AML mutation-guided drugging of DNA repair

目前急性髓细胞白血病（AML）的治疗清除了疾病负担，主要包括 白血病祖细胞（LPCs），但它们通常无法根除白血病干细胞 （LSC）。改变的DNA修复机制可能是LSC和/或LPC存活的原因 基因毒性压力下。DNA双链断裂（DSB）是最致命的DNA损伤， 通常在复制时通过BRCA介导的同源重组（HR）修复 叉子BRCA-HR修复涉及几种蛋白质，如BRCA 1，BRCA 2，RAD 54和RAD 51。 另一种HR途径依赖于RAD 52-RAD 51（RAD 52-HR）。PARP 1介导的碱基 切除修复（BER）和PARP 1依赖性非同源末端连接（P-NHEJ）作为 防止和/或修复争端解决机构的备用/替代机制。 DNA修复中的癌症特异性缺陷创造了一个机会， 称为合成致死性，例如通过PARP 1抑制剂消除BRCA 1/2突变的癌细胞 （PARP1i）。由于BRCA-HR通路的失活突变在AML中很少见，我们获得了 初步数据表明，BRCA缺乏和BRCA熟练对个体AML 可以通过AML诱导遗传学的综合基因突变分析（GMA）来预测 畸变这一方法将在目标1中得到检验。 BRCA缺陷型AML LSC/LPC应易于发生PARP 1 i诱导的合成致死性。 然而，PARP 1 i在BRCA 1/2缺陷细胞中的治疗效果可能会因以下因素而降低： 替代的RAD 52-HR，其可以至少部分地保护BRCA缺陷型PARP 1 i治疗的 细胞免受DSB的致死作用。因此，在目标#2中，我们建议结合 PARP 1 i + RAD 52 i可能在BRCA缺陷型LSC/LPC中诱导更有效的合成致死性。 我们还将开发药物级RAD 52 i。 另一方面，富含BRCA的AML细胞应该对BRCA抑制剂敏感。 HR通路与PARP 1 i结合。初步数据表明，RAD 54可能是一个有效的目标， 以诱导BRCA-活性细胞中的BRCA-缺陷。在目标#3中，我们将检查是否针对 RAD 54使BRCA-熟练AML对PARP 1 i介导的合成致死性敏感。 我们期望个性化的药物引导的合成杀伤力结合药物靶向 DNA修复可以被设计为消除个体患者中的AML LSC/LPC。

Current treatments of acute myeloid leukemia (AML) clear the disease burden consisting mostly of leukemia progenitor cells (LPCs), but they usually fail to eradicate leukemia stem cells (LSCs). Altered DNA repair mechanisms may be responsible for survival of LSCs and/or LPCs under genotoxic stress. DNA double-strand breaks (DSBs), the most lethal DNA lesions, are usually repaired by BRCA -mediated homologous recombination (HR) repair at the replication forks. BRCA-HR repair involves several proteins such as BRCA1, BRCA2, RAD54 and RAD51. An alternative HR pathway depends on RAD52-RAD51 (RAD52-HR). PARP1-mediated base excision repair (BER) and PARP1-dependent non-homologous end-joining (P-NHEJ) serve as back-ups/alternative mechanisms to prevent and/or repair DSBs. Cancer-specific defects in DNA repair create the opportunity to employ a phenomenon called synthetic lethality, e.g. elimination of BRCA1/2-mutated cancer cells by PARP1 inhibitor (PARP1i). Since inactivating mutations in BRCA-HR pathway are rare in AMLs, we obtained preliminary data suggesting that BRCA deficiency and BRCA proficiency on individual AMLs can be predicted by a comprehensive Gene Mutation Analysis (GMA) of AML-inducing genetic aberrations. This approach will be tested in Aim #1. BRCA-deficient AML LSCs/LPCs should be prone to PARP1i-induced synthetic lethality. However, therapeutic effect of PARP1i in BRCA1/2-deficient cells may be reduced by alternative RAD52-HR, which can protect, at least partially, BRCA-deficient PARP1i-treated cells from lethal effect of DSBs. Therefore, in Aim #2 we propose that combination of PARP1i+RAD52i may induce more effective synthetic lethality in BRCA deficient LSCs/LPCs. We will also develop drug-grade RAD52i. On the other hand, BRCA-proficient AML cells should be sensitive to the inhibitors of BRCA- HR pathway combined with PARP1i. Preliminary data suggest that RAD54 may be a valid target to induce BRCA-deficiency in BRCA-proficient cells. In Aim #3 we will examine if targeting RAD54 sensitizes BRCA-proficient AMLs to PARP1i - mediated synthetic lethality. We expect that personalized medicine-guided synthetic lethality combining drugs targeting DNA repair may be designed to eliminate AML LSCs/LPCs in individual patients.