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Induction of apoptosis in androgen-independent human prostate cancer cells undergoing thymineless death
N Kyprianou1, A K Bains, S C Jacobs
1Department of Surgery, University of Maryland Medical Center, Baltimore 21201.
Abstract:
Previous studies have demonstrated that androgen responsive human prostate cancer cells can be induced to undergo programmed cell death after androgen ablation. By contrast, androgen-independent human prostate cancer cells do not activate this apoptotic pathway in response to androgen ablation. In the present study, two androgen-independent human prostatic cell lines, PC-3 and DU-145, were used as in vitro model systems to investigate the possibility of induction of programmed cell death in response to non-androgen ablative cytotoxic drugs. Treatment of these cells with the fluorinated pyrimidines, 5-fluoro-2-deoxyuridine or trifluorothymidine, resulted in a significant decrease in cell viability, over a period of 96 hr of exposure to the drugs, as determined by the trypan blue exclusion assay. The characteristic DNA fragmentation into a nucleosomal ladder and induction of expression of specific apoptosis-related genes, such as TRPM-2/SGP-2, and TGF-beta 1, but not the growth-related genes, c-myc, c-fos, and p53, temporally correlated with activation of apoptotic cell death in both systems. Simultaneous treatment with exogenous thymidine completely abrogated the fluoropyrimidine-induced cytotoxic effect in both cell lines, as well as the nucleosomal fragmentation of DNA, indicating that this apoptotic process is due to the induction of "thymineless" state. These results suggest that androgen-independent human prostate cancer cells retain the ability to activate the apoptotic cascade, after treatment with cytotoxic drugs that induce a "thymineless" state.
Insights
Androgen-independent prostate cancer cells can be induced to undergo programmed cell death using cytotoxic drugs that create a "thymineless" state. This research shows a potential new therapeutic pathway for advanced prostate cancer.
Area of Science:
- Oncology
- Molecular Biology
- Cell Death Research
Background:
- Androgen-dependent prostate cancer cells undergo apoptosis upon androgen ablation.
- Androgen-independent prostate cancer cells typically resist apoptosis induced by androgen ablation.
Purpose of the Study:
- To investigate if androgen-independent prostate cancer cells can be induced to undergo programmed cell death (apoptosis) using non-androgen ablative cytotoxic drugs.
- To explore the mechanisms of drug-induced apoptosis in these resistant cell lines.
Main Methods:
- Utilized androgen-independent human prostate cancer cell lines (PC-3 and DU-145) in vitro.
- Treated cells with fluorinated pyrimidines (5-fluoro-2-deoxyuridine or trifluorothymidine).
- Assessed cell viability using trypan blue exclusion assay and analyzed DNA fragmentation and gene expression (TRPM-2/SGP-2, TGF-beta 1, c-myc, c-fos, p53).
Main Results:
- Fluoropyrimidine treatment significantly decreased cell viability in both cell lines over 96 hours.
- Characteristic DNA fragmentation and induction of apoptosis-related genes (TRPM-2/SGP-2, TGF-beta 1) were observed.
- Co-treatment with thymidine abolished the cytotoxic effects and DNA fragmentation, confirming a "thymineless" state mechanism.
Conclusions:
- Androgen-independent prostate cancer cells retain the capacity to activate the apoptotic cascade.
- Cytotoxic drugs inducing a "thymineless" state represent a viable strategy for inducing apoptosis in these resistant cancer cells.
- These findings suggest potential therapeutic avenues for advanced, androgen-independent prostate cancer.