Human Hematopoietic Cell Transformation by BCR/ABL

BCR/ABL 人类造血细胞转化

• 批准号: 7074724
• 负责人: RAVI BHATIA
• 金额: $ 37.13万
• 依托单位: BECKMAN RESEARCH INSTITUTE/CITY OF HOPE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7074724
• 关键词: CD34 molecule; biological signal transduction; cell adhesion; cell growth regulation; cell transformation; chemotaxis; chronic myelogenous leukemia; flow cytometry; gene expression; hematopoietic stem cells; human tissue; immunoprecipitation; neoplastic transformation; oncogenes; phosphorylation; polymerase chain reaction; protein tyrosine kinase; small interfering RNA; western blottings

DESCRIPTION (provided by applicant): Chronic myelogenous leukemia (CML) results from the transformation of a very primitive hematopoietic cell by the BCR/ABL oncogene and is characterized by increased myeloproliferation and abnormal trafficking of malignant progenitors. CML progenitors demonstrate several abnormalities in hematopoietic regulation including increased growth factor-induced proliferation, reduced adhesion to fibronectin and reduced chemotaxis towards SDF-1a. Although the tyrosine kinase inhibitor imatinib mesylate is very effective in the treatment of CML, elimination of malignant progenitors is often incomplete and clinical resistance can occur. Therefore, additional treatment approaches to target BCR/ABL activated signaling mechanisms important for transformation are of high priority. The contribution of different BCR/ABL mechanisms to transformation varies from 1 cell type to the other, and the contribution of known mechanisms to human hematopoietic cell transformation is not clear. The goal of the proposed studies is to investigate molecular mechanisms that are critical for human progenitor transformation. In preliminary studies, we have investigated abnormalities in intracellular signaling in CD34+ progenitor cells from CML patients. We have also developed a novel CML model based on ectopic expression of the BCR/ABL gene in human CD34+ cells, which reproduces abnormalities in hematopoietic regulation seen in primary CML progenitors and facilitates study of molecular mechanisms of transformation. Preliminary studies have identified BCR/ABL protein domains that may significantly contribute to abnormal progenitor growth and adhesion. In Specific Aim 1 we will investigate the role of an autophosphorylation site at BCR Y177 and downstream signaling through Grb2, Gab2 and Shp2 in abnormal proliferation and apoptosis of BCR/ABL expressing human progenitors. In Specific Aim 2 we will investigate the mechanisms of abnormal adhesion and chemotaxis in BCR/ABL transformed human progenitors. Finally, in Specific Aim 3 we will investigate whether inhibition of the above signaling pathways can enhance suppression of CML progenitors growth when combined with imatinib, and/or can suppress growth of progenitors resistant to imatinib because of kinase domain mutations. These studies are expected to result in improved understanding of mechanisms critical for human progenitor transformation in CML and guide rational development of additional mechanism-based therapies.

描述（由申请人提供）：慢性髓性白血病（CML）是由BCR/ABL癌基因转化非常原始的造血细胞引起的，其特征是骨髓增生增加和恶性祖细胞的异常转运。CML祖细胞表现出几种造血调节异常，包括生长因子诱导的增殖增加、纤维连接蛋白粘附减少和对SDF-1a的趋化性降低。虽然酪氨酸激酶抑制剂甲磺酸伊马替尼治疗CML非常有效，但恶性祖细胞的消除往往不完全，可能出现临床耐药。因此，针对BCR/ABL激活的信号机制的其他治疗方法对转化至关重要，是高度优先考虑的。不同的BCR/ABL机制对转化的贡献因细胞类型而异，已知机制对人造血细胞转化的贡献尚不清楚。所提出的研究的目标是调查的分子机制是至关重要的人类祖细胞转化。在初步研究中，我们研究了CML患者CD34+祖细胞细胞内信号的异常。我们还开发了一种基于人CD34+细胞中BCR/ABL基因异位表达的新型CML模型，该模型再现了原发性CML祖细胞中出现的造血调节异常，并有助于研究转化的分子机制。初步研究已经确定BCR/ABL蛋白结构域可能显著促进异常祖细胞生长和粘附。在Specific Aim 1中，我们将研究BCR Y177的自磷酸化位点以及通过Grb2、Gab2和Shp2的下游信号通路在表达BCR/ABL的人类祖细胞异常增殖和凋亡中的作用。在特异性目标2中，我们将研究BCR/ABL转化的人类祖细胞异常粘附和趋化的机制。最后，在Specific Aim 3中，我们将研究上述信号通路的抑制是否可以增强与伊马替尼联合时对CML祖细胞生长的抑制，和/或是否可以抑制因激酶结构域突变而对伊马替尼耐药的祖细胞的生长。这些研究有望提高对CML中人类祖细胞转化的关键机制的理解，并指导合理开发其他基于机制的治疗方法。