Therapeutic targeting of MicroRNA-21 in Myelodysplastic syndromes

MicroRNA-21 在骨髓增生异常综合征中的治疗靶向

• 批准号: 9135836
• 负责人: Amit K. Verma
• 金额: $ 26.85万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE, INC
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9135836
• 关键词: 3' Untranslated Regions; Accounting; Acute leukemia; Age; Anemia; Attenuated; Binding; Binding Sites; Biochemical; Biological Markers; Blood; Bone Marrow; Cell Differentiation process; Cell Proliferation; Cell membrane; Cells; Characteristics; Clinical; Cytoskeleton; Development; Dysmyelopoietic Syndromes; Dysplasia; Epigenetic Process; Erythrocytes; Erythroid; Erythropoiesis; Event; Failure; Functional disorder; Gene Amplification; Genes; Growth; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate Phosphohydrolases; Health; Hematocrit procedure; Hematologic Neoplasms; Hematopoiesis; Hematopoietic; Hematopoietic Neoplasms; Hematopoietic stem cells; Human; In Vitro; Ineffective Hematopoiesis; Lead; MADH7 gene; Marrow; Mediating; MicroRNAs; Modeling; Modification; Molecular; Morbidity - disease rate; Pancytopenia; Pathway interactions; Patients; Phosphotransferases; Play; Pyrimethamine; Role; STAT3 gene; Sampling; Signal Pathway; Signal Transduction; Specificity; Subgroup; Testing; Therapeutic; Transgenic Mice; Up-Regulation; Xenograft procedure; base; clinically relevant; cytokine; cytopenia; effective therapy; in vitro Model; in vitro testing; in vivo; inhibitor/antagonist; leukemia; mortality; mouse model; novel; overexpression; progenitor; receptor; stem; stem cell differentiation; stem cells; therapeutic target

DESCRIPTION (provided by applicant): Myelodysplastic syndromes (MDS) are hematologic malignancies characterized by hematopoietic stem cell dysfunction that leads to low blood counts. Even though MDS can transform to acute leukemias, most of mortality in MDS is due to cytopenias. Development of effective treatments has been impeded by a limited understanding of the molecular pathways that lead to dysplastic growth and differentiation of stem cells. We demonstrated that the signaling pathways stimulated by myelosuppressive cytokine TGF-� are overactivated in stem cells in MDS. We further determined that SMAD7, a negative regulator of TGF-� receptor-I kinase, is markedly reduced in MDS, and leads to ineffective hematopoiesis by overactivation of Smad2 mediated TGF-� signaling. We also determined that SMAD7 is directly targeted by microRNA-21 whose expression is increased in MDS stem cells. Most importantly, inhibition of miR-21 attenuates the overactivated TGF-� signaling in MDS and stimulates hematopoiesis in vivo and in vitro. Thus, we hypothesize that increased expression of miR-21 is the critical molecular alteration that leads to hematopoietic alterations in MDS. Therefore, Aim 1 will study the mechanisms of constitutive activation of miR-21 in MDS. We have shown that STAT3 is selectively overexpressed in MDS stem cells and has been shown to regulate miR-21 expression in other models. We will determine the role of STAT3 expression/activation in upregulation of miR-21 and stimulation of TGF-� signaling in MDS using a combination of biochemical and functional approaches. We will also determine whether miR-21 is overexpressed due to gene amplification or epigenetic alterations in primary MDS samples. Aim 2 will determine the functional role of miR-21 overexpression on ineffective hematopoiesis in MDS and identify its downstream effectors. Anemia is the predominant clinical alteration in MDS and we will utilize an in vitro model of human erythropoiesis to examine the role of miR-21 overexpression on red cell differentiation and proliferation. In addition to SMAD7, miR-21 can target many other potentially pathogenic genes. Thus, we will determine the role of miR-21 in mediating red cell dysplasia via targeting of a GTPase exchange factor DOCK4 that has essential roles in red cell membrane formation. Finally, Aim 3 will determine the efficacy of novel, clinically relevant inhibitors of miR-21 in primary MDS samples in vitro and in mouse models of bone marrow failure in vivo. Chemically stabilized antisense inhibitors of miR-21 and a clinically relevant STAT3 inhibitor Pyrimethamine will be tested in vitro and in vivo for their efficacy in reversing abnormally increased TGF-� signaling in MDS. The alb/TGF+ transgenic mouse model will be used to determine the efficacy of these inhibitors in reversing cytokine mediated bone marrow failure in vivo. Primary MDS xenografts will also be used for these studies. The efficacy of these inhibitors will also be evaluated in vitro on a large number of primary MDS bone marrow progenitors and will be correlated with patient characteristics to identify subsets of MDS that will potentially benefit from therapeutics based on inhibition of miR-21 pathway.

描述（由申请人提供）：骨髓增生异常综合征（MDS）是一种血液系统恶性肿瘤，其特征是造血干细胞功能障碍，导致低血细胞计数。尽管MDS可以转化为急性白血病，但MDS的大部分死亡是由于血细胞减少所致。由于对导致干细胞发育异常生长和分化的分子途径了解有限，治疗受到阻碍。骨髓抑制性细胞因子 TGF-β 在 MDS 干细胞中过度激活，我们进一步确定 SMAD7（TGF-β 受体-I 激酶的负调节因子）在 MDS 中显着减少，并通过 Smad2 介导的 TGF-β 过度激活导致造血无效。我们还确定 SMAD7 是 microRNA-21 的直接靶标，而 microRNA-21 在 MDS 干细胞中的表达增加，最重要的是，抑制 miR-21 会减弱这种信号传导。 MDS 中 TGF-β 信号过度激活并刺激体内和体外造血作用，因此，我们认为 miR-21 表达增加是导致 MDS 造血改变的关键分子改变，因此，目标 1 将研究组成性机制。 MDS 中 miR-21 的激活 我们已经证明 STAT3 在 MDS 干细胞中选择性过表达，并且在其他模型中也显示出调节 miR-21 的表达。我们将结合生化和功能方法确定 STAT3 表达/激活在 MDS 中 miR-21 上调和 TGF-β 信号传导中的作用。我们还将确定 miR-21 是否由于基因扩增或表观遗传而过度表达。目标 2 将确定 miR-21 过表达对 MDS 无效造血的功能作用，并确定其下游效应因子：贫血是主要的临床改变。在 MDS 中，我们将利用人类红细胞生成的体外模型来检查 miR-21 过表达对红细胞分化和增殖的作用。除了 SMAD7 之外，miR-21 还可以靶向许多其他潜在致病基因。 miR-21 通过靶向 GTP 酶交换因子 DOCK4 在介导红细胞发育不良中的作用，DOCK4 在红细胞膜形成中发挥重要作用。最后，目标 3 将确定新型临床相关药物的功效。 miR-21 抑制剂在体外原发性 MDS 样本和体内骨髓衰竭小鼠模型中的作用将在体外和体内测试化学稳定的 miR-21 反义抑制剂和临床相关的 STAT3 抑制剂乙胺嘧啶的逆转功效。 MDS 中异常增加的 TGF-β 信号传导将用于确定这些抑制剂在逆转细胞因子介导的骨髓衰竭中的功效。原发性 MDS 异种移植物也将用于这些研究，这些抑制剂的功效也将在大量原发性 MDS 骨髓祖细胞上进行体外评估，并将与患者特征相关联，以确定可能受益的 MDS 子集。来自基于抑制 miR-21 通路的治疗。