Mechanisms of enhanced apoptosis in HL-60 cells by UV-irradiated n-3 and n-6 polyunsaturated fatty acids.
We examined the effects of arachidonic acid (AA), eicosapentaenoic acid (EPA), and their ultraviolet (UV)-irradiated products on HL-60 cells and isolated mitochondria to explore the following four obscure points in the mechanism of polyunsaturated fatty acids (PUFAs)-induced apoptosis: (i). the role of reactive oxygen species, (ii). the interaction of PUFAs and their metabolites with mitochondria in situ, (iii). the cyclosporine A (CsA)-sensitivity in PUFA-induced membrane permeability transition, (iv). the specificity of oxidized n-3 PUFAs in the induction of apoptosis in cancer cells. UV-oxidized PUFAs contained conjugated dienes and thiobarbituric acid reactive substances (TBARS). The apoptotic effects of PUFAs on HL-60 cells were increased by UV-irradiation whereas the swelling effect of PUFAs on isolated mitochondria was decreased. Both oxidized n-3 and n-6 PUFAs induced increased depolarization, ferricytochrome c release, the activation of various caspases, and DNA-fragmentation in a CsA-insensitive mechanism concomitant with a slight increase in the value of TBARS in cells. Furthermore, there were no significant differences in the mechanism of apoptosis induced by either oxidized AA or oxidized EPA. On the basis of these results, it was concluded that both oxidized n-3 or n-6 PUFAs induced apoptosis in HL-60 cells by a similar mechanism in a CsA-insensitive manner and also that oxidized products of PUFAs, but not the cellular oxidation process itself, play an important role in the mechanism of apoptosis in HL-60 cells.
Arita
Kayo
K
Institute of Medical Science, Kurashiki Medical Center, Kurashiki, Japan.
Yamamoto
Yorihiro
Y
Takehara
Yoshiki
Y
Utsumi
Toshihiko
T
Kanno
Tomoko
T
Miyaguchi
Chosei
C
Akiyama
Jitsuo
J
Yoshioka
Tamotsu
T
Utsumi
Kozo
K
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology / Q000528:radiation effects; D051023:BH3 Interacting Domain Death Agonist Protein; D002352:Carrier Proteins / Q000378:metabolism; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D015118:Eicosapentaenoic Acid / Q000378:metabolism / Q000494:pharmacology / Q000528:radiation effects; D004789:Enzyme Activation / Q000187:drug effects; D005231:Fatty Acids, Unsaturated / Q000378:metabolism / Q000494:pharmacology* / Q000528:radiation effects*; D018922:HL-60 Cells; D006801:Humans; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays
D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; C494816:Bid protein, rat; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D005231:Fatty Acids, Unsaturated; D017382:Reactive Oxygen Species; D016718:Arachidonic Acid; D016572:Cyclosporine; D045304:Cytochromes c; D015118:Eicosapentaenoic Acid; D020169:Caspases