Role of Vav and Rac in KIT oncogenesis

Vav 和 Rac 在 KIT 肿瘤发生中的作用

• 批准号: 8387734
• 负责人: Reuben Kapur
• 金额: $ 36.29万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-19 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8387734
• 关键词: AML1-ETO fusion protein; Acute Myelocytic Leukemia; Adult Acute Myeloblastic Leukemia; Binding; Cells; Childhood Acute Myeloid Leukemia; Chromosomal translocation; Chromosome abnormality; Chronic Myeloid Leukemia; Chronic Myelomonocytic Leukemia; Clinical; Core-Binding Factor; Dimerization; Disease; Etiology; FLT3 gene; Family; Gastrointestinal Stromal Tumors; Gene Mutation; Genetic; Germ Cells; Germ cell tumor; Gleevec; Goals; Growth; Guanine; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate Phosphohydrolases; Hematological Disease; Hematopoietic; Hematopoietic stem cells; Imatinib; Imatinib mesylate; In Vitro; Interstitial Cell of Cajal; KIT gene; Ligand Binding; Ligands; Link; Lobe; Lymphoma; MYH11 gene; Mediating; Membrane; Molecular Conformation; Molecular Target; Mus; Mutate; Mutation; Myeloproliferative disease; Nature; PDGFRB gene; Pathway interactions; Pharmaceutical Preparations; Phosphorylation; Phosphotransferases; Physiological; Play; Protein Tyrosine Kinase; RUNX1 gene; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Stem cells; Systemic Mastocytosis; Testing; Tissues; Transcription factor genes; Transgenes; Tyrosine; Tyrosine Kinase Domain; Tyrosine Kinase Inhibitor; Ursidae Family; base; bcr-abl Fusion Proteins; disease phenotype; effective therapy; fusion gene; in vivo; indexing; insight; leukemia; leukemogenesis; mast cell; melanocyte; mutant; new therapeutic target; outcome forecast; receptor; rho; rho GTP-Binding Proteins; stem; t(8; 21)(q22; q22); transcription factor; tumorigenesis

ABSTRACT KIT is a unique receptor with important functional roles in melanocytes, germ cells, interstitial cells of Cajal, mast cells, and hematopoietic stem cells. Consistent with the importance of KIT in these defined tissues, activating mutations of KIT have been described in germ cell tumors, gastrointestinal stromal tumors (GISTs), sinonasal lymphomas, acute myeloid leukemia (AML), and systemic mastocytosis (SM). A significant proportion of these diseases commonly bear the KIT activation loop mutation KITD816V. Activation loop mutations of KIT have also been observed in core binding factor-acute myeloid leukemia (CBF-AML), leukemias that bear either the t(8;21) or inv(16) cytogenetic abnormality, generating the fusion genes AML1- ETO or CBF¿-MYH11, respectively. Studies examining both adult and pediatric AML have indicated that the presence of the KITD816V mutation in CBF-AML carrying t(8;21) worsens the prognosis based on several clinical indices. Although KIT mutations within the juxtamembrane region that are commonly found in GISTs are sensitive to inhibition by the tyrosine kinase inhibitor, imatinib mesylate (Gleevec); KIT mutations within the carboxy-terminal lobe of the tyrosine kinase domain, such as KITD816V, stabilizes the KIT activation loop conformation in its active form, which precludes sufficient imatinib binding for tyrosine kinase inhibition. Therefore, in contrast to successful use of Gleevec to treat GISTs, Gleevec is ineffective for the treatment of the hematologic diseases harboring the KIT activation loop mutants (i.e. KITD816V), including SM and CBF- AML. Importantly, nature of the receptor proximal and/or downstream signals by which activation loop mutations in KIT (KITD816V) induce transformation in primary hematopoietic cells are poorly defined. We have evidence to demonstrate that KITD816V (KITD814V in mice) induced transformation in primary hematopoietic stem and progenitor cells results in constitutive activation of GEF Vav/Rho GTPase Rac pathway and that genetic disruption of hematopoietic specific Vav1 and/or Rac2 in mice abrogates ligand independent growth via KITD814V, leading us to hypothesize that signals involved in KITD814V induced transformation may in part be mediated via the hyperactivation of this pathway. Furthermore, we have evidence demonstrating that mutating the tyrosine residues within the intracellular domain of KITD814V results in complete loss of KITD814V induced ligand independent growth, leading us to hypothesize that the intracellular tyrosines within the juxtamembrane and the kinase insert region of KITD814V are likely to contribute to KITD814V induced transformation. Based on these findings, the central hypothesis of this application is that hyperactivation of the Vav/Rac pathway contributes to the etiology of diseases associated with systemic mastocytosis, AML as well as other diseases involving the KITD814V mutation. Our proposed studies will provide mechanistic insight into the physiologic significance of the Vav/Rac pathway as well as the involvement of the juxtamembrane and the kinase insert sequences in regulating KITD814V induced transformation for which currently no drugs exist.

摘要 KIT是一种独特的受体，在黑素细胞、生殖细胞、Cajal间质细胞、 肥大细胞和造血干细胞。与试剂盒在这些定义的组织中的重要性一致， KIT的激活突变已在生殖细胞瘤、胃肠道间质瘤(GIST)、 鼻腔淋巴瘤、急性髓系白血病(AML)和全身性肥大细胞增多症(SM)。一个重要的 这些疾病中有一部分通常携带KIT激活环突变KITD816V。激活循环 在核心结合因子-急性髓系白血病(CBF-AML)中也观察到KIT突变， 携带t(8；21)或inv(16)细胞遗传学异常的白血病，产生融合基因AML1- ETO和CBF？-MYH11。对成人和儿童急性髓细胞白血病的研究表明， 在携带t(8；21)的CBF-AML中存在KITD816V突变会恶化预后 临床指标。尽管在GIST中常见的KIT膜旁区域的KIT突变 对酪氨酸激酶抑制剂甲磺酸伊马替尼(格列卫)的抑制敏感；试剂盒内的突变 酪氨酸激酶域的羧基末端叶，如KITD816V，稳定KIT激活环 其活性形式的构象，这排除了足够的伊马替尼结合酪氨酸激酶抑制。 因此，与成功使用格列卫治疗GIST相比，格列卫在治疗GIST方面无效。 含有KIT激活环突变株(即KITD816V)的血液病包括SM和CBF- AML。重要的是，受体近端和/或下游信号的性质是通过哪个激活环 KIT(KITD816V)中的突变诱导原代造血细胞转化的研究尚不清楚。我们有 KITD816V(小鼠为KITD814V)诱导原代造血细胞转化的证据 干细胞和祖细胞导致全球环境基金Vav/Rho GTP酶Rac通路的结构性激活 小鼠造血特异性Vav1和/或rac2的基因破坏通过以下途径剥夺配体非依赖性生长 KITD814V，使我们假设参与KITD814V诱导的转化的信号可能部分是 通过这一途径的过度激活而起作用。此外，我们有证据表明，突变 KITD814V胞内区的酪氨酸残基导致KITD814V的完全丧失 诱导不依赖配体的生长，使我们假设细胞内的酪氨酸在 KITD814V膜旁和KITD814V插入区可能参与了KITD814V的诱导 转型。基于这些发现，这一应用的中心假设是 Vav/Rac途径与系统性肥大细胞增多症、急性髓系白血病相关疾病的病因学有关 与其他涉及KITD814V突变的疾病一样。我们提议的研究将提供对 Vav/Rac通路的生理学意义以及膜旁和膜旁的参与 调节KITD814V诱导的转化的激酶插入序列，目前还没有药物。