Lysophosphatidic acid enhances epithelial ovarian carcinoma invasion through the increased expression of interleukin-8.
OBJECTIVE
We previously reported that lysophosphatidic acid (LPA) stimulates cellular invasion of ovarian cancer (OVCA) cells by enhancing membrane-type-1-matrix metalloproteinase (MT1-MMP)-mediated activation of MMP2. Here, we investigate a second mechanism in which LPA enhances cellular invasion through the increased expression of IL-8, independent of the expression or activation of MMP2.


METHODS
Epithelial ovarian carcinoma cells (DOV 13) were exposed to LPA (80 microM) and IL-8 (100 ng/ml) for 24 h. IL-8 expression was quantified by enzyme-linked immunosorbent assay (ELISA). Cellular invasion (Matrigel invasion), migration (colloidal gold), and urinary-type plasminogen activator (uPA) activity (colorimetric assay) were quantified. Conditioned medium was also assayed for MMP activation and expression by SDS-PAGE gelatin zymography, ELISA, and Western blotting. In addition, IL-8 neutralizing antibody and MMP inhibitors were employed.


RESULTS
Our results found LPA to increase IL-8 expression threefold. IL-8 did not affect cellular migration, MMP2 activation, or uPA expression. However, exposure to various concentrations of IL-8 increased cellular invasiveness. Using an IL-8 blocking antibody and various MMP inhibitors, we determined that the increase in invasion was IL-8-dependent, while independent of the activation of MMP2 or MMP9. We further determined IL-8 exposure increased the expression of matrilysin (MMP7). Cells exposed to LPA and IL-8 resulted in a synergistic effect on cellular invasion. Adding the IL-8 blocking antibody, slightly decreased cellular invasion, indicating LPA in part, increases cellular invasion through the increased expression of IL-8.


CONCLUSIONS
We have identified a separate mechanism of enhanced cellular invasion, which is independent of MMP2 activation and involves the increased expression of IL-8 and subsequent increased expression of MMP7.
So
John
J
Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, New York University School of Medicine, New York, NY 10016, USA.
Navari
Jason
J
Wang
Feng-Qiang
FQ
Fishman
David A
DA
D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008246:Lysophospholipids / Q000494:pharmacology*; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism; D061965:Matrix Metalloproteinase Inhibitors; D009361:Neoplasm Invasiveness; D010051:Ovarian Neoplasms / Q000201:enzymology / Q000276:immunology / Q000473:pathology*
D016209:Interleukin-8; D008246:Lysophospholipids; D061965:Matrix Metalloproteinase Inhibitors; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1; C032881:lysophosphatidic acid