Background Microtubes (MTs), cytoplasmic extensions of glioma cells, are important cell communication structures promoting invasion and treatment resistance through network formation. MTs are abundant in chemoresistant gliomas, in particular, glioblastomas (GBMs), while they are uncommon in chemosensitive IDH-mutant and 1p/19q co-deleted oligodendrogliomas. The aim of this study was to identify potential signaling pathways involved in MT formation. Methods Bioinformatics analysis of TCGA was performed to analyze differences between GBM and oligodendroglioma. Patient-derived GBM stem cell lines were used to investigate MT formation under transforming growth factor-beta (TGF-β) stimulation and inhibition in vitro and in vivo in an orthotopic xenograft model. RNA sequencing and proteomics were performed to detect commonalities and differences between GBM cell lines stimulated with TGF-β. Results Analysis of TCGA data showed that the TGF-β pathway is highly activated in GBMs compared to oligodendroglial tumors. We demonstrated that TGF-β1 stimulation of GBM cell lines promotes enhanced MT formation and communication via calcium signaling. Inhibition of the TGF-β pathway significantly reduced MT formation and its associated invasion in vitro and in vivo. Downstream of TGF-β, we identified thrombospondin 1 (TSP1) as a potential mediator of MT formation in GBM through SMAD activation. TSP1 was upregulated upon TGF-β stimulation and enhanced MT formation, which was inhibited by TSP1 shRNAs in vitro and in vivo. Conclusion TGF-β and its downstream mediator TSP1 are important mediators of the MT network in GBM and blocking this pathway could potentially help to break the complex MT-driven invasion/resistance network.

中文翻译：

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TGF-β通过血小板反应蛋白1促进胶质母细胞瘤中的微管形成

背景微管（MTs）是神经胶质瘤细胞的细胞质延伸，是重要的细胞通讯结构，通过网络形成促进侵袭和治疗抗性。MT 在化学抗性神经胶质瘤中含量丰富，特别是胶质母细胞瘤 (GBM)，而它们在化学敏感性 IDH 突变体和 1p/19q 共缺失少突胶质细胞瘤中并不常见。本研究的目的是确定参与 MT 形成的潜在信号通路。方法对TCGA进行生物信息学分析，分析GBM与少突胶质细胞瘤的差异。患者来源的 GBM 干细胞系用于研究在原位异种移植模型中体外和体内在转化生长因子-β (TGF-β) 刺激和抑制下的 MT 形成。进行 RNA 测序和蛋白质组学以检测用 TGF-β 刺激的 GBM 细胞系之间的共性和差异。结果 TCGA 数据分析表明，与少突胶质细胞肿瘤相比，GBM 中的 TGF-β 通路高度激活。我们证明了 TGF-β1 刺激 GBM 细胞系通过钙信号传导促进增强的 MT 形成和通讯。TGF-β途径的抑制显着减少了MT的形成及其在体外和体内的相关侵袭。在 TGF-β 的下游，我们将血小板反应蛋白 1 (TSP1) 鉴定为通过 SMAD 激活在 GBM 中形成 MT 的潜在介质。TSP1 在 TGF-β 刺激和增强的 MT 形成后上调，这在体外和体内被 TSP1 shRNA 抑制。