Background/Objectives: Ewing sarcoma (ES), a highly aggressive bone and soft tissue cancer occurring in children and young adults, is defined by the ETS fusion oncoprotein EWS::FLI1. Although event-free survival rates remain high in ES patients with localized disease, those with metastatic or relapsed disease face poor long-term survival odds. Topoisomerase 1 (TOP1) inhibitors are commonly used therapeutics in ES relapse regimens. Methods: In this work, we used a genome-wide CRISPR knockout library screen to identify the deletion of theTOP1gene as a mechanism for resistance to topoisomerase 1 inhibitors. Using isogenic cell line models, we performed a high-throughput small-molecule screen to discover a small molecule, GNF-7, which had an IC50 that was 10-fold lower inTOP1-deficient cells when compared to the wild-type cells. Results: The characterization of GNF-7 demonstrated the molecule was highly active in the inhibition of CSK, p38α, EphA2, Lyn, and ZAK and specifically downregulated genes induced by the EWS::FLI1 fusion oncoprotein. Conclusions: Together, these results suggest that GNF-7 or small molecules with a similar kinase profile could be effective treatments for ES patients in combination with TOP1 inhibitors or for those patients who have developed resistance to TOP1 inhibitors.
背景/目的：尤文肉瘤（ES）是一种高侵袭性的骨与软组织恶性肿瘤，好发于儿童及青少年，其分子特征为ETS融合癌蛋白EWS::FLI1。尽管局限性病变的ES患者无事件生存率较高，但转移性或复发性患者的长期生存率仍不乐观。拓扑异构酶1（TOP1）抑制剂是ES复发治疗方案中的常用药物。方法：本研究通过全基因组CRISPR敲除文库筛选，发现TOP1基因缺失是导致细胞对拓扑异构酶1抑制剂产生耐药性的机制。利用同基因细胞系模型，我们进行了高通量小分子筛选，发现小分子化合物GNF-7在TOP1缺陷细胞中的IC50值较野生型细胞降低10倍。结果：对GNF-7的特性分析表明，该分子能高效抑制CSK、p38α、EphA2、Lyn和ZAK激酶活性，并特异性下调EWS::FLI1融合癌蛋白诱导的基因表达。结论：综合以上结果提示，GNF-7或具有类似激酶抑制谱的小分子化合物，或可作为联合TOP1抑制剂治疗ES的有效方案，也可用于已对TOP1抑制剂产生耐药性的患者。
The Kinase Inhibitor GNF-7 Is Synthetically Lethal in Topoisomerase 1-Deficient Ewing Sarcoma
肿瘤(癌症)患者之家