Lysophosphatidic acid induction of vascular endothelial growth factor expression in human ovarian cancer cells.
BACKGROUND
Lysophosphatidic acid (LPA) stimulates ovarian tumor growth at concentrations present in ascitic fluid. Vascular endothelial growth factor (VEGF) stimulates angiogenesis and plays a pivotal role in the formation of ovarian cancer-associated ascites. We examined whether LPA promotes ovarian tumor growth by increasing angiogenesis via VEGF.


METHODS
VEGF expression was examined in a simian virus 40 T-antigen-immortalized ovarian surface epithelial cell line (IOSE-29) and in ovarian cancer cell lines (OVCAR-3, SKOV-3, and CAOV-3) treated with LPA. VEGF promoter activity was measured in OVCAR-3 cells after transfection or cotransfection with c-Fos and c-Jun, components of AP1 transcription factor, potential binding sites for which are present in the VEGF promoter. The expression of the LPA receptors Edg2 and Edg4 was also assessed. All statistical tests were two-sided.


RESULTS
LPA treatment increased steady-state VEGF messenger RNA (mRNA) levels in OVCAR-3 cells in a time- and dose-dependent fashion and stimulated VEGF promoter activity without prolonging mRNA half-life in these cells, but LPA had little effect on IOSE-29 cells. Forced overexpression of c-Jun and c-Fos in OVCAR-3 cells stimulated VEGF promoter activity fourfold. LPA also elevated VEGF protein levels by 1.5-fold in SKOV-3 cells (P =.0148), 1.9-fold in CAOV-3 cells (P<.001), and threefold in OVCAR-3 cells (P<.0001). Both Edg2 and Edg4 were detected in ovarian cancer cells; however, only Edg2 was present in normal ovarian surface epithelial cells and IOSE-29 cells.


CONCLUSIONS
LPA stimulates ovarian tumor growth, at least in part, via induction of VEGF expression through transcriptional activation. However, this LPA response is not evident in normal ovarian surface epithelial cells. Our data suggest that Edg4, but not Edg2, plays a role in LPA stimulation of ovarian tumor growth.
Hu
Y L
YL
Center for Reproductive Sciences, University of California, San Francisco, USA.
Tee
M K
MK
Goetzl
E J
EJ
Auersperg
N
N
Mills
G B
GB
Ferrara
N
N
Jaffe
R B
RB
D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D001665:Binding Sites; D015152:Blotting, Northern; D002460:Cell Line; D002461:Cell Line, Transformed; D017077:Culture Media, Conditioned / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016228:Endothelial Growth Factors / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D017353:Gene Deletion; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008222:Lymphokines / Q000096:biosynthesis*; D008246:Lysophospholipids / Q000494:pharmacology*; D010051:Ovarian Neoplasms / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000903:Antibiotics, Antineoplastic; D017077:Culture Media, Conditioned; D016228:Endothelial Growth Factors; D008222:Lymphokines; D008246:Lysophospholipids; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049368:Receptors, Lysophosphatidic Acid; D011993:Recombinant Fusion Proteins; D018808:Transcription Factor AP-1; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D003609:Dactinomycin; D008156:Luciferases