IRF8 as a Biomarker of Aging, Malignant Transformation, and AML Prognosis

描述（由申请人提供）：更好地了解衰老如何促进恶性转化，可能会发现用于癌症检测的新生物标志物和未来治疗的潜在靶点。初步研究发现，IRF 8的表达随着年龄的增长在造血祖细胞/干细胞（HPC/HSC）和骨髓恶性肿瘤中降低。此外，先前的鼠研究表明，沉默IRF 8促进“白血病前期”克隆的发展，这些克隆转化为具有次级遗传“命中”的急性髓性白血病（AML）。3，20，21因此，老化HPC/HSC中IRF 8表达的降低可能是在获得二次“命中“后导致骨髓恶性肿瘤的早期转化前事件。具体目标1。确定沉默人CD 34+细胞中的IRF 8表达是否促进向AML的转化。在鼠模型中，沉默IRF 8阻断单核细胞分化，抑制细胞凋亡，并导致祖细胞数量增加。4，18，19鉴于鼠和人造血细胞之间的差异，22-25我们将沉默人CD 34+细胞中的IRF 8表达，并确定这种沉默的体外和体内功能效应。我们假设，沉默人CD 34+细胞中的IRF 8表达将阻断单核细胞分化，抑制凋亡，并增加祖细胞的数量。此外，我们假设移植了人IRF 8缺陷型CD 34+细胞的NOD/SCID小鼠将发生MPD，随着时间的推移，MPD将发展为AML。具体目标2。研究IRF 8在AML中表达的预后意义。我们的初步分析表明，IRF 8表达减少促进体外化疗耐药性，并与AML患者的年龄增加，不利的细胞遗传学和难治性疾病有关。因此，我们将检查IRF 8在细胞遗传学正常的AML患者流式分选白血病原始细胞中的表达，并确定IRF 8表达是否与人口统计学、实验室值、其他预后因素和临床结局相关。我们假设IRF 8表达降低是细胞遗传学正常的AML患者的一个独立的不良预后因素。长期目标。这些实验将促进我们对正常和恶性造血细胞中IRF 8表达减少的功能和临床意义的理解。如果IRF 8表达降低是促进AML和其他恶性肿瘤发展的早期起始事件，则将开发基于IRF 8的测定以鉴定和检查这些功能失调的HPC/HSC，并分析IRF 8表达降低与疾病发展风险之间的关联。此外，如果IRF 8表达降低是一个预后不良的因素，IRF 8表达将被纳入未来的研究作为一个预后因素，我们将开展研究，以检查驱动化疗耐药性的根本原因和克服它的潜在治疗方案。 公共卫生相关性：初步研究发现，IRF 8在造血细胞中的表达随着年龄的增长而降低，可能与白血病的发生有关。拟议的研究将检查IRF 8作为衰老，恶性转化和AML预后的生物标志物的潜在作用。这些研究的结果可能会导致开发新的基于IRF 8的检测方法，可用于在疾病发生之前和之后对受试者进行风险分层，以便启动有针对性的预防和治疗干预措施。

DESCRIPTION (provided by applicant): A better understanding of how aging promotes malignant transformation may identify novel biomarkers for cancer detection and potential targets for future therapies. Preliminary studies have found that IRF8 expression decreases with increasing age in hematopoietic progenitor/stem cells (HPCs/HSCs) and in myeloid malignancies. In addition, previous murine studies suggest that silencing IRF8 promotes the development of "pre-leukemic" clones that transform into an acute myeloid leukemia (AML) with secondary genetic "hits."3,20,21 Therefore, decreased IRF8 expression in aging HPCs/HSCs may be an early pre-transforming event that leads to myeloid malignancies upon the acquisition of secondary "hits." Specific Aim 1. Determine if silencing IRF8 expression in human CD34+ cells promotes transformation into AML. In murine models, silencing IRF8 blocks monocytic differentiation, inhibits apoptosis, and leads to increased numbers of progenitor cells.4,18,19 Given the differences between the murine and human hematopoietic cells,22-25 we will silence IRF8 expression in human CD34+ cells and determine the in vitro and in vivo functional effects of this silencing. We hypothesize that silencing IRF8 expression in human CD34+ cells will block monocytic differentiation, inhibit apoptosis, and increase the number of progenitor cells. Furthermore, we hypothesize that NOD/SCID mice transplanted with human IRF8-deficient CD34+ cells will develop a MPD, which will develop into AML over time. Specific Aim 2. Investigate the prognostic significance of IRF8 expression in AML. Our preliminary analyses suggest that decreased IRF8 expression promotes in vitro chemoresistance and is associated with increasing age, unfavorable cytogenetics, and refractory disease in AML patients. Thus, we will examine IRF8 expression in flow-sorted leukemic blasts from AML patients with normal cytogenetics and determine whether IRF8 expression is associated with demographics, laboratory values, other prognostic factors, and clinical outcomes. We hypothesize that decreased IRF8 expression will be an independent poor prognostic factor for AML patients with normal cytogenetics. Long-term objectives. These experiments will advance our understanding of the functional and clinical significance of diminished IRF8 expression in normal and malignant hematopoietic cells. If decreased IRF8 expression is an early initiation event that promotes development of AML and other malignancies, IRF8-based assays will be developed to identify and examine these dysfunctional HPCs/HSCs and analyze associations between decreased IRF8 expression and risk of disease development. Furthermore, if decreased IRF8 expression is a poor prognostic factor, IRF8 expression will be incorporated into future studies as a prognostic factor, and we will develop studies to examine the underlying cause of driving the chemoresistance and potential therapeutic options to overcome it. PUBLIC HEALTH RELEVANCE: Preliminary studies have found that IRF8 expression decreases with increasing age in hematopoietic cells and may be associated with the development of leukemia. The proposed studies will examine the potential role of IRF8 as a biomarker of aging, malignant transformation, and AML prognosis. The results from these studies may lead to the development of novel IRF8-based assays that can be utilized to risk-stratify subjects prior to and after disease development, so that targeted preventative and therapeutic interventions can be initiated.