胰腺癌细胞中BAG3的表达对间质纤维化的影响及其机制解析

Interstitial fibrosis is one of the typical pathological features and closely associates with a poor prognosis of pancreatic cancer. It has been reported that IL6 plays a critical role in occurrence and development of interstitial fibrosis in pancreatic cancer, while the molecular mechanisms underlying its upregulation is not fully understood. BAG3 is a multifunctional protein and often overexpressed in human tumor tissues, functions like anoncogene. It has been reported that BAG3 is increased in pancreatic cancer,and its expression levels are positively correlated with poor prognosis of patients with pancreatic cancer, but the mechanismsis not clarified.Recently for the first time we identified that BAG3 interacted with and stabilized IL6 mRNA.These results indicate that BAG3 might be implicated in the occurrence and development of interstitial fibrosis and poor prognosis of pancreatic cancer via posttranscriptional regulation of IL6 expression. The current project aims to clarify the mechanisms by which BAG3 and IL6 mRNA interaction regulates the expression of IL6,as well as the effect of interaction on interstitial fibrosis in pancreatic cancer. This project will shed light on understanding the mechanisms underlying regulation of IL6 expression in pancreatic cancer, which might enhance our understanding on the influence and mechanisms of BAG3 in pancreatic cancer, as well as provide potential target for therapy of pancreatic cancer.

间质纤维化是胰腺癌的典型病理特性之一，与胰腺癌的预后不良密切相关。研究表明IL6在胰腺癌间质纤维化的发生发展中发挥重要作用，但其在胰腺癌中表达上调的分子机制尚未完全阐明。BAG3是一种多功能蛋白，在许多肿瘤中高表达，发挥癌基因的功能。研究表明BAG3在胰腺癌中高表达，并且与胰腺癌预后不良正相关，但其机制远未阐明。最近我们首次发现BAG3与IL6 mRNA结合，并且稳定IL6 mRNA的表达。这些结果提示我们BAG3可能通过在转录后水平调控IL6的表达，在胰腺癌间质纤维化的发生发展及胰腺癌患者预后不良中发挥作用。本项目拟阐明BAG3与IL6 mRNA相互作用对IL6的表达调控机制，及其在胰腺癌间质纤维化中的作用。本项目有助于我们对胰腺癌中炎症因子IL6表达调控机制的进一步理解，有助于深入了解BAG3在胰腺癌中的作用及其机制，为胰腺癌的治疗提供新的潜在治疗靶点。

BAG家族蛋白最初是因为其与抗凋亡蛋白Bcl-2结合，可促进细胞生存，因此而得名。除骨骼、心肌组织、脑组织及周围神经组织BAG3具有较高表达水平之外，在其它正常组织中BAG3的表达很弱或者不表达；而在一些肿瘤细胞如白血病、实体性肿瘤细胞内BAG3表达水平较高，维持肿瘤细胞的存活。. 本项目的前期工作结果表明BAG3能够调控胰腺癌恶化进程，并且发现细胞白介素家族成员IL6及IL8的表达随BAG3的下调而下调。本项目前期已经证实，BAG3是一种RNA结合蛋白与转录后调控密切相关。鉴于肿瘤微环境在癌症治疗中的重要意义及转录后调控在基因表达的重要作用，本实验旨在前期工作基础上明确BAG3对胰腺癌恶化进程的调节，并进一步探索BAG3在转录后水平调控IL6及IL8表达的具体机制。. 本项目培养胰腺癌细胞及胰腺星形细胞，利用慢病毒感染的方法构建稳定敲低BAG3和空载体的SW1990、BxPC3细胞系。检测目的mRNA和蛋白质的表达水平；检测上清液中相关因子释放；检测细胞增殖和迁移、侵袭能力；分析患者样本中BAG3表达与细胞纤维化相关性；检测新生目的mRNA的表达及目的mRNA的半衰期；检测启动子或其他元件的活性；检测RNA与蛋白的相互作用；检测相关蛋白质之间的相互作用。. 本项目证实：1、在PDAC中，BAG3通过增加Ago2 Ser387的磷酸化抑制其加载到IL6 mRNA促进IL6的释放，从而活化PSC，影响胰腺导管腺癌的发展。.2、在PDAC中，BAG3的敲低一方面通过促进HuR Ser202的磷酸化抑制其与IL8 mRNA的结合，另一方面上调Ago2磷酸化，促进IL8与包含miRNA-4312的miRISC结合，促进IL8的降解，从而降低PDAC的迁移和侵袭。