IL-13调控一种新颖小RNA分子:PIWI蛋白结合RNA在甲状腺乳头状癌发生中的作用机制

Papillary thyroid carcinoma (PTC) is one of the fastest growing tumors in China, but its pathogenesis is not clear. High expression of IL-13 was found in PTC in our previous results and promoted the development and progression of PTC. Furthermore, IL-13 high-expression led to recruitment of tumor-associated macrophages and M2 formation which enhanced release of CXCL8 cytokine and promoted PTC development. However, the molecular mechanism of this forward feedback regulation is unclear. PiRNA is a small molecule RNA that has gradually emerged in tumor research in recent years. We found that IL-13 could lead to expression profile changes of PTC and macrophages such as the classic piR-823, including piRNA. There are differentiated expression of these IL-13-related piRNA in the tumor and normal tissue, suggesting that the important role of piRNA in IL- 13 regulates PTC. Using piRNA-mediated DNA methylation and targeted silencing transcripts, the molecular mechanism of piRNA in IL-13-regulated tumorigenesis and PTC-macrophage signal exchange will be elucidated by molecular biology and cell function experiments. Otherwise, screening key piRNA will provide research targets for the prevention and treatment of thyroid cancer.

甲状腺癌乳头状癌（PTC）为我国发病率增长最快的肿瘤之一，然而其发病机制尚未明确。课题组前期研究发现PTC发生高频IL-13基因扩增现象，高表达IL-13不仅促进PTC的发生、发展；而且导致肿瘤相关巨噬细胞的招募及M2型形成,增强其CXCL8细胞因子释放以及对PTC促进作用；然而，此正向反馈调节的分子机制尚不明朗。piRNA是近年来在肿瘤研究中逐渐崭露头角的小分子RNA。我们发现IL-13可导致PTC及巨噬细胞中诸如经典piR-823在内的piRNA表达谱改变，而这些IL-13相关piRNA在肿瘤及正常组织中又存在差异化表达，提示piRNA在IL-13调控PTC中的重要作用。利用piRNA介导DNA甲基化和靶向沉默转录本特点，申请人拟通过分子生物学和细胞功能学实验，阐明piRNA在IL-13调控肿瘤发生及PTC-巨噬细胞信号交换中的分子机制，筛选关键piRNA，为甲状腺癌防治提供研究靶点。

我们前期研究发现了IL-13在甲状腺乳头状癌（PTC）中的表达高于良性结节。高表达IL-13不仅促进PTC的发生以及发展；而且导致肿瘤相关巨噬细胞的招募及M2型形成，增强其CXCL8细胞因子释放以及对PTC促进作用，研究表明，与PIWI相互作用的RNA(piRNA)参与了癌症的发展。我们假设IL-13可能通过piRNA影响PTC的生物学行为。首先，对五对PTC样品的piRNA表达谱进行了piRNA测序。RT-qPCR进一步验证了所有上调的piRNA的表达。配对t和非参数检验用于评估所有上调的piRNA与临床分期之间的关联。通过人口统计数据校正关键piRNA的表达水平，以构建多变量模型来区分恶性肿瘤和良性结节。此外，使用癌症基因组图谱 (TCGA)PTC样本中关键piRNA的靶基因与差异表达基因之间的交集进行富集分析。piR-13643和piR-21238在PTC中显著上调并与临床分期相关。此外与目前使用的生物标志物 HBME1（AUC:0.590）相比，piR-13643（AUC：0.821）和 piR-21238（AUC：0.823）在区分良性结节和恶性肿瘤方面表现出更好的潜能。我们通过PTC样本和良性甲状腺结节样本进行验证，观察到piR-13643和piR-21238在PTC 中显著上调。此外，我们还分析了piR-13643和piR-21238潜在的靶位点，同时功能富集分析表明，PI3K-Akt信号通路和MAPK信号通路等一些重要的基因和通路可能是piR-13643和piR-21238的潜在下游靶点，最后我们确认了IL-13可以调控piR-13643和piR-21238的表达，而且piR-13643和piR-21238在IL-3导致的PTC生物学行为的改变中发挥作用。上述结果提示我们，IL-13调控的piR-13643和piR-21238可以作为潜在的预测PTC发生和发展的新型生物标志物。