2004 Fiscal Year Final Research Report Summary
Fundamental research on the treatment for pancreatic cancer based on developmental biology of the pancreas
| Project/Area Number |
15390395
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Digestive surgery
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
DOI Ryuichiro Kyoto University, Graduate School of Medicine, Lecturer, 医学研究科, 講師 (20301236)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIMOTO Koji Kyoto University, Graduate School of Medicine, Assistant Professor, 医学研究科, 助手 (70335280)
KAWAGUCHI Yoshiya Kyoto University, Graduate School of Medicine, Assistant Professor, 医学研究科, 助手 (60359792)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Pancreatic duodenal homeobox gene-1 / Pancreatic ductal carcinoma / Invasion / Insulin / Streptozocin |
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| Research Abstract |
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
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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
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