Y-box结合蛋白1/Wnt5a途径诱导上皮间质转化促进胰腺癌干细胞侵袭转移的机制研究

Y box binding protein 1(YB-1) plays an important role in regulating cancer stem cell (CSC)-like properties, which can induce the process of epithelial-mesenchymal transition (EMT). The upregulation of Wnt5a can induce EMT. We found that the expression of pancreatic cancer stem cell genes were associated with the the degree of malignancy of pancreatic cancer patients. YB-1, Wnt5a and EMT-related genes were induced in pancreatic cancer stem cells. Importantly, silencing YB-1 decreased Wnt5a expression prominently. Accordingly, the hypothesis is that the direct interaction between YB-1 and Wnt5a involves in the invasiveness and metastasis of pancreatic cancer stem cells on transcriptional level.The project aims to examine the expression of YB-1 and Wnt5a in surgically resected pancreatic adenocarcinomal and adjacent normal pancreatic tissues by using immunohistochemistry to analyze the associations of their expression with malignancy of pancreatic cancer patients. Secondly, we will intervent the expression of YB-1 and Wnt5a in pancreatic cancer stem cells to detect the expression of EMT-related genes and analyze the influence of the invasion and metastasis. Thirdly, traditional ChIP，Luciferase Assay and EMSA will be used to query the regulatory relationships between YB-1 and Wnt5a. Lastly, The expression of YB-1 will be regulated to detect the change of Wnt5a expression and the effect on tumorigenicity and metastasis in vivo.This study will offer a new regulation mechanism in the pancreatic cancer stem cells research. It will also provide a new way and theoretical basis for the clinical treatment of pancreatic cancer.

Y-box结合蛋白1（YB-1）与肿瘤干细胞生物学特性维持密切相关，可诱导上皮间质转化（EMT）促进肿瘤侵袭和转移。Wnt5a高表达可诱导肿瘤发生EMT。我们前期研究发现胰腺癌恶性程度与胰腺癌干细胞干性基因表达相关；胰腺癌干细胞中YB-1、Wnt5a和EMT标志基因高表达，YB-1调节Wnt5a表达。据此推断YB-1与Wnt5a直接相互作用调控胰腺癌干细胞侵袭转移过程。本项目拟完成：1.检测临床获取的胰腺癌标本中YB-1和Wnt5a表达，分析两者与胰腺癌恶性程度的相关性；2.干预胰腺癌干细胞中YB-1和Wnt5a表达，检测EMT标志基因表达，分析对胰腺癌侵袭转移的影响；3.体外细胞水平研究YB-1与Wnt5a的结合位点及其转录调控机制，体内裸鼠模型研究YB-1对Wnt5a的调控对致瘤和转移能力的影响，以论证YB-1/Wnt5a途径对胰腺癌干细胞侵袭转移的调控机制，为治疗胰腺癌提供新的途径。

胰腺癌是一种恶性程度很高的消化道肿瘤，早期易发生转移，并具有高度侵袭性。YB-1是一种转录及转译因子，通过调节基因转录翻译促进肿瘤侵袭转移。本研究通过临床样本和细胞表达分析，发现YB-1在胰腺癌组织和胰腺癌细胞系中均呈高表达，并且与神经侵犯及侵袭转移呈正相关。下调YB-1表达显著降低胰腺癌细胞的侵袭能力，降低MMPs家族中MMP-11和MMP-14的表达，且对PI3k/Akt信号通路产生影响。通过生物信息学分析和荧光素酶报告实验发现miR-216a靶向调控YB-1。miR-216a在胰腺癌细胞中呈低表达，与YB-1的表达呈负相关。过表达miR-216a后显著抑制胰腺癌细胞的侵袭能力。Wnts是YB-1的下游靶基因之一，Wnt家族中Wnt5A和Wnt5B在胰腺癌细胞中呈高表达，过表达wnt5A后EMT相关标志基因表达发生变化。LV-YB-1慢病毒转染对胰腺癌细胞中Wnt5A和Wnt5B的表达以及EMT相关标志基因的表达没有显著影响。综上所述，miR-216a通过靶向调控YB-1，调节MMP-11和MMP-14的表达从而调控胰腺癌的侵袭。