Osteosarcoma (OS) is one of the most malignant tumors of childhood and adolescence. Research on mitochondrial dynamics (fusion/fission) and biogenesis has received much attention in last few years, as they are crucial for death of cancer cells. Specifically, it was shown that increased expression of the cytoplasmic dynamin-related protein 1 (Drp1) triggers mitochondrial fission (division), which activates BAX and downstream intrinsic apoptosis, effectively inhibiting OS growth. In the presented study, human OS cells (metastatic 143B OS cell line) were incubated with 2-methoxyestradiol (2-ME) at both physiologically and pharmacologically relevant concentrations. Cell viability was determined by the MTT assay. Confocal microscopy and western blot methods were applied to examine changes in Drp1 and BAX protein levels. Mitochondrial Division Inhibitor 1, MDIVI-1, was used in the study to further examine the role of Drp1 in 2-ME-mediated mechanism of action. To determine quantitative and qualitative changes in mitochondria, electron microscopy was used. 2-ME at all used concentrations increased mitochondrial fission and induced autophagy in OS cells. At the concentration of 1 µM 2-ME increased the area density of mitochondria in OS cells. Subsequent, upregulated expression of Drp1 and BAX proteins by 2-ME strongly suggests the activation of the intrinsic apoptosis pathway. We further observed 2-ME-mediated regulation of glycolytic state of OS cells. Therefore, we suggest that changes of mitochondrial dynamics may represent a novel mechanism of anticancer action of 2-ME. This finding may open new approaches to improve the efficacy of chemotherapy in the treatment of OS, however, it has to be confirmed by in vivo studies.

骨肉瘤 (OS) 是儿童和青春期最恶性的肿瘤之一。线粒体动力学（融合/裂变）和生物发生的研究在过去几年受到了很多关注，因为它们对癌细胞的死亡至关重要。具体而言，研究表明细胞质动力蛋白相关蛋白 1 (Drp1) 的表达增加会触发线粒体裂变（分裂），从而激活 BAX 和下游内在细胞凋亡，从而有效抑制 OS 生长。在本研究中，人类 OS 细胞（转移性 143B OS 细胞系）与生理学和药理学相关浓度的 2-甲氧基雌二醇 (2-ME) 一起孵育。通过MTT测定法测定细胞活力。应用共聚焦显微镜和蛋白质印迹方法检查 Drp1 和 BAX 蛋白水平的变化。线粒体分裂抑制剂 1，MDIVI-1，用于该研究以进一步检查 Drp1 在 2-ME 介导的作用机制中的作用。为了确定线粒体的定量和定性变化，使用了电子显微镜。所有使用浓度的 2-ME 都会增加线粒体分裂并诱导 OS 细胞自噬。在 1 µM 的浓度下，2-ME 增加了 OS 细胞中线粒体的面积密度。随后，2-ME 上调 Drp1 和 BAX 蛋白的表达强烈表明内在凋亡途径的激活。我们进一步观察了 2-ME 介导的 OS 细胞糖酵解状态的调节。因此，我们认为线粒体动力学的变化可能代表 2-ME 抗癌作用的新机制。