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Treatment of cells with the polyamine analog N, N11-diethylnorspermine retards S phase progression within one cell
K Alm1, P S Berntsson, D L Kramer
1Department of Animal Physiology, Lund University, Sweden; Roswell Park Cancer Institute, Grace Cancer Drug Center, Buffalo, New York, USA. Kersti.Alm@zoofys.lu.se
Abstract:
When Chinese hamster ovary cells were seeded in the presence of the spermine analog N1,N11-diethylnorspermine (DENSPM), cell proliferation ceased; this was clearly apparent by cell counting 2 days after seeding the cells. However, 1 day after seeding there was a slight difference in cell number between control and DENSPM-treated cultures. To investigate the reason for this easily surpassed slight difference, we used a sensitive bromodeoxyuridine/flow cytometry method. Cell cycle kinetics were studied during the first cell cycle after seeding cells in the absence or presence of DENSPM. Our results show that DENSPM treatment did not affect the progression of the cells through G1 or the first G1/S transition that took place after seeding the cells. The first cell cycle effect was a delay in S phase as shown by an increase in the DNA synthesis time. The following G2/M transition was not affected by DENSPM treatment. DENSPM treatment inhibited the transient increases in putrescine, spermidine, and spermine pools that took place within 24 h after seeding. Thus, in conclusion, the first cell cycle phase affected by the inhibition of polyamine biosynthesis caused by DENSPM was the S phase. Prolongation of the other cell cycle phases occurred at later time points, and the G1 phase was affected before the G2/M phase.
Insights
The spermine analog N1,N11-diethylnorspermine (DENSPM) inhibits polyamine biosynthesis, delaying S phase progression in Chinese hamster ovary cells. This study reveals S phase as the first cell cycle phase impacted by DENSPM.
Area of Science:
- Cell Biology
- Biochemistry
- Molecular Biology
Background:
- Polyamine biosynthesis is crucial for cell proliferation.
- Spermine analogs can disrupt normal polyamine metabolism.
- Understanding polyamine analog effects on cell cycle is important.
Purpose of the Study:
- To investigate the cell cycle kinetics of Chinese hamster ovary cells treated with N1,N11-diethylnorspermine (DENSPM).
- To determine the specific cell cycle phase affected by DENSPM-induced inhibition of polyamine biosynthesis.
Main Methods:
- Cell counting to assess proliferation.
- Bromodeoxyuridine/flow cytometry to analyze cell cycle progression.
- Measurement of intracellular polyamine pools (putrescine, spermidine, spermine).
Main Results:
- DENSPM treatment inhibited cell proliferation, with effects apparent by day 2.
- DENSPM did not affect G1 progression or the G1/S transition.
- A delay in S phase, indicated by increased DNA synthesis time, was the first observed cell cycle effect.
- G2/M transition remained unaffected.
- DENSPM inhibited transient increases in putrescine, spermidine, and spermine pools within 24 hours.
Conclusions:
- The S phase is the first cell cycle phase affected by DENSPM-induced polyamine biosynthesis inhibition.
- G1 phase was affected before G2/M phase at later time points.
- DENSPM provides a tool to study the role of polyamines in cell cycle regulation.