Related Experiment Videos
VP-16-induced nucleotide pool changes and poly(ADP-ribose) synthesis: the role of VP-16 in interphase death
A Tanizawa1, M Kubota, H Hashimoto
1Department of Pediatrics, Kyoto University, Japan.
Abstract:
Exposure of human promyelocytic leukemia cell line (HL-60) to VP-16 resulted in accumulation of DNA strand breaks. Concomitantly, intracellular NAD levels fell at 1 h, followed by declines in ATP at 2 h and in GTP, CTP, and UTP at 3 h. Furthermore, marked morphological changes, such as loss of microvilli or bleb formation, appeared at 4 h and cell death by 8-10 h. The addition of an inhibitor of poly(ADP-ribose) polymerase, 3-aminobenzamide (5 mM), theophylline (2 mM), or thymidine (1 mM), prevented these sequential reductions of nucleotide pools and cell death. In fact, the activation of poly(ADP-ribose) synthesis was detectable within a few hours after treatment with VP-16, although it was smaller than that induced by N-methyl-N'-nitro-N-nitrosoguanidine. These results may suggest the possible role of activation of poly(ADP-ribosyl)ation in VP-16-induced nucleotide pool changes and subsequent interphase death.
Insights
VP-16 exposure causes DNA damage and nucleotide depletion in leukemia cells. Inhibiting poly(ADP-ribose) polymerase prevents these changes and cell death, suggesting its role in VP-16 toxicity.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- VP-16 (etoposide) is a chemotherapy drug known to induce DNA damage.
- Understanding the precise mechanisms of VP-16-induced cell death is crucial for optimizing cancer therapy.
Purpose of the Study:
- To investigate the sequential biochemical and morphological changes in HL-60 cells following VP-16 exposure.
- To determine the role of poly(ADP-ribose) polymerase activation in VP-16-induced cytotoxicity.
Main Methods:
- Exposure of human promyelocytic leukemia (HL-60) cells to VP-16.
- Monitoring of DNA strand breaks, intracellular nucleotide levels (NAD, ATP, GTP, CTP, UTP), and cell morphology.
- Assessment of poly(ADP-ribose) synthesis activation.
- Evaluation of the effects of poly(ADP-ribose) polymerase inhibitors (3-aminobenzamide, theophylline, thymidine) on VP-16 toxicity.
Main Results:
- VP-16 induced DNA strand breaks and subsequent depletion of intracellular nucleotide pools (NAD, ATP, GTP, CTP, UTP).
- Morphological changes indicative of cell death were observed.
- Inhibition of poly(ADP-ribose) polymerase prevented nucleotide depletion and cell death.
- VP-16 treatment led to the activation of poly(ADP-ribose) synthesis.
Conclusions:
- Activation of poly(ADP-ribose) polymerase plays a significant role in VP-16-induced nucleotide pool alterations.
- These nucleotide changes contribute to the interphase cell death observed after VP-16 treatment.
- Targeting poly(ADP-ribose) polymerase may offer a strategy to mitigate VP-16 toxicity.