Alkyllysophospholipid ET-18-OCH3 acts as an activator of protein kinase C in HL-60 cells.
HL-60 cells are very sensitive to the cytotoxic action of ether lipids. Several hypotheses have been proposed to explain this cytotoxicity. We investigated the influence of the alkylphospholipid ET-18-OCH3 on the activity of protein kinase C. HL-60 cells were incubated with ET-18-OCH3 at a concentration of 20 micrograms/ml for 4 h. After the incubation the membrane fraction of the HL-60 cells was isolated and the activity of protein kinase C was determined while it was still associated with the membrane, using the synthetic peptide substrate [Ser25]-protein kinase C (19-31) as a protein kinase C specific substrate. The activity of the membrane-bound protein kinase C was increased in HL-60 cells treated with ET-18-OCH3 compared to untreated HL-60 cells. The increase in protein kinase C activity was not a consequence of translocation and appeared to be additive to the effect of the phorbol ester 12-myristate 13-acetate. In contrast, solubilized protein kinase C from HL-60 cells could be inhibited or stimulated in vitro by ET-18-OCH3, dependent on the mode of addition of ET-18-OCH3 and phospholipids.
Department of Hematology, University Hospital, Utrecht, The Netherlands.
E C
EC
Heesbeen
L F
LF
Verdonck
S W
SW
Hermans
H G
HG
van Heugten
G E
GE
Staal
G
G
Rijksen
D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D008823:Micelles; D010742:Phospholipid Ethers / Q000737:chemistry / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D008823:Micelles; D010742:Phospholipid Ethers; C026659:edelfosine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate