Gemcitabine as a molecular targeting agent that blocks the Akt cascade in platinum-resistant ovarian cancer.
BACKGROUND
Gemcitabine (2', 2' -difluorodeoxycytidine) is one of many nonplatinum drugs that exhibit activity in recurrent, platinum-resistant ovarian cancer. However, the molecular mechanisms by which Gemcitabine treatment inhibits the proliferation of platinum-resistant ovarian cancer cells still remain unclear. We investigated whether Gemcitabine increases the efficacy of Cisplatin in platinum-resistant ovarian cancer models in vitro and in vivo.


METHODS
We used Cisplatin-resistant Caov-3 cells, A2780CP cells and Cisplatin-sensitive A2780 cells to examine the sensitivity of the cell viability of Cisplatin and Gemcitabine using a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and the sensitivity of the invasive activity of Cisplatin and Gemcitabine using an invasion assay with Matrigel. We examined the Akt kinase activity and matrix metalloproteinase 9 (MMP9) expression following Cisplatin and Gemcitabine treatment using a Western blot analysis and the mRNA expression of vascular endothelial growth factor (VEGF) using semi-quantitative RT-PCR. Moreover, we evaluated the effects of Cisplatin and Gemcitabine on the intra-abdominal dissemination of ovarian cancer in vivo.


RESULTS
Gemcitabine significantly inhibited Cisplatin-induced Akt activation in the Caov-3 and A2780CP cells, but not in the A2780 cells. In the presence of Gemcitabine, Cisplatin-induced growth inhibition and apoptosis were significantly enhanced in the Caov-3 and A2780CP cells. Co-treatment with Cisplatin and Gemcitabine almost completely inhibited invasion of both types of cells through the Matrigel; however, neither Cisplatin nor Gemcitabine alone inhibited the invasion of both types of cells. Gemcitabine inhibited not only the Cisplatin-induced activation of Akt, but also the MMP9 and mRNA expression of VEGF. Moreover, treatment with Gemcitabine increased the efficacy of Cisplatin-induced growth inhibition of the intra-abdominal dissemination and production of ascites in the athymic nude mice inoculated with Caov-3 cells.


CONCLUSIONS
We herein demonstrated that Gemcitabine inhibits the Akt kinase activity and angiogenetic activity following treatment with Cisplatin in platinum-resistant ovarian cancer cells. These results provide a rationale for using Gemcitabine in clinical regimens containing molecular targeting agents against platinum-resistant ovarian cancers.
Hiroshi
H
Kawaguchi
Yoshito
Y
Terai
Akiko
A
Tanabe
Hiroshi
H
Sasaki
Masaaki
M
Takai
Satoe
S
Fujiwara
Keisuke
K
Ashihara
Yoshimichi
Y
Tanaka
Tomohito
T
Tanaka
Satoshi
S
Tsunetoh
Masanori
M
Kanemura
Masahide
M
Ohmichi
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000494:pharmacology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004195:Disease Models, Animal; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D009362:Neoplasm Metastasis; D009389:Neovascularization, Pathologic / Q000188:drug therapy; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010984:Platinum / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays; D000093542:Gemcitabine
D000964:Antimetabolites, Antineoplastic; D042461:Vascular Endothelial Growth Factor A; D003841:Deoxycytidine; D010984:Platinum; D051057:Proto-Oncogene Proteins c-akt; D020780:Matrix Metalloproteinase 9; D002945:Cisplatin; D000093542:Gemcitabine