线粒体ATP酶在慢性粒细胞白血病格列卫耐药中的作用及机制

Down-regulation of mitochondrial ATP synthase expression has been reported in several solid tumors such as carcinomas of the liver, lung and colon. The altered mitochondrial ATP synthase expression is also attributed to 5-fluorouracil resistance in human colon cancer cells. Our previously studies indicated that down-regulation of mitochondrial ATP synthase could induce adriamycin resistance in chronic myeloid leukemia (CML) cells, possibly through DNA methylation regulation. We also found that the mitochondrial ATP synthase expression was decreased in CML Imatinib-resistant cells, suggesting that it may be associated with CML Imatinib-resistance. In this study, we will analyze the difference of mitochondrial ATP synthase expression in CML cell lines and its imatinib resistance counterpart and in bone marrow CD34 + cells of CML patients. The expression of mitochondrial ATP synthase will be regulated through gene transfection and RNA interference. After that, the changes of mitochondrial morphology, functions and proteins expression level of mitochondrial apoptosis related signaling pathway are observed. The changes in signal transduction pathway of NF-κ b will also be studied. Our research will explore the novel mechanisms involved in Imatinib resistance and provide the basis for positioning new target to reverse drug resistance.

线粒体ATP酶在肝癌、肺癌、结肠癌等多种实体肿瘤中表达下降，并与结肠癌耐药相关。申请人首次发现线粒体ATP酶表达下降与慢性粒细胞白血病阿霉素耐药相关，并揭示了其表观遗传学调控机制。同时,我们的前期研究发现线粒体ATP酶在慢粒格列卫耐药株中表达下降，提示线粒体ATP酶可能与慢粒格列卫耐药相关。本研究拟对慢粒格列卫耐药细胞株及慢粒患者骨髓CD34+细胞的线粒体ATP酶表达进行分析，并通过基因转染及RNA干扰策略调控线粒体ATP酶的表达，观察调控前后线粒体形态、功能及线粒体相关的增殖凋亡相关信号途径蛋白表达水平的变化，并追踪NF-κb相关的分子信号转导途径的变化，为揭示慢粒白血病格列卫耐药机制、定位新的逆转耐药的分子靶点提供依据。

线粒体ATP酶是线粒体能量转换的关键酶，参与线粒体氧化磷酸化，研究表明线粒体ATP酶在多种实体瘤中表达下降，并与结肠癌的5-Fu耐药相关。我们之前的研究显线粒体ATP酶可作为一个独立的耐药相关蛋白参与调节慢性粒细胞白血病急变患者的阿霉素耐药。本研究旨在观察慢粒白血病伊马替尼耐药细胞中线粒体ATP酶的表达及活性的变化，分析其与伊马替尼耐药的关系，探讨可能的机制，为慢粒白血病伊马替尼耐药机制研究提供新的思路。研究结果发现：1.线粒体ATP酶蛋白及基因在慢粒白血病伊马替尼耐药细胞株K562/IR以及慢粒白血病伊马替尼耐药患者的骨髓单个核细胞中表达均下降，同时，耐药细胞株K562/IR细胞的线粒体ATP酶活性低于其亲本的伊马替尼敏感细胞株K562；2.通过RNA干扰下调慢粒伊马替尼敏感细胞株K562的线粒体ATP酶表达后，K562细胞对伊马替尼的凋亡抵抗能力增加；3.通过RNA干扰K562细胞株线粒体ATP酶表达后，抗凋亡基因Bcl-xL的蛋白表达上调，并出现转录因子NF-kB激活。这些研究结果提示，线粒体ATP酶在慢粒白血病伊马替尼耐药中发挥重要作用，其表达下调可能与慢粒白血病细胞伊马替尼耐药相关，可能的耐药机制与抗凋亡基因Bcl-xL的表达上调以及转录因子NF-Kb的活化相关。