慢性淋巴细胞白血病(CLL)存在多种因素导致的细胞凋亡受抑，其中MDM4是新发现的p53调控因子之一，可以通过结合p53抑制其功能及下游的miRNA-34a表达，参与CLL的凋亡过程。但我们预试验发现转染miR-34a模拟体可以使CLL细胞凋亡增加，并呈p53依赖性，提示经典的MDM4-p53-MiR-34a通路可能存在反馈机制调节CLL细胞凋亡。本研究拟针对此假说开展以下研究：①研究CLL中miR-34a异常表达及是否存在甲基化对此的调控；②免疫共沉淀法验证MDM4/p53相互作用，检测CLL患者MDM4表达并进行功能研究；③应用生物信息学方法预测miR-34a/MDM4相互作用并采用双荧光素酶报告系统确认；④体外细胞水平开展针对miR-34a/MDM4/p53通路的分子靶向治疗。通过研究阐明miR-34a/MDM4/p53反馈通路在CLL凋亡中的机理并为临床诊治提供思路。

Chronic lymphocytic leukemia(CLL) remains incurable disease,despite of the recent progress in clinical and translational field. Multiple mechanisms are involved in apoptosis-resistant of chronic lymphocytic leukemia cells, among which MDM4 is a novel regulatory factor in p53 signaling pathway. MDM4 plays a crucial role in regulating p53 activity and involved in apoptosis of CLL, it can inhibit p53 function and its downstream molecular-miRNA-34a by binding to p53 functional domain. Recent studies suggest that miRNA-34a may act as a tumor suppressor by regulating apoptosis in several malignant cell lines. However, the accurate mechanism by which miRNA-34a regulates tumour cells apoptosis is unclear..Our preliminary experiment displayed that transfection of miRNA-34 mimics will induce apoptosis of primary CLL cells in vitro in p53-dependent manner, which indicated that there is potential feedback regulation involving classic MDM4-p53-MiR-34a pathway regulating apoptosis of CLL. The purpose of our study is to verify the hypothesis: ①To determine miRNA-34a expression in large-scale samples of CLL patients and its methylation regulation; ② To comfirm the interaction between MDM4 and p53 by using co-immunoprecipitation, and explore expression and exact function of MDM4 in primary CLL leukemia cells; ③ To predict direct interaction between miR-34a and MDM4 through bioinformatics database, and further verify it by employing dual-luciferase reporter assay system; ④To investigate potential targeted therapy basing on miR-34a/MDM4/p53 feedback signaling pathway. .We expect to comfirm and elucidate exact role of miR-34a/MDM4/p53 feedback circuitry in apoptosis of CLL,which will provide a novel direction of CLL diagnosis and treatment paradigm.