新型调节分子tRNA来源的RNA片段在胰腺癌发生发展中的作用及机制研究

tRNA-derived RNA Fragments (tRFs) are new identified small non-coding RNAs which exhibit miRNA-like trans-silencing capacity. tRFs are implicated in development of some cancer. There are no reports about the role of tRFs in the progression of pancreatic cancer. We have found that the level of 5’tRF-GluCTC was lower in pancreatic cancer tissue relative to adjacent non-cancerous tissue by high throughput sequencing and the level of this was negatively associated with the stage of TNM. We constructed a sensor plasmid harboring a reverse complementary sequence of 5’tRF-GluCTC in the 3’-untranslated region of the fire-fly luciferase gene (Pp). Compared with 5’tRF-GluCTC negative control, 5’tRF-GluCTC mimic significantly decreased the relative luciferase activity of “Pp- anti-5’tRF-GluCTC _WT” but did not affect that of “Pp-vector”, suggesting that 5’tRF-GluCTC could have a trans-silencing activity like miRNA. Transfected by 5’tRF-GluCTC mimic, the growth of pancreatic cell was inhibited. So we hypothesized that 5’tRF-GluCTC affected the pathogenesis of pancreatic cancer as antitumorigenic factor. In our further study, we will clarify the biologic function of 5’tRF-GluCTC by colony formation assay, apoptosis assay and cell cycle analysis, nude mouse xenografts and wound healing assay, and identify the target genes with the way we used. This study will shed new light on the improvement of the survival rate in pancreatic cancer patients.

tRNA来源的片段（tRFs）是一类新近发现的非小编码RNA，具有类似miRNA样作用。tRFs在胰腺癌发生中作用目前尚无报道。前期我们通过第二代测序技术发现5’tRF-GluCTC的丰度在胰腺癌组织中明显低于癌旁组织，和胰腺癌的TNM分期呈负相关，我们构建了荧光素酶报告质粒PP-ant-5’tRF-GluCTC，发现5’tRF-GluCTC mimic可降低该荧光素酶活性，表明这是一个有功能的分子，具有反式沉默能力，并发现5’tRF-GluCTC mimic可抑制细胞增值。因而，我们提出假设：5’tRF-GluCTC可能是个“抑癌基因”，在胰腺癌的进展中起重要调控作用。本课题将进一步研究5’tRF-GluCTC对胰腺癌细胞细胞周期、凋亡、迁移和体内成瘤的影响，并鉴定该tRF的直接靶标，阐明它发挥调控作用的分子机制。本研究将深化我们对胰腺癌发生发展分子机制的认识，为胰腺癌的治疗提供新线索。

tRNA衍生片段（tRNA derived RNA fragments）与以往的认知所不同，其并非为tRNA的随意降解产物，而是一群具有异质性的群体，tRFs由不同长度大小的核苷酸片段所构成，在生物体内发挥着不同的功能。而胰腺癌是一种恶性程度非常高的消化系统肿瘤，迄今为止鲜有关于tRFs在胰腺癌中的作用研究。在本次课题研究中，在对tRFs的功能和作用机制探索中，本团队发现一些tRFs具备非编码RNA的特性（类似于miRNA），以互补序列方式结合其靶标基因的非编码区，调节靶基因表达，从而决定胰腺癌的发展进程。并且，我们还发现tRNA-Gly-CCC这类特殊的tRF在胰腺癌组织中显著低表达，并且首次探索发现tRNA-Gly-CCC可以通过特异性结合PI3K，影响AKT信号通路，从而在胰腺癌中起到抑制肿瘤生长和侵袭迁移的作用。以上研究结果阐明tRFs在胰腺癌的进展中发挥着重要作用，其中tRNA-Gly-CCC可以作为一个特异性的生物标志物影响着胰腺癌的进展，为今后胰腺癌的治疗提供新的依据。