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Evidence for a non-estrogenic cytostatic effect of estramustine on human prostatic carcinoma cells in vivo
Abstract:
Estramustine is one of the main metabolites of estramustine phosphate (EstracytR), a drug used in the treatment of advanced prostatic cancer. In the present study the hormone independent human prostatic carcinoma cell line DU 145 implanted subcutaneously in nude mice (NMRI) was used to investigate the mode of action of estramustine in vivo. Metaphase arrest was found in mice treated with estramustine intraperitoneally, 200 and 400 micrograms daily for 2 weeks, 5 days a week. A significant dose dependent decrease in the number of anaphase figures was found. A 7 to 8 fold increase in the number of abnormal metaphases, i.e., highly contracted and unaligned chromosomes, was found. Uptake and retention of 3H-estramustine was found in tumour tissue. No increase in the mitotic index or the number of abnormal metaphases was found in animals treated with polyestradiol phosphate (EstradurinR). This is the first time evidence has been presented demonstrating the anti-mitotic effect of estramustine in vivo.
Insights
Estramustine, a metabolite of estramustine phosphate, demonstrates an anti-mitotic effect in vivo. It causes metaphase arrest and abnormal chromosome structures in prostate cancer cells, indicating its mechanism of action.
Area of Science:
- Oncology
- Pharmacology
- Cell Biology
Background:
- Estramustine phosphate (EstracytR) is used for advanced prostate cancer.
- Estramustine is a key metabolite of estramustine phosphate.
- The in vivo mechanism of estramustine remains to be fully elucidated.
Purpose of the Study:
- To investigate the in vivo mode of action of estramustine.
- To assess the anti-mitotic effects of estramustine in a relevant cancer model.
Main Methods:
- Utilized hormone-independent human prostate carcinoma DU 145 cell line xenografts in nude mice.
- Administered estramustine intraperitoneally at doses of 200 and 400 micrograms daily for 2 weeks.
- Analyzed mitotic figures, including metaphase arrest and abnormal chromosome structures.
- Quantified uptake and retention of 3H-estramustine in tumor tissue.
- Compared effects with polyestradiol phosphate (EstradurinR).
Main Results:
- Estramustine treatment induced metaphase arrest in tumor cells.
- A dose-dependent decrease in anaphase figures was observed.
- A significant increase (7-8 fold) in abnormal metaphases (contracted, unaligned chromosomes) was noted.
- 3H-estramustine was detected in tumor tissue, confirming uptake and retention.
- Polyestradiol phosphate did not affect the mitotic index or abnormal metaphases.
Conclusions:
- This study provides the first in vivo evidence of estramustine's anti-mitotic activity.
- Estramustine disrupts mitosis by inducing metaphase arrest and chromosomal abnormalities.
- The findings support estramustine's role in the treatment of advanced prostate cancer through its cytotoxic effects on cancer cells.