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

致癌酪氨酸激酶(OTK)如Flt3(ITD)和JAK2(V617F)诱导急性髓系白血病 白血病(AML)和骨髓增生性肿瘤(MPN)。OTK可能是 伴有“额外”突变(如TET2、DNMT3A)，使遗传/表观遗传复杂化 签名。选择性OTK抑制剂(OTKi)是针对Flt3(ITD)阳性的AML和 JAK2(V617F)阳性的MPN，但在接受OTKi治疗的患者中很少见完全缓解，以及 在最初的反应后，疾病往往进展到更恶性的阶段。 Flt3(ITD)阳性的AML和JAK2(V617F)阳性的MPN积累致命的DNA倍数 链断裂(DSB)。DSB由两个主要机制修复，即BRCA介导的 同源重组和DNA-PK介导的非同源末端连接 NHEJ)。HR和D-NHEJ在增殖细胞中修复DSB，D-NHEJ在 静止的细胞。依赖PARP1的备份NHEJ(B-NHEJ)在增殖和 静止的细胞。Flt3(ITD)和JAK2(V617F)阳性的AML/MPN干细胞通常具有耐药性 因为这些OTK调节DNA修复途径以促进生存。 DSB修复中的癌症特异性缺陷创造了使用合成致命性的机会， 例如，通过PARP抑制剂(PARPI)消除BRCA1/2突变的癌细胞。我们报道了 OTKis导致HR和D-NHEJ缺陷，从而使静止和增殖变得敏感 Flt3(ITD)/JAK2(V617F)阳性的AML/MPN干细胞对PARPI触发的合成致死性。 然而，我们最近的报告和初步数据强烈表明， 突变(如TET2、DNMT3A)可改变Flt3(ITD)和JAK2(V617F)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Flt3(ITD)和JAK2(V617F)敏感性的“附加”突变和机制- OTKi+PARPI介导的合成杀伤力阳性细胞。 我们还报道并获得了骨髓微环境(BMM)的初步数据。 诱导对OTKi+PARPI处理产生抗性。因此，我们将确定与BMM相关的 OTKi+PARPI介导的合成杀伤障碍及BMM抑制剂(BMMI)的应用 具体目标#2：克服骨髓基质细胞对OTKi+PARPI治疗的保护作用。 最后，我们将测试OTKi+PARPI+/-BMMI对AMLS/MPN的治疗潜力 携带突变的异种移植瘤在特定目的中有利于合成致死效应#3.治疗性 OTKi+PARPI+/-BMMI对携带特异性驱动基因突变的AMLS/MPN的影响 [Flt3(ITD/TKD)、JAK2(V617F)]和“额外的”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).