T-ALL中靶向WNT通路可作用高甲基化位点SFRP5的分子机制研究

Targeting the WNT pathway is one of the focuses of cancer therapy, but it is difficult to precisely target the WNT pathway due to the multi-layer complex interaction regulation mode and the toxicity of WNT pathway inhibitor to normal cells, which severely restricts its application. Our previous studies found that WNT pathway is abnormally activated in T-ALL and that there is a distinct WNT hyper-methylation profiling in T-ALL; the knockout of DNA methylation reader MBD2 could selectively target the WNT hyper-methylation regulators and inhibits its downstream activity, and repress the development and maintenance of T-ALL, but had no significant effect on normal hematopoiesis. The hyper-methylation locus SFRP5, the epigenetically regulation downstream of MBD2, was further selected as a key target of WNT pathway. In this project, we will investigate in depth the molecular mechanism of hyper-methylation locus SFRP5 targeting WNT signaling pathway in T-ALL. We will use the strategies of overexpression and knockdown of SFRP5 in T-ALL mouse models, cell lines and normal T cells to observe its phenotypes and the effects on WNT pathway, and then validated in primary T-ALL specimens. The successful completion of this project will specify the extensive epigenetic regulation mode, providing avenues to find the precise target to specifically inhibit WNT pathway efficiently with low toxicity, and provide novel epigenetic therapeutic targets for T-ALL.

靶向WNT通路是肿瘤治疗研究的焦点之一，但WNT通路多层面复杂交互的调控模式难以精确靶向，WNT通路抑制剂对正常细胞的毒性也严重制约其应用。申请人前期研究发现，T-ALL中WNT通路异常激活，存在T-ALL独特的WNT高甲基化位点；敲除DNA甲基化阅读器MBD2能选择性靶向WNT通路高甲基化位点并抑制其下游活性，阻遏T-ALL发展与维持，而对正常造血无显著影响；并筛选出高甲基化位点SFRP5为MBD2表观修饰下游的WNT通路关键靶点。本项目拟深入探讨T-ALL中靶向WNT通路可作用高甲基化位点SFRP5的分子机制，在T-ALL小鼠模型、细胞系和正常T细胞中正义和反义表达SFRP5，观察其生物动力学效应和对WNT通路影响，并在T-ALL原代标本验证。本项目的完成，将泛性表观调控模式具体化，为寻找高效低毒、特异性抑制WNT通路的精确作用靶点提供理论依据，为T-ALL表观修饰治疗靶点提供新思路。

靶向WNT通路是肿瘤治疗研究的焦点之一，但WNT通路多层面复杂交互的调控模式难以精确靶向，WNT通路抑制剂对正常细胞的毒性也严重制约其应用。申请人前期研究发现，T-ALL中WNT通路异常激活，存在T-ALL独特的WNT高甲基化位点；敲除DNA甲基化阅读器MBD2能选择性靶向WNT通路高甲基化位点并抑制其下游活性，阻遏T-ALL发展与维持，而对正常造血无显著影响；并筛选出高甲基化位点SFRP5为MBD2表观修饰下游的WNT通路关键靶点。.我们收集临床原代T-ALL标本，检测发现SFRP5在T-ALL中呈高甲基化、低表达状态；同时我们在人T-ALL细胞系中构建SFRP5敲降和过表达稳定细胞株，发现SFRP5能抑制白血病细胞增殖，与WNT通路活性呈负相关；我们通过构建SFRP5敲降的T-ALL小鼠体内模型，发现敲降SFRP5能显著加速小鼠T-ALL的发生发展。综上所述，靶向SFRP5将泛性表观调控模式具体化，为高效低毒、特异性抑制WNT通路以及T-ALL表观修饰治疗靶点开辟了新的方向。