Sanduja S K, Mehta K, Xu X M, Hsu S M, Sanduja R, Wu K K
Department of Internal Medicine, University of Texas Medical School, Houston 77030.
Blood. 1991 Dec 15;78(12):3178-85.
To elucidate the differentiation-associated expression of enzymes catalyzing arachidonic acid metabolism, we measured arachidonate metabolites by reverse-phase high pressure liquid chromatography in monocytoid leukemia (ML-1, THP-1, and U937) and myeloid leukemia (KG-1) cell lines. Undifferentiated ML-1 or THP-1 cells produced trace amounts of eicosanoids via the cyclooxygenase (COX) and lipoxygenase (LOX) pathways. Upon differentiation induced by phorbol ester (phorbol 12-myristate 13-acetate [PMA]), metabolites via the COX pathway were increased by 100-fold in ML-1 and THP-1 cells, while the LOX products remained barely detectable. All the COX metabolites were elevated, but thromboxane A2 (TXA2) formation was threefold higher in ML-1 cells than in THP-1 cells. Similar time-related increases in COX metabolites were observed in THP-1 cells induced to differentiate with retinoic acid. Undifferentiated U937 cells were capable of generating a much higher quantity of COX products than ML-1 or THP-1 cells, but, upon PMA-induced differentiation, COX products were increased by only two-fold to threefold over the undifferentiated cells and the total COX products in differentiated U937 cells were only one-seventh of those produced by differentiated ML-1 or THP-1 cells. KG-1 cells had an entirely different metabolic profile. They produced a large quantity of a metabolite coeluted with prostaglandin D2, and PMA had no effect on inducing changes in arachidonic acid (AA) metabolism. Increased COX metabolite formation in differentiated THP-1 and ML-1 cells was due to an enhanced level of prostaglandin H synthase enzyme mass, as measured by Western blot analysis. The TXA synthase activity was also increased by approximately 100-fold in PMA-induced ML-1 cells and 10-fold in THP-1 cells. These findings indicate that increased expression of prostaglandin H and TXA synthase enzymes is a feature of differentiated monocytoid leukemia cell lines.
为阐明催化花生四烯酸代谢的酶与分化相关的表达情况，我们通过反相高压液相色谱法测定了单核细胞白血病（ML-1、THP-1和U937）及髓系白血病（KG-1）细胞系中的花生四烯酸代谢产物。未分化的ML-1或THP-1细胞通过环氧化酶（COX）和脂氧合酶（LOX）途径产生微量类花生酸。在用佛波酯（佛波醇12-肉豆蔻酸酯13-乙酸酯[PMA]）诱导分化后，ML-1和THP-1细胞中通过COX途径产生的代谢产物增加了100倍，而LOX产物仍几乎检测不到。所有COX代谢产物均升高，但ML-1细胞中血栓素A2（TXA2）的生成量比THP-1细胞高两倍。在用视黄酸诱导分化的THP-1细胞中也观察到了与时间相关的类似COX代谢产物增加情况。未分化的U937细胞能够产生比ML-1或THP-1细胞更多的COX产物，但在PMA诱导分化后，COX产物仅比未分化细胞增加了两倍至三倍，且分化后的U937细胞中总的COX产物仅为分化后的ML-1或THP-1细胞产生量的七分之一。KG-1细胞具有完全不同的代谢谱。它们产生大量与前列腺素D2共洗脱的代谢产物，且PMA对诱导花生四烯酸（AA）代谢变化没有影响。通过蛋白质印迹分析测定，分化后的THP-1和ML-1细胞中COX代谢产物形成增加是由于前列腺素H合酶酶量水平升高。在PMA诱导的ML-1细胞中，TXA合酶活性也增加了约100倍，在THP-1细胞中增加了10倍。这些发现表明，前列腺素H和TXA合酶表达增加是分化的单核细胞白血病细胞系的一个特征。
