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Estrogen mustard induces cell cycle arrest of human epithelial ovarian cancer cell lines
J D Nathan1, D L Keefe, M A Weinstein
1Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510-8063, USA.
Objective:
Pharmacologic disruption of microtubule function may provide effective therapy for advanced epithelial ovarian cancer, as has been observed in clinical trials using taxol. However, the limited availability of taxol and taxol's side effects emphasize a need to develop alternative antimicrotubule agents. Estramustine (EM) inhibits binding of microtubule-associated proteins (MAPs) to microtubules, promotes microtubule disassembly, disrupts spindle formation, and induces metaphase arrest in human prostate carcinoma and glioma cells in culture. We studied the effect of EM on DNA synthesis and on the cell cycle in four human ovarian carcinoma cell lines and examined the cell lines for evidence of MAP-like immunoreactivity.
Methods:
The effect of EM on DNA synthesis and on the cell cycle was determined using [3H]thymidine incorporation assays and flow cytometry, respectively. Microtubule-associated protein-like immunoreactivity was determined using monoclonal antibodies directed against MAP 1A, MAP 1B, and MAP 2(2A + 2B) for Western analysis after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Results:
We demonstrated a dose-dependent inhibitory response to EM in BIXLER, DK2NMA, and SKOV3. BIX3 showed a dose-dependent inhibitory response to EM concentrations from 25 micrograms/mL to 100 micrograms/mL, but a stimulatory response at 10 micrograms/mL. Estramustine inhibited exponentially growing cells by causing mitotic arrest with subsequent accumulation of cells in G2/M phase of the cell cycle in all four cell lines. We found MAP 1A, MAP 1B, and MAP 2-like immunoreactivity in all four cells lines studied.
Conclusions:
These results are consistent with a MAP-microtubule mechanism of action for EM in ovarian carcinoma cells and provide reason to conduct further study of EM for potential use in the treatment of human epithelial ovarian cancer.
Insights
Estramustine (EM) effectively inhibits ovarian cancer cell growth by disrupting microtubule function and causing cell cycle arrest. This study supports further investigation of EM as a potential treatment for epithelial ovarian cancer.
Area of Science:
- Oncology
- Cell Biology
- Pharmacology
Background:
- Microtubule disruption is a promising therapeutic strategy for advanced epithelial ovarian cancer, as demonstrated by taxol.
- Limited taxol availability and side effects necessitate the development of alternative antimicrotubule agents.
- Estramustine (EM) is known to inhibit microtubule-associated protein (MAP) binding, promote microtubule disassembly, and induce cell cycle arrest in other cancer types.
Purpose of the Study:
- To investigate the effects of Estramustine (EM) on DNA synthesis and cell cycle progression in human ovarian carcinoma cell lines.
- To examine ovarian carcinoma cell lines for the presence of MAP-like immunoreactivity.
Main Methods:
- DNA synthesis was assessed using [3H]thymidine incorporation assays.
- Cell cycle analysis was performed using flow cytometry.
- MAP-like immunoreactivity was determined via Western analysis using monoclonal antibodies against MAP 1A, MAP 1B, and MAP 2(2A + 2B).
Main Results:
- Estramustine (EM) exhibited a dose-dependent inhibitory effect on three of the four ovarian cancer cell lines (BIXLER, DK2NMA, SKOV3).
- EM induced mitotic arrest and subsequent accumulation of cells in the G2/M phase of the cell cycle across all four cell lines.
- MAP 1A, MAP 1B, and MAP 2-like immunoreactivity were detected in all four studied ovarian cancer cell lines.
Conclusions:
- The findings suggest that Estramustine (EM) acts via a MAP-microtubule mechanism in ovarian carcinoma cells.
- Estramustine (EM) shows potential as a therapeutic agent for human epithelial ovarian cancer.
- Further research into Estramustine (EM) for ovarian cancer treatment is warranted.