骨髓微环境半胱氨酸代谢异常介导急性髓系白血病耐药的机制研究

Great progress has been made in the chemotherapy of acute myeloid leukemia (AML). However, chemo-resistance severely impairs treatment efficiency and survival. A specialized amino acid microenvironment existed in bone marrow microenvironment， which is indispensable for the proliferation and maintenance of hematopoietic stem cell. Previously study verified that stromal control of cystine metabolism promoted cancer cell survival in chronic lymphocytic leukemia. Our previous study has shown that hydrogen sulfide, a metabolite of cystine, contributed to AML chemo-resistance. We speculated cysteine metabolic abnormality in bone marrow microenvironment mediated chemo-resistance in AML. In the following study, we intend to detect cystine/cysteine in the bone marrow microenvironment of newly diagnose and refractory AML patients. Then observe the effects of cysteine on drug sensitivity of AML cells and investigate the down-stream signaling pathways associated with cysteine/hydrogen sulfide. We will further determine the effects of cysteine/hydrogen sulfide on AML chemo-resistance in the CSE knockout and C57BL/6 mouse models engrafted with AML cells. Our study is of great importance in overcoming drug resistance and eliminating minimal residual disease in AML.

急性髓系白血病（AML）化疗已取得较大进展，但耐药仍严重影响患者治疗及生存。骨髓微环境中存在独特的氨基酸微环境，在造血干细胞的自我维持中发挥重要作用，且骨髓微环境半胱氨酸代谢异常在CLL耐药中发挥重要作用。我们前期研究结果显示半胱氨酸代谢产物硫化氢参与AML耐药，因此我们推测AML患者骨髓微环境半胱氨酸代谢异常可能在AML耐药中发挥重要作用。本课题拟检测初诊和复发难治AML患者化疗前后骨髓微环境中胱氨酸/半胱氨酸含量；观察半胱氨酸对AML细胞药物敏感性的影响；研究半胱氨酸产物硫化氢及其相关靶基因，阐明半胱氨酸/硫化氢参与AML耐药的具体作用机制；利用CSE基因敲除小鼠及C57BL/6小鼠构建AML小鼠模型，体内研究半胱氨酸/硫化氢介导AML耐药的作用及其具体机制。预期目标的实现将揭示骨髓氨基酸微环境介导AML耐药的新机制，对克服AML耐药、清除微小残留病变具有重要意义。

多药耐药(MDR)是急性髓性白血病(AML)难治/复发的重要原因，也是制约AML治疗的瓶颈。骨髓微环境中存在独特的氨基酸微环境，在造血干细胞的自我维持中发挥重要作用，且骨髓微环境半胱氨酸代谢异常在CLL耐药中发挥重要作用。我们前期研究结果显示半胱氨酸代谢产物硫化氢参与AML耐药。本课题拟在前期研究基础上，对L-半胱氨酸在AML多药耐药中的作用及具体机制进行深入研究。研究结果证实0.05mM浓度的L-半胱氨酸可抑制HL-60细胞凋亡；饥饿THP1细胞8小时后在0.05M和0.01M氯化钴诱导的乏氧条件下加入0.1mM和0.4mM浓度的L-半胱氨酸可促进THP1细胞增殖；应用半胱氨酸含量检测试剂盒检测到初诊或难治复发AML患者外周血上清中的半胱氨酸浓度高于正常对照组；qRT-PCR验证与AML敏感细胞株HL-60相比，在AML耐药细胞HL-60/ADM中CSE(CTH)表达水平明显升高，xCT(SLC7A11)和ASCT1(SLC1A4)表达水平亦有所升高。综上，半胱氨酸代谢异常可能在AML耐药中发挥重要作用，针对半胱氨酸的治疗方案可能让AML患者获益。