Pathophysiology of Adult T-cell leukemia/lymphoma

T细胞急性淋巴细胞白血病（T-ALL）是一种侵袭性癌症，在成人患者。成人T-ALL通常 早期T细胞前体（ETP-ALL）亚型，表现为治疗抵抗和复发的高风险。 成人T-ALL的人口统计与年轻退伍军人的人口统计相匹配，因此这笔赠款有可能影响 诊断和护理这些退伍军人。与许多侵袭性人类白血病和淋巴瘤一样，T-ALL 可以通过细胞毒性化疗缓解，但大多数患者复发。我们已经从 我们的研究表明，针对刺激增殖的突变癌基因（如JAK 1/3）的靶向治疗也会诱导 反应是短暂的。在这些癌症中，完全缓解率高，其次是高复发率。 复发的原因是存在具有造血功能的耐药白血病起始细胞（LIC）， 干细胞样特征。LIC在化疗期间处于休眠状态并存活，然后在缓解后扩大- 诱导因此，针对这一低收入国家人口是实现治愈的关键。LIM domain Only-2（LMO 2）是一种 T-ALL中的主要驱动癌基因，其中它赋予正常T细胞祖细胞干细胞特征。 靶向LMO 2诱导的T-ALL LIC将涉及靶向LMO 2复合物。为此，我们 生物化学表征LMO 2复合物，以了解其结构和功能。根据初步数据，我们 表明LMO 2的致癌功能需要它作为多亚基大分子复合物的一部分。 LMO 2的直接结合配偶体包括碱性螺旋-环-螺旋蛋白质、TAL 1或LYL 1和加塔基序 结合蛋白GATA 1、2和3。我们发现，LMO 2诱导T-ALL的能力是非常依赖于 在另一种蛋白质LIM结构域结合1（LDB 1）上，LMO 2与其组成性结合。LDB 1有自己的 相互作用伴侣，即单链结合蛋白SSBP 1 -4。重要的是，LMO 2复合物 形成赋予蛋白质稳定性。在我们的研究过程中，我们观察到了可能是 更好地理解LMO 2对LIC的诱导作用，并更好地靶向LMO 2复合物。虽然LMO 2 已经广泛研究了小鼠模型中LIC的诱导，但尚未将其转化为人类细胞。 我们假设LIC特性是由LMO 2复合物赋予T细胞祖细胞的。 此外，我们的蛋白质组学研究揭示了LMO 2复合物中的一系列旁系同源蛋白，但我们没有发现。 认为它们在功能上是等同的。我们假设不同的旁系同源物具有独特的功能作用， LMO 2复合物、TAL 1 v. LYL 1、加塔因子1-3和SSBP因子2 v. 3。我们将在一本小说中对此进行研究 人体建模系统最后，我们假设针对LMO 2的靶向治疗将涉及干扰 LMO 2复合体这项赠款的具体目标将促进我们对LMO 2功能的理解， 它是如何在这些侵袭性白血病中发挥作用的

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive cancer in adult patients. Adult T-ALL is frequently the Early T-cell Precursor (ETP-ALL) subtype that manifests with treatment-resistance and high risk of relapse. The demographic of adult T-ALL matches that of young Veterans so this grant has the potential to impact the diagnosis and care of this Veteran population. Like many aggressive human leukemias and lymphomas, T-ALL can be put into remission by cytotoxic chemotherapy yet the majority of patients relapse. We have learned from our studies that targeted therapies against mutant oncogenes stimulating proliferation, like JAK1/3, also induce responses that are short lived. In these cancers, the high rate of complete remission followed by the high rate of relapse is explained by the presence of treatment-resistant leukemia-initiating cells (LIC) that have hematopoietic stem cell-like features. The LIC lie dormant and survive during chemotherapy and then expand after remission- induction. Hence, targeting this LIC population is crucial to achieving cures. LIM domain Only-2 (LMO2) is a major driver oncogene in T-ALL, where it confers stem cell characteristics upon normal T-cell progenitor cells. Targeting LMO2-induced T-ALL LIC will involve targeting the LMO2 complex. Towards this end, we have biochemically characterized the LMO2 complex to understand its structure and function. In preliminary data, we show that LMO2’s oncogenic function requires it to act as part of a multisubunit macromolecular complex. LMO2’s direct binding partners include the basic helix-loop-helix proteins, TAL1 or LYL1, and the GATA motif binding proteins GATA1, 2, and 3. We discovered that LMO2’s ability to induce T-ALL is exquisitely dependent upon another protein, LIM domain binding 1 (LDB1), to which LMO2 is constitutively bound. LDB1 has its own interaction partners, namely the Single Stranded Binding Proteins SSBP1-4. Importantly, LMO2 complex formation confers protein stability. In the course of our studies, we made observations that could hold the key to better understanding LMO2’s induction of the LIC and to better targeting of the LMO2 complex. Although LMO2’s induction of the LIC in mouse models has been extensively studied, this has not been translated to human cells. We hypothesize that LIC properties are conferred by the LMO2 complex upon T-cell progenitor cells. Furthermore, our proteomic studies reveal a panoply of paralogous proteins in the LMO2 complex but we do not believe they are functionally equivalent. We hypothesize unique functional roles for the various paralogues of the LMO2 complex, TAL1 v. LYL1, GATA factors 1-3, and SSBP factors 2 v. 3. We will investigate this in a novel human modeling system. Lastly, we hypothesize that targeted therapy against LMO2 will involve perturbation of the LMO2 complex. The Specific Aims of this grant will advance our understanding of how LMO2 functions and how it may be targeted in these aggressive leukemias.