Targeting Leukemic Stem Cells

描述(申请人提供)：尽管近年来我们对涉及血液、器官和其他组织的疾病的基因异常的了解取得了显著进展，但通过基因治疗方法在靶细胞中引入或操纵基因表达的能力一直受到限制。虽然许多强大的病毒载体已经被开发并在实验和人类系统中使用，但一些问题，特别是安全性，已经证明了开发用于基因治疗的非病毒载体的必要性。最近的发现也表明，靶向正常的造血干细胞(HSC)以及白血病干细胞(LSC)是至关重要的，HSC是一种具有自我更新能力并在特定组织中产生所有细胞类型的细胞，白血病干细胞是一种具有恶性白血病克隆自我更新特性的癌细胞亚群。正常人HSC和大多数LSC表达干细胞抗原CD34，本研究将利用这一表面标志的特异性，以及一种新的小鼠HSC表达人CD34抗原的模型。因此，该项目的长期目标是开发针对正常和白血病干细胞的新型非病毒基因治疗方法。为了实现这些目标，我们提出了以下具体目标：(1)检测人CD34抗体介导的siRNA在人CD34细胞系中的传递；(2)在小鼠体内模型中检测人CD34抗体介导的siRNA；以及(3)检测人CD34抗体介导的bcr/abl或SALL4沉默是否 抑制人原代髓系LSCs的增殖和白血病形成能力。这些目标的实现将为临床试验奠定基础，并导致针对其他癌基因的治疗方法的开发，以及改变干细胞基因的表达。

DESCRIPTION (provided by applicant): Although advances in our understanding of gene abnormalities in diseases involving blood organs and other tissues has been remarkable in recent years, the ability to introduce or manipulate expression of genes in target cells through gene therapy methods has been limited. Although a number of powerful viral vectors have been developed and utilized in both experimental and human systems, a number of issues, particularly safety, have demonstrated the need to develop non-viral based vectors for gene therapy. Recent discoveries have also demonstrated that it is essential to target normal hematopoietic stem cells (HSC), cells which have the potential to both self-renew and to give rise to all cell types in a given tissue, as well as leukemic stem cells (LSC), a subpopulation of cancer cells which confer the self-renewal properties of the malignant leukemic clone. Normal human HSC, and a majority of LSC, express the stem cell antigen CD34, and this proposal will utilize the specificity of this surface marker, as well as a novel murine model in which murine HSC express the human CD34 antigen. Therefore, the long range goals of this project are to develop novel non-viral gene therapy methods targeting normal and leukemic stem cells. In order to accomplish these goals, we propose the following Specific Aims: (1) to test human CD34 antibody mediated siRNA delivery in human CD34 cell lines; (2) to test human CD34 antibody mediated siRNA in murine models in vivo; and (3) to test whether human CD34 antibody mediated silencing of BCR/ABL or SALL4 will inhibit proliferation and leukemia-initiating ability of human primary myeloid LSCs. Accomplishment of these goals will set the stage for clinical trials, as well as lead to development of therapies directed against other oncogenes as well as altering stem cell gene expression.