Role of phospholipase D in agonist-stimulated lysophosphatidic acid synthesis by ovarian cancer cells.
Lysophosphatidic acid (LPA) is a receptor-active lipid mediator with a broad range of biological effects. Ovarian cancer cells synthesize LPA, which promotes their motility, growth, and survival. We show that a murine homolog of a human protein previously reported to hydrolyze LPA is a highly selective detergent-stimulated LPA phosphatase that can be used to detect and quantitate LPA. Use of this protein in novel enzymatic assay demonstrates that SK-OV-3 ovarian cancer cells release physiologically relevant levels of biologically active LPA into the extracellular space. LPA release is markedly increased by nucleotide agonists acting through a P2Y4 purinergic receptor. Promotion of LPA formation by nucleotides is accompanied by stimulation of phospholipase D (PLD) activity. Overexpression of both PLD1 and PLD2 in SK-OV-3 cells produces active enzymes, but only overexpression of PLD2 results in significant amplification of both nucleotide-stimulated PLD activity and LPA production. SK-OV-3 cells express and secrete a phospholipase A2 activity that can generate LPA from the lipid product of PLD, phosphatidic acid. Our results identify a novel role for nucleotides in the regulation of ovarian cancer cells and suggest an indirect but critical function for PLD2 in agonist-stimulated LPA production.
Luquain
Celine
C
Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7090, USA.
Singh
Anurag
A
Wang
Lixin
L
Natarajan
Vishwanathan
V
Morris
Andrew J
AJ
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D005260:Female; D006801:Humans; D008246:Lysophospholipids / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000378:metabolism*; D010739:Phospholipase D / Q000378:metabolism* / Q000494:pharmacology; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D011956:Receptors, Cell Surface / Q000819:agonists*; D011983:Receptors, Purinergic / Q000378:metabolism; D048348:Reverse Transcription; D016415:Sequence Alignment; D013498:Suramin / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D008246:Lysophospholipids; D009711:Nucleotides; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D013498:Suramin; D000255:Adenosine Triphosphate; D010741:Phospholipases A; D054467:Phospholipases A2; D010739:Phospholipase D