Oncogenic tyrosine kinases inhibitors abrogate DNA repair and sensitive leukemias to PARP inhibitors

致癌性酪氨酸激酶（OTKs）如FLT 3（ITD）和JAK 2（V617 F）诱导急性髓系白血病 白血病（AML）和骨髓增生性肿瘤（MPN）。OTK可以是 伴有“另外的”突变（例如，TET 2、DNMT 3A）遗传/表观遗传并发症 签名.针对FLT 3（ITD）阳性AML开发了选择性OTK抑制剂（OTKi）， JAK 2（V617 F）阳性MPN，但OTKi治疗患者中完全缓解罕见， 在最初的反应之后，疾病通常进展到更恶性的阶段。 FLT 3（ITD）阳性AML和JAK 2（V617 F）阳性MPN蓄积致死性DNA双链， 链断裂（DSB）。DSB通过两种主要机制修复，BRCA介导的 同源重组（HR）和DNA-PK介导的非同源末端连接（D- NHEJ）。HR和D-NHEJ修复增殖细胞中的DSB，并且D-NHEJ在增殖细胞中起主要作用。 静止细胞PARP 1依赖性备份NHEJ（B-NHEJ）在增殖和 静止细胞FLT 3（ITD）和JAK 2（V617 F）阳性AML/MPN干细胞通常具有耐药性 因为这些OTK调节DNA修复途径以促进存活。 DSB修复中的癌症特异性缺陷创造了使用合成杀伤力的机会， 例如通过PARP抑制剂（PARPi）消除BRCA 1/2突变的癌细胞。我们报道了 OTKis诱导HR和D-NHEJ缺陷，其使静止和增殖的 FLT 3（ITD）/JAK 2（V617 F）阳性AML/MPN干细胞对PARPi引发的合成致死性的影响。 然而，我们最近的报告和初步数据强烈表明，“额外” 突变（例如，在TET 2中，DNMT 3A）可改变FLT 3（ITD）和JAK 2（V617 F）阳性 AML/MPN细胞对OTKi + PARPi的敏感性因此，在具体目标#1中，我们建议确定 影响FLT 3（ITD）和JAK 2（V617 F）敏感性的“额外”突变和机制- 阳性细胞对OTKi+ PARPi介导的合成致死性的反应。 我们还报道并获得了骨髓微环境（BMM） 诱导对OTKi + PARPi处理的抗性。因此，我们将查明与BM相关的 OTKi + PARPi介导的合成致死性的障碍，并将BMM抑制剂（BMMi）应用于 具体目标#2：克服BMM对OTKi + PARPi治疗的保护作用。 最后，我们将测试OTKi + PARPi +/- BMMi针对AML/MPN的治疗潜力。 异种移植物携带有利于特定目标#3中的合成致死效应的突变。治疗 OTKi + PARPi +/- BMMi对携带特异性“驱动”突变的AML/MPN的作用 [FLT 3（ITD/TKD），JAK 2（V617 F）]和“另外的”突变（例如，TET2）。

Oncogenic tyrosine kinases (OTKs) such as FLT3(ITD) and JAK2(V617F) induce acute myeloid leukemia (AML) and myeloproliferative neoplasms (MPNs), respectively. OTKs may be accompanied by “additional” mutations (e.g., TET2, DNMT3A) complicating genetic/epigenetic signature. Selective OTK inhibitors (OTKi) are developed against FLT3(ITD)-positive AMLs and JAK2(V617F)-positive MPNs, but complete remissions were rare in OTKi-treated patients, and after initial response the disease progressed often in to more malignant stage. FLT3(ITD)-positive AMLs and JAK2(V617F)-positive MPNs accumulate lethal DNA double- strand breaks (DSBs). DSBs are repaired by two major mechanisms, BRCA-mediated homologous recombination (HR) and DNA-PK –mediated non-homologous end-joining (D- NHEJ). HR and D-NHEJ repair DSBs in proliferating cells and D-NHEJ plays a major role in quiescent cells. PARP1–dependent back-up NHEJ (B-NHEJ) works in proliferating and quiescent cells. FLT3(ITD) and JAK2(V617F)-positive AML/MPN stem cells are usually resistant to DSBs because these OTKs modulate DNA repair pathways to promote survival. Cancer-specific defects in DSB repair create the opportunity to employ synthetic lethality, e.g. elimination of BRCA1/2-mutated cancer cells by PARP inhibitor (PARPi). We reported that OTKis induce HR and D-NHEJ deficiencies, which sensitize quiescent and proliferating FLT3(ITD)/JAK2(V617F)-positive AML/MPN stem cells to synthetic lethality triggered by PARPi. However, our recent reports and preliminary data strongly suggest that “additional” mutations (e.g., in TET2, DNMT3A) can change FLT3(ITD) and JAK2(V617F)-positive AML/MPN cells sensitivity to OTKi + PARPi. Therefore in Specific Aim #1 we propose to identify “additional” mutations and mechanisms which affect sensitivity of FLT3(ITD) and JAK2(V617F)- positive cells to OTKi+PARPi-mediated synthetic lethality. We also reported and obtained preliminary data that bone marrow microenvironment (BMM) induces resistance to OTKi + PARPi treatment. Therefore we will pinpoint BMM-related obstacles for OTKi + PARPi-mediated synthetic lethality and apply BMM inhibitor (BMMi) in Specific Aim #2: Overcoming the protective effect of BMM against OTKi + PARPi treatment. Finally, we will test therapeutic potential of OTKi + PARPi +/- BMMi against AMLs/MPNs xenografts carrying mutations favoring synthetic lethal effect in Specific Aim #3. Therapeutic effect of OTKi + PARPi +/- BMMi against AMLs/MPNs carrying specific “driver” mutations [FLT3(ITD/TKD), JAK2(V617F)] and “additional” mutations (e.g., TET2).