[Impact of hypoxia on taxol-induced apoptosis in human ovarian cancer cell line A2780 and its mechanism].
OBJECTIVE
Hypoxia, a feature and important living microenvironment of solid tumors, might be related to drug-resistance of tumors. This study was to establish a hypoxic model of ovarian cancer cell line A2780, and to investigate impacts of hypoxia and hypoxia inducible factor-1alpha (HIF-1alpha) on Taxol-induced apoptosis in A2780 cells.


METHODS
Cobalt chloride (CoCl(2)), a chemical hypoxia inducer, was added in A2780 cells to develop a hypoxic model. A2780 cells were divided into 4 groups: group A (control), group B (normoxia plus Taxol), group C (hypoxia plus Taxol), and group D (hypoxia, Decoy plus Taxol). Decoy method was used to block the function of HIF-1alpha. Protein and mRNA levels of HIF-1alpha were detected by Western blot and reverse transcription-polymerase chain reaction (RT-PCR). Cell apoptosis was detected by TdT-mediated dUTP nick end labeling (TUNEL), and flow cytometry (FCM).


RESULTS
CoCl(2) evidently increased protein level of HIF-1alpha, but had no effect on mRNA level of HIF-1alpha. Decoy didn't affect its expression. TUNEL showed that apoptotic index (AI) was significantly higher in group B,and group D than in group C after treatment of Taxol [(41.1+/-25.6)%,and (35.2+/-21.7)% vs. (24.1+/-15.2)%, P < 0.05]. The apoptosis rates detected by FCM displayed the same tendency as TUNEL results did.


CONCLUSIONS
Hypoxia could weaken the effect of Taxol on inducing apoptosis of A2780 cells. HIF-1alpha might confer to resistance of cell apoptosis induced by Taxol.
Huang
Lei
L
Molecular Cancer Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, 430030, P. R. China.
Ao
Qi-Lin
QL
Li
Fang
F
Xing
Hui
H
Lu
Yun-Ping
YP
Ma
Ding
D
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D003035:Cobalt; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics; D010051:Ovarian Neoplasms / Q000378:metabolism / Q000473:pathology*; D017239:Paclitaxel / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
D000972:Antineoplastic Agents, Phytogenic; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D003035:Cobalt; C018021:cobaltous chloride; D017239:Paclitaxel