PPDPF对ERK信号的调控作用及其在胰腺细胞恶性转化中的功能研究

Over-activation of Ras/Raf/ERK signaling is very common in PDAC. It is very important to understanding the mechanisms for the over-activation of Ras/Raf/ERK signaling and the regulation of ERK phosphorylation. In the previous study, it was found that the expression of PPDPF (pancreatic progenitor cell differentiation and proliferation factor) was up-regulated in PDAC clinical samples and mouse model (PDX-Cre; LSL-K-RasG12D). Forced expression of PPDPF promoted the transformation of non-cancerous NIH3T3 cells, while knockdown the expression of PPDPF inhibited the colony formation of pancreatic cancer cells on soft agar. Moreover, knockout PPDPF in PDAC mouse model (PDX-Cre; LSL-K-RasG12D) inhibited the transformation of pancreatic cells driven by RasG12D and formation of PanIN (Pancreatic Intraepithelial Neoplasia). In the study of the molecular mechanism, PPDPF was found to interact with ERK and promoted its phosphorylation. Consistent with these observations, knocking out PPDPF in the pancreatic tissues down-regulated the phosphorylation of ERK. These studies indicated that PPDPF might promoted the tumorigenesis of pancreatic cells through positively regulating Ras-ERK signaling. In this study, we will study the correlation between the expression of PPDPF and the clinical features of PDAC using clinical samples, investigate the function of PPDPF in the tumorigenesis of pancreatic cells by using cell model and animal model, and explore the molecular mechanism through which PPDPF positively regulated Ras-ERK signaling by using biochemistry and molecular biological techniques. Our study will discover the role of PPDPF in the tumorigenesis of PDAC and provide the novel therapeutic target for PDAC.

Ras/Raf/ERK信号在胰腺导管腺癌（PDAC）中异常活化，研究其异常活化的机制对PDAC的治疗意义重大。前期研究发现PPDPF在PDAC标本和动物模型中表达上调。 PPDPF促进NIH3T3恶性转化，沉默PPDPF的表达抑制胰腺癌细胞克隆集落。PPDPF与ERK相互作用，促进ERK磷酸化。在PDAC动物模型中敲除PPDPF的表达抑制胰腺上皮内瘤变（PanIn）形成及ERK的磷酸化。这些结果提示，PPDPF可能激活Ras-ERK信号从而促进PDAC的发生发展。在本项目中，我们将利用PDAC临床标本研究PPDPF的表达与临床病理特征之间的关系；应用细胞模型和PDAC动物模型研究PPDPF在PDAC发生中的功能；应用分子生物学技术研究PPDPF对Ras-ERK信号的调控机制，及其对PDAC的治疗作用。 我们的研究将揭示PPDPF在PDAC发生中的功能，为PDAC的治疗提供靶点。

Ras/Raf/ERK信号在胰腺导管腺癌（PDAC）中异常活化，研究其异常活化的机制对PDAC的 治疗意义重大。在本项目中，我们利用PD AC临床标本研究PPDPF的表达与临床病理特征之间的关系；应用细胞模型和PDAC动物模型研究PPDPF在PDAC发生中的功能；应用分子生物学技术研究PPDPF对Ras-ERK信号的调控机制。 我们的研究发现，PPDPF在胰腺癌中表达上调。虽然PPDPF的表达与肿瘤大小、转移等临床特征没有相关性，但是PPDPF的表达与胰腺癌病人的生存时间显著负相关。在生物学功能研究中，我们发现PPDPF表达下调抑制KrasG12D 诱导的细胞恶性转化，但是PPDPF表达下调对突变的p53驱动的细胞恶性转化没有显著影响。与此一致的是，在小鼠胰腺组织中敲除PPDPF的表达对小鼠体重和胰腺重量没有明显影响。但是，在胰腺癌模型KC小鼠中敲除PPDPF的表达抑制PanINs形成。在分子机制研究中，我们发现PPDPF与Kras相互作用，促进Ras的活化。综上所述，我们的研究揭示了PPDPF在胰腺癌中通过激活Ras-ERK 信号通路促进肿瘤进展，为PDAC的治疗提供靶点。