GATA6调控MUC1促进胆管癌细胞上皮间质表型转化的分子机制

Cholangiocarcinoma (CCA) has one of the highest mortality rates among solid malignancies because of invasion and metastasis. Our previous study has shown that aberrant expression of GATA6, an conserved transcriptional factor, promotes invasion and metastasis in CCA. However, the relative mechanism is not clear. Mucins are a kind of glycoproteins, are overexpressed in many digestive malignancies and play important roles in invasion and metastasis. Our preliminary experiment shows that GATA6 knockdown significantly downregulated MUC1 mRNA expression in QBC 939 cells, a cholangiocarcinoma cell lines. Moreover, GATA motif could be found in the MUC1 promoter region by the bioinformatics analysis. Based on previous reports and our results, we postulate that GATA6 increases epithelial to mesenchymal transition thourgh upregulating MUC1 expression by binding to its promoter region in cholangiocarcinoma cells. In the presrnt study, we try to demonstrate the above postulation by lentivirus transfection, real-time PCR, western-blot, luciferase reporter gene assay, deletion mutations, point mutations, electrophoretic mobility shift and chromatin immunoprecipitation assay in vitro and in vivo. The aim of this study is to demonstrate the mechanism of GATA6 promoting invasion and metastasis in cholangiocarcinoma cells, and provide more research evidences for clinical targeted therapy.

侵袭转移是胆管癌高死亡率的主要原因，其相关分子机制还不完全清楚。我们前期研究提示：胆管癌中转录因子GATA6异常表达，发挥癌基因作用，显著促进侵袭转移；但其调控机制尚不完全明确。粘蛋白是一类大分子量糖蛋白，在多种消化道肿瘤侵袭转移中发挥重要作用。我们预实验筛选GATA6潜在靶基因发现：胆管癌细胞QBC939中干扰GATA6后MUC1的mRNA显著降低；生物预测发现MUC1基因启动子区存在GATA6的结合位点。结合文献报道和预实验结果，我们提出本项目研究假说：胆管癌中GATA6与MUC1基因启动子结合，增强转录活性，上调MUC1表达，促进癌细胞EMT，促进侵袭转移。本项目拟在细胞、动物和临床标本实验中，通过慢病毒转染、PCR、WB、荧光素酶活性检测、EMSA、ChIP、免疫组化等实验证实研究假说，阐明GATA6促进胆管癌侵袭转移的分子机制，为胆管癌靶向治疗提供理论依据。

我们前期研究发现：胆管癌中GATA6表达显著增高，促进侵袭转移。而其相关调控机制不清。在本基金资助下，我们研究发现：GATA6通过与MUC1启动子结合，增强其转录活性，上调MUC1表达，进而促进癌细胞上皮间质表型转化；而且，miR-124能与GATA6 mRNA结合，从而下调GATA6表达。本研究拓宽了胆管癌侵袭转移的机制研究，为抗转移靶向治疗提供实验基础。