SOCS-1新结合蛋白CUEDC2在急性白血病发生发展中的作用机制研究

Leukemia stem cells (LSC) are the source of disease relapse after remission in patients, and effective remove of LSC is difficult in leukemia therapy. The origin of LSC might be from the deregulation of the key signaling pathway of hemopoietic stem cell (HSC). Thus further study of the deregulation mechanism of key signaling pathway in the conversion of HSC to LSC will provide clues for leukemia treatment. Previous studies suggested that the JAK1-STAT3 signaling pathway played key roles in the maintenance of stem cell self-renewal and pluripotency and the ubiquitination degradation of SOCS-1 often resulted in the activation of this signaling pathway in acute leukemia. A new SOCS-1 interaction protein CUEDC2 was detected by proteomic approach. Studies have indicated that CUEDC2 had a close relationship to the cancer stem cell (CSC) by regulating proteins ubiquitination degradation. However, whether CUEDC2 associated with the pathogenesis of leukemia or with LSC has not been reported. Our studies have demonstrated that the expression of CUEDC2 were deregulated in a variety of acute leukemia primary cell and cell lines, and its overexpression affected the biological behavior of leukemia cells. The purpose of this project is to elucidate whether CUEDC2 affected the maintenance of LSC or the biological behavior of leukemia cells by influenced JAK1-STAT3 signaling pathway though regulating proteins ubiquitination degradation. This study may provide clues in understanding the nature of leukemia and new targets for leukemia treatment.

白血病干细胞（LSC）是患者缓解后复发的根源，有效清除LSC是治疗白血病的难点。LSC可能起源于造血干细胞（HSC）关键信号通路失调。因此研究HSC向LSC转化过程中关键信号通路失调的机制将为白血病治疗提供新思路。JAK1-STAT3信号通路在干细胞自我更新和特性维持中起关键作用，白血病中SOCS-1泛素化降解导致该通路过激活。通过蛋白组学我们发现了SOCS-1新结合蛋白CUEDC2，已有研究显示CUEDC2调控泛素化降解过程与肿瘤干细胞密切相关。但CUEDC2是否与白血病发生或LSC相关未见报道。本研究已证实急性白血病原代细胞和细胞株中CUEDC2表达失调，其上调抑制JAK1-STAT3通路影响白血病细胞的生物学行为。本课题拟通过上调或下调CUEDC2证实其是否通过调控泛素化降解影响了LSC特性维持和白血病细胞的生物学行为。本研究可加深对白血病发病和LSC的认识，为白血病治疗提供新靶点。

结题摘要.白血病干细胞（LSC）是患者缓解后复发的根源。LSC可能起源于造血干细胞（HSC）关键通路失调，研究HSC向LSC转化过程中关键通路失调机制将为其治疗提供新思路。JAK1-STAT3通路在LSC特性维持中起关键作用，AL中SOCS1泛素化降解导致该通路过激活。本研究探索了SOCS1的新结合控蛋白CUEDC2在JAK1-STAT3通路和LSC干性调控中的机制。结果：①AL中SOCS1和CUEDC2均表达下调，在40-50%的AL病人中SOCS1因泛素化降解而下调，CUEDC2表达下调，提示其可能参与SOCS1的泛素化降解。②CUEDC2通过与SOCS1的H2结构域相互作用影响SH2结构域招募泛素化蛋白降低SOCS1的泛素化降解进而抑制JAK1-STAT3通路活性；AL中CUEDC2须通过与SOCS1的相互作用才能抑制JAK1-STAT3通路的活性。③在AL细胞系中分别下调和过表达CUEDC2，结果提示过表达CUEDC2抑制AL细胞的增殖、克隆形成、使细胞处于G0/G1期、提高细胞对化疗药物柔红霉素和阿糖胞苷的敏感性、降低干细胞标志物表达，不影响细胞凋亡；而下调则结果相反。⑤通过表达谱发现了3个可能参与CUEDC2调控的基因。⑥建立了人缘化小鼠模型，结果提示过表达CUEDC2可减缓HEL和JM-1细胞株引起AML小鼠的发病时间，延长生存期并提高生存率、减缓AL细胞对肝、脾和骨髓的浸润并抑制LSC的干性维持和干细胞标志物表达，而下调则相反。⑦在小鼠模型上，敲除CUEDC2可以促进MLL-AF9诱导的小鼠原发白血病的发病进程和LSC的干性维持，降低生存率。⑧通过基因芯片发现了调控CUEDC2表达的LncRNA-NA2332并初步进行了机制研究。⑨分析了JAK1 S518、CUEDC2 F157、JAK2 R683G和JAK2 E627等点突变在AL发生中的机制，为靶向药物开发提供新思路。进行了CUEDC2和SOCS1复合物晶体筛选，已获3.4埃晶体。意义：基本阐明了CUEDC2调控SOCS1泛素化降解和JAK1-STAT3通路的作用机制及其在LSC干性维持和AML发生发展中的作用，为AL治疗提供了新的潜在靶点。点突变在AL发生中的机制，有望为白血病药物开发提借鉴。此外，LncRNA研究拓宽了研究视角，获得了新的研究增长点。