靶向预激态BCL2逆转FLT3-ITD AML对FLT3抑制剂耐药的机制研究

FLT3-ITD是AML中常见突变，其抑制剂（FLT3i）疗效不佳，这与FLT3i耐药后激活抗凋亡信号通路相关。我们前期研究发现，对FLT3i耐药的FLT3-ITD AML中，线粒体氧化磷酸化及活性氧水平上升，预激态BCL2（与BIM、BAX结合的BCL2）水平增高，耐药细胞对BCL2抑制剂（BCL2i）较亲本细胞更加敏感。因此我们提出靶向预激态BCL2逆转FLT3-ITD AML对FLT3i的耐药。本项目将研究以下科学问题：1）耐药FLT3-ITD AML中预激态BCL2发生的分子机制；2）预激态BCL2在耐药FLT3-ITD AML中的作用；3）评估FLT3i与BCL2i联用在耐药FLT3-ITD AML中的疗效。本项目将阐明预激态BCL2在耐药FLT3-ITD AML中的作用与机制，验证FLT3i与BCL2i联用的疗效，为耐药FLT3-ITD AML的治疗提供新思路。

Internal tandem duplication (ITD) of the fms-like tyrosine kinase 3 (FLT3) is one of the most common mutations in acute myeloid leukemia (AML), which confers a poor prognosis. There are a number of specific inhibitors on FLT3, but clinical studies have shown that the efficacy of these inhibitors is not good, indicating the existence of drug-resistance mechanism. The activation of anti-apoptosis signaling pathway is pivotal in conferring the primary and secondary drug-resistance of FLT3-ITD AML to FLT3 inhibitors (FLT3i). Therefore, targeting BCL2 may provide a new strategy to reverse FLT3i resistance in FLT3-ITD AML. In recent years, BCL2 inhibitors (BCL2i) have exerted promising therapeutic effect on AML. Besides, it was reported that the effectiveness of BCL2i depends on the amount of BCL2 bound to the pro-apoptosis proteins BIM or BAX, which is so-called “primed BCL2”. In our preliminary experiments, we found that primed BCL2 was significantly up-regulated in FLT3i-resistance FLT3-ITD AML cells, and BCL2i treatment induced remarkable apoptosis in these cells. However, the underlying mechanism of BCL2 being primed needs further investigation. Based on this, we propose that targeting the up-regulated primed BCL2 may reverse the FLT3i resistance of FLT3-ITD AML. This project will utilize FLT3-ITD AML cell lines, de novo and relapsed/ refractory primary AML with FLT3-ITD mutations, and the Patient-Derived Xenograft (PDX) mouse models to study the following questions: 1) The mechanism of BCL2 being primed in FLT3i resistance FLT3-ITD AML; 2) The function of primed BCL2 in FLT3i resistance FLT3-ITD AML; 3) Evaluation of the effect of FLT3i and BCL2i in FLT3i resistance FLT3-ITD AML. This project will reveal the mechanism of targeting primed BCL2 in reversing drug-resistance of FLT3-ITD AML to FLT3 inhibitors, and provide a novel strategy for FLT3i-resistance FLT3-ITD AML treatment through exploring the effect of FLT3i and BCL2i combination.