Shiohara M, Dawson M I, Hobbs P D, Sawai N, Higuchi T, Koike K, Komiyama A, Koeffler H P
Department of Pediatrics, Shinshu University School of Medicine, Matsumoto Japan.
Blood. 1999 Mar 15;93(6):2057-66.
Retinoids such as all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid (9-cis-RA) have an important role in many aspects of proliferation and differentiation of hematopoietic cells. They exert their effects by binding to retinoic acid receptors (RARs) and/or retinoid X receptors (RXRs). We studied the effects of novel retinoids on proliferation and differentiation of HL-60 and NB4 myeloid leukemic cells, as well as acute promyelocytic leukemia (APL) cells from patients. RXR-selective SR11345 (Retinoid C) had little ability to inhibit the clonal growth and to induce the differentiation of either HL-60 or NB4 cells. However, SR11276 (Retinoid E), which activated both the RAR and RXR classes, and SR11278 (Retinoid D), which activated the RAR subtypes alpha, beta, and gamma, could inhibit clonal growth of both cell types, as well as leukemic cells from APL patients. The combination of ATRA and either SR11276 or SR11278 additively inhibited APL cell proliferation. SR11302 (Retinoid A), with reported anti-AP-1 activity and no activation of RARs and RXR and SR11363 (Retinoid B), which selectively activated RARbeta and gamma, were inactive. The clonal proliferation of both HL-60 and NB4 cells that were pulse-exposed to 10(-9) mol/L ATRA, SR11276, SR11278, or SR11345 for 3 days, washed, and plated in methylcellulose culture were inhibited by 0%, 51%, 21%, and 1% for HL-60 cells and 43%, 41%, 35%, and 1% for NB4, respectively, compared with nontreated control cells. When the HL-60 cells were pulse-exposed to 10(-9) mol/L of either SR11278 or SR11276, plus 10(-9) mol/L ATRA for 3 days, colony numbers were reduced by 46% and 64%, respectively. Induction of leukemic cell differentiation as determined by the nitroblue tetrazolium (NBT) assay showed that the combination of 10(-7) mol/L of either SR11278 or SR11276 with 10(-7) mol/L ATRA had additive effects on HL-60 cells, NB4 cells, and fresh APL cells. Induction of CD11b expression on both HL-60 and NB4 cells occurs during their differentiation. Expression of this antigen was synergistically augmented by the combination of either 10(-7) to 10(-8) mol/L SR11278 or 10(-7) to 10(-9) mol/L SR11276 with 10(-9) mol/L ATRA compared with either analog alone in HL-60 cells. Expression of the novel myeloid specific transcription factor C/EBPepsilon was increased by SR11278 and SR11276 in both the HL-60 and NB4 cell lines. We conclude that retinoids or combination of retinoids with specificities for both RAR and RXR may markedly enhance the ability of ATRA to inhibit clonal growth and induce differentiation of HL-60 and NB4 leukemic cells. This occurs in the absence of continuous contact with retinoids.
维甲酸类物质，如全反式维甲酸（ATRA）和9-顺式维甲酸（9-cis-RA），在造血细胞增殖和分化的许多方面发挥着重要作用。它们通过与维甲酸受体（RARs）和/或维甲酸X受体（RXRs）结合来发挥作用。我们研究了新型维甲酸对HL-60和NB4髓系白血病细胞以及患者急性早幼粒细胞白血病（APL）细胞增殖和分化的影响。RXR选择性的SR11345（维甲酸C）几乎没有抑制HL-60或NB4细胞克隆生长及诱导其分化的能力。然而，同时激活RAR和RXR类别的SR11276（维甲酸E）以及激活RAR亚型α、β和γ的SR11278（维甲酸D），能够抑制这两种细胞类型以及APL患者白血病细胞的克隆生长。ATRA与SR11276或SR11278联合使用可累加性抑制APL细胞增殖。据报道具有抗AP-1活性且不激活RARs和RXR的SR11302（维甲酸A）以及选择性激活RARβ和γ的SR11363（维甲酸B）均无活性。HL-60和NB4细胞脉冲暴露于10⁻⁹ mol/L的ATRA、SR11276、SR11278或SR11345 3天，洗涤后接种于甲基纤维素培养基中培养，与未处理的对照细胞相比，HL-60细胞的克隆增殖抑制率分别为0%、51%、21%和1%，NB4细胞分别为43%、41%、35%和1%。当HL-60细胞脉冲暴露于10⁻⁹ mol/L的SR11278或SR11276加10⁻⁹ mol/L ATRA 3天时，集落数分别减少46%和64%。通过硝基蓝四氮唑（NBT）试验测定白血病细胞分化诱导情况，结果显示10⁻⁷ mol/L的SR11278或SR11276与10⁻⁷ mol/L ATRA联合使用对HL-60细胞、NB4细胞和新鲜APL细胞具有累加效应。HL-60和NB4细胞在分化过程中均会诱导CD11b表达。与单独使用任何一种类似物相比，在HL-60细胞中，10⁻⁷至10⁻⁸ mol/L的SR11278或10⁻⁷至10⁻⁹ mol/L的SR11276与10⁻⁹ mol/L ATRA联合使用可协同增强该抗原的表达。新型髓系特异性转录因子C/EBPε的表达在HL-60和NB4细胞系中均被SR11278和SR11276上调。我们得出结论，对RAR和RXR均具有特异性的维甲酸或维甲酸组合可能显著增强ATRA抑制HL-60和NB4白血病细胞克隆生长及诱导其分化的能力。这在不持续接触维甲酸的情况下也会发生。
