Characterization of Myeloid Tumor Suppressor Genes on Chromosome 5

治疗相关骨髓增生异常综合征(t-MDS)和急性髓系白血病(t-AML)较晚 恶性和非恶性疾病细胞毒治疗的并发症。特征重现 T-MDS/t-AML常伴有5号和/或7号染色体异常。在芝加哥大学 在306例t-MDS/t-AML患者中，我们观察到214例(70%)患者的5q或7q丢失。在……里面 在之前的研究中，我们在D5S479两侧的5q31内定义了一个970kb的共同缺失片段(CDS 和D5S500。在随后的研究中，我们生成了这个CDS的完整转录图谱，并确定了 并克隆了20个基因。我们对5q的CDS内所有候选基因的突变分析尚未揭示 其余等位基因的突变失活，也没有证据表明通过DMA转录沉默 甲基化，符合单倍体不足模型的观察结果。通过使用鼠标模型，我们 已经确定Egr1是5q的CDS中的候选肿瘤抑制基因(TSG)，通过 单倍体功能不全，并与烷化剂诱导的突变协同诱导髓系白血病。 此外，编码转录因子的Egr1参与了小鼠的应激性红细胞生成。 我们假设5q31包含一个或多个单倍体功能不全的髓系TSG。在目标1中， 我们将通过鉴定Egr1在小鼠模型中的造血和白血病发生中的作用来检验Egr1的作用 在髓系疾病的发病机制中与Egr1协同的突变，并询问人类t- 已确定的基因突变的AML。在目标2中，我们将评估体内多个基因的丢失 5q的CDS通过产生条件性和生殖系小鼠而在白血病的发生中发挥作用 CDS的同线区域，我们将使用杂合和纯合子缺失的小鼠来 确定CDS中的候选基因，以及与CDS中的缺失相关的其他基因 白血病的发生。在目标3中，我们将提炼7q22的最小CDS，并定义更多删除的片段 利用细胞遗传学作图技术和分子分析技术对7q的拷贝数变化进行检测 7q缺失或易位的白血病(与项目2和4合作)。 从5q和7q的CDS中鉴定髓系白血病基因具有较高的实验价值 优先，因为这些异常的频率很高，而且与这些异常相关的结果很差 异常，以及对识别有t-AML发展风险的个人的影响， 并在治疗原发恶性疾病时选择合适的治疗方法。最后， 了解编码蛋白的生化功能可能有助于深入了解骨髓生成和 白血病的转化，并可能最终导致合理的新疗法的发展。

Therapy-related myelodysplastic syndrome (t-MDS) and acute myeloid leukemia (t-AML) are late complications of cytotoxic therapy of both malignant and non-malignant diseases. Characteristic recurring abnormalities of chromosomes 5 and/or 7 are frequently noted in t-MDS/t-AML. In the University of Chicago series of 306 patients with t-MDS/t-AML, we observed loss of 5q or 7q in 214 (70%) patients examined. In previous studies, we defined a 970 kb commonly deleted segment (CDS) within 5q31 flanked by D5S479 and D5S500. In subsequent studies, we generated a complete transcript map of this CDS, and identified and cloned 20 genes. Our mutation analysis of all candidate genes within the CDS of 5q has not revealed inactivating mutations in the remaining alleles, nor is there evidence of transcriptional silencing via DMA methylation, observations that are compatible with a haploinsufficiency model. By using mouse models, we have determined that EGR1, a candidate tumor suppressor gene (TSG) within the CDS of 5q, acts by haploinsufficiency and cooperates with mutations induced by alkylating agents to induce myeloid leukemias. Moreover, EGR1, which encodes a transcription factor, is involved in murine stress erythropoiesis. We hypothesize that 5q31 contains one or more myeloid TSGs that act by haploinsufficiency. In Aim 1, we will examine the role of Egr1 in hematopoiesis and leukemogenesis in our mouse model by identifying mutations that cooperate with Egr1 in the pathogenesis of myeloid disorders, and interrogating human t- AMLs for mutations of the genes identified. In Aim 2, we will evaluate whether loss of multiple genes within the CDS of 5q plays a role in leukemogenesis by generating conditional and germline mice with a deletion of the region syntenic to the CDS, and we will use mice with heterozygous and homozygous deletions to identify candidate genes within the CDS, as well as other genes that cooperate with the deletion in leukemogenesis. In Aim 3, we will refine the smallest CDS of 7q22, and define additional deleted segments of 7q by using cytogenetic mapping techniques and molecular analysis of copy number changes to examine leukemias with deletions or translocations of 7q (collaboration with Projects 2 and 4). The identification of myeloid leukemia genes from the CDSs of 5q and 7q represent a high experimental priority due to the high frequency of these abnormalities, and the poor outcome associated with these abnormalities, as well as the ramifications toward identifying individuals at risk for the development of t-AML, and in the selection of the appropriate therapy for treatment of the primary malignant disease. Finally, understanding the biochemical functions of the encoded proteins may provide insights into myelopoiesis and leukemic transformation, and may ultimately lead to the development of rational new therapeutics.