神经轴突外向生长因子PTN促进胰腺癌神经浸润的发生

The characteristics of pancreatic cancer perineural growth has become an important subject for the study of pancreatic carcinoma. Perineural invasion of pancreatic cancer is the result of the nerve interaction with the factors expressed by tumor cells. Pleiotrophin(PTN), a type of neurotrophic factor, and also known as the neurite growth-promoting factor. In previous experiments, we investigated PTN and its receptor(N-syndecan) protein levels in 38 patients with pancreatic cancer by immunohistochemistry, and analyzed for its correlation with clinicopathological features, perineural invasion, and prognosis. We found that high expression of PTN combined with N-syndecan may contribute to the highly perineural invasion and poor prognosis of pancreatic cancer; The reduction in PTN expression resulted in the inhibition of neurite outgrowth from DRG neurons. We concluded that high expression of PTN combined with N-syndecan may contribute to the increased perineural invasion and poor prognosis of pancreatic cancer..In further studies, the follows would be studied: 1. To construct the recombinant lentivirus shRNA-PTN specific to Ptn gene; 2. To detect the silencing effects of recombinant lentivirus shRNA-PTN on Ptn gene in pancreatic cancer cells in vitro; 3.To investigate the inhibition effects on neurites outgrowth of dorsal root ganglion neurons(DRGn) in vitro by using the recombinant lentivirus shRNA-PTN; 4. To set up a model of pancreatic cancer in situ in nude mice. By injecting shRNA-PTN stock, we can investigate the effects of the PTN gene and lentivirus construct shRNA-PTN on the neural invasion of pancreatic cancer in vivo.

胰腺癌神经浸润与肿瘤细胞表达的因子有关。神经轴突外向生长因子（PTN蛋白）为神经营养因子，PTN在不同人类肿瘤如乳腺癌、前列腺癌及胰腺癌中高表达，而神经浸润也正好容易发生在这些PTN阳性表达的恶性肿瘤。我们前期研究显示：PTN蛋白阳性表达的胰腺癌其受体N-syndecan的阳性表达也高，与神经浸润发生密切相关；我们通过共培养发现PTN蛋白能促进鼠背根神经节神经元神经突起的生长。我们认为：PTN蛋白通过与其受体的结合诱导神经轴突的生长以及神经元的移动，可能与胰腺癌神经浸润的形成密切相关。本实验应用RNA沉默技术，先构建Ptn基因慢病毒载体；通过体外检测干扰前后胰腺癌细胞中PTN, N-syndecan表达量，然后体外胰腺癌细胞与鼠背根神经节神经元共培养，观察神经元轴突生长及移动；再建立裸鼠原位胰腺癌神经浸润模型，通过构建好的慢病毒载体沉默Ptn基因,以明确PTN蛋白在胰腺癌神经浸润中的作用。

胰腺癌神经浸润与肿瘤细胞表达的因子有关。神经轴突外向生长因子（PTN蛋白）为神经营养因子，PTN在不同人类肿瘤如乳腺癌、前列腺癌及胰腺癌中高表达，而神经浸润也正好容易发生在这些PTN阳性表达的恶性肿瘤。我们前期研究显示：PTN蛋白阳性表达的胰腺癌其受体N-syndecan 的阳性表达也高，与神经浸润发生密切相关；我们通过共培养发现PTN蛋白能促进鼠背根神经节神经元神经突起的生长。我们认为：PTN蛋白通过与其受体的结合诱导神经轴突的生长以及神经元的移动，可能与胰腺癌神经浸润的形成密切相关。本实验应用RNA沉默技术，先构建Ptn基因慢病毒载体；通过体外检测干扰前后胰腺癌细胞中PTN,N-syndecan表达量，然后体外胰腺癌细胞与鼠背根神经节神经元共培养，观察神经元轴突生长及移动；再建立裸鼠原位胰腺癌神经浸润模型，通过构建好的慢病毒载体沉默Ptn基因,明确PTN蛋白在胰腺癌神经浸润中的作用。重要结果及科学意义：成功构建针对Ptn基因干扰效果最佳的慢病毒表达载体PLV-shRNA-PTN，构建的慢病毒表达载体PLV-shRNA-PTN体外能有效抑制Ptn基因的表达，可以作为下一步研究PTN与胰腺癌神经浸润关系的重要技术手段，抑制PTN蛋白能有效减少胎鼠DRGn神经突起的形成；原位胰腺癌造模成功后，胰腺癌生长较快，特别是两周以后生长更为迅速，处死后发现，大部分血性腹水形成，肝脏、腹膜、大网膜等多脏器转移灶形成，尤以肝脏最为明显；在裸鼠胰腺癌组织中，PTN蛋白高表达，在发生神经浸润的胰腺癌组织中，PTN蛋白和其受体N-syndecan的表达水平高于无神经浸润的胰腺癌组织；构建的慢病毒表达载体ShRNA-PTN能有效抑制Ptn基因的表达，PTN蛋白的减少能有效减少小鼠胰腺癌组织内神经浸润的形成。