DNA甲基化特异性改变对结肠癌干细胞上皮间质转化表型及肝转移的调控

Cancer stem cell(CSC) has EMT phenotype and contributes to tumor metastasis, recurrence and resistence to chemotherapy. The epigenetic regulation is involved in these process related to CSC. Our previous studies showed that CD133+CXCR4+ colon cancer cell not only has stem cell characteristics, but also EMT phenotype and higher capacity of invasion and hepatic metastasis. Methylation inhibitor could inhibit the occurrence of EMT and hepatic metastasis, the underlying mechanism of which is far from clear now. This study will isolate CSC from both cell line and patient samples, and screen for the differential methylated genes which will be identified by MSP. We will explore the correlation of methylated genes with clinical prognosis and the potential mechanisms underlying these genes regulating EMT and hepatic metastasis, and finally find the key DNMT and possible signalling pathway. The study tries to uncover the EMT characteristics of colon CSC and its methylation regulating mechanisms in order to provide new path for judgment of colon cancer metastasis, recurrence and prognosis as well as for CSC-targeted cancer therapy. This study is innovative without previous report published.

肿瘤干细胞具EMT表型,是导致肿瘤耐药及转移复发的根源。研究发现肿瘤干细胞的表观遗传修饰,特别是DNA甲基化特异性改变参与肿瘤耐药和转移复发。我们前期工作发现,CD133+CXCR4+结肠癌细胞不仅具有干细胞特性,且具有EMT表型,有较强的侵袭性及肝转移倾向；甲基化抑制剂可以抑制结肠癌干细胞肝转移及EMT进程。但调控机制尚未明确。本研究拟结合临床标本，分选结肠癌干/非干细胞，应用高通量DNA甲基化芯片筛选差异基因并采用MSP鉴定；研究甲基化改变的基因与结肠癌临床预后的相关性；并深入探讨结肠癌干细胞DNA甲基化特异性改变对EMT表型及结肠癌肝转移的影响及分子机制；试图寻找调节DNA甲基转移酶的调控分子和信号转导途径。研究结果试图阐明结肠癌干细胞EMT特性及甲基化调控机制，为结肠癌转移复发及预后判断提供新方法，为以结肠癌干细胞为靶点的药物研发提供新策略。本研究内容未见报道，有较好的创新性。

转移肿瘤干细胞是导致肿瘤耐药、转移和复发的重要原因。我们的前期研究结果表明，CD133+CXCR4+结肠癌干细胞与DNA甲基化在结肠癌肝转移中有着重要的作用，因此可以通过结肠癌干细胞与甲基化作为潜在的治疗结肠癌肝转移的策略。相关研究表明，抑制DNA甲基调控主要功能酶DNMT可显著抑制结肠癌干细胞的增殖与成瘤能力。本研究结合临床样本，分选结肠癌干/非干细胞，应用高通量DNA甲基化芯片筛选差异基因并采用甲基化特异性PCR鉴定，发现并筛选甲基化改变与结肠癌临床预后有相关性的基因；通过对其功能研究观察其对结肠癌干细胞的干性、成瘤能力和肝转移能力的影响。同时，体外和体内实验结果证实DNA甲基化抑制剂与5-Fu/P85可以成为抑制结肠癌及结肠癌肝转移瘤潜在的治疗手段，且Sirt1和LPS在结肠癌干细胞干性维持和肝癌生长中发挥着重要作用。