Estrogen mustard induces cell cycle arrest of human epithelial ovarian cancer cell lines.
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.
Nathan
J D
JD
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510-8063, USA.
Keefe
D L
DL
Weinstein
M A
MA
Chen
Z
Z
Naftolin
F
F
D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D015153:Blotting, Western; D002277:Carcinoma / Q000188:drug therapy*; D002453:Cell Cycle / Q000187:drug effects*; D004273:DNA, Neoplasm / Q000096:biosynthesis*; D004961:Estramustine / Q000627:therapeutic use*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D008869:Microtubule-Associated Proteins / Q000032:analysis; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000473:pathology; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014407:Tumor Cells, Cultured
D018931:Antineoplastic Agents, Hormonal; D004273:DNA, Neoplasm; D008869:Microtubule-Associated Proteins; D014316:Tritium; D004961:Estramustine; D013936:Thymidine