雄激素受体（AR）通过调控CDX1/Snail致分化障碍促进慢性胃炎恶性转化的分子机制研究

The intestinal gastric cancer develops from chronic atrophy gastritis, intestinal metaplasia, dysplasia,to carcinoma. This carcinogenesis sequence accompany with cell dys-differentiation. Our previous work found that androgen receptor (AR) expression was upregulated and co-expressed with MAGE-A11 in GC tissues. As a nuclear receptor, AR is a ligand-dependent transcription factor. Based on the previous found, the aims of present project are to illustrate scientific hypothesis as follows. AR and MAGE-A11 were upregulated in chronic inflammatory microenvironment. Then AR combines with MAGE-A11 and transfers into nucleus then recruiting co-factors (such as, CBP/p300, FOXA1, GATA2), in turn induce differentiation disorder of gastric epithelium by activating downstream transcription factors CDX1 and Snail, which crate a necessary condition for gastric cancer development. The present project contributes to further understand biological function of AR in carcinogenesis of GC ,demonstrate the mechanisms of that activating AR transfers into nucleus and recruits co-activator and co-repressor through which activating critical downstream genes in inflammatory microenvironment, and then illustrate the mechanisms of AR on promoting cell differentiation disorder, proliferation, and EMT. The study will establish a theoretical and experimental foundation for GC individualized treatment based on therapeutic strategy targeting on AR.

肠型胃癌的发生经过慢性萎缩性胃炎-肠化生-异形增生至胃癌，其中伴有明显的细胞分化障碍，前期研究发现胃癌组织中雄激素受体（AR）高表达，且与MAGE-A11具有共表达现象，AR是一种核受体，为配体依赖性转录因子。本项目拟在前期研究的基础上证明如下科学假说，慢性炎症微环境上调AR和MAGE-A11表达，AR和MAGE-A11结合入核后招募共因子（CBP/p300、FOXA1、GATA2），在CBP/p300介导下组蛋白乙酰化，启动下游转录因子CDX1和Snail表达，从而导致胃上皮细胞分化障碍，为胃癌的发生创造必要的条件，揭示AR在促进胃癌细胞分化障碍、细胞增殖、EMT等的分子机制；为将基于AR的靶向治疗策略应用于胃癌个体化治疗奠定理论与实验基础。

胃癌(Gastric cancer, GC)是世界范围内癌症相关死亡的主要原因之一，其主要原因是肿瘤转移和化疗耐药，其预后不良与肿瘤干细胞(cancer stem cells, CSC)的存在密切相关。雄激素受体(AR)已成为乳腺癌一个重要的预后标志物，在一些实体肿瘤中已评估了AR与CSC标志物的相关性。但AR在调节GC细胞干细胞中的作用尚不清楚。在本研究中，我们旨在研究AR对GC干细胞的调控作用，并阐明靶向治疗GC的潜在机制。通过对The Cancer Genome Atlas (TCGA)数据库中获取的基因表达和临床数据进行分析，我们发现AR高表达的GC患者预后较低表达的患者差。基因集富集分析(GSEA)显示，高AR表型在CSC相关通路中显著富集。我们的实验数据显示AR上调了CSC标记物CD44和ALDH的表达，这与数据分析得出的AR表达与CD44呈正相关的结果一致。此外，AR过表达可明显增强GC细胞的瘤球形成能力，增加其体外对化疗药物的耐药性，而使用其拮抗剂MDV 3100抑制AR则可减弱这种作用。这一结果在体内进一步验证了过表达AR的MGC803细胞比对照细胞具有更强的启动胃癌发生的特性。荧光素酶报告基因和染色质免疫沉淀(ChIP)实验证实AR通过直接结合CD44启动子区上调CD44的表达，同时也增加了CTGF、CYR61等YAP1靶基因的表达。更重要的是，AR对胃癌细胞干细胞的促进作用被YAP1 shRNA所抵消，这表明AR以YAP1依赖的方式调控胃CSC的致瘤特性。综上所述，AR通过转录激活胃癌细胞中的CD44，促进了CSC的性状，这为靶向CSC降低胃癌复发和耐药提供了一种新的治疗策略。