Zirpoli Sara, Copperman Noah, Patel Shrey, Forrest Alexander, Hou Zhanjun, Matherly Larry H, Loeb David M, Di Cristofano Antonio
bioRxiv. 2025 Apr 29:2025.04.13.647987. doi: 10.1101/2025.04.13.647987.
Ewing sarcoma (EWS) is the second most common primary bone malignancy in adolescents and young adults. Patients who present with localized disease have experienced a steadily improving survival rate over the years, whereas those who present with metastatic disease have the same dismal prognosis as 30 years ago, with long term survival rates less than 20%, despite maximal intensification of chemotherapy. Thus, novel treatment approaches are a significant unmet clinical need. Targeting metabolic differences between EWS and normal cells offers a promising approach to improve outcomes for these patients. One-carbon metabolism utilizes serine and folate to generate glycine and tetrahydrofolate (THF)-bound one-carbon units required for nucleotide biosynthesis. Elevated expression of several one-carbon metabolism genes is significantly associated with reduced survival in EWS patients. We show that both genetic and pharmacological inhibition of a key enzyme of the mitochondrial arm of the one-carbon metabolic pathway, serine hydroxymethyltransferase 2 (SHMT2), leads to substantial inhibition of EWS cell proliferation and colony-forming ability, and that this effect is primarily caused by depletion of glycine and one-carbon units required for synthesis of purine nucleotides. Inhibition of one-carbon metabolism at a different node, using the clinically relevant dihydrofolate reductase inhibitor Pralatrexate, similarly yields a profound growth inhibition, with depletion of thymidylate and purine nucleotides. Genetic depletion of dramatically impairs tumor growth in a xenograft model of EWS. Together, these data establish the upregulation of the one-carbon metabolism as a novel and targetable vulnerability of EWS cells, which can be exploited for therapy.
Using both genetic and pharmacologic approaches, this study identifies Ewing sarcoma's dependence on the mitochondrial arm, but not the cytoplasmic arm, of one-carbon metabolism as a targetable vulnerability that can be effectively harnessed for therapy.
尤因肉瘤（EWS）是青少年和年轻成年人中第二常见的原发性骨恶性肿瘤。多年来，表现为局限性疾病的患者生存率稳步提高，而表现为转移性疾病的患者预后仍与30年前一样糟糕，尽管化疗强度已达到最大，但长期生存率仍低于20%。因此，新的治疗方法是一项重大的未满足临床需求。针对EWS与正常细胞之间的代谢差异提供了一种有望改善这些患者预后的方法。一碳代谢利用丝氨酸和叶酸生成甘氨酸和与四氢叶酸（THF）结合的一碳单位，这些是核苷酸生物合成所必需的。几种一碳代谢基因的高表达与EWS患者生存率降低显著相关。我们发现，对一碳代谢途径线粒体分支的关键酶丝氨酸羟甲基转移酶2（SHMT2）进行基因和药理学抑制，均会导致EWS细胞增殖和集落形成能力受到显著抑制，且这种效应主要是由甘氨酸和嘌呤核苷酸合成所需的一碳单位耗竭引起的。使用临床相关的二氢叶酸还原酶抑制剂普拉曲沙在不同节点抑制一碳代谢，同样会产生显著的生长抑制，伴有胸苷酸和嘌呤核苷酸的耗竭。在EWS异种移植模型中基因敲除[此处原文缺失具体基因名称]会显著损害肿瘤生长。总之，这些数据表明一碳代谢的上调是EWS细胞一种新的且可靶向的脆弱点，可用于治疗。
本研究通过基因和药理学方法，确定尤因肉瘤对一碳代谢的线粒体分支而非细胞质分支的依赖性，是一种可有效用于治疗的可靶向脆弱点。
