Shureiqi I, Chen D, Lee J J, Yang P, Newman R A, Brenner D E, Lotan R, Fischer S M, Lippman S M
Department of Clinical Cancer Prevention, The University of Texas M. D. Anderson Cancer Center, Houston 77030-4085, USA.
J Natl Cancer Inst. 2000 Jul 19;92(14):1136-42. doi: 10.1093/jnci/92.14.1136.
Nonsteroidal anti-inflammatory drugs (NSAIDs) appear to act via induction of apoptosis-programmed cell death-as potential colorectal cancer chemopreventive agents. NSAIDs can alter the production of different metabolites of polyunsaturated fatty acids (linoleic and arachidonic acids) through effects on lipoxygenases (LOXs) and cyclooxygenases. 15-LOX-1 is the main enzyme for metabolizing colonic linoleic acid to 13-S-hydroxyoctadecadienoic acid (13-S-HODE), which induces apoptosis. In human colorectal cancers, the expression of this enzyme is reduced. NSAIDs can increase 15-LOX enzymatic activity in normal leukocytes, but their effects on 15-LOX in neoplastic cells have been unknown. We tested the hypothesis that NSAIDs induce apoptosis in colorectal cancer cells by increasing the protein expression and enzymatic activity of 15-LOX-1.
We assessed 15-LOX-1 protein expression and enzymatic activity, 13-S-HODE levels, and 15-LOX-1 inhibition in association with cellular growth inhibition and apoptosis induced by NSAIDs (primarily sulindac and NS-398) in two colorectal cancer cell lines (RKO and HT-29). All P values are two-sided.
Sulindac and NS-398 progressively increased 15-LOX-1 protein expression in RKO cells (at 24, 48, and 72 hours) in association with subsequent growth inhibition and apoptosis. Increased 13-S-HODE levels and the formation of 15-hydroxyeicosatetraenoic acid on incubation of the cells with the substrate arachidonic acid confirmed the enzymatic activity of 15-LOX-1. Inhibition of 15-LOX-1 in RKO cells by treatment with caffeic acid blocked NS-398-induced 13-S-HODE production, cellular growth inhibition, and apoptosis (P =. 007, P<.0001, and P<.0001, respectively); growth inhibition and apoptosis were restored by adding exogenous 13-S-HODE (P<.0001 for each) but not its parent compound, linoleic acid (P = 1.0 for each). Similar results occurred with other NSAIDs and in HT-29 cells.
These data identify 15-LOX-1 as a novel molecular target of NSAIDs for inducing apoptosis in colorectal carcinogenesis.
非甾体抗炎药（NSAIDs）似乎通过诱导细胞凋亡（程序性细胞死亡）来发挥作用，作为潜在的结直肠癌化学预防剂。NSAIDs可通过影响脂氧合酶（LOXs）和环氧化酶来改变多不饱和脂肪酸（亚油酸和花生四烯酸）不同代谢产物的生成。15-LOX-1是将结肠亚油酸代谢为13-S-羟基十八碳二烯酸（13-S-HODE）的主要酶，后者可诱导细胞凋亡。在人类结直肠癌中，这种酶的表达降低。NSAIDs可增加正常白细胞中15-LOX的酶活性，但其对肿瘤细胞中15-LOX的作用尚不清楚。我们检验了以下假设：NSAIDs通过增加15-LOX-1的蛋白表达和酶活性来诱导结直肠癌细胞凋亡。
我们评估了两种结直肠癌细胞系（RKO和HT-29）中与NSAIDs（主要是舒林酸和NS-398）诱导的细胞生长抑制和凋亡相关的15-LOX-1蛋白表达、酶活性、13-S-HODE水平及15-LOX-1抑制情况。所有P值均为双侧。
舒林酸和NS-398使RKO细胞中15-LOX-1蛋白表达在24、48和72小时逐渐增加，同时伴有随后的生长抑制和凋亡。细胞与底物花生四烯酸孵育后13-S-HODE水平升高以及15-羟基二十碳四烯酸的形成证实了15-LOX-1的酶活性。用咖啡酸处理抑制RKO细胞中的15-LOX-1可阻断NS-398诱导的13-S-HODE生成、细胞生长抑制和凋亡（P分别为0.007、<0.0001和<0.0001）；添加外源性13-S-HODE可恢复生长抑制和凋亡（每项P<0.0001），但添加其母体化合物亚油酸则不能（每项P = 1.0）。其他NSAIDs及在HT-29细胞中也出现了类似结果。
这些数据确定15-LOX-1是NSAIDs在结直肠癌发生过程中诱导细胞凋亡的一个新分子靶点。
