TY - JOUR

T1 - Induction of apoptotic cell death by putrescine

AU - Takao, Koichi

AU - Rickhag, Karl Mattias

AU - Hegardt, Cecilia

AU - Oredsson, Stina

AU - Persson, Lo

PY - 2006

Y1 - 2006

N2 - The polyamines are essential for cellular growth and differentiation. Ornithine decarboxylase (ODC), which catalyses the first step in the biosynthesis of the polyamines, has a very fast turnover and is subject to a strong feedback control by the polyamines. In the present study, we show that overexpression of a metabolically stable ODC in CHO cells induced a massive cell death unless the cells were grown in the presence of the ODC inhibitor alpha-difluoromethylornithine (DFMO). Cells overexpressing wild-type (unstable) ODC, on the other hand, were not dependent on the presence of DFMO for their growth. The induction of cell death was correlated with a dramatic increase in cellular putrescine levels. Analysis using flow cytometry revealed perturbed cell cycle kinetics, with a large accumulation of cells with sub-G1 amounts of DNA, which is a typical sign of apoptosis. Another strong indication of apoptosis was the finding that one of the key enzymes in the apoptotic process, caspase-3, was induced when DFMO was omitted from the growth medium. Furthermore, inhibition of the caspase activity significantly reduced the recruitment of cells to the sub-G1 fraction. In conclusion, deregulation of polyamine homeostasis may negatively affect cell proliferation and eventually lead to cell death by apoptosis if putrescine levels become too high.

AB - The polyamines are essential for cellular growth and differentiation. Ornithine decarboxylase (ODC), which catalyses the first step in the biosynthesis of the polyamines, has a very fast turnover and is subject to a strong feedback control by the polyamines. In the present study, we show that overexpression of a metabolically stable ODC in CHO cells induced a massive cell death unless the cells were grown in the presence of the ODC inhibitor alpha-difluoromethylornithine (DFMO). Cells overexpressing wild-type (unstable) ODC, on the other hand, were not dependent on the presence of DFMO for their growth. The induction of cell death was correlated with a dramatic increase in cellular putrescine levels. Analysis using flow cytometry revealed perturbed cell cycle kinetics, with a large accumulation of cells with sub-G1 amounts of DNA, which is a typical sign of apoptosis. Another strong indication of apoptosis was the finding that one of the key enzymes in the apoptotic process, caspase-3, was induced when DFMO was omitted from the growth medium. Furthermore, inhibition of the caspase activity significantly reduced the recruitment of cells to the sub-G1 fraction. In conclusion, deregulation of polyamine homeostasis may negatively affect cell proliferation and eventually lead to cell death by apoptosis if putrescine levels become too high.

KW - Animals

KW - Apoptosis

KW - CHO Cells

KW - Caspase 3

KW - Caspases

KW - Cell Differentiation

KW - Cell Proliferation

KW - Cricetinae

KW - Cricetulus

KW - Eflornithine

KW - Enzyme Inhibitors

KW - G1 Phase

KW - Ornithine Decarboxylase

KW - Ornithine Decarboxylase Inhibitors

KW - Putrescine

U2 - 10.1016/j.biocel.2005.10.020

DO - 10.1016/j.biocel.2005.10.020

M3 - Journal article

C2 - 16406751

VL - 38

SP - 621

EP - 628

JO - International Journal of Biochemistry & Cell Biology

JF - International Journal of Biochemistry & Cell Biology

SN - 1357-2725

IS - 4

ER -