Reactive oxygen species-regulated glycogen synthase kinase-3β activation contributes to all-trans retinoic acid-induced apoptosis in granulocyte-differentiated HL60 cells

All-trans retionic acid (ATRA) treatment confers disease remission in acute promyelocytic leukemia (APL) patients by inducing granulocytic differentiation, which is followed by cell apoptosis. Although glycogen synthase kinase (GSK)-3β is known to be required for spontaneous cell death in neutrophils, the requirement of GSK-3β activation for the apoptotic effects remains unknown. This question is addressed in the present study using a model of ATRA-induced granulocytic differentiation and apoptosis in APL HL60 cells. ATRA at a therapeutic concentration (1 μM) induced granulocytic differentiation, followed by apoptosis. ATRA treatment caused decreased Mcl-1, caspase-3 activation, and PARP cleavage following the inactivation of phosphatidylinositol 3-kinase/AKT and the activation of GSK-3β. Pharmacologically and genetically inhibiting GSK-3β effectively retarded ATRA-induced Mcl-1 degradation and apoptosis. Additional differentiation inducers, phorbol 12-myristate 13-acetate and dimethyl sulfoxide, also triggered GSK-3β-dependent apoptosis. Mechanistically, ATRA caused the generation of reactive oxygen species (ROS) through increased expression of NADPH oxidase subunits (p47^phox and p67^phox) to facilitate ATRA-induced GSK-3β activation and cell apoptosis. This study indicates that ROS initiate GSK-3β-dependent apoptosis in granulocyte-differentiated cells after long-term ATRA treatment.     

Differential enhancement of leukaemia cell differentiation without elevation of intracellular calcium by plant-derived sesquiterpene lactone compounds

Background and purpose:

All-trans retinoic acid (ATRA) induces complete remission in a majority of acute promyelocytic leukaemia patients, but resistance of leukaemic cells to ATRA and its toxicity, such as hypercalcaemia, lead to a limitation of treatment. Therefore, combination therapies with differentiation-enhancing agents at non-toxic concentrations of ATRA may overcome its side effects. Here, we investigated the effect of plant-derived sesquiterpene lactone compounds and their underlying mechanisms in ATRA-induced differentiation of human leukaemia HL-60 cells.

Experimental approach:

HL-60 cells were treated with four sesquiterpene lactones (helenalin, costunolide, parthenolide and sclareolide) and cell differentiation was determined by NBT reduction, Giemsa and cytofluorometric analyses. Signalling pathways were assessed by western blotting, gel-shift assay and kinase activity determinations and intracellular calcium levels were determined using a calcium-specific fluorescent probe.

Key results:

Helenalin, costunolide and parthenolide, but not sclareolide, increased ATRA-induced HL-60 cell differentiation into a granulocytic lineage. Signalling kinases PKC and ERK were involved in the ATRA-induced differentiation enhanced by all of the effective sesquiterpene lactones, but JNK and PI3-K were involved in the ATRA-induced differentiation enhanced by costunolide and parthenolide. Enhancement of cell differentiation closely correlated with inhibition of NF-κB DNA-binding activity by all three effective compounds. Importantly, enhancement of differentiation induced by 50 nM ATRA by the sesquiterpene lactones was not accompanied by elevation of basal intracellular calcium concentrations.

Conclusions and implications:

These results indicate that plant-derived sesquiterpene lactones may enhance ATRA-mediated cell differentiation through distinct pathways.     

Regulation of CYP26A1 expression by selective RAR and RXR agonists in human NB4 promyelocytic leukemia cells

All-trans retinoic acid (ATRA) can induce complete remission in acute promyelocytic leukemia (APL), but resistance to this treatment develops rapidly partly due to increased ATRA metabolism. Among the cytochrome P450s (CYPs) involved in ATRA metabolism, the ATRA-inducible cytochrome P450 26A1 (CYP26A1) is particularly active although the molecular mechanisms involved in its regulation are not well defined in the target leukemia cells. To study CYP26A1 expression and regulation in APL cells, we used the NB4 promyelocytic leukemia cell line. CYP26A1 constitutive expression was barely detectable in NB4 cells, but ATRA could induce high levels of CYP26A1 expression, which reached a maximum at 72h. To further define CYP26A1 induction mechanisms in the NB4 leukemia cells, we used RARs and RXR selective agonists. The RARalpha agonist BMS753 could elicit maturation, as expected, but not CYP26A1 expression. Treatment with the RARbeta agonist BMS641, or the RARbeta/gamma agonist BMS961, could not elicit maturation, as expected, nor induce CYP26A1 expression. Because CYP26A1 expression could not be induced by RAR ligands alone, NB4 cells were then co-treated with the RXR agonist BMS649. The RXR agonist alone could not induce CYP26A1 expression, nor in combination with either the RARbeta agonist or the RARbeta/gamma agonist. However, the combination of the RXR agonist and the RARalpha agonist could elicit a marked induction of CYP26A1 expression. In conclusion, we have shown that CYP26A1 induction is not essential for the granulocytic maturation of NB4 leukemia cells, and that CYP26A1 induction requires the activation of both RARalpha and RXR in these cells.     

