Purpose

Exosomes play important roles in intercellular communication through signaling pathways affecting tumor microenvironment modulation and tumor proliferation, including those in glioblastoma (GBM). As yet, however, limited studies have been conducted on the inhibitory effect of human bone marrow-derived mesenchymal stem cell (hBMSC)-derived exosomes on GBM development. Therefore, we set out to assess the role of hBMSC secreted exosomes, in particular those carrying microRNA-34a (miR-34a), in the development of GBM.

Methods

Microarray-based expression analysis was employed to identify differentially expressed genes and to predict miRNAs regulating MYCN expression. Next, hBMSCs were transfected with a miR-34a mimic or inhibitor after which exosomes were isolated. Proliferation, apoptosis, migration, invasion and temozolomide (TMZ) chemosensitivity of exosome-exposed GBM cells (T-98G, LN229 and A-172) were measured in vitro. The mechanism underlying MYCN regulation was investigated using lentiviral transfections. The in vivo inhibitory effect of exosomal miR-34a was measured in nude mice xenografted with GBM cells through subcutaneous injection of hBMSCs with an upregulated miR34a content.

Results

We found that poorly-expressed miR-34a specifically targeted and negatively regulated the expression of MYCN in GBM cells. In addition we found that miR-34a was delivered to T-98G, LN229 and A-172 GBM cells via hBMSC-derived exosomes. Exogenous overexpression of miR-34a in hBMSC-derived exosomes resulted in inhibition of GBM cell proliferation, invasion, migration and tumorigenesis in vitro and in vivo, while promoting the chemosensitivity of GBM cells to TMZ by silencing MYCN.

Conclusions

From our data we conclude that hBMSC-derived exosomes overexpressing miR-34a may be instrumental for the therapeutic targeting and clinical management of GBM.

中文翻译：

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人骨髓间充质干细胞分泌的外泌体过度表达 microRNA-34a，通过下调 MYCN 改善胶质母细胞瘤的发展。

 目的

外泌体通过影响肿瘤微环境调节和肿瘤增殖（包括胶质母细胞瘤（GBM））的信号通路，在细胞间通讯中发挥重要作用。然而，迄今为止，关于人骨髓间充质干细胞（hBMSC）来源的外泌体对 GBM 发育的抑制作用的研究还很有限。因此，我们着手评估 hBMSC 分泌的外泌体，特别是携带 microRNA-34a (miR-34a) 的外泌体，在 GBM 发育中的作用。

 方法

采用基于微阵列的表达分析来识别差异表达基因并预测调节 MYCN 表达的 miRNA。接下来，用 miR-34a 模拟物或抑制剂转染 hBMSC，然后分离外泌体。体外测量外泌体暴露的 GBM 细胞（T-98G、LN229 和 A-172）的增殖、凋亡、迁移、侵袭和替莫唑胺（TMZ）化学敏感性。使用慢病毒转染研究了 MYCN 调节的机制。通过皮下注射 miR34a 含量上调的 hBMSCs，在异种移植 GBM 细胞的裸鼠中测量外泌体 miR-34a 的体内抑制作用。

 结果

我们发现低表达的 miR-34a 特异性靶向并负向调节 GBM 细胞中 MYCN 的表达。此外，我们发现 miR-34a 通过 hBMSC 衍生的外泌体递送至 T-98G、LN229 和 A-172 GBM 细胞。 hBMSC 来源的外泌体中外源性过表达 miR-34a 可在体外和体内抑制 GBM 细胞增殖、侵袭、迁移和肿瘤发生，同时通过沉默 MYCN 促进 GBM 细胞对 TMZ 的化疗敏感性。

 结论

根据我们的数据，我们得出结论，过度表达 miR-34a 的 hBMSC 衍生的外泌体可能有助于 GBM 的治疗靶向和临床管理。