Role of downstream metabolic processing of proinflammatory fatty acids by 5-lipoxygenase in HL-60 cell apoptosis.
BACKGROUND
Proinflammatory eicosanoids formed from arachidonic acid (AA) by lipoxygenase (LO) and cyclooxygenase (COX) pathways have been shown to inhibit apoptosis in certain cell types. This study determined whether inhibition of LO and COX increased apoptosis in AA-treated HL-60 cells in vitro.


METHODS
HL-60 cells were incubated with 50 micromol/L AA and an enzyme inhibitor (1-10 micromol/L) for COX, LO, 12-LO, and 5-LO for 12 hours. Flow cytometry was used to assess viability, apoptosis, and necrosis. Apoptosis was further assessed using terminal dUTP nick end-labeling and DNA fragmentation.


RESULTS
The highest concentration of LO inhibitors, but not COX inhibitors, decreased viability and increased apoptosis and necrosis in the presence of exogenous AA.


CONCLUSIONS
These results suggest that disruption of the metabolism of AA by LO, in particular 5-LO, decreases cell survival and increases apoptosis. Thus, downstream metabolic processing of AA by LO but not COX plays a critical role in the regulation of HL-60 cell apoptosis.
Gillis
Robert C
RC
Division of Trauma and Critical Care, Department of Surgery, Graduate School of Medicine, The University of Tennessee Medical Center, Knoxville, Tennessee 37920, USA.
Daley
Brian J
BJ
Enderson
Blaine L
BL
Karlstad
Michael D
MD
D017209:Apoptosis / Q000502:physiology*; D001094:Arachidonate 5-Lipoxygenase / Q000502:physiology*; D016227:Benzoquinones / Q000494:pharmacology; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005395:Fish Oils / Q000494:pharmacology; D044950:Flavanones; D005419:Flavonoids / Q000494:pharmacology; D005434:Flow Cytometry; D018922:HL-60 Cells / Q000378:metabolism*; D006801:Humans; D007052:Ibuprofen / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D007211:Indoles / Q000494:pharmacology; D007249:Inflammation; D016859:Lipoxygenase Inhibitors; D009336:Necrosis; D009504:Neutrophils / Q000276:immunology; D011451:Prostaglandin-Endoperoxide Synthases / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control; D002722:Chlorobenzenes
D001094:Arachidonate 5-Lipoxygenase; D016227:Benzoquinones; D016861:Cyclooxygenase Inhibitors; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D044950:Flavanones; D005419:Flavonoids; D007052:Ibuprofen; D007211:Indoles; D016859:Lipoxygenase Inhibitors; D011451:Prostaglandin-Endoperoxide Synthases; C060893:MK-886; D002722:Chlorobenzenes; C006680:baicalein; C036837:2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone