
The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, Department of Neurosurgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.
出版信息
J Exp Clin Cancer Res. 2021 Jan 6;40(1):16. doi: 10.1186/s13046-020-01810-9.
BACKGROUND
Exosomes are membrane-bound extracellular vesicles of 40-150 nm in size, that are produced by many cell types, and play an important role in the maintenance of cellular homeostasis. Exosome secretion allows for the selective removal of harmful substances from cells. However, it remains unclear whether this process also takes place in glioma cells.
METHODS
Herein, the role of the tumour-suppressor miR-375 was explored in human glioma cells. Immunoblotting and qRT-PCR experiments demonstrated a functional link between miR-375 and its target, connective tissue growth factor (CTGF), which led to the identification of the underlying molecular pathways. The exosomes secreted by glioma cells were extracted by ultracentrifugation and examined by transmission electron microscopy. Exosomal expression of miR-375 was then analysed by qRT-PCR; while the exosome secretion inhibitor, GW4869, was used to examine the biological significance of miR-375 release. Moreover, the dynamics of miR-375 release by glioma cells was investigated using fluorescently labelled exosomes. Finally, exosomal miR-375 release was examined in an orthotopic xenograft model in nude mice.
RESULTS
MiR-375 expression was downregulated in gliomas. MiR-375 suppressed glioma proliferation, migration, and invasion by inhibiting the CTGF-epidermal growth factor receptor (EGFR) signalling pathway. MiR-375-containing exosomes were also identified in human peripheral blood samples from glioma patients, and their level correlated with disease progression status. Exosomal miR-375 secretion impacted the CTGF-EGFR pathway activity. Once secreted, exosomal miR-375 was not taken back up by glioma cells.
CONCLUSIONS
Exosomal miR-375 secretion allowed for sustained activation of the CTGF-EGFR oncogenic pathway, promoting the proliferation and invasion of glioma cells. These findings enhance our understanding of exosome biology and may inspire development of new glioma therapies.
背景
外泌体是一种大小为 40-150nm 的膜结合细胞外囊泡，由许多细胞类型产生，在维持细胞内稳态方面发挥着重要作用。外泌体的分泌允许细胞选择性地去除有害物质。然而，目前尚不清楚这一过程是否也发生在神经胶质瘤细胞中。
方法
本文探讨了肿瘤抑制因子 miR-375 在人神经胶质瘤细胞中的作用。免疫印迹和 qRT-PCR 实验证明了 miR-375与其靶标结缔组织生长因子（CTGF）之间存在功能联系，从而确定了潜在的分子途径。通过超速离心提取神经胶质瘤细胞分泌的外泌体，并通过透射电子显微镜进行检查。然后通过 qRT-PCR 分析外泌体中 miR-375 的表达；同时使用外泌体分泌抑制剂 GW4869 来研究 miR-375 释放的生物学意义。此外，还使用荧光标记的外泌体研究了神经胶质瘤细胞中 miR-375 的释放动力学。最后，在裸鼠原位移植模型中检查了外泌体 miR-375 的释放情况。
结果
miR-375 在神经胶质瘤中表达下调。miR-375 通过抑制 CTGF-表皮生长因子受体（EGFR）信号通路抑制神经胶质瘤的增殖、迁移和侵袭。还在来自神经胶质瘤患者的人外周血样本中鉴定出含有 miR-375 的外泌体，其水平与疾病进展状态相关。外泌体 miR-375 的分泌影响 CTGF-EGFR 通路的活性。一旦被分泌，外泌体 miR-375 就不会被神经胶质瘤细胞重新摄取。
结论
外泌体 miR-375 的分泌允许持续激活 CTGF-EGFR 致癌通路，促进神经胶质瘤细胞的增殖和侵袭。这些发现增强了我们对外泌体生物学的理解，并可能激发新的神经胶质瘤治疗方法的发展。
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