Normal Cellular Prion Protein in Pancreatic Cancer

正常细胞蛋白(Prpc)是一种GPI锚定的膜蛋白，存在于许多 单元类型。而PrPC的表达在一组致命的神经退行性变中起关键作用 PrPC的正常功能仍然是一个谜。我们 在一组人类肿瘤细胞系中筛选PrPC表达，发现人类 胰腺肿瘤细胞株持续表达高水平的PrPC并产生大量的 PrPC在他们的培养上清液中。这些发现促使我们调查PrPC是否在运行 在人胰腺导管腺癌组织中的调节作用 用抗PrPC单抗进行免疫组织化学染色。纸巾来自 患有慢性胰腺炎和癌前状态的患者，如胰腺上皮内 肿瘤(Panin-1、2、3)作为对照。在正常导管细胞中未检测到PrPC，在 慢性胰腺炎，在Panin-1或Panin-2组织中。仅有4例(14%)Panin-3表达 PrPC水平低。PrPC在41%的泛ADC中表达上调。此外， PrPC的表达与预后不良有关。癌组织中PrPC蛋白的表达 与1,000天相比，患者的中位生存时间为360天要短得多 不表达PrPC(P&lt；0.001)。此外，siRNA下调PrPC的表达 PAN-DAC细胞株BXPC-3抑制BxPC-3细胞的增殖。这些结果表明， PrPC的表达可能在人泛发性DAC的发生中起重要作用。这一假设是 由使用转基因小鼠品系的研究支持，该品系具有激活的K-ras，但已被删除 TGFa受体2在胰腺特异性启动子Ptfia的控制下(Ptf1/+；K-RasG12D/+； Tgfbr2FLOX/FLOX)。这个转基因小鼠产生了泛ADC，其特征使人联想到人类 泛DAC。PrPC在PAN-DAC中表达，但在导管细胞、PAN-IN组织和 该转基因小鼠系中的正常胰腺导管细胞。我们假设PrPC参与了 在泛ADCs亚群的致癌过程中，无论是通过其配体受体激活还是通过 功能失调的细胞凋亡级联反应。我们提出了三个特定的目标，使用体外细胞模型， 转基因动物模型和额外的人体组织进一步研究PrPC所起的作用 在人类泛-DAC的起源中。这些研究的结果将为我们提供对 发病机制，并可能确定新的靶点，为治疗干预这种致命的 疾病。 项目叙事 胰腺导管腺癌是世界上导致死亡的第四大癌症。 美国每年有超过30,000人死亡。所有泛美儿童的总体中位数存活率 DAC为6个月，5年生存率不到10%。目前，潜在的 导致泛发性发作性胆囊炎的机制仍然知之甚少。我们发现一个子集(41%) 人泛-DAC增加了正常细胞内PrPC和PrPC的表达 发现PrPC表达的这种增加与不良的临床结果有关 (宝洁0.001)。我们还发现，表达更多PrPC的人泛DAC细胞株具有更高的 体外增殖率。此外，在一个转基因的泛DAC小鼠模型中，我们发现 PrPC在肿瘤中也表达上调，但在癌前病变中不表达。因此，我们的 在体外细胞模型和动物模型中总结了在人类泛型DAC中的发现。我们 建议利用体外细胞进一步研究PrPC在泛-DAC发育中的作用 模型、额外的患者组织和转基因小鼠模型。这些研究的结果将 为人类泛DAC的发病机制提供新的见解，并可能确定新的靶点 对这种致命疾病进行治疗干预。

The normal cellular prion protein (PrPC) is a GPI-anchored membrane protein present on many cell types. While the expression of PrPC is critical for a group of fatal neurodegenerative conditions, known as prion diseases, the normal functions of PrPC remain an enigma. We screened for PrPC expression in a panel of human tumor cell lines, and found that human pancreatic tumor cell lines consistently express high levels of PrPC and produce high amounts of PrPC in their culture supernatants. These findings lead us to investigate whether PrPC is up regulated in human pancreatic ductal adenocarcinoma (Pan-DAC) tissues by immunohistochemical staining with anti-PrPC monoclonal antibodies (Mabs). Tissues from patients with chronic pancreatitis and pre-cancerous conditions, such as pancreatic intraepithelial neoplasia (PanIN-1, 2, 3) were included as controls. PrPC is not detected in normal ductal cells, in chronic pancreatitis, in PanIN-1 or in PanIN-2 tissues. Only four cases (14%) of PanIN-3 express low levels of PrPC. PrPC expression is uniquely up regulated in 41% of Pan-ADCs. Furthermore, PrPC expression is associated with poorer prognosis. Patients with PrPC expression in carcinoma had a much shorter median survival time of 360 days compared to >1,000 days for patients without PrPC expression (P<0.001). In addition, siRNA down regulation of PrPC expression in a Pan-DAC cell line, BXPC-3 reduces the proliferation of BxPC-3 cells. These results suggest that PrPC expression may be important in the genesis of human Pan-DAC. This hypothesis was supported by studies using a transgenic mouse line, which had an activated K-ras, with deleted TGFa receptor 2, under the control of a pancreatic specific promoter, Ptfia, (Ptf1acre/+; K-rasG12D/+; Tgfbr2flox/flox). This transgenic mouse line develops Pan-ADC with features reminiscent of human Pan-DAC. PrPC expression was detected in Pan-DAC but not in ductal cells, Pan-IN tissues or normal pancreatic ductal cells in this transgenic mouse line. We hypothesize that PrPC is involved in carcinogenesis of a subgroup of Pan-ADCs, either through its ligand-receptor activation or dysfunctional apoptosis cascade. We proposed three specific aims, using in vitro cell models, transgenic animal models and additional human tissues to further investigate the role PrPC plays in the genesis of human Pan-DAC. Results from these studies will provide new insights into the pathogenesis and may also identify new targets for therapeutic intervention of this deadly disease. Project Narrative Pancreatic ductal adenocarcinoma (Pan-DAC) is the fourth leading cancer causing deaths in the United States with more than 30,000 deaths per year. The overall median survival for all Pan- DAC is 6 months and the 5-year survival rate is less than 10%. At present, the underlying mechanisms that cause Pan-DAC are still poorly understood. We found that a subset (41%) of human Pan-DAC has increased expression of the normal cellular prion protein, PrPC, and identified that such an increase in PrPC expression is associated with poor clinical outcome (P>0.001). We also found that human Pan-DAC cell lines that express more PrPC have a higher proliferative rate in vitro. In addition, in a transgenic mouse model of Pan-DAC, we found that PrPC is also up regulated in the tumors but not in the precancerous lesions. Therefore, our findings in human Pan-DAC are recapitulated in vitro in a cell model and in an animal model. We propose to further investigate the role PrPC plays in Pan-DAC development using in vitro cell models, additional patient tissues and a transgenic mouse model. Results from these studies will provide new insights into the pathogenesis of human Pan-DAC and may also identify new targets for therapeutic intervention of this deadly disease.