靶向MEF2C/HDACs相互作用小分子化合物CC1007抗急性淋巴细胞白血病的效应及机制研究

Acute lymphoblastic leukemia（ALL）is an malignant clonal neoplasm origins from lymphoid stem or progenitors, and characterized by high heterogeneity in phenotypes, a poor reaction or resistance to chemotherapies, ease to relapse, and constitutes great challenge on ALL therapy. Recent data have indicated that myocyte enhancer factor 2C(MEF2C)plays an important role on mediating the differentiation and development of T-lymphocytic or B-lymphocytic cells. The interaction of MEF2C with class IIa histone deacetylases(HDACs)contributes to their recruitment to specific transcription factor, which regulates the growth and differentiation of lymphoid cells. It has also been shown that there is dys-expression or mutation of MEF2C gene in ALL patients and suggest aberrant regulation of "MEF2C/HDACs axis" is involved in the pathogenesis of ALL. Our previous works showed that CC1007, a small molecular compound, which may target to the interaction of "MEF2C/HDACs", could inhibit cells proliferation, induces apoptosis significantly both on T-ALL and B-ALL cell lines, and induces B-ALL cells differentiation from lymphoid to monocytic lineage. In the present project, we want to extend the study: (1)To determine the anti-leukemic effect of CC1007 on primary CD34+ leukemia cells from patients with T-ALL or B-ALL, and investigate the change or influence of CC1007 on MEF2C/HDACs gene and proteins; (2)To further confirm the "across-lineage" differentiation from lymphoid lineage to myeloid lineage and elucidates the regulating mechanism of CC1007 promoting differentiation; (3)To set up human primary B-ALL xenograft NOD/SCID mouse model and suffering "T-ALL" zebrafish model respectively, and observe the anti-leukemic activity of CC1007 in vivo; (4)To explore whether CC1007 blocks the interaction between MEF2C/HDACs compound and transcription factor KLF4 gene, and uncovers the exact molecular mechanism of CC1007 against ALL. Our results will open up a new path and present an alternative approach for ALL treatment.

急性淋巴细胞白血病(ALL)表现的异质性、易耐药和复发构成了治疗上的挑战。研究显示肌细胞增强因子2C（MEF2C）对T、B-淋巴细胞分化有重要调节作用；MEF2C与IIa型组蛋白去乙酰化酶（HDACs）互作并募集特异转录因子对淋系细胞分化进行调控；ALL病人MEF2C表达失调提示MEF2C/HDACs轴紊乱介导了淋系白血病发病机制。我们前期工作显示CC1007-一种靶向MEF2C/HDACs小分子化合物，能显著抑制T-或B-ALL细胞生长、诱导B-ALL细胞向单核细胞分化。本项目欲深入研究CC1007对原代T-，B-ALL CD34+ 细胞抗白血病作用及机制；确证药物诱导"淋系"细胞"跨系分化"现象及机理；探讨cc1007是否"卡位"在MEF2c/HDACs复合物与转录因子KLF4之间的"界面"；并在负B-ALL鼠和负T-ALL斑马鱼模型观察药物抗白血病活性，为ALL靶向治疗提供实验依据。

本研究在前期工作及研究背景的基础上提出研究CC1007 抗急性淋巴细胞白血病的活性效应，明确CC1007 诱导急淋白血病细胞分化/ 凋亡及抑制增殖效应的相关信号转导途径； 寻找CC1007 对“MEF2C/HDACs/特异转录因子”复合物的关键“卡位”分子，揭示CC1007 抗白血病作用的深层分子机制；2.建立人源性B-ALL 原代细胞移植小鼠模型以及MYC 高表达T-ALL 斑马鱼模型，观察CC1007 在负白血病鼠/斑马鱼模型的抗白血病效应。从课题实施到目前，上述目标基本完成：（1）确定了CC1007能抑制T-ALL和B-ALL增殖活性,诱导白血病细胞凋亡；小剂量CC1007能够诱导Nalm-6 细胞向单核细胞跨系分化。CC1007抗急性淋巴细胞白血病的主要机制与作用靶标是干扰了MEF2C/HDAC7复合物形成，抑制了MEF2C和HDAC7基因表达，和诱导一种肿瘤抑制基因- KLF4 过表达，因此揭示了CC1007的抗淋系白血病的分子机制。成功建立了人源性B-ALL 原代细胞移植小鼠模型以及MYC 高表达T-ALL 斑马鱼模型，并分别予以CC1007干预，观察到了药物的体内抗淋系白血病效应。