Xu Jiuhui, Shi Qianyu, Zeng Fanwei, Ren Tingting, Wei Ran, Tang Xiaodong
Department of Musculoskeletal Tumor, Peking University People's Hospital, Beijing, China.
Beijing Key Laboratory of Musculoskeletal Tumor, Peking University People's Hospital, Beijing, China.
Front Immunol. 2025 Sep 1;16:1647913. doi: 10.3389/fimmu.2025.1647913. eCollection 2025.
Osteosarcoma (OS) is the most common primary bone malignancy, characterized by aggressive local invasion and a high propensity for metastasis. We previously reported that cyclin E1 is upregulated in osteosarcoma. In this study, we identified a cytoplasmic, low molecular weight cyclin E1 isoform (LMW-cyclin E1) in osteosarcoma that is significantly associated with poor patient outcomes.
We collected RNA sequencing data to analyze the cyclin E1 () expression and performed Western blot assay, immunofluorescence, and immunohistochemistry staining to validate cyclin E1 expression in OS. We also analyzed the correlation between its expression levels and the overall and progression-free survival rates of patients with OS. Small interfering RNA and plasmids were constructed to regulate neutrophil elastase (ELA2) expression to explore the mechanism of low molecular weight cyclin E1 formation in OS. Neutrophils isolated from healthy donors were cocultured with OS cells to test the function of ELA2, and its effect was further validated in BALB/c mice. The relationship between neutrophil infiltration and OS progression was analyzed in 34 primary OS tissues and 33 OS lung metastasis tissues.
Mechanistically, we found that ELA2, primarily derived from tumor-associated neutrophils, cleaves full-length cyclin E1 to generate LMW-cyclin E1, which accelerates OS proliferation. Moreover, neutrophil infiltration was associated with OS lung metastasis. OS cells also induced neutrophil extracellular trap formation, which further amplified ELA2 release. Depleting neutrophils or inhibiting ELA2 significantly suppressed OS malignancy. Hence, targeting neutrophil-osteosarcoma crosstalk may be a potential novel therapeutic strategy.
骨肉瘤（OS）是最常见的原发性骨恶性肿瘤，其特征是具有侵袭性的局部浸润和高转移倾向。我们之前报道过细胞周期蛋白E1在骨肉瘤中上调。在本研究中，我们在骨肉瘤中鉴定出一种细胞质低分子量细胞周期蛋白E1亚型（LMW-细胞周期蛋白E1），其与患者的不良预后显著相关。
我们收集RNA测序数据以分析细胞周期蛋白E1（）的表达，并进行蛋白质免疫印迹分析、免疫荧光和免疫组织化学染色以验证骨肉瘤中细胞周期蛋白E1的表达。我们还分析了其表达水平与骨肉瘤患者总生存率和无进展生存率之间的相关性。构建小干扰RNA和质粒以调节中性粒细胞弹性蛋白酶（ELA2）的表达，以探索骨肉瘤中低分子量细胞周期蛋白E1形成的机制。将从健康供体分离的中性粒细胞与骨肉瘤细胞共培养以测试ELA2的功能，并在BALB/c小鼠中进一步验证其作用。在34例原发性骨肉瘤组织和33例骨肉瘤肺转移组织中分析中性粒细胞浸润与骨肉瘤进展之间的关系。
从机制上讲，我们发现主要来源于肿瘤相关中性粒细胞的ELA2可切割全长细胞周期蛋白E1以生成LMW-细胞周期蛋白E1，从而加速骨肉瘤增殖。此外，中性粒细胞浸润与骨肉瘤肺转移有关。骨肉瘤细胞还诱导中性粒细胞胞外陷阱形成，这进一步放大了ELA2的释放。清除中性粒细胞或抑制ELA2可显著抑制骨肉瘤的恶性程度。因此，靶向中性粒细胞与骨肉瘤的相互作用可能是一种潜在的新型治疗策略。
