P53 Activation as Novel Therapeutic Stratgey for Acute Myelogenous Leukemia

髓系白血病治疗的主要挑战是开发策略， 在对化疗产生耐药性之前最大限度地诱导白血病细胞凋亡。p53是 一个决定受压力的细胞是否发生凋亡的主开关，从而起到肿瘤的作用 抑制器。p53突变导致这种抑制功能的失活。鼠标双分钟2（HDM2） 其同源物HDMX也可以抑制p53活性：而HDM2是一种泛素连接酶， 通过泛素介导的蛋白水解降解p53，HDMX抑制p53的转录活性。p53 导致p53失活的突变在新诊断和复发的AML中是罕见的。据报道， 在大约50%的AML病例中，由于HDM2的过度表达而导致p53功能丧失; HDMX尚未在AML中进行研究。通过抑制HDM2/p53相互作用恢复p53活性 利用非遗传毒性小分子抑制剂（Nutlin 3a，M163）诱导AML细胞凋亡， 未突变的p53。虽然这些HDM2抑制剂显著增加启动转录的p53水平， p53靶向，p53与Bcl-2家族成员的转录非依赖性直接相互作用也发生。 此外，化疗药物如阿糖胞苷和柔红霉素与BH 3模拟物同步， 和MARK抑制剂，其抑制抗凋亡p21的诱导并调节亚细胞凋亡。 p53的分布因此，我们建议研究临床试验的分子和临床后果 HDM2的小分子抑制剂（Nutlin 3a，MI-63），并更好地了解 调节p53活化的机制以及观察到的与化疗的协同作用。如果成功，这些 研究将为基于非遗传毒性激活的AML新治疗策略提供理论依据。 p53信号转导。具体目标1：确定非遗传毒性诱导的细胞凋亡的分子决定因素 白血病细胞系、原代白血病细胞和干细胞中的HDM2的小分子抑制剂（Nutlin 3a，M163） 细胞具体目标2确定HDM2抑制与化疗协同作用的机制（Ara-2015） C，阿霉素）。具体目标3进行HDM2抑制剂的首次人体I期试验（Nutlin 3a 类似物R7112，M163） 急性髓细胞白血病是一种骨髓干细胞的恶性肿瘤。一个被称为 "p53"是细胞存活和死亡的主要调节因子，在癌症和白血病中经常失调。 虽然癌症有很高的p53突变频率，但白血病没有。这一发现打开了一扇窗， 通过释放p53从其抑制剂HDM2蛋白中激活该基因的功能， 具有很好治疗前景的药物。这一建议为一个全新的概念奠定了基础， AML的治疗。

The main therapeutic challenge in the treatment of myeloid leukemias is the development of strategies that maximize the induction of leukemia cell apoptosis before resistance to chemotherapy develops. p53 is the master switch that determines whether a stressed cell undergoes apoptosis, thus acting as a tumor suppressor. p53 mutations lead to inactivation of this suppressor function. Mouse Double Minute 2 (HDM2) and its homolog HDMX can also inactivate p53 activity: while HDM2 is an ubiquitin ligase that mediates degradation of p53 by ubiquitin-mediated proteolysis, HDMX inhibits the transcriptional activity of p53. p53 mutations leading to p53 inactivation are rare in newly diagnosed and relapsed AML. There is a reported loss of p53 function through over-expression of HDM2 in approximately 50% of AML cases; expression of HDMX have not been investigated in AML. Restoration of p53 activity by inhibiting HDM2/p53 interaction utilizing non-genotoxic small molecule inhibitors (Nutlin 3a, Ml 63) induces apoptosis in AML cells with unmutated p53. While these HDM2 inhibitors dramatically increase p53 levels that initiate transcription of p53 targets, transcription-independent direct interactions of p53 with Bcl-2 family members also occur. Furthermore, Chemotherapeutic agents such as cytarabine and daunorubicin syngergize with BH3 mimetics, and with MARK inhibitors, which inhibit induction of anti-apoptotic p21 and regulate the subcellular distribution of p53. Thus, we propose to investigate the molecular and clinical consequences of a clinical trial with small molecule inhibitors of HDM2 (Nutlin 3a, MI-63) and to develop a better understanding of the mechanisms regulating p53 activation and the observed synergism with chemotherapy. If successful, these studies will provide rationale for a novel therapeutic strategy in AML based on the non-genotoxic activation of p53 signaling. Specific Aim 1: Identify the molecular determinants of apoptosis induced by non-genotoxic small molecule inhibitors of HDM2 (Nutlin 3a, Ml 63) in leukemia cell lines, primary leukemia cells and stem cells. Specific Aim 2 Determine mechanisms by which HDM2 inhibition synergizes with chemotherapy (Ara- C, Doxorubicin) in AML. Specific Aim 3 Conduct first-in-man Phase I trial of HDM2 inhibitors (Nutlin 3a analog R7112, Ml 63) in AML Lay Language Summary: AML is a largely incurable malignancy of bone marrow stem cells. A gene termed "p53", a master regulator of cell survival and death, is frequently dysregulated in cancers and leukemias. While cancers have a high frequency of p53 mutations, leukemias do not. This finding opens a window to activate the function of this gene by releasing p53 from its inhibitor, the HDM2 protein, by a novel class of drugs with great therapeutic promise. This proposal lays the groundwork for an entirely novel concept for the treatment of AML.