Saito T, Koyama T, Nagata K, Kamiyama R, Hirosawa S
School of Allied Health Sciences, Tokyo Medical and Dental University, Japan.
Blood. 1996 Jan 15;87(2):657-65.
We have recently found that all-trans retinoic acid (ATRA) upregulates thrombomodulin (TM) and downregulates tissue factor (TF) expression in acute myelogenous leukemia (AML) M3 cells (NB4) and acute monoblastic leukemia cells (U937) (Koyama et al, Blood 84:3001, 1994). We have further investigated the effects of ATRA on leukemic cells freshly isolated from patients at diagnosis. Increase of TM antigen was documented in all AML cells: M0 (n = 1), M2 (n = 5), M3 (n = 3), M4 (n = 3), M5 (n = 3), and M6 (n = 1). Decrease of TF antigen was observed in 4 M2, 1 M4, and all M3 and M5 patients. However, no TM and TF antigens were detected in all chronic lymphocytic leukemia cells (n = 3) with or without ATRA treatment. Changes of TM and TF antigen levels were associated with those of TM and TF cofactor levels on the cell surface. A stereoisomer of RA, 9-cis RA, is a high-affinity ligand for the RA receptors (RARs) and the retinoid X receptors, although ATRA and another isomer, 13-cis RA, solely bind to RARs. We have also studied the effects of 9-cis RA and 13-cis RA on the expressions of TM and TF in NB4 and U937 cells. A relatively wide range of 9-cis RA concentrations (0.01 to 1 mumol/L) compared with ATRA was optimal for prolongation of normal plasma-based recalcification time (reduction of cell surface TF activity), decrease of TF antigen, and increase of TM antigen on the surface and in the lysates of NB4 and U937 cells. Western blot analysis under nonreducing conditions showed that both ATRA and 9-cis RA markedly induced the prominent band at 75 kD of TM and reduced the band at 45 kD of TF. Northern blot analysis has shown similar changes of mRNA levels, which indicates that RAs regulate TM and TF expression in leukemic cells at transcriptional levels. Anticoagulant effects of ATRA, ie, upregulation of TM expression and downregulation of TF expression, are applied not only to established cell lines of specific subtypes (M3 and M5) but also to more universal AML (most cases of M3 and M5 and a part of the other types of AML) cells freshly isolated from patients. 9-cis RA may be more effective than ATRA as an inducer of differentiation of AML M3 cells and as an anticoagulant agent for patients with certain types of AML as well.
我们最近发现，全反式维甲酸（ATRA）可上调急性髓性白血病（AML）M3细胞（NB4）和急性单核细胞白血病细胞（U937）中血栓调节蛋白（TM）的表达，并下调组织因子（TF）的表达（小山等，《血液》84:3001，1994）。我们进一步研究了ATRA对诊断时从患者体内新鲜分离出的白血病细胞的影响。在所有AML细胞中均记录到TM抗原增加：M0（n = 1）、M2（n = 5）、M3（n = 3）、M4（n = 3）、M5（n = 3）和M6（n = 1）。在4例M2、1例M4以及所有M3和M5患者中观察到TF抗原减少。然而，在所有慢性淋巴细胞白血病细胞（n = 3）中，无论是否进行ATRA治疗，均未检测到TM和TF抗原。TM和TF抗原水平的变化与细胞表面TM和TF辅因子水平的变化相关。RA的一种立体异构体9-顺式维甲酸（9-cis RA）是维甲酸受体（RARs）和类视黄醇X受体的高亲和力配体，而ATRA和另一种异构体13-顺式维甲酸（13-cis RA）仅与RARs结合。我们还研究了9-顺式维甲酸和13-顺式维甲酸对NB4和U937细胞中TM和TF表达的影响。与ATRA相比，相对较宽范围的9-顺式维甲酸浓度（0.01至1μmol/L）最适合延长基于正常血浆的复钙时间（降低细胞表面TF活性）、降低TF抗原以及增加NB4和U937细胞表面和裂解物中的TM抗原。非还原条件下的蛋白质印迹分析表明，ATRA和9-顺式维甲酸均显著诱导了TM在75 kD处的突出条带，并减少了TF在45 kD处的条带。Northern印迹分析显示mRNA水平有类似变化，这表明维甲酸在转录水平上调节白血病细胞中TM和TF的表达。ATRA的抗凝作用，即上调TM表达和下调TF表达，不仅适用于特定亚型（M3和M5）的已建立细胞系，也适用于从患者体内新鲜分离出的更普遍的AML（大多数M3和M5病例以及部分其他类型的AML）细胞。9-顺式维甲酸作为AML M3细胞分化诱导剂以及某些类型AML患者的抗凝剂可能比ATRA更有效。
