Glioblastoma, the most lethal primary brain tumor, harbors glioma stem cells (GSCs) that not only initiate and maintain malignant phenotypes but also enhance therapeutic resistance. Although frequently mutated in glioblastomas, the function and regulation of PTEN in PTEN-intact GSCs are unknown. Here, we found that PTEN directly interacted with MMS19 and competitively disrupted MMS19-based cytosolic iron-sulfur (Fe-S) cluster assembly (CIA) machinery in differentiated glioma cells. PTEN was specifically succinated at cysteine (C) 211 in GSCs compared with matched differentiated glioma cells. Isotope tracing coupled with mass spectrometry analysis confirmed that fumarate, generated by adenylosuccinate lyase (ADSL) in the de novo purine synthesis pathway that is highly activated in GSCs, promoted PTEN C211 succination. This modification abrogated the interaction between PTEN and MMS19, reactivating the CIA machinery pathway in GSCs. Functionally, inhibiting PTEN C211 succination by reexpressing a PTEN C211S mutant, depleting ADSL by shRNAs, or consuming fumarate by the US Food and Drug Administration–approved prescription drug N-acetylcysteine (NAC) impaired GSC maintenance. Reexpressing PTEN C211S or treating with NAC sensitized GSC-derived brain tumors to temozolomide and irradiation, the standard-of-care treatments for patients with glioblastoma, by slowing CIA machinery–mediated DNA damage repair. These findings reveal an immediately practicable strategy to target GSCs to treat glioblastoma by combination therapy with repurposed NAC.

中文翻译：

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重新激活 PTEN 通过抑制胞质铁硫组装来损害神经胶质瘤干细胞

胶质母细胞瘤是最致命的原发性脑肿瘤，它含有胶质瘤干细胞（GSC），不仅可以启动和维持恶性表型，还可以增强治疗耐药性。尽管在胶质母细胞瘤中经常发生突变，但 PTEN 在 PTEN 完整 GSC 中的功能和调节尚不清楚。在这里，我们发现 PTEN 直接与 MMS19 相互作用，并竞争性破坏分化神经胶质瘤细胞中基于 MMS19 的胞质铁硫 (Fe-S) 簇组装 (CIA) 机制。与匹配的分化神经胶质瘤细胞相比，GSC 中的 PTEN 在半胱氨酸 (C) 211 处被特异性琥珀化。同位素示踪结合质谱分析证实，在 GSC 中高度激活的从头嘌呤合成途径中，由腺苷酸琥珀酸裂解酶 (ADSL) 产生的富马酸促进 PTEN C211 琥珀化。这种修饰消除了 PTEN 和 MMS19 之间的相互作用，重新激活了 GSC 中的 CIA 机械通路。从功能上来说，通过重新表达 PTEN C211S 突变体来抑制 PTEN C211 琥珀化、通过 shRNA 消耗 ADSL 或使用美国食品和药物管理局批准的处方药N-乙酰半胱氨酸 (NAC) 消耗富马酸盐会损害 GSC 维持。重新表达 PTEN C211S 或用 NAC 治疗，通过减缓 CIA 机制介导的 DNA 损伤修复，使 GSC 衍生的脑肿瘤对替莫唑胺和放射（胶质母细胞瘤患者的标准治疗方法）敏感。这些发现揭示了一种立即可行的策略，通过与重新利用的 NAC 联合治疗，靶向 GSC 来治疗胶质母细胞瘤。