Activation of the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase pathway overcomes cisplatin resistance in ovarian carcinoma cells.
OBJECTIVE
This study was aimed to elucidate the roles of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3'-kinase (PI3K)/Akt pathways in regulating cytotoxicity induced by cisplatin (CDDP) in ovarian carcinoma cells.


METHODS
We treated 7 ovarian cancer cell lines with CDDP alone or with CDDP and either a PI3K inhibitor (LY294002), a MEK inhibitor (PD98059), or a MEK/ERK activator (phorbol 12-myristate 13-acetate [PMA]) and assessed cell viability, expression of MEK/ERK and PI3K/Akt, cell cycle distribution, and apoptosis. We also investigated the effect of combination treatment on survival in a xenograft model.


RESULTS
The cell lines showed half-maximal inhibitory concentrations (IC50) of CDDP from 2.4 to 26.9 μmol/L. KFr, a CDDP-resistant cell line developed from KF cells, showed an IC50 of CDDP of 9.6 μmol/L. Five of the cell lines with IC50 values of 9.6 μmol/L or greater were defined as CDDP-resistant. Cisplatin and LY294002 had an additive effect on inhibiting cell growth, and CDDP and PD98059 had and antagonistic effect on cell growth in all cell lines. In CDDP-resistant cells, CDDP and PMA dramatically suppressed the cell growth, up-regulated the expression of phosphorylated ERK and cleaved caspase-9, down-regulated the expression of checkpoint kinases, and increased the proportion of cells in the synthesis-phase fraction and apoptotic cells. The treatment of nude mice with CDDP and PMA prolonged survival in an ovarian cancer xenograft model.


CONCLUSIONS
The present study indicates that further study is warranted to determine the effectiveness of combination treatment with CDDP and PMA for platinum-resistant ovarian carcinoma.
Department of Obstetrics and Gynecology, Tottori University Faculty of Medicine, Yonago, Japan.
Michiko
M
Nonaka
Hiroaki
H
Itamochi
Wakae
W
Kawaguchi
Akiko
A
Kudoh
Seiya
S
Sato
Kazunori
K
Uegaki
Jun
J
Naniwa
Shinya
S
Sato
Muneaki
M
Shimada
Tetsuro
T
Oishi
Naoki
N
Terakawa
Junzo
J
Kigawa
Tasuku
T
Harada
D000230:Adenocarcinoma / Q000188:drug therapy*; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology / Q000627:therapeutic use*; D002945:Cisplatin / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004357:Drug Synergism; D005260:Female; D005419:Flavonoids / Q000494:pharmacology / Q000627:therapeutic use*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D009025:Morpholines / Q000494:pharmacology / Q000627:therapeutic use*; D010051:Ovarian Neoplasms / Q000188:drug therapy*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016196:S Phase / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; D002867:Chromones; D005419:Flavonoids; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C016658:phorbolol myristate acetate; D020929:Mitogen-Activated Protein Kinase Kinases; D013755:Tetradecanoylphorbol Acetate; D002945:Cisplatin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one