Arita K, Kobuchi H, Utsumi T, Takehara Y, Akiyama J, Horton A A, Utsumi K
Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, 753-8515, Yamaguchi, Japan.
Biochem Pharmacol. 2001 Oct 1;62(7):821-8. doi: 10.1016/s0006-2952(01)00723-7.
The biochemical properties and specificity of n-3 and n-6 polyunsaturated fatty acids (PUFAs) are not well known. Because PUFAs induce apoptosis of different cells, we studied the effect of various PUFAs, such as arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA), on the fate of cultured human promyelocytic leukemia cells (HL-60) to elucidate the mechanism of apoptosis and the difference in action between n-3 and n-6 PUFAs. Fairly low concentrations of PUFAs inhibited the growth of HL-60 cells and induced their apoptosis by a mechanism that is sensitive to DMSO, an antioxidant, and z-Val-Ala-Asp(OMe)-fluoromethylketone (z-VAD-fmk), a pan-caspase inhibitor. PUFAs stimulated the generation of reactive oxygen species (ROS) and activated various types of caspase-like proteases, such as caspase-3, -6, -8, and -9, but not caspase-1. In addition, PUFAs triggered the reaction leading to the cleavage of Bid, a death agonist member of the Bcl-2 family, and also released cytochrome c from mitochondria into the cytosol. PUFAs also decreased the mitochondrial membrane potential of intact HL-60 cells. All of these actions of n-3 PUFAs were stronger than those of AA, an n-6 PUFA, although the mechanism is not known. PUFAs stimulate swelling and membrane depolarization of isolated mitochondria in a cyclosporin A-sensitive manner. The results indicated that PUFA-induced apoptosis of HL-60 cells may be caused, in part, by direct action on the cells and by activation of the caspase cascade through cytochrome c release coupled with mitochondrial membrane depolarization.
n-3和n-6多不饱和脂肪酸（PUFAs）的生化特性和特异性尚不为人所知。由于PUFAs可诱导不同细胞凋亡，我们研究了各种PUFAs，如花生四烯酸（AA）、二十碳五烯酸（EPA）和二十二碳五烯酸（DPA）对培养的人早幼粒细胞白血病细胞（HL-60）命运的影响，以阐明凋亡机制以及n-3和n-6 PUFAs作用的差异。相当低浓度的PUFAs通过一种对二甲基亚砜（一种抗氧化剂）和z-缬氨酸-丙氨酸-天冬氨酸（甲酯）-氟甲基酮（z-VAD-fmk，一种泛半胱天冬酶抑制剂）敏感的机制抑制HL-60细胞生长并诱导其凋亡。PUFAs刺激活性氧（ROS）的产生并激活各种类型的半胱天冬酶样蛋白酶，如半胱天冬酶-3、-6、-8和-9，但不激活半胱天冬酶-1。此外，PUFAs引发导致Bid（Bcl-2家族的一种死亡激动剂成员）裂解的反应，还使细胞色素c从线粒体释放到细胞质中。PUFAs还降低了完整HL-60细胞的线粒体膜电位。尽管机制尚不清楚，但n-3 PUFAs的所有这些作用都比n-6 PUFA的花生四烯酸更强。PUFAs以环孢菌素A敏感的方式刺激分离线粒体的肿胀和膜去极化。结果表明，PUFA诱导的HL-60细胞凋亡可能部分是由于对细胞的直接作用以及通过细胞色素c释放与线粒体膜去极化相结合激活半胱天冬酶级联反应所致。
