Hypoxia up-regulates the effects of prostaglandin E2 on tumor angiogenesis in ovarian cancer cells.
OBJECTIVE
Emerging evidence supports a role for prostaglandins (PG) and their synthesizing enzyme, cyclooxygenase (COX), in tumor angiogenesis. The objective of this study was to investigate the effects of prostaglandin E(2) (PGE(2)) on the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible transcription factor-1 alpha (HIF-1alpha) genes in epithelial ovarian cancer (EOC) cells.


METHODS
Two human EOC cell lines, MDAH-2774 and SKOV-3, were treated with exogenous dimethyl prostaglandin E(2) (dmPGE(2)) at two doses of 10 and 50 microg/ml and cultured for 24 h under both normoxic and hypoxic conditions. Total RNA was extracted from EOC cells with the use of a monophasic solution of phenol and GITC/Trizol method. The levels of COX-2, VEGF, and HIF-1alpha mRNA were measured by quantitative reverse transcription PCR (RT-PCR).


RESULTS
Under normoxic conditions, treatment of both ovarian cancer cell lines with dmPGE(2) resulted in a significant increase in VEGF expression but had no effect on HIF-1alpha. Culturing the cells under hypoxic conditions resulted in an increase in HIF-1alpha and VEGF mRNAs. The combination of hypoxia and dmPGE(2) treatment resulted in the highest levels of VEGF and HIF-1alpha when compared to either individual treatment.


CONCLUSIONS
PGE(2) is a potent stimulator of VEGF expression in ovarian cancer cells. This effect of PG is further potentiated under hypoxic conditions where it is also associated with a significant increase in HIF-1alpha expression.
Division of Reproductive Endocrinology, Department of Obstetrics and Gynecology, Wayne State University, 4160 John R, Detroit, MI 48201, USA.
Genhai
G
Zhu
Ghassan M
GM
Saed
Gunter
G
Deppe
Michael P
MP
Diamond
Adnan R
AR
Munkarah
D015064:16,16-Dimethylprostaglandin E2 / Q000494:pharmacology*; D015687:Cell Hypoxia / Q000502:physiology; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000098:blood supply* / Q000235:genetics / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015064:16,16-Dimethylprostaglandin E2