Translocation of lysophosphatidic acid phosphatase in response to gonadotropin-releasing hormone to the plasma membrane in ovarian cancer cell.
OBJECTIVE
Lysophosphatidic acid mediates proliferative and/or morphologic effects on multiple cell lineages, which include ovarian cancer cells. Lysophosphatidic acid hydrolysis limits the duration of lysophosphatidic acid's action. We examined hormonal translocation of lipid phosphate phosphatase type 3 to the plasma membrane in gonadotropin-releasing hormone-responsive ovarian cancers.


METHODS
Ovarian cancers that were removed surgically and the ovarian cancer cell lines Caov-3 and SK-OV-3 were examined. Lipid phosphate phosphatase type 3 protein and activity in plasma membranes were assessed by immunohistochemical staining with lipid phosphate phosphatase type 3-specific antibodies and by the measurement of the conversion of exogenous [(3)H-oleoyl]lysophosphatidic acid to mono[(3)H-oleoyl]glycerol, respectively.


RESULTS
In ovarian cancers that were removed surgically, the cell surface staining and activity measurements indicated that a portion of the enzyme was localized to the plasma membrane. In Caov-3 cells and SK-OV-3 cells, lipid phosphate phosphatase type 3 protein was present both in the cytoplasm and at the plasma membrane. Treatment of the cells with a gonadotropin-releasing hormone agonist buserelin produced a rapid and progressive translocation of lipid phosphate phosphatase type 3 protein to the plasma membrane, with a concomitant loss of cytoplasmic staining. The enzyme activity in plasma membrane was also increased when the cell lines were exposed to the gonadotropin-releasing hormone agonist in intact cells before the assay of the cell membranes.


CONCLUSIONS
These findings support the presence of lipid phosphate phosphatase type 3 in plasma membrane of ovarian cancers and provide for the ability of agonists (such as gonadotropin-releasing hormone) to induce the translocation of lipid phosphate phosphatase type 3 to plasma membrane in ovarian cancer cells.
Department of Obstetrics and Gynecology, Gifu University School of Medicine, Tsukasamachi, Japan.
Wen-Shu
WS
Sun
Atsushi
A
Imai
Michiyo
M
Sugiyama
Tatsuro
T
Furui
Teruhiko
T
Tamaya
Masanao
M
Saio
Andrew J
AJ
Morris
D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000201:enzymology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007150:Immunohistochemistry; D010051:Ovarian Neoplasms / Q000201:enzymology*; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics*; D014178:Translocation, Genetic
D007987:Gonadotropin-Releasing Hormone; C076020:lysophosphatidic acid phosphatase; D010744:Phosphoric Monoester Hydrolases