Abstract

Background

The tumorigenic potential of glioma stem cells (GSCs) is associated with multiple reversible molecular alternations, but the role of posttranslational protein sumoylation in GSCs has not been elucidated. The development of GSC-targeting drugs relies on the discovery of GSC-preferential molecular modifications and the relevant signaling pathways. In this work, we investigated the protein sumoylation status, the major sumoylated substrate, and the key regulatory enzyme in GSCs to explore the therapeutic potential of disrupting protein sumoylation for glioblastoma (GBM) treatment.

Methods

Patient-derived GSCs, primary GBM sections, and intracranial GBM xenografts were used to determine protein sumoylation and the related molecular mechanisms by immunoblot, quantitative PCR, immunoprecipitation, immunofluorescence, and immunohistochemistry. Orthotopic GBM xenograft models were applied to investigate the inhibition of tumor growth by disrupting protein sumoylation with short hairpin (sh)RNAs or molecular inhibitors.

Results

We show that high levels of small ubiquitin-related modifier 1 (SUMO1)—but not SUMO2/3—modified sumoylation are preferentially present in GSCs. The promyelocytic leukemia (PML) protein is a major SUMO1-sumoylated substrate in GSCs, whose sumoylation facilitates its interaction with c-Myc to stabilize c-Myc proteins. The prolyl-isomerase Pin1 is preferentially expressed in GSCs and functions as the key enzyme to promote SUMO1 sumoylation. Disruption of SUMO1 sumoylation by Pin1 silencing with shRNAs or inhibition with its inhibitor Juglone markedly abrogated GSC maintenance and mitigated GSC-driven tumor growth.

Conclusions

Our findings indicate that high SUMO1-modified protein sumoylation as a feature of GSCs is critical for GSC maintenance, suggesting that targeting SUMO1 sumoylation may effectively improve GBM treatment.

中文翻译：

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Pin1 促进胶质瘤干细胞中 SUMO1 的蛋白质苏糖化增强胶质母细胞瘤的恶性程度。

摘要

背景

胶质瘤干细胞 (GSCs) 的致瘤潜能与多种可逆的分子改变有关，但翻译后蛋白苏木酰化在 GSCs 中的作用尚未阐明。GSC靶向药物的开发依赖于GSC优先分子修饰和相关信号通路的发现。在这项工作中，我们研究了 GSCs 中的蛋白质 sumoylation 状态、主要的 sumoylated 底物和关键调节酶，以探索破坏蛋白质 sumoylation 对胶质母细胞瘤 (GBM) 治疗的治疗潜力。

方法

患者来源的 GSC、原发性 GBM 切片和颅内 GBM 异种移植物通过免疫印迹、定量 PCR、免疫沉淀、免疫荧光和免疫组织化学来确定蛋白质 sumoylation 和相关分子机制。原位 GBM 异种移植模型用于研究通过用短发夹 (sh) RNA 或分子抑制剂破坏蛋白质 sumoylation 来抑制肿瘤生长。

结果

我们表明高水平的小泛素相关修饰剂 1 (SUMO1) - 但不是 SUMO2/3 - 修饰的 sumoylation 优先存在于 GSCs 中。早幼粒细胞白血病 (PML) 蛋白是 GSC 中主要的 SUMO1-sumoylated 底物，其 sumoylation 促进其与 c-Myc 的相互作用以稳定 c-Myc 蛋白。脯氨酰异构酶 Pin1 优先在 GSCs 中表达，是促进 SUMO1 苏木酰化的关键酶。用 shRNA 沉默 Pin1 或用其抑制剂 Juglone 抑制 SUMO1 SUMO1 化可显着消除 GSC 维持并减轻 GSC 驱动的肿瘤生长。

结论

我们的研究结果表明，作为 GSC 的一个特征的高 SUMO1 修饰的蛋白质 sumoylation 对 GSC 的维持至关重要，这表明靶向 SUMO1 的 sumoylation 可以有效地改善 GBM 治疗。