S1P regulation of ovarian carcinoma invasiveness.
OBJECTIVE
Within the tumor microenvironment the invasiveness of epithelial ovarian carcinoma (EOC) cells is stimulated by biologically active lipids such as lysophosphatidic acid (LPA). We tested the in vitro effect of another bioactive lysophospholipid, sphingosine-1-phosphate (S1P), on the invasiveness of EOC cells.


METHODS
Dov13 EOC cells were tested for invasion through matrigel-coated chambers and for gelatinase activity using a fluorogenic assay. cDNA was analyzed through real-time PCR. Cell surface proteins, isolated through biotinylation and affinity purification, were analyzed by Western blots.


RESULTS
Invasion of Dov13 cells was enhanced by low (0.5 microM) and inhibited by high (20 microM) concentrations of S1P, which correlated with increased and reduced gelatinase activity in conditioned media. Low and high S1P dose also differently affected the presentation of surface S1P receptors; low S1P dose increased S1P1 and decreased S1P2, while high S1P increased S1P3. LPA and S1P differently altered transcript levels of their respective and reciprocal receptors; receptors that were upregulated by one lysophospholipid (S1P2,3 and LPA1 by LPA, LPA3,4 and S1P1,4,5 by S1P) were downregulated or unchanged by the other.


CONCLUSIONS
The dual effect of high and low S1P concentration on invasion was probably caused by the diverse changes to the presentation of surface S1P receptors. The opposite effect of S1P and LPA on expression of each receptor suggests a homeostatic transcriptional mechanism that abrogates the effects of LPA and S1P on EOC cells. Altogether this study demonstrates a complex role of S1P in EOC cell invasion, a process highly balanced and regulated by LPA and S1P within the tumor microenvironment.
Smicun
Yoel
Y
Department of Obstetrics and Gynecology, New York University School of Medicine, 550 First Avenue, NB-9N28, New York, NY 10016, USA.
Reierstad
Scott
S
Wang
Feng-Qiang
FQ
Lee
Cathy
C
Fishman
David A
DA
D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008246:Lysophospholipids / Q000494:pharmacology*; D009361:Neoplasm Invasiveness; D009375:Neoplasms, Glandular and Epithelial / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000473:pathology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects
D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D013110:Sphingosine