Offenbacher Rachel, Jackson Kyle W, Hayashi Masanori, Zhang Jinghang, Peng Da, Tan Yuqi, Stewart Tracy Murray, Ciero Paul, Foley Jackson, Casero Robert A, Cahan Patrick, Loeb David M
Albert Einstein College of Medicine, Bronx, United States.
Indiana University School of Medicine, Indianapolis, Indiana, United States.
Clin Cancer Res. 2025 Jul 24. doi: 10.1158/1078-0432.CCR-24-1778.
Despite decades of clinical trials, no progress has been made in improving the survival of patients with Ewing sarcoma who either present with metastatic disease or suffer a metastatic relapse. In our preclinical models, we found differential levels of polyamines in tumors that metastasize compared to tumors that do not, leading us to investigate the potential for D, L-alpha-difluoromethylornithine (DFMO), an inhibitor of polyamine synthesis, to prevent Ewing sarcoma metastasis.
The effect of DFMO on Ewing sarcoma cell lines in vitro was studied by measuring proliferation, sphere formation, and clonogenic growth in soft agar. The effect in vivo was investigated using our orthotopic implantation/amputation model of metastasis. Transcriptomic changes were evaluated by RNA sequencing.
DFMO causes a cell cycle arrest and inhibits both sarcosphere formation and clonogenic growth in soft agar. In vivo, DFMO slows primary tumor growth and inhibits metastasis. RNA sequencing demonstrated gene expression patterns consistent with induction of ferroptosis caused by polyamine depletion, which was validated in vitro by demonstrating that DFMO treatment induces lipid peroxidation and ferrostatin-1 and liproxstatin-1 allow sphere formation even in the presence of DFMO.
DFMO slows the growth of Ewing sarcoma cells in vitro, with a profound impact on sphere formation and clonogenic growth, and impacts all aspects of Ewing sarcoma tumorigenesis, including tumor initiation, tumor growth, and metastasis, probably through induction of ferroptosis mediated by polyamine depletion. Our results provide preclinical justification to test the ability of DFMO to prevent metastatic recurrence in Ewing sarcoma patients.
尽管进行了数十年的临床试验，但在改善患有转移性疾病或发生转移性复发的尤因肉瘤患者的生存率方面仍未取得进展。在我们的临床前模型中，我们发现与未发生转移的肿瘤相比，发生转移的肿瘤中多胺水平存在差异，这促使我们研究多胺合成抑制剂D，L-α-二氟甲基鸟氨酸（DFMO）预防尤因肉瘤转移的潜力。
通过测量体外增殖、球体形成和软琼脂中的克隆生长，研究了DFMO对尤因肉瘤细胞系的影响。使用我们的原位植入/截肢转移模型研究了其在体内的作用。通过RNA测序评估转录组变化。
DFMO导致细胞周期停滞，并抑制软琼脂中的肌球体形成和克隆生长。在体内，DFMO减缓原发性肿瘤生长并抑制转移。RNA测序显示基因表达模式与多胺耗竭引起的铁死亡诱导一致，这在体外得到验证，即DFMO处理可诱导脂质过氧化，并且即使在存在DFMO的情况下，铁死亡抑制因子-1和脂氧素-1也能使球体形成。
DFMO在体外减缓尤因肉瘤细胞的生长，对球体形成和克隆生长有深远影响，并影响尤因肉瘤肿瘤发生的各个方面，包括肿瘤起始、肿瘤生长和转移，可能是通过多胺耗竭介导的铁死亡诱导。我们的结果为测试DFMO预防尤因肉瘤患者转移性复发的能力提供了临床前依据。
