p38 Mitogen-activated protein kinases is required for counteraction of 2-methoxyestradiol to estradiol-stimulated cell proliferation and induction of apoptosis in ovarian carcinoma cells via phosphorylation Bcl-2.
BACKGROUND
2-Methoxyestradiol (2ME2), a natural endogenous product of estradiol (E2) metabolism, has been shown to be a selective apoptotic agent for cancer cells but not for normal cells. In this study, we determined that 2ME2 counteracts E2-stimulated cell growth and induces apoptosis in ovarian carcinoma cells. In addition, we demonstrate that 2ME2 induces apoptosis via p38 and phospho-Bcl2 pathway.


METHODS
2ME2 and/or E2 were administered to the OVCAR-3 (human ovarian cancer) cell line. Cell growth inhibition was analyzed by [3H] Thymidine incorporation assay and DNA fluorometric assay. Cell apoptosis was tested by DNA fragmentation analysis and FACS. The signaling pathway was determined by a series of biochemical assays.


RESULTS
2ME2 inhibited estradiol-stimulated cell growth and induced apoptosis in an ovarian carcinoma cell line. MAPK and p38, but not JNK, were found to be critical mediators in this process. Expression of a dominant negative mutant of p38 kinase or p38 specific inhibitor, SB 203580, almost completely blocked the process. Furthermore, Bcl-2 phosphorylation was required for 2ME2-induced effects.


CONCLUSIONS
Our data suggest that 2ME2 inhibits E2-stimulated proliferation and induces apoptosis in ovarian carcinoma cells. Furthermore, activation of p38 and phosphorylation of Bcl-2 plays a critical role in the mechanism. 2ME2 therefore, may have a clinical application for the treatment of ovarian cancer.
Bu
S Z
SZ
Department of Physiology, Basic Medicine College Second Military Medical University, Shanghai, PR China.
Huang
Q
Q
Jiang
Y M
YM
Min
H B
HB
Hou
Y
Y
Guo
Z Y
ZY
Wei
J F
JF
Wang
J W
JW
Ni
X
X
Zheng
S S
SS
D000077584:2-Methoxyestradiol; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D053938:DNA Fragmentation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D006801:Humans; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010053:Ovary / Q000166:cytology; D010766:Phosphorylation; D017354:Point Mutation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D050257:Tubulin Modulators / Q000378:metabolism / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D019253:Proto-Oncogene Proteins c-bcl-2; D050257:Tubulin Modulators; D004958:Estradiol; D000077584:2-Methoxyestradiol; D048051:p38 Mitogen-Activated Protein Kinases