title: Phorbol ester stimulates ethanolamine release from the metastatic basal prostate cancer cell line PC3 but not from prostate epithelial cell lines LNCaP and P4E6.
abstract: BACKGROUND
  Malignancy alters cellular complex lipid metabolism and membrane lipid composition and turnover. Here, we investigated whether tumorigenesis in cancer-derived prostate epithelial cell lines influences protein kinase C-linked turnover of ethanolamine phosphoglycerides (EtnPGs) and alters the pattern of ethanolamine (Etn) metabolites released to the medium.
  
  
  METHODS
  Prostate epithelial cell lines P4E6, LNCaP and PC3 were models of prostate cancer (PCa). PNT2C2 and PNT1A were models of benign prostate epithelia. Cellular EtnPGs were labelled with [1-(3)H]-Etn hydrochloride. PKC was activated with phorbol ester (TPA) and inhibited with Ro31-8220 and GF109203X. D609 was used to inhibit PLD (phospholipase D). [(3)H]-labelled Etn metabolites were resolved by ion-exchange chromatography. Sodium oleate and mastoparan were tested as activators of PLD2. Phospholipase D activity was measured by a transphosphatidylation reaction. Cells were treated with ionomycin to raise intracellular Ca(2+) levels.
  
  
  RESULTS
  Unstimulated cell lines release mainly Etn and glycerylphosphorylEtn (GPEtn) to the medium. Phorbol ester treatment over 3h increased Etn metabolite release from the metastatic PC3 cell line and the benign cell lines PNT2C2 and PNT1A but not from the tumour-derived cell lines P4E6 and LNCaP; this effect was blocked by Ro31-8220 and GF109203X as well as by D609, which inhibited PLD in a transphosphatidylation reaction. Only metastatic PC3 cells specifically upregulated Etn release in response to TPA treatment. Oleate and mastoparan increased GPEtn release from all cell lines at the expense of Etn. Ionomycin stimulated GPEtn release from benign PNT2C2 cells but not from cancer-derived cell lines P4E6 or PC3. Ethanolamine did not stimulate the proliferation of LNCaP or PC3 cell lines but decreased the uptake of choline (Cho).
  
  
  CONCLUSIONS
  Only the metastatic basal PC3 cell line specifically increased the release of Etn on TPA treatment most probably by PKC activation of PLD1 and increased turnover of EtnPGs. The phosphatidic acid formed will maintain a cancer phenotype through the regulation of mTOR. Ethanolamine released from cells may reduce Cho uptake, regulating the membrane PtdEtn:PtdCho ratio and influencing the action of PtdEtn-binding proteins such as RKIP and the anti-apoptotic hPEBP4. The work highlights a difference between LNCaP cells used as a model of androgen-dependent early stage PCa and androgen-independent PC3 cells used to model later refractory stage disease.
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, UK.
authors.forename: J
authors.initials: J
authors.lastname: Schmitt
authors.affiliation: 1] Department of Biology, University of York, York, YO10 5DD, UK [2] Yorkshire Cancer Research Laboratory, University of York, York YO10 5DD, UK.
authors.forename: A
authors.initials: A
authors.lastname: Noble
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, UK.
authors.forename: M
authors.initials: M
authors.lastname: Otsuka
authors.affiliation: 1] Department of Biology, University of York, York, YO10 5DD, UK [2] Yorkshire Cancer Research Laboratory, University of York, York YO10 5DD, UK.
authors.forename: P
authors.initials: P
authors.lastname: Berry
authors.affiliation: 1] Department of Biology, University of York, York, YO10 5DD, UK [2] Yorkshire Cancer Research Laboratory, University of York, York YO10 5DD, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Maitland
authors.affiliation: Department of Biology, University of York, York, YO10 5DD, UK.
authors.forename: M G
authors.initials: MG
authors.lastname: Rumsby
mesh_terms: D002460:Cell Line; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D019856:Ethanolamine / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D009362:Neoplasm Metastasis; D010455:Peptides / Q000494:pharmacology; D010739:Phospholipase D / Q000378:metabolism; D011467:Prostate / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014862:Wasp Venoms / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; D019856:Ethanolamine; C037500:mastoparan; D010739:Phospholipase D; D013755:Tetradecanoylphorbol Acetate