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Synthesis of procaspases-3 and -7 during apoptosis in prostate cancer cells
C Bowen1, H J Voeller, K Kikly
1Division of Hematology/Oncology, Department of Medicine, Lombardi Cancer Center, Georgetown University Medical Center, 3800 Reservoir Road, NW, Washington, District of Columbia 20007-2197, USA.
Abstract:
Cells differ in the time required to execute cell death after receipt of a death signal. One reason may be the requirement for de novo synthesis of components of the death pathway. TSU-Pr1 prostate cancer cells treated with okadaic acid demonstrated activation of caspase-3, PARP cleavage, and nuclear fragmentation by 24 h and apoptosis by 72 h. Levels of procaspase-3 and procaspase-7, the precursor molecules of two effector caspases, were not depleted during apoptosis. Levels of procaspase-3 and -7 mRNA increased steadily in TSU-Pr1 cells up to 72 h after exposure to okadaic acid. Nuclear run-off experiments showed that the increase in mRNA was not due to transcriptional activation of caspase-3 and -7 mRNA. Antisense caspase-3 and caspase-7 oligodeoxynucleotides caused a depletion of procaspases-3 and -7 and a delay in apoptosis of TSU-Pr1 cells. Caspase antisense oligodeoxynucleotides inhibited apoptosis to a similar extent as peptide inhibitors of cysteine proteases. Synthesis of procaspases-3 and -7 was necessary to sustain programmed cell death in TSU-Pr1 prostate cancer cells.
Insights
De novo synthesis of procaspase-3 and procaspase-7 is essential for programmed cell death in prostate cancer cells. Inhibiting this synthesis delays apoptosis, highlighting its critical role in cell death pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Cell death timing varies, potentially due to the need for new protein synthesis.
- Prostate cancer cells (TSU-Pr1) exhibit delayed apoptosis after okadaic acid treatment.
Purpose of the Study:
- To investigate the role of de novo synthesis of effector caspases in programmed cell death.
- To determine if procaspase-3 and procaspase-7 synthesis is required for apoptosis in TSU-Pr1 cells.
Main Methods:
- TSU-Pr1 cells treated with okadaic acid to induce apoptosis.
- Analysis of caspase-3, PARP cleavage, nuclear fragmentation, and caspase mRNA levels.
- Use of antisense oligodeoxynucleotides to inhibit procaspase synthesis.
Main Results:
- Okadaic acid induced apoptosis markers by 72 hours.
- Procaspase-3 and -7 mRNA levels increased, but not due to transcriptional activation.
- Antisense inhibition of procaspase synthesis delayed apoptosis.
Conclusions:
- De novo synthesis of procaspase-3 and procaspase-7 is necessary for sustained programmed cell death in prostate cancer.
- This synthesis is a critical factor in the timing of apoptosis execution.