IGF2BP2-LncRNA DANCR-Lin28B Axis促进胰腺癌干细胞特性的分子机制研究

Pancreatic cancer is a common tumor of gastrointestinal system with high degree of malignance and poor prognosis. There is evidence that high recurrence and drug resistance of pancreatic cancer is closely related with cancer stem cell. Our previous study indicated that IGF2BP2 was an independent prognostic marker in pancreatic cancer. IGF2BP2 could regulate the expression of LncRNA DANCR through binding with it, which increased the stemness feature of pancreatic cancer. The DANCR could directly bind with Lin28B using RNA-pulldown. Therefore, we give the hypothesis that IGF2BP2-DANCR-Lin28B axis increases the stemness features of pancreatic cancer. To test this hypothesis, several experiments were carried out as following: (1) How IGF2BP2 stabilizes DANCR through binding to it? (2) The mechanism of IGF2BP2-DANCR regulating Lin28B: ① DANCR binding with Lin28B increases the transcription activity of Lin28B; ② DANCR up-regulates Lin28B through ceRNA function. (3) The clinical significance of IGF2BP2-DANCR-Lin28B axis. The aim of this project is to clarifies the molecular mechanism and signal pathway of pancreatic cancer stem cell maintenance, in order to provide further scientific basis for targeting therapy of pancreatic cancer.

胰腺癌是恶性程度高、预后极差的消化道常见恶性肿瘤。证据显示胰腺癌高复发率及放化疗不敏感与肿瘤干细胞密切相关。我们前期研究发现，IGF2BP2在胰腺癌中高表达，且与预后不良正相关；IGF2BP2结合LncRNA DANCR而调控其表达，促进胰腺癌干细胞特性；RNA共沉淀证实DANCR直接结合干细胞基因Lin28B。因此我们提出“IGF2BP2-DANCR-Lin28B信号轴促进胰腺癌干细胞特性”的假设。为了证实该假设，本课题拟研究：1、IGF2BP2如何结合并稳定DANCR表达；2、IGF2BP2-DANCR是否通过以下机制调控Lin28B：①DANCR结合Lin28B增强其下游转录活性；②DANCR通过ceRNA功能促进Lin28B表达；3、IGF2BP2,DANCR,Lin28B在胰腺癌中的临床生物学意义。本项目为阐明胰腺癌干细胞特性维持的分子机制及关键环节、研发靶向药物提供科学依据。

胰腺癌是恶性程度高、预后极差的消化道常见恶性肿瘤。较多证据显示胰腺癌高复发性及放化疗不敏感的特征与肿瘤干细胞密切相关。胰岛素样生长因子2 mRNA结合蛋白2（Insulin-like growth factor 2 mRNA-binding protein 2，IGF2BP2）的主要功能是调节细胞代谢。越来越多的证据表明IGF2BP2在肿瘤的发生发展中起到重要的作用，但其机制仍不十分清楚。我们通过免疫组化实验提示IGF2BP2在胰腺癌组织中高表达，并与预后不良相关。细胞功能学实验提示IGF2BP2可促进胰腺癌细胞的增殖和干细胞特征，而敲除IGF2BP2后上述表型明显抑制。进一步我们发现IGF2BP2可调控LncRNA DANCR的表达，敲减IGF2BP2后LncDANCR的表达明显降低，而过表达IGF2BP2后LncDANCR的表达明显上升，RIP实验证实IGF2BP2和LncDANCR直接结合。细胞功能学实验提示LncDANCR可促进胰腺癌细胞的增殖和干细胞特征，而敲除LncDANCR后上述表型明显抑制。分子功能研究表明IGF2BP2可通过识别LncDANCR A664位点的m6A修饰调节其稳定性，从而增加Lnc DANCR的表达水平。以上结果提示IGF2BP2可通过识别LncDANCR的 m6A修饰调节其稳定性，从而显著增强胰腺癌的增殖和干细胞特性。