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This Article Accepted manuscript (PDF) All Versions of this Article: ERC-09-0004v1 16/2/649    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Suzuki, J.-i. Articles by Oka, T. Search for Related Content PubMed PubMed Citation Articles by Suzuki, J.-i. Articles by Oka, T.

J Suzuki, Nishi-Tokyo, Japan
Y Murakami, Faculty of Pharmacy, Musashino university, Nishi-Tokyo, Japan
K Samejima, Faculty of Pharmacy, Musashino university, Nishi-Tokyo, Japan
K Kohda, Faculty of Pharmacy, Musashino university, Nishi-Tokyo, Japan
M Ohtani, Faculty of Pharmacy, Musashino university, Nishi-Tokyo, Japan
T Oka, Faculty of Pharmacy, Musashino university, Nishi-Tokyo, Japan

Correspondence: Takami Oka, Email: toka{at}musashino-u.ac.jp

Abstract

Human pancreatic tumor cell lines, AsPC-1, PANC-1, MIA paca2, KP-1 and KP-59 cells, can be induced to differentiate into pancreatic hormone-producing cells by brief trypsin treatment and the subsequent culture in a serum-free, chemically defined medium. During culture, AsPC-1 cells formed cell clusters resembling the pancreatic islets, expressed genes associated with the pancreatic development and produced glucagon but not insulin. When PANC-1, MIA paca2, KP-1 and KP-59 cells were treated and cultured the same way, they underwent similar morphological changes and produced insulin and glucagon. We used these systems to identify intracellular regulatory molecules involved in the conversion of pancreatic tumor cells into glucagon-producing cells. We found that the expression of antizyme 1, a negative regulator of ornithine decarboxylase, was increased and its localization was altered from the nucleus to the cytoplasm during AsPC-1 cell differentiation. Transient transfection of AsPC-1 cells with antizyme 1 siRNA resulted in inhibition of the morphological and functional cell differentiation as well as the specific suppression of antizyme 1 expression. In contrast, constitutive overexpression of antizyme 1 in AsPC-1 cells led to the enhancement of glucagon production. We also found that PANC-1 cells reduced the expression of glucagon mRNA when treated with antizyme 1 siRNA. These results suggested that antizyme 1 was necessary for conversion of pancreatic tumor cells into glucagon-producing cells. Glucagon production in AsPC-1 cells was not affected by addition of putrescine, suggesting that the polyamines were not directly involved in the antizyme 1-mediated convertion of pancreatic tumor cells to differentiated state.