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线粒体转移对白血病进展的影响

方文佳^1,2, 张标^1,2, 程涛^1,2, 程辉^1,2,*

¹北京协和医学院/中国医学科学院/血液学研究所/血液病医院，血液与健康全国重点实验室，国家血液系统疾病临床医学研究中心，细胞生态海河实验室，天津 300020；²天津医学健康研究院，天津 300020

摘要

本文旨在研究骨髓微环境细胞对白血病细胞线粒体数量的调控作用和机制，从代谢层面上解析白血病进展的机制。建立MLL-AF9 (MA9)融合蛋白诱导的急性髓系白血病(acute myeloid leukemia, AML)小鼠模型，将AML小鼠骨髓细胞移植入线粒体荧光报告mitochondria-Dendra2 (mito-Dendra2)小鼠体内，用流式细胞分析仪检测不同发病时期小鼠骨髓白血病细胞中Dendra2⁺细胞的比例，用流式分选发生线粒体转移(Dendra2⁺)和未发生线粒体转移(Dendra2⁻)的白血病细胞，进行功能实验和转录组测序。消化小鼠骨髓微环境细胞，与白血病细胞进行体外共培养，用流式细胞仪检测发生线粒体转移的白血病细胞比例和白血病细胞的凋亡水平。结果显示，在AML小鼠模型中，骨髓微环境细胞的线粒体向白血病细胞转移，线粒体转移的比例随AML进展而降低。线粒体向白血病干细胞(leukemia stem cell, LSC)转移的比例低于成熟AML细胞。Dendra2⁺白血病细胞的活性氧(reactive oxygen species, ROS)和凋亡水平均显著增加，蛋白翻译水平和体外集落形成能力降低，移植Dendra2⁺白血病细胞的野生型小鼠生存期显著大于移植Dendra2⁻白血病细胞的野生型小鼠。转录组测序提示，Dendra2⁺白血病细胞的翻译、有氧呼吸和线粒体组装等通路显著下调。体外共培养实验结果显示，小鼠骨髓微环境的间充质细胞(mesenchymal stromal cell, MSC)倾向于向白血病细胞转移线粒体，并促进白血病细胞的凋亡。上述结果提示，在MA9 诱导的AML小鼠模型中，骨髓微环境细胞可向白血病细胞转移线粒体，线粒体转移后白血病细胞生存和功能降低，提示骨髓微环境细胞可能通过向白血病细胞转移线粒体抑制白血病进展，具有一定的自身防御功能。

关键词： 急性髓系白血病; 线粒体; 骨髓微环境

The impact of mitochondrial transfer on leukemia progression

FANG Wen-Jia^1,2, ZHANG Biao^1,2, CHENG Tao^1,2, CHENG Hui^1,2,*

¹ State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China；²Tianjin Institutes of Health Science, Tianjin 300020, China

Abstract

The objective of the present study was to investigate the role and mechanism of bone marrow microenvironmental cells in regulating the mitochondrial mass of leukemia cells, and to uncover the mechanism of leukemia progression at the metabolic level. A mouse model of acute myeloid leukemia (AML) induced by the overexpression of the MLL-AF9 (MA9) fusion protein was established, and the bone marrow cells of AML mice were transplanted into mitochondrial fluorescence reporter mice expressing the Dendra2 protein (mito-Dendra2 mice). The proportion of Dendra2⁺ cells in bone marrow leukemia cells at different stages of AML was quantified by flow cytometry. The effects of transferred mitochondria on leukemia cells were studied by fluorescence-activated cell sorting (FACS), followed by functional experiments and bulk RNA sequencing. Finally, components within the bone marrow niche, such as mesenchymal stromal cells (MSCs) and endothelial cells (ECs), were co-cultured with leukemia cells in vitro. The proportion of leukemia cells that underwent mitochondrial transfer and the apoptosis level of leukemia cells were then detected by flow cytometry. The results showed that mitochondria from bone marrow cells were transferred to leukemia cells in the AML mouse model, and the proportion of mitochondrial transfer decreased with AML progression. The proportion of mitochondria transferred to leukemia stem cells (LSCs) was lower than that of mature AML cells. In AML cells receiving Dendra2⁺ mitochondria, there was a significant increase in the levels of intracellular reactive oxygen species (ROS) and apoptosis, while the levels of protein translation and their colony-forming capacities were decreased. The transplantation of Dendra2⁺ AML cells resulted in an extension of the survival of mice. RNA sequencing analysis demonstrated a significant downregulation of pathways related to translation, aerobic respiration and mitochondrial organization in AML cells that had received mitochondria. In vitro co-culture experiments indicated that MSCs within the bone marrow niche tended to transfer their mitochondria to leukemia cells and promoted the apoptosis of leukemia cells. These results indicate that in the MA9-induced AML mouse model, bone marrow niche cells can transfer mitochondria to leukemia cells, resulting in a reduction in the overall survival and function of the leukemia cells. Mitochondrial transfer in the bone marrow microenvironment may serve as a self-defensive mechanism of the host bone marrow niche cells, inhibiting the progression of AML.

Key words: acute myeloid leukemia; mitochondria; bone marrow microenvironment

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通讯作者：程辉　　E-mail:

引用本文：

方文佳, 张标, 程涛, 程辉. 线粒体转移对白血病进展的影响[J]. 生理学报 2024; 76 (6): 943-952.

FANG Wen-Jia, ZHANG Biao, CHENG Tao, CHENG Hui. The impact of mitochondrial transfer on leukemia progression. Acta Physiol Sin 2024; 76 (6): 943-952 (in Chinese with English abstract).