Multi-agent chemotherapeutic regimes remain the cornerstone treatment for Ewing sarcoma, the second most common bone malignancy diagnosed in pediatric and young adolescent populations. We have reached a therapeutic ceiling with conventional cytotoxic agents, highlighting the need to adopt novel approaches that specifically target the drivers of Ewing sarcoma oncogenesis. As KDM1A/lysine-specific demethylase 1 (LSD1) is highly expressed in Ewing sarcoma cell lines and tumors, with elevated expression levels associated with worse overall survival (P = 0.033), this study has examined biomarkers of sensitivity and mechanisms of cytotoxicity to targeted KDM1A inhibition using SP-2509 (reversible KDM1A inhibitor). We report, that innate resistance to SP-2509 was not observed in our Ewing sarcoma cell line cohort (n = 17; IC50 range, 81 –1,593 nmol/L), in contrast resistance to the next-generation KDM1A irreversible inhibitor GSK-LSD1 was observed across multiple cell lines (IC50 > 300 μmol/L). Although TP53/STAG2/CDKN2A status and basal KDM1A mRNA and protein levels did not correlate with SP-2509 response, induction of KDM1B following SP-2509 treatment was strongly associated with SP-2509 hypersensitivity. We show that the transcriptional profile driven by SP-2509 strongly mirrors KDM1A genetic depletion. Mechanistically, RNA-seq analysis revealed that SP-2509 imparts robust apoptosis through engagement of the endoplasmic reticulum stress pathway. In addition, ETS1/HIST1H2BM were specifically induced/repressed, respectively following SP-2509 treatment only in our hypersensitive cell lines. Together, our findings provide key insights into the mechanisms of SP-2509 cytotoxicity as well as biomarkers that can be used to predict KDM1A inhibitor sensitivity in Ewing sarcoma. Mol Cancer Ther; 17(9); 1902–16. ©2018 AACR.

中文翻译：

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使用 SP-2509 在尤文肉瘤中靶向治疗 KDM1A/LSD1 参与内质网应激反应

多药化疗方案仍然是尤文肉瘤的基石治疗，尤文肉瘤是儿科和青少年人群中诊断出的第二大常见骨恶性肿瘤。我们已经达到了传统细胞毒性药物的治疗上限，强调需要采用专门针对尤文肉瘤肿瘤发生驱动因素的新方法。由于 KDM1A/赖氨酸特异性去甲基化酶 1 (LSD1) 在尤文肉瘤细胞系和肿瘤中高度表达，表达水平升高与较差的总体存活率相关（P = 0.033），本研究检查了敏感性生物标志物和靶向靶向药物的细胞毒性机制。使用 SP-2509（可逆 KDM1A 抑制剂）抑制 KDM1A。我们报告说，在我们的尤文肉瘤细胞系队列中未观察到对 SP-2509 的先天抗性（n = 17；IC50 范围，81 –1,593 nmol/L），相反，在多个细胞系中观察到对下一代 KDM1A 不可逆抑制剂 GSK-LSD1 的抗性 (IC50 > 300 μmol/L)。尽管 TP53/STAG2/CDKN2A 状态和基础 KDM1A mRNA 和蛋白质水平与 SP-2509 反应无关，但 SP-2509 治疗后 KDM1B 的诱导与 SP-2509 超敏反应密切相关。我们表明，由 SP-2509 驱动的转录谱强烈反映了 KDM1A 遗传耗竭。从机制上讲，RNA-seq 分析显示 SP-2509 通过参与内质网应激途径赋予强大的细胞凋亡。此外，仅在我们的过敏细胞系中，在 SP-2509 处理后，ETS1/HIST1H2BM 分别被特异性诱导/抑制。一起，我们的研究结果提供了对 SP-2509 细胞毒性机制以及可用于预测尤文肉瘤中 KDM1A 抑制剂敏感性的生物标志物的关键见解。摩尔癌症治疗; 17(9); 1902-16。©2018 AACR。