表没食子儿茶素没食子酸酯调控淀粉样前体蛋白代谢诱导肿瘤细胞凋亡的表观遗传学机制

As the common genes of pathogenesis of Alzheimer's disease, the abnormal expressions of amyloid precursor protein (APP) and neprilysin (NEP) are close relate to tumor occurrence, invasion, metastasis and drug resistance. Our preliminary experimental results indicated that histone modification mediated the high expression of APP, and promoted tumor growth. We and others have shown the inhibitory activity of EGCG on HDAC1. Our previous project verified that EGCG attenuates cognitive deterioration in AD mice by up-regulation NEP expression. Meanwhile, EGCG down-regulated APP expression both in AD and tumor, however, presented the opposite effects which were neuron protection and cellular apoptosis induction, respectively. The positive and negative arguments will be employed by in vivo and in vitro experiments. The present study aims to investigate the relationship between NEP silence and APP over-expression, and the epigenetic mechanism in which EGCG regulates the metabolism of APP and induces tumor cell apoptosis. Moreover, the targets on cancer cell of EGCG which acts as HDAC inhibitor will also be clarified. Furthermore, compare the different and crosstalk of APP-NEP signal pathway mediated by HDAC1 in AD and tumor under the treatment of EGCG, and provide sufficient theoretical foundation for anti-tumor and AD therapy.

作为阿尔茨海默病发生的共性基因淀粉样前体蛋白（APP）和中性内肽酶（NEP）在肿瘤的异常表达与肿瘤的发生、侵袭、转移、耐药等有着密切的关系。预实验结果表明组蛋白修饰介导了APP高表达，与肿瘤生长有着直接关系。EGCG具有抑制组蛋白去乙酰化酶（HDAC1）表达的作用。我们其它项目研究证实EGCG促进AD模型小鼠的学习和认知能力的改善，与激活NEP表达有关。同时EGCG具有下调APP的作用，但在AD和肿瘤中分别呈现的是神经细胞保护和诱导肿瘤细胞凋亡截然相反的作用。本项目拟从细胞和整体水平通过正、反实验论证肿瘤中NEP沉默及APP高表达之间的关系；明确EGCG调控APP代谢诱导肿瘤细胞凋亡的表观遗传学机制，阐明EGCG作为HDAC抑制剂对肿瘤细胞高度靶向性的物质基础；对比分析HDAC1介导EGCG调控APP-NEP信号通路的串话在肿瘤和AD中的差异，为EGCG的抗肿瘤及AD治疗提供充分理论依据。

随着研究的不断深入，越来越多的证据表明表观遗传学机制在肿瘤和阿尔茨海默病（Alzheimer’s disease, AD）发生发展中起到关键的作用。作为AD发生的共性基因淀粉样前体蛋白（amyloid precursor protein, APP）和中性内肽酶（neprilysn, NEP）在肿瘤的异常表达与肿瘤的发生、侵袭、转移、耐药等有着密切的关系。预实验结果表明组蛋白修饰介导了APP高表达，与肿瘤生长有着直接关系。在肿瘤和AD中，EGCG都可以下调APP的表达，EGCG分别呈现的是诱导肿瘤细胞凋亡和神经细胞保护截然相反的作用，其机制又是什么？ .在细胞和动物水平上分别证实了EGCG抑制肿瘤的生长，初步阐明了EGCG作为HDAC抑制剂抑制肿瘤生长与APP的关系。同时在临床的肝癌病人标本上探索了APP与HDAC1之间的关系，发现肝癌癌组织APP和HDAC1都呈现高表达，为EGCG作为HDAC1抑制剂的应用价值提供理论依据。进一步，我们在肿瘤模型中研究了APP的代谢情况，发现EGCG在mRNA和蛋白水平下调APP的表达；同时APP分解代谢的关键酶ADAM10，BACE1和PS-1也受到不同程度的调控。与此同时，我们在研究中还发现EGCG在AD的体内和体外模型中可以减少淀粉样蛋白的沉积，同时提高SAMP8小鼠的学习和认知能力, 在这过程中伴随着中性内肽酶的上调，呈现了EGCG对AD模型中APP代谢的调节情况。此外，我们在研究过程中新发现HuR介导了EGCG对APP代谢的调控。.本课题研究，从理论上证明EGCG作为HDAC1抑制剂调控APP代谢诱导肿瘤细胞凋亡的分子机制；同时在临床标本上进一步阐明EGCG作为HDAC1抑制剂的应用价值，对比分析HDAC1介导EGCG调控APP-NEP信号通路之间的串话在肿瘤和AD中的差异，新发现HuR介导了EGCG对APP代谢的调控，这些研究将有助于将关键分子设计为肿瘤和AD防治的新靶点，为EGCG及其他HDAC抑制剂的研发提供理论依据。