Genomic instability causes imatinib resistance in CML

Bcr/abl基因起源于t(9；22)易位，在大多数慢性髓系白血病中存在。 白血病(CML)和一组急性淋巴细胞白血病(ALL)患者。Bcr/abl致癌酪氨酸 激酶调节对DNA损伤的反应，导致对遗传毒性治疗的抵抗。此外，BCR/ABL 刺激基因组不稳定，这可能导致BCR/ABL激酶突变，导致对伊马替尼的耐药性 甲磺酸。 我们假设：BCR/ABL提高了体内活性氧自由基(ROS)的水平，从而导致 “自发的”DNA损伤(例如尿嘧啶残留物)，其不忠实的修复引入了氨基酸 Bcr/abl激酶域的替换导致对IM的抵抗。 ROS在DNA氧化损伤导致突变和对伊马替尼耐药中的作用 甲磺酸将在慢性粒细胞白血病造血干细胞(HSC)、普通髓系祖细胞(CMP)和 粒细胞/巨噬细胞祖细胞(GMP)的体外和体内模型及抗氧化方法 Bcr/abl白血病的发生。 BCR/ABL细胞中ROS依赖的DNA氧化损伤处理机制的效率和保真度 白血病细胞将通过研究碱基切除修复(BER)来确定，重点是UDG糖基酶 清除尿嘧啶残留物。这些反应将使用定义良好的报告/底物系统和 包括免疫荧光、非磷酸化和相互作用在内的不同方法的组合- 剥夺突变体、转基因小鼠和测序。将研究BCR/ABL-UDG功能相互作用 通过诱变和适体靶向抑制对甲磺酸伊马替尼的耐药性。

Bcr/abl gene is derived from the t(9;22) reciprocal translocation and is present in most of chronic myelogenous leukemia (CML) and a cohort of acute lymphoblastic leukemia (ALL) patients. BCR/ABL oncogenic tyrosine kinase modulates response to DNA damage inducing resistance to genotoxic therapies. In addition BCR/ABL stimulates genomic instability, which may lead to mutations in BCR/ABL kinase causing resistance to imatinib mesylate. We hypothesize that: BCR/ABL elevates the levels of reactive oxygen species (ROS) which induce "spontaneous" DNA lesions (for example uracil residues), whose unfaithful repair introduces amino acid substitutions in the BCR/ABL kinase domain causing resistance to IM. The role of ROS in generation of oxidative DNA damage leading to mutagenesis and resistance to imatinib mesylate will be studied in CML hematopoietic stem cells (HSC), common myeloid progenitor cells (CMP), and granulocyte/macrophage progenitor cells (GMP) using anti-oxidant approaches and in vitro and in vivo models of BCR/ABL leukemogenesis. The efficiency and fidelity of the mechanisms processing ROS-dependent oxidative DNA damage in BCR/ABL leukemia cells will be determined by studying base excision repair (BER), focusing on UDG glycosylase removing uracil residues. These reactions will be examined using well-defined reporter/substrate systems and a combination of different approaches including immunofluorescence, phosphorylation-less and interaction- deprived mutants, transgenic mice, and sequencing. BCR/ABL-UDG functional interaction will be investigated by mutagenesis and targeted by aptamers to inhibit resistance to imatinib mesylate.