Fundamental research on the treatment for pancreatic cancer based on developmental biology of the pancreas

胰腺十二指肠同源框基因-1(PDX-1)作为胰腺器官发生和成人胰岛β细胞功能维持的关键调节因子具有双重功能。PDX-1被认为是去分化细胞的标志，具有重新分化为几种类型胰腺细胞的能力。在本项目中，我们分析了PDX-1在人胰腺癌标本以及胰腺癌细胞系中的表达，并分析了PDX-1在胰腺癌细胞中强制表达的影响。此外，我们还分析了在肝再生条件下，PDX-1在链脲佐菌素(STZ)治疗的小鼠中强制表达对肝脏的可塑性。在胰腺癌中，PDX-1表达阳性的占43%，阴性的占57%。淋巴结转移(p=0.02)和组织学分级(p=0.04)与PDX-1的表达显著相关。PDX-1阳性患者的预后明显差于PDX-1阴性患者(p=0.02)。Imor…更确切地说，PDX-1是影响总存活率的独立变量(p=0.03)。胰腺癌细胞系未见PDX-1表达。Ad-PDX-1和Ad-LacZ感染的PANC-1细胞在细胞增殖和细胞形态上均无明显差异。然而，Ad-PDX-1感染的PANC-1细胞的迁移速度明显高于Ad-LacZ感染的PANC-1细胞。在小鼠实验中，免疫组织化学结果显示，Ad-PDX-1感染的小鼠肝细胞大部分呈PDX-1阳性表达。在未经治疗的小鼠中，很少有细胞表达胰岛素和其他激素。相反，胰岛素和生长抑素在STZ处理的小鼠中表达，并且在STZ+HX处理的小鼠中表达更多的细胞。STZ组和STZ+HX组小鼠的高血糖均得到改善。STZ组和STZ+HX组小鼠血清和肝提取液IRI均升高。STZ加HX治疗的小鼠肝脏胰岛素阳性面积大于未治疗和STZ治疗的小鼠。从目前的项目来看，PDX-1的重新表达可能代表着更具侵袭性的胰腺癌恢复到更去分化的状态，也可能是这些侵袭性癌症的一个重要的新的肿瘤标志物。我们观察到的PDX-1表达模式也强烈表明，特定的胚胎分化途径可能在胰腺癌的肿瘤进展中发挥作用。在该项目的后期，仅异位表达PDX-1可能不足以诱导肝脏中产生胰岛素的细胞。STZ诱导的高血糖加上部分肝切除导致糖尿病状态和肝再生，可能会刺激肝细胞转分化为胰岛素产生细胞。较少

Pancreatic duodenal homeobox gene-1 (pdx-1) has a dual task as a key regulator in pancreatic organogenesis and in functional maintenance of beta cells in adults. Pdx-1 is thought to be a marker of de-differentiated cells with the capacity to re-differentiate into several pancreatic cell types. In this project, we analyzed pdx-1 expression in human pancreatic cancer specimens, as well as pancreatic cancer cell lines, and also analyzed the effects of forced expression of pdx-1 in pancreatic cancer cells. In addition, we analyzed the plasticity of the liver by enforced expression of pdx-1 in streptozotocin(STZ)-treated mice under the condition of hepatic regeneration.Forty-three percent of pancreatic cancers were positive for pdx-1 expression and 57% were negative. Lymph node metastasis (p=0.02) and histological grade (p=0.04) were significantly correlated with pdx-1 expression. Patients with positive pdx-1 had a significantly worse prognosis than those with negative pdx-1 (p=0.02). Impor … More tantly, pdx-1 was an independent variable that affected overall survival (p=0.03). Pancreatic cancer cell lines showed no pdx-1 expression. There were no significant differences in cell proliferation or morphology between Ad-pdx-1 and Ad-lacZ infected Panc-1 cells. However, Ad-pdx-1 infected Panc-1 cells did show a significantly higher migration rate than Ad-lacZ infected Panc-1 cells. In experiments in mice, most hepatocytes of Ad-pdx-1 infected mice were positive for pdx-1 expression by immunohistochemistry. In non-treated mice, very few cells expressed insulin and other hormones. In contrast, insulin and somatostatin were expressed in STZ treated-mice, and the more cells expressed in STZ plus Hx-treated mice. Hyperglycemia was improved in STZ-treated mice and STZ plus Hx-treated mice. IRI of serum and liver extract was increased in STZ-treated mice and STZ plus Hx-treated mice. The insulin positive area of the liver in STZ plus Hx-treated mice was larger than that in non-treated and STZ-treated mice.From the current project, re-expression of pdx-1 may represent a return to a more de-differentiated state by more aggressive pancreatic cancers, and may also represent an important new tumor marker for these aggressive cancers. The pdx-1 expression pattern that we observed also strongly suggests that specific embryonic differentiation pathways may be active in tumor progression of pancreatic cancers. From the latter part of the project, ectopic pdx-1 expression alone may be insufficient to induce insulin-producing cells in the liver. STZ-induced hyperglycemia plus partial hepatectomy that leads to diabetic state and hepatic regeneration may stimulate the transdifferentiation of liver cells into insulin-producing cells. Less