Apoptosis in myelofibrosis with myeloid metaplasia

骨髓纤维化伴骨髓化生中的细胞凋亡

• 批准号: 6800349
• 负责人: Ruben A. Mesa
• 金额: $ 12.37万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6800349
• 关键词: BCL2 gene /protein; apoptosis; cell growth regulation; clinical research; cysteine endopeptidases; cytokine; granulocyte; human subject; metaplasia; molecular pathology; myelofibrosis; myeloid stem cell; patient oriented research; phosphatidylinositol 3 kinase

DESCRIPTION (provided by applicant): Myelofibrosis with myeloid metaplasia is a clonal hematopoietic stem cell disorder that results in progressive cytopenias, splenomegaly, blastic transformation, and death. No broadly applicable therapy is available. The pathogenetic mechanism of MMM is currently unknown. A defect in the normal process of apoptosis has been demonstrated in the related myeloproliferative disorders of chronic myeloid leukemia and polycythemia vera. We have shown that apoptosis (spontaneous, serum deprivation, and TNF-alpha induced) is quantitively diminished in the granulocytes of patients with MMM. We have also observed that erythroid precursors from MMM patients can be grown in vitro in the absence of the prerequisite cytokine erythropoietin. Cytokine independent growth has been characterized in polycythemia Vera to arise from over-expression of Bcl-XL (an anti-apoptotic member of the Bcl-2 family). We believe the diminished apoptosis we have observed in MMM may be linked to cytokine hypersensitivity and, potentially, to the anti-apoptotic pathways of Bcl-2 or the Akt pathway. We hypothesize that apoptosis is dysregulated in granulocytes in MMM, and this is a reflection of the corresponding defect in the aberrant clone. In this grant application we propose to: 1.Compare baseline levels of apoptotic proteins and regulators across the spectrum of MMM patients and controls. Baseline levels of apoptotic proteins (caspases), and regulators (lAP's, Bcl-2 family members) will be assessed across a spectrum of MMM patients and normal controls. 2. Evaluate the regulation of caspase activation in MMM neutrophils subjected to apoptotic stimuli through both cellular and cell free systems. Isolated neutrophils from MMM patients and controls will be subjected to various apoptotic stimuli to delineate which pathway of apoptosis is aberrantly regulated. Subsequent experiments will use both immunoblotting and a cytosol caspase activation assay to determine which caspases and regulators are responsible for the apoptotic defect seen in MMM neutrophils. 3. Evaluate the role of the phosphatidylinositol 3- kinase pathway on cytokine independent growth in myeloid progenitors in MMM. Cytokine independent growth of myeloid colonies will be confirmed across a spectrum of MMM patients. Subsequent experiments will delineate the role of the phosphatidylinositol-3 kinase pathway in both apoptosis resistance and cytokine independent colony growth. Successful accomplishments of these goals will provide the scientific basis for targeted anti-myeloproliferative therapy for the treatment of patients suffering from MMM and potentially related chronic myeloid disorders.

描述（由申请人提供）：骨髓纤维化伴髓样化生是一种克隆性造血干细胞疾病，可导致进行性血细胞减少、脾肿大、母细胞转化和死亡。 目前尚无广泛适用的治疗方法。MMM的发病机制目前尚不清楚。 正常凋亡过程中的缺陷已在慢性髓细胞白血病和真性红细胞增多症的相关骨髓增生性疾病中得到证实。 我们已经表明，MMM患者的粒细胞凋亡（自发的、血清剥夺和TNF-α诱导的）在数量上减少。 我们还观察到，来自MMM患者的红细胞前体可以在体外生长，在没有必要的细胞因子促红细胞生成素的情况下。在真性红细胞增多症中，细胞因子非依赖性生长的特征在于Bcl-XL（Bcl-2家族的抗凋亡成员）的过度表达。 我们认为，我们在MMM中观察到的细胞凋亡减少可能与细胞因子超敏反应有关，并且可能与Bcl-2或Akt通路的抗凋亡通路有关。 我们假设MMM中粒细胞凋亡失调，这是异常克隆中相应缺陷的反映。 在本补助金申请中，我们建议： 1.比较MMM患者和对照组的凋亡蛋白和调节因子的基线水平。 将在一系列MMM患者和正常对照中评估凋亡蛋白（半胱天冬酶）和调节剂（IAP、Bcl-2家族成员）的基线水平。 2.评价通过细胞和无细胞系统受到凋亡刺激的MMM中性粒细胞中半胱天冬酶激活的调节。来自MMM患者和对照的分离的中性粒细胞将经受各种凋亡刺激以描绘哪种凋亡途径被异常调节。 随后的实验将使用免疫印迹法和胞质半胱天冬酶激活试验，以确定哪些半胱天冬酶和调节剂负责MMM中性粒细胞中观察到的凋亡缺陷。 3.评价磷脂酰肌醇3-激酶途径在MMM髓系祖细胞中细胞因子非依赖性生长中的作用。骨髓集落的细胞因子非依赖性生长将在一系列MMM患者中得到证实。 随后的实验将描述磷脂酰肌醇-3激酶途径在细胞凋亡抗性和细胞因子非依赖性集落生长中的作用。 这些目标的成功实现将为靶向抗骨髓增殖治疗MMM和潜在相关慢性髓系疾病患者提供科学依据。