RNA解旋酶DDX17通过m6A阅读器IGF2BP2识别YAP1 RNA甲基化修饰促进肝癌干细胞自我更新的机制研究

肝癌干细胞与肝癌起始和转移密切相关，但其自我更新机制不明。申请人前期发现，RNA解旋酶DDX17高表达可促进肝癌转移（Hepatology, 2021）。近期预实验显示，敲减DDX17可抑制肝癌干细胞自我更新，筛选发现干性驱动因子YAP1的m6A修饰及表达水平显著降低。初步机制解析发现，DDX17敲减可显著下调m6A阅读器IGF2BP2蛋白水平，但对其mRNA水平和蛋白稳定性影响不明显。据此推测：DDX17可能通过促进IGF2BP2翻译上调其表达水平，后者通过识别并结合YAP1 m6A修饰位点，增强YAP1 mRNA稳定性，进而促进肝癌干细胞自我更新。本研究拟从细胞、动物、临床三个层次，证实DDX17异常高表达在肝癌干细胞干性维持中的重要作用，阐明DDX17通过促进IGF2BP2翻译从而增强YAP1 mRNA稳定性，促进细胞干性的分子机制，有助于为靶向肝癌干细胞治疗提供新的治疗靶点。

Liver cancer stem cells (LCSC) are closely related to Hepatocellular carcinoma (HCC) initiation and metastasis, but their self-renewal mechanism is unclear. The applicant has previously found that high expression of RNA helicase DDX17 promotes HCC metastasis (Hepatology, 2021). Recent preliminary experiments showed that DDX17 knockdown inhibited self-renewal of LCSC, and m6A modification and expression level of YAP1, which has been identified as the cancer stem driver. Furthermore, preliminary mechanism analysis showed that DDX17 knockdown significantly down-regulated the protein level of the m6A reader IGF2BP2, but had no significant effect on mRNA level and protein stability. Therefore, we speculated that DDX17 may up-regulate IGF2BP2 expression by promoting IGF2BP2 translation, which enhances the stability of YAP1 mRNA by recognizing and binding to the m6A modification site of YAP1, thus promoting the self-renewal of HCC stem cells. This study aims to confirm the important role of DDX17 high expression in the maintenance of LCSC self-renewal from the cellular, animal and clinical levels. And to elucidate the molecular mechanism of DDX17 enhancing the stability of YAP1 mRNA and promoting LCSC self-renewal by promoting IGF2BP2 translation, thus providing a new therapeutic target for LCSC therapy.