Abstract
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.
| Original language | English |
|---|---|
| Journal | International Journal of Biochemistry & Cell Biology |
| Volume | 38 |
| Issue number | 4 |
| Pages (from-to) | 621-8 |
| Number of pages | 8 |
| ISSN | 1357-2725 |
| DOIs | |
| Publication status | Published - 2006 |
Keywords
- Animals
- Apoptosis
- CHO Cells
- Caspase 3
- Caspases
- Cell Differentiation
- Cell Proliferation
- Cricetinae
- Cricetulus
- Eflornithine
- Enzyme Inhibitors
- G1 Phase
- Ornithine Decarboxylase
- Ornithine Decarboxylase Inhibitors
- Putrescine