Targeting non-classical oncogenes as therapy for T-ALL

描述(由申请人提供)： T细胞急性淋巴细胞性白血病(T-ALL)是一种侵袭性血液病，儿童和成人均可发病。尽管进行了密集的治疗，25%的儿童和青少年以及50%的成人T-ALL最终将死于这种疾病。此外，癌症治疗的后遗症，包括永久性器官损伤、荷尔蒙和生殖功能障碍，以及第二种癌症，是儿童特别关注的问题，因为目前的治疗方法不分青红皂白地针对所有分裂细胞。这项建议的目标是确定并在治疗上靶向一条对T-ALL的生长和生存至关重要的途径，其抑制的毒性将比标准化疗低得多。据报道，I类磷脂酰肌醇3-激酶(PI3K)/Akt信号通路在40%以上的T-ALL中被激活。尽管四种不同的I类PI3K亚型可能参与T-ALL的发病，但没有一种参与这一过程。利用转基因动物和新型小分子抑制剂，我们已经确定了对T-ALL的发展和生存至关重要的特定亚型。基于这些观察，我们认为利用这种血液系统恶性肿瘤对这些特殊的PI3K亚型的“成瘾”作为治疗T-ALL的新途径是可能的。为了实现这些目标，我们提出了以下具体目标：目的1.确定两种新的异构体特异性PI3K抑制剂对T-ALL发病的影响的有效性和作用机制(S)。这将通过评估这些抑制剂在PTEN基因缺失T-ALL动物模型、人类T-ALL细胞系和原发患者样本上的效果来实现。重点将放在使用生化和遗传方法相结合的方式来询问调节细胞周期进程、蛋白质合成和细胞生存的下游途径。目的2.揭示PI3K依赖和独立的可能导致继发耐药的机制。这包括识别在药物结合、化学诱导突变和动物药物诱导耐药疾病的计算机模型中使用的与耐药性相关的点突变和替代信号通路。将进行生化和遗传分析，后者包括基因表达微阵列和基于阵列的比较基因组杂交。目的3.研究异构体特异性PI3K抑制剂对人T细胞发育、外周血扩增、存活和功能的影响。这将通过在一种独特的人类胸腺/CD34+干细胞异种移植模型中评估药物效果来实现。

DESCRIPTION (provided by applicant): T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic cancer that occurs in children as well as adults. Despite intensive therapies, 25% of children and adolescents and 50% of adults with T-ALL will ultimately succumb to the disease. Moreover, the late effects of cancer treatment, including permanent organ damage, hormonal and reproductive dysfunction, and second cancers are a special concern in children as current therapies indiscriminately target all dividing cells. The goal of this proposal is to identify and therapeutically target a pathway that is essential for the growth and survival of T-ALL, the inhibition of which will be considerably less toxic than standard chemotherapy. Class I phosphoinositide 3-kinase (PI3K)/Akt signaling pathway has been reported to be activated in over 40% of cases of T-ALL. Although four distinct class I PI3K isoforms could participate in T-ALL pathogenesis, none have been implicated in this process. Using genetically altered animals and novel small molecule inhibitors, we have identified specific isoforms that appear to be essential for the development and survival of T- ALL. Based on these observations, we propose that it is possible to exploit the "addiction" of this hematological malignancy to these particular PI3K isoforms as a new therapeutic avenue for T-ALL. To achieve these objectives, we propose the following specific aims: Aim 1. To determine the efficacy and to define the mechanism(s) of action by which 2 novel isoform specific PI3K inhibitors may impact on T-ALL pathogenesis. This will be accomplished by evaluating the effects of these inhibitors in an animal model of PTEN null T-ALL, on human T-ALL cell lines, and on primary patient samples. Emphasis will be placed on interrogating downstream pathways that regulate cell cycle progression, protein synthesis, and cell survival using a combination of biochemical and genetic approaches. Aim 2. To uncover potential PI3K-dependent and independent mechanisms that may result in secondary resistance. This includes identifying resistance-conferring point mutations and alternative signaling pathways using in silico models of drug binding, chemical-induced mutagenesis, and drug-induced resistant disease in animals. Biochemical and genetic analyses will be performed, the latter including gene expression microarrays and array-based comparative genomic hybridization. Aim 3. To determine the effects of isoform specific PI3K inhibitors on the development, peripheral expansion, survival and function of human T cells. This will be accomplished by evaluating drug effects in a unique human thymus/CD34+ stem cell xenograft model.