启动子低甲基化诱导PRIM2/KLF5复合体形成促进胰腺癌侵袭转移的分子机制

启动子区域甲基化异常与肿瘤发生发展密切相关。国家重点研发计划资助发现：胰腺癌中PRIM2高表达且其启动子区域（TSS1500）低甲基化；生信分析提示PRIM2可与KLF5互作形成复合体（经Co-IP证实），RalBP1启动子区域存在KLF5结合位点；下调PRIM2表达显著抑制胰腺癌细胞侵袭迁移且RalBP1表达明显降低。已知RalBP1可诱导侵袭性伪足形成。故推测：启动子TSS1500区域低甲基化上调PRIM2表达，形成PRIM2/KLF5复合体，增强RalBP1转录，诱导侵袭性伪足形成，促进胰腺癌细胞侵袭转移。拟通过大样本检测PRIM2表达及其启动子区域甲基化与胰腺癌患者临床资料相关性；采用甲基化报告基因、dCas9系统、酵母双杂交等方法在细胞和动物模型中验证假说。有望阐明PRIM2启动子区域低甲基化介导PRIM2/KLF5复合体形成促进胰腺癌侵袭转移的分子机制，为胰腺癌诊治提供新思路。

Promoter aberrant methylation is closely associated with carcinoma development and progression. Supported by the National KEY R&D Program of China we found that: PRIM2 was strongly expressed and promoter (TSS1500) region was hypomethylation in pancreatic cancer; bioinformatic analysis and Co-IP confirmed that PRIM2 can interact with KLF5 to form complex; and there are KLF5 binding sites in the promoter region of RalBP1; silencing PRIM2 significantly decreased the migration of PDAC cells and the expression of RalBP1. RalBP1 is known to induce invadopodia formation. Therefore, we speculate that: promoter TSS1500 region hypomethylation upregulates the expression of PRIM2, PRIM2 and KLF5 forms complex to enhance the transcription of RalBP1 which induces invadopodia formation, and promotes the invasion and metastasis of pancreatic cancer cells. This hypothesis is intended to be tested by analyzing the correlations between PRIM2 expression and its promoter methylation status and the clinicopathological features by large clinical specimens, using luciferase assay, dCas9 system, yeast two hybrid in cells and animal models. We can elucidate the molecular mechanism that the hypomethylation of PRIM2 promoter mediates the formation of PRIM2/KLF5 complex to promote invasion and metastasis of pancreatic cancer, and to provide new strategy for pancreatic cancer diagnosis and treatment.