Epothilone B enhances surface EpCAM expression in ovarian cancer Hey cells.
OBJECTIVE
Epothilone B (EpoB), like Taxol, stabilizes microtubules resulting in an inhibition of microtubule dynamic instability. The drug is being evaluated in phase III clinical trials. An EpoB analog, Ixabepilone, was approved by the FDA for the treatment of taxane-resistant metastatic breast cancer. Epithelial cell adhesion antigen (EpCAM) expression is significantly higher in epithelial ovarian cancer cells compared to normal cells. The effects of EpoB and other microtubule-interacting agents on surface EpCAM expression were studied.


METHODS
Biochemical methods, immunofluorescence and flow cytometry were used to identify EpCAM expression on the surface of the ovarian cancer cell line, Hey, after exposure to EpoB. The relationship between EpoB-mediated surface EpCAM expression and EpoB-induced α-tubulin acetylation, a surrogate marker for stable microtubules, in Hey cells also was investigated.


RESULTS
Nanomolar concentrations of EpoB, Taxol, discodermolide or vinblastine caused a marked increase in surface EpCAM expression in Hey cells. Alpha-tubulin acetylation was increased following treatment with Taxol, EpoB and discodermolide, but not with vinblastine, indicating that drug-enhanced surface EpCAM expression does not correlate with tubulin acetylation or stabilization. Unexpectedly, EpoB did not have a significant effect on EpCAM mRNA expression, nor did it alter the level of total cellular EpCAM in Hey cells.


CONCLUSIONS
The results indicate that disruption of the microtubule cytoskeleton is associated with the redistribution of cell surface antigens in ovarian cancer cells. The increase in cell surface EpCAM antigen density may facilitate the antibody targeting of EpCAM-positive ovarian cancer cells.
Shahabi
Shohreh
S
Division of Gynecologic Oncology, Department of Obstetrics & Gynecology and Women's Health, Montefiore Medical Center Bronx, NY 10461, USA.
Yang
Chia-Ping Huang
CP
Goldberg
Gary L
GL
Horwitz
Susan Band
SB
D000107:Acetylation / Q000187:drug effects; D000473:Alkanes / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D002219:Carbamates / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D000071858:Epithelial Cell Adhesion Molecule; D034261:Epothilones / Q000494:pharmacology*; D005260:Female; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism; D050257:Tubulin Modulators / Q000494:pharmacology; D014747:Vinblastine / Q000494:pharmacology
D000473:Alkanes; D000951:Antigens, Neoplasm; D002219:Carbamates; D015815:Cell Adhesion Molecules; C499379:EPCAM protein, human; D000071858:Epithelial Cell Adhesion Molecule; D034261:Epothilones; D006877:Hydroxamic Acids; D007783:Lactones; D011753:Pyrones; D014404:Tubulin; D050257:Tubulin Modulators; C012589:trichostatin A; D014747:Vinblastine; C071229:discodermolide; D017239:Paclitaxel; C093788:epothilone B