Ph+ALL衍生miRNA93微泡阻抑骨髓基质GJIC功能致白血病残留耐药作用及机制

Minimal residual disease (MRD) and drug resistance were main causes for the poor outcome of Philadelphia chromosome positive acute lymphocytic leukemia (Ph+ALL). In previous Natural Science Foundation study, we found that the low expression of CX43 on the surface of bone marrow stromal cells in patients with ALL results in the dysfunction of gap junction intercellular communication (GJIC), which contributed to MRD and drug resistance. But the reason of decreased expression of CX43 remains unclear. Our previous studies found that miR-93 exosome derived from Ph＋ALL cells could restrain the function of GJIC of bone marrow stromal cells, but its intracellular signal pathway remains unclear. We speculate that the target gene EphA4 disturb membrane localization of CX43 and suppress the function of GJIC by downregulating the expression of E-cadherin . In this study, microarray bioinformatics, molecular biology, phenotypic validation,animal experiments and other methods will be used to investigate the effect and mechanism of Ph＋ALL cells for the reform of hematopoietic microenvironment. We explore the mechanism of residual disease and drug resistance from the perspective of the "crosstalk " between leukemia cells and hematopoietic microenvironment, and seek a new method to completely eliminate residual leukemic cells.

Ph＋急性淋巴细胞白血病（Ph＋ALL）疗效差，微小残留病和耐药是其难以治愈主要原因。申请者在既往自然基金研究中发现：CX43缺失导致骨髓基质GJIC功能降低有助于急性淋巴细胞白血病的残留耐药，但CX43缺失的具体原因不清楚。前期研究证明：Ph+ALL通过衍生miR-93微泡发挥阻抑骨髓基质GJIC功能的作用但其胞内通路不明，推测其可能通过EphA4下调E-cadherin表达而实现对CX43膜定位的干扰，从而达到阻抑骨髓基质GJIC功能作用，继而有助于Ph＋ALL残留耐药作用。本研究应用基因芯片结合生物信息学、基因组学、表型验证、动物实验等方法从一新的角度探讨Ph＋ALL细胞对白血病造血微环境的“改造”作用及机制，从白血病与造血微环境“crosstalk”这一新的角度去探索白血病细胞的残留耐药机制，寻求清除残留白血病的新方法。

外泌体是细胞在生理和病理条件下产生的直径在30–150 nm 小膜囊泡. 这些小膜囊泡携带蛋白质或遗传物质（RNA、miRNA、DNA）介导受体细胞功能发生重编程。在血液系统肿瘤中，白血病来源的外泌体（TEX）可重编程骨髓微环境，抑制Cx43表达干扰间充质干细胞（MSCs）的间隙连接通讯功能。前期研究发现，富含miRNA的外泌体在白血病中异常分泌，如: miR-93，然而在研究工作中发现miR-93对Cx43的调控并不稳定，而miR-130a高表达可显著下调Cx43基因和EHPA4，随即展开的研究发现，在急性淋巴白血病中，miR-130a与mIR-130b 表达正相关，BCR-ABL调控miR-130a/b的表达；首次发现 BCR-abl阳性白血病细胞来源的外泌体中miR-130a/b高表达可下调Cx43基因的表达，进而显著影响MSCs的间隙连接通讯功能，发挥对白血病的“庇护”作用。单细胞转录组分析表明Cx43在不同MSC亚群中的表达存在异质性，Cx43可能参与维持MSC亚群多样性。动物实验证实含miR-130a的微泡具有促白血病复发的作用。后续我们将深入进行Cx43在此方面的功能研究，阐明白血病BCR-ABL融合基因是如何改造有利于自身生存的微环境机制。