Temozolomide (TMZ) is a chemotherapeutic agent that has been the first-line standard of care for the aggressive brain cancer glioblastoma (GBM) since 2005. Although initially beneficial, TMZ resistance is universal and second-line interventions are an unmet clinical need. Here, we took advantage of the known mechanism of action of TMZ to target guanines (G) and investigated G-rich G-quadruplex (G4) and splice site changes that occur upon TMZ resistance. We report that TMZ-resistant GBM has guanine mutations that disrupt the G-rich DNA G4s and splice sites that lead to deregulated alternative splicing. These alterations create vulnerabilities, which are selectively targeted by either the G4-stabilizing drug TMPyP4 or a novel splicing kinase inhibitor of cdc2-like kinase. Last, we show that the G4 and RNA binding protein EWSR1 aggregates in the cytoplasm in TMZ-resistant GBM cells and patient samples. Together, our findings provide insight into targetable vulnerabilities of TMZ-resistant GBM and present cytoplasmic EWSR1 as a putative biomarker.

中文翻译：

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替莫唑胺诱导的鸟嘌呤突变使耐药神经胶质瘤中富含鸟嘌呤的 DNA 和 RNA 区域产生可利用的脆弱性

替莫唑胺 (TMZ) 是一种化疗药物，自 2005 年以来一直是侵袭性脑癌胶质母细胞瘤 (GBM) 的一线治疗标准。尽管最初有益，但 TMZ 耐药性普遍存在，二线干预措施尚未满足临床需求。在这里，我们利用 TMZ 的已知作用机制来靶向鸟嘌呤 (G)，并研究了富含 G 的 G 四链体 (G4) 和 TMZ 抗性时发生的剪接位点变化。我们报告说，TMZ 抗性 GBM 具有鸟嘌呤突变，会破坏富含 G 的 DNA G4 和剪接位点，从而导致选择性剪接失调。这些改变产生了漏洞，G4 稳定药物 TMPyP4 或 cdc2 样激酶的新型剪接激酶抑制剂选择性地针对这些漏洞。最后，我们发现 G4 和 RNA 结合蛋白 EWSR1 在 TMZ 耐药 GBM 细胞和患者样本的细胞质中聚集。总之，我们的研究结果提供了对 TMZ 耐药性 GBM 的可靶向脆弱性的深入了解，并将细胞质 EWSR1 作为假定的生物标志物。