Pttg1调控Ras/Myc介导的细胞恶性转化及其在胰腺癌形成中的作用机制

Abstract: Ras and Myc signaling pathway play a key role in tumor initiation and progression with the ability to induce and regulate the transformation of normal cells to malignant tumor cells. Pttg1 has been identified to be highly expressed in multiple type of cancer, which leads to trans-activate Myc signaling pathway. Our previous study showed that deletion of Pttg1 in MEF cells can inhibit cellular transformation induced with Ras and/or Myc. And our data also showed that the proliferation of pancreatic cancer cell was significantly inhibited by loss of Pttg1 expression. These results suggest that Pttg1 may promote pancreatic cancer malignance through regulating Ras and Myc signaling pathway. In the current study, Pttg1 knockout mouse will be used to further study, Aim 1: the role of Pttg1 in Ras and Myc induced MEF cellular transformation, Aim 2: the role of Pttg1 in pancreatic cancer cell involving Ras and Myc signaling pathway , Aim3: the role of Pttg1 in PDAC formation in pancreatic tumor mouse model. Thus, the proposed studies will emphasize targeting Pttg1 regulating Ras and Myc signaling pathway involved cellular transformation as a new therapeutic avenue to pancreatic cancer. And the study will explore the novel method of Pttg1 as a new intervention therapeutic target for clinical treatment of pancreatic cancer.

Ras和Myc在肿瘤发生和发展中起着重要的作用。在胰腺癌中Myc是Kras转录激活下游的信号分子。Pttg1可转录激活Myc信号通路，并在多种肿瘤中表达升高，但对Pttg1在胰腺癌中的作用尚无报道。前期研究发现，Pttg1缺失可抑制Ras和/或Myc诱导的小鼠成纤维细胞（MEF）的恶性转化，并能有效抑制胰腺癌细胞的生长。提示Pttg1可能通过Ras和/或Myc途径促进胰腺癌的恶性转化。项目通过Pttg1基因敲除小鼠研究：1) Pttg1对Ras和Myc诱导的MEF细胞恶性转化的调控机制；2) Pttg1调节Ras和Myc信号通路在胰腺癌细胞中的作用机制；3) Pttg1在胰腺癌小鼠PDAC形成中的作用机制。旨在以Pttg1调控Ras/Myc信号通路为靶向，探索以Pttg1为靶向抑制胰腺肿瘤细胞恶性转化的新方法，为胰腺癌的临床治疗提供新思路。

项目通过PTTG1敲除小鼠，研究Pttg1在胰腺癌小鼠PDAC形成和发展进程中的作用和机制。细胞实验结果发现PTTG1 KO抑制小鼠胚胎成纤维细胞的增殖和转化；PTTG1在人胰腺癌细胞株AsPC-1、CEPAC-1、SW1990、PANC-1、BxPC-3中高表达。首先，通过咪喹莫特诱导的小鼠银屑病模型和B16 F10细胞小鼠黑色素移植瘤模型探究PTTG1缺失对小鼠免疫功能以及肿瘤免疫的影响。结果发现，PTTG1 KO小鼠银屑病皮损较WT小鼠更为严重，并且皮损组织中TNF-α、IL-12β、IL-1βA的表达较WT小鼠皮损组织中高，提示PTTG1缺失可能影响小鼠的免疫功能。PTTG1敲除能抑制小鼠皮下B16 F10细胞移植瘤的生长；PTTG1 KO小鼠的瘤组织中DC细胞和NC细胞数量较WT小鼠瘤组织中的多；qPCR检测结果表明TNF-α、IL-12β、IL-1βA表达较WT小鼠高; 转录组测序分析得出NK和DC相关免疫因子如IL-15、IFN-γ的分值较高，提示NK和DC在其中的作用。接下来利用胰腺原位癌小鼠模型，探讨PTTG1 缺失对胰腺癌进程的影响及其是否改变胰腺癌组织的免疫微环境，结果发现PTTG1缺失能减缓小鼠胰腺原位癌的进程，但未检测到免疫细胞及相关细胞因子表达的差异;PTTG1 KO小鼠和WT小鼠原位胰腺癌组织中E-cadherin,MMP9,MMP2的表达有差异。提示PTTG1 缺失对胰腺癌发展进程的影响可能通过改变肿瘤微环境，对此还需要进一步的研究。