白血病微环境MSC HHIP调控急性髓系白血病耐药机制研究

The mechanism of drug resistance is complicated in acute myeloid leukemia (AML), bone microenvironment provides protection niche for leukemia stem cells (LSC), and considered as an internal environment for AML cells to escape from chemotherapeutics cytotoxicity, but mechanism of drug resistance induced by microenvironment mesenchymal stem cell (MSC) isn’t completely clear. In prophase study, it was found that Ptch/Smo/Glis pathway was the key to the network of drug resistance in AML. Smo inhibition could improved the survival of AML-bearing mice. Lowexpression of HHIP was found in refractory AML MSC and bone morrow liquid, overexpression of Smo and Gli-1 was verified in AML primary cells, and negatively correlated with prognosis in AML patients. Chemotherapeutic sensitivity was decreased in AML cells after co-cultured with AML MSC in hypoxia environment. Based on our studies, we will take advantage of coculture in hypoxia environment to imitate leukemic microenvironment, and construct human extramedullary bone marrow in mice to test the effect in vivo. This study is to demonstrate the activity of Ptch/Smo/Glis in AML is negatively regulated by AML BM-MSC HHIP, which results in drug resistance in AML cells and survival of LSC, MSC HHIP may be a target of hypomethylation treatment. This project is connected with basic research and clinic, provides support for diagnosis and targeted therapy with certain clinical value.

急性髓系白血病耐药机制复杂，白血病骨髓微环境为LSC提供“庇护”作用的微龛，也是AML逃避化疗杀伤的机体内环境，微环境MSC介导AML耐药机制不完全清楚。前期研究结果表明，Ptch/Smo/Glis是AML耐药调控网络的关键通路，Smo抑制剂可延长AML荷瘤小鼠生存期。AML患者来源MSC及骨髓液中HHIP低表达，AML细胞Smo、Gli-1高表达，与其预后负相关。MSC与AML细胞缺氧共培养，AML BM-MSC可降低AML化疗药物敏感性。在此基础上，我们利用AML与MSC缺氧共培养模拟白血病骨髓微环境，并构建AML小鼠髓外骨髓模型进行体内验证。旨在证明BM-MSC HHIP负调控AML细胞Ptch/Smo/Glis活性，介导AML耐药和支持LSC存活，MSC HHIP可能是去甲基化治疗靶点。课题基础紧密结合临床，为AML分层诊治、靶向治疗及提高疗效提供依据，具有一定临床应用价值。

急性髓系白血病耐药机制复杂，骨髓微环境为LSC提供“庇护”作用的微龛，也是AML逃避化疗杀伤的机体内环境，骨髓微环境MSC介导AML耐药机制不完全清楚。我们前期研究表明，Ptch/Smo/Glis是AML耐药调控网络的关键通路。本课题是在前期工作上的深入研究，我们研究结果表明，AML患者来源MSC及骨髓液HHIP低表达，原代AML细胞Smo、Gli-1高表达，难治性AML患者表达更高，AML患者原代细胞Gli-1高表达预示着患者预后不良。在此研究基础上，我们利用AML细胞与MSC低氧共培养，模拟白血病骨髓微环境。骨髓微环境中难治性AML骨髓来源BM-MSC HHIP低表达，对AML细胞Ptch抑制作用减弱，通过活化Ptch/Smo/Glis通路，诱导AML细胞耐药和支持LSC自我更新。Hedgehog通路活化是AML耐药的重要原因，Hedgehog通路Smo抑制剂LED25可以抑制难治性AML细胞Gli-1/PI3K/AKT、AKT/MPR1、NF-κB等通路及下游信号活性，抑制细胞增殖、诱导细胞凋亡，增加化疗及放疗的敏感性。荷瘤小鼠体内研究表明，LED25可以抑制荷瘤裸鼠体内肿瘤生长，延长其生存期。进一步研究发现，AML患者BM-MSC HHIP低表达与其CPG岛基因高甲基化状态有关，去甲基化药物可以提高MSC HHIP的表达。临床利用去甲基化药物联合化疗可以提高难治复发高危AML患者缓解(CR)率，延长其总生存(OS)及无复发生存(DFS)。本课题通过BM-MSC HHIP诱导AML耐药、支持LSC存活机制及干预研究，阐明HHIP调控Ptch/Smo/Glis通路活性及耐药机制，揭示骨髓微环境诱导耐药的新机制，探索靶向干预的新策略。本研究为AML分层诊治和个体化治疗提供依据，为难治性AML的靶向治疗奠定理论基础，具有一定临床应用价值。