Therapeutic targeting of MDS stem cells

MDS通常是一种无法治愈的血液系统疾病，与疾病启动干细胞有关。 不能通过传统疗法消除，需要针对潜在的治愈 战略。我们最近证明了异常的造血干细胞在 MDS可以在表型缓解期间持续存在，并可以预测复发。在初步研究中， 我们证明了白细胞介素8(IL8)在干细胞中持续和选择性地过表达 来自MDS患者。在大型MDS中，IL8受体CXCR2也显著增加 患者队列，并与更差的预后相关。从功能上讲，IL8/CXCR2途径 ShRNA介导的基因敲除或药物方法的抑制作用被废除 在细胞系和原代MDS样本中增殖。重要的是，对IL8/CXCR2的抑制 途径选择性抑制MDS样本中的未成熟干细胞而不影响健康 HSCs，并且在异种移植中也证明了有效性。全面审视这一角色 在MDS中，Aim 1将确定IL-8/CXCR2途径在MDS生长中的功能作用 在MDS中启动疾病干细胞并确定临床相关抑制物的疗效 这条途径在大量的原始人类样本中存在。此外，对IL8/CXCR2的回应 小分子抑制和一种新的人源化抗体将与临床和 突变亚型，以确定对IL8/CXCR2抑制敏感的靶向亚群。 患者来源的MDS异种移植也将用于确定体内疗效。目标2将 通过以下方法确定CXCR2在体内启动异型增生/疾病进展中的需求 两种MDS小鼠模型中CXCR2基因缺失。以及NUP-Hoxd13型号；a 我们新近建立的MDS异型增生和转化的新模型 杂合子PU1增强子缺失，将用于研究CXCR2缺失对 疾病启动干细胞和疾病进展。目标3将确定以下机制： 激活IL8-CXCR2通路并确定其在MDS中的下游效应。IL8是一种 先天免疫信号的已知成分，我们将确定上游 免疫激活剂IL1RAP、TLRs和IRAK1/4驱动IL8/CXCR2过度激活 MDS中的通路。我们还将评估PI3Kinase的激活和功能意义 MAP激酶通路作为MDS中IL8/CXCR2通路的下游效应因子。已被占用 总之，这些研究将研究IL8/CXCR2通路在MDS发病机制和 确定其作为针对MDS中未成熟的疾病启动细胞的治疗靶点的潜力。

MDS is a generally incurable hematologic disorder associated with disease initiating stem cells that are not eliminated by conventional therapies and need to be targeted for potentially curative strategies. We recently demonstrated that aberrant hematopoietic stem cells are expanded in MDS, can persist during phenotypic remissions and can predict relapse. In preliminary studies, we demonstrate that Interleukin 8 (IL8) is consistently and selectively overexpressed in stem cells from MDS patients. The receptor for IL8, CXCR2, is also significantly increased in large MDS patient cohorts and is associated with a worse prognosis. Functionally, IL8/CXCR2 pathway inhibition by either shRNA-mediated knockdown or pharmacologic approaches abrogated proliferation in cell lines and primary MDS samples. Importantly, inhibition of the IL8/CXCR2 pathway selectively inhibited immature stem cells from MDS samples without an effect on healthy HSCs, and also had demonstrated efficacy in xenografts. To comprehensively examine the role of this pathway in MDS, Aim 1 will define the functional role of IL-8/CXCR2 pathway on growth of disease initiating stem cells in MDS and determine the efficacy of clinically relevant inhibitors of this pathway in large cohort of primary human samples. Additionally, responses to IL8/CXCR2 inhibition with small molecules and a novel humanized antibody will be correlated with clinical and mutational subtypes to identify targetable subsets that will be sensitive to IL8/CXCR2 inhibition. Patient derived MDS xenografts will also be used to determine in vivo efficacy. Aim 2 will determine the requirement for CXCR2 in initiation of dysplasia/disease progression in vivo by genetic deletion of CXCR2 in two mouse models of MDS. Along with the NUP-HOXD13 model; a novel model of MDS dysplasia and transformation which we have recently developed, induced by heterozygous PU.1 enhancer deletion, will be used to study the effect of CXCR2 deletion on disease initiating stem cells and disease progression. Aim 3 will identify the mechanisms of activation of the IL8-CXCR2 pathway and determine its downstream effectors in MDS. IL8 is a known component of innate immune signaling cascades, and we will determine whether upstream immune activators, IL1RAP, TLRs and IRAK1/4 are driving overactivation of the IL8/CXCR2 pathway in MDS. We will also evaluate the activation and functional significance of PI3Kinase and MAP kinase pathways as downstream effectors of the IL8/CXCR2 pathway in MDS. Taken together, these studies will study the role of the IL8/CXCR2 pathway in MDS pathogenesis and determine its potential as a therapeutic target against immature, disease initiating cells in MDS.