Additive growth inhibition after combined treatment of 2-methoxyestradiol and conventional chemotherapeutic agents in human pancreatic cancer cells.
OBJECTIVE
Most chemotherapeutic regimens for pancreatic cancer (PC) use combination therapy. 2-Methoxyestradiol (2-ME2) is a natural estrogen metabolite with proven tumor-inhibiting effect as a single agent. The aim of this study was to determine whether a combination of 2-ME2 with other established chemotherapeutic compounds increases its tumor-inhibiting effect on human PC cells.


METHODS
The human PC cell lines AsPC-1 and MiaPaCa-2 were treated with 2-ME2 alone or in combination with different doses of gemcitabine, cisplatin, cetuximab, 5-fluorouracil and paclitaxel in vitro (range: 0.5-5 μM). FACS analysis and nuclear staining were used to reveal apoptotic cells and cell-cycle changes after treatment. Subsequent in vivo experiments were performed on a subcutaneous tumor model in nude mice using AsPC-1 cells.


RESULTS
A tumor-reductive effect of 2-ME2 was found in both human PC cell lines. The combination of 2-ME2 with other agents resulted in additive growth inhibition of both cell lines through the induction of apoptosis and cell-cycle arrest. The growth inhibition was confirmed in vivo. After 32 days' treatment, gemcitabine alone showed no effect on tumor growth at a dose of 75 mg/kg body-weight. However, 2-ME2 at a daily dose of 2 mg per animal led to a growth inhibition of 63% with no evident toxicity. The combination of 2-ME2 and gemcitabine caused a growth-inhibition of 83%. Major toxicity was observed in the combination group, with six deaths out of eight animals in this group.


CONCLUSIONS
2-ME2 can be successfully combined with other chemotherapeutic agents. However, toxicity in the in vivo experiment is strong and requires further investigation.
Department of Gynecology, Charite, Universitatsmedizin Berlin, 13353 Berlin, Germany.
Christina
C
Fotopoulou
Daniel
D
Baumunk
Sven C
SC
Schmidt
Guido
G
Schumacher
D000077584:2-Methoxyestradiol; D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D000068818:Cetuximab; D002945:Cisplatin / Q000008:administration & dosage; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D004357:Drug Synergism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005472:Fluorouracil / Q000008:administration & dosage; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D017239:Paclitaxel / Q000008:administration & dosage; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D050257:Tubulin Modulators / Q000627:therapeutic use*; D000093542:Gemcitabine
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D050257:Tubulin Modulators; D003841:Deoxycytidine; D004958:Estradiol; D000077584:2-Methoxyestradiol; D017239:Paclitaxel; D000068818:Cetuximab; D002945:Cisplatin; D005472:Fluorouracil; D000093542:Gemcitabine