Tamibarotene

Tamibarotene is a new synthetic retinoid drug recently approved for relapsed or refractory acute promyelocytic leukemia (APL) in Japan. It is a specific agonist for retinoic acid receptor alpha/beta. Compared to all-trans retinoic acid (ATRA), a natural retinoid indicated for a first-line treatment of APL, tamibarotene is chemically more stable and several times more potent as an inducer of differentiation in promyelocytic leukemia cells. In contrast to ATRA, whose plasma concentration declines considerably during daily administration, tamibarotene sustains plasma level probably due to a lower affinity for cellular retinoic acid binding protein. Furthermore, adverse side effects were milder than those of ATRA in clinical trials. Clinical trials held in Japan showed that tamibarotene had efficacy in APL patients who had relapsed from ATRA-induced complete remission. Recently, better understanding of the various mechanisms of action of retinoids has stimulated great interest in its potential use for treatment of various diseases. Tamibarotene is being investigated for treatment of multiple myeloma and Crohn's disease in clinical trials. This review focuses on tamibarotene's mechanisms of action, chemical properties, pharmacokinetics and its use in APL as well as its potential use in various disorders.     

粒系集落刺激因子与急性早幼粒细胞白血病关系的研究

24例急性早幼粒细胞白血病（APL）患者，在全反式维甲酸（ATRA）治疗过程中，用ELISA法检测其血清、骨髓单个核细胞及NB4细胞用ATRA诱导前后上清液及冻融物中G－CSF水平。结果表明，在治疗前血清中G－CSF检出率为20．8％，治疗后检出率升高，在白细胞达高峰前阳性率最高，而后逐渐下降。上清液及冻融物中G－CSF均未能检出。分析表明血清G－CSF水平与外周血白细胞呈正相关（P＜0．05）。结果提示G－CSF在APL患者用ATRA治疗过程中白细胞升高的发生机制中起一定作用，APL细胞不分泌G－CSF。     

全反式维甲酸-正丁酸（丙戊酸）前体药物的设计、合成及抗肿瘤活性研究

目的合成全反式维甲酸（ATRA）的前体药物，增强ATRA对急性早幼粒白血病（APL）细胞的分化诱导作用。方法以乙二醇、对苯二酚、乙醇胺及乙二胺等为连接物，通过酯键和酰胺键将分化诱导剂ATRA与组蛋白去乙酰酶（mAC）抑制剂正丁酸、丙戊酸连接起来，形成前体药物。结果合成了13个ATRA与正丁酸或丙戊酸相连接的前体药物，化合物的结构经^1H-NMR、MS和IR确证。结论考察部分化合物对急性早幼粒细胞白血病细胞株NB4的生长抑制作用和对急性早幼粒白血病（APL）细胞分化诱导作用，初步的药理实验结果表明，ATRA与丙戊酸通过酰胺键连接时，对NB4细胞分化诱导能力显著增加。     

全反式维甲酸与亚砷酸联合化疗对急性早幼粒细胞白血病高危患者的疗效

目的观察全反式维甲酸(ATRA)与亚砷酸(ATO)联合化疗对急性早幼粒细胞白血病(APL)患者的疗效。方法回顾性分析86例不同危险分级的初治APL患者的临床资料。根据治疗前白细胞和血小板数将APL患者分为低、中、高危三组。采用ATRA+ATO+蒽环类药诱导缓解,蒽环类药+阿糖胞苷巩固治疗,ATRA+ATO+甲氨蝶呤(MTX)[部分加用6-巯基嘌呤(6-MP)]维持治疗。结果治疗后,完全缓解(CR)率高达95.3%(82/86)。中位随访37个月,高危组和中低危组无事件生存率及中枢神经系统累积复发率差异均无统计学意义(P>0.05)。维持治疗单用MTX者或MTX+6-MP者CR率均为100%。结论 APL患者尤其是高危患者可以从ATO+ATRA+化疗中受益;该方案作为初治APL的一线治疗方案优势明显。     

全反式维甲酸和三氧化二砷治疗初治急性早幼粒细胞白血病的疗效观察

目的观察全反式维甲酸(ATRA)联合三氧化二砷(As2O3)治疗初治急性早幼粒细胞白血病(APL)的疗效。方法对应用ATRA和As2O3联合诱导治疗的20例APL患者的完全缓解(CR)率、达CR所需时间和不良反应进行观察,并与单独应用ATRA组30例进行比较。联合用药组治疗方法为ATRA 25mg/(m2.d),0.1%As2O310ml/d直至CR。结果联合用药组与单独应用ATRA组相比,CR率差异无统计学意义(分别为95%、86.7%,均P>0.05);联合用药组获得CR所需的时间短于单独用药组(平均时间分别为24d、45d,均P<0.05),早期死亡率较单独用药组差异无统计学意义(分别为5%、13.3%,均P>0.05);与单独用药组相比,联合用药组的不良反应并未增加。结论联合用药诱导初发APL缓解的疗效优于单用药组,不良反应少,是一种值得推广应用的方案。     

Transglutaminase-2 Is Involved in All-Trans Retinoic Acid-Induced Invasion and Matrix Metalloproteinases Expression of SH-SY5Y Neuroblastoma Cells via NF-κB Pathway

All-trans retinoic acid (ATRA) is currently used in adjuvant differentiation-based treatment of residual or relapsed neuroblastoma (NB). It has been reported that short-term ATRA treatment induces migration and invasion of SH-SY5Y via transglutaminase-2 (Tgase-2). However, the detailed mechanism of Tgase-2''s involvement in NB cell invasion remains unclear. Therefore we investigated the role of Tgase-2 in invasion of NB cells using SH-SY5Y cells. ATRA dose-dependently induced the invasion of SH-SY5Y cells. Cystamine (CTM), a well known tgase inhibitor suppressed the ATRA-induced invasion of SH-SY5Y cells in a dose-dependent manner. Matrix metalloproteinase-9 (MMP-9) and MMP-2, well known genes involved in invasion of cancer cells were induced in the ATRA-induced invasion of the SH-SH5Y cells. Treatment of CTM suppressed the MMP-9 and MMP-2 enzyme activities in the ATRA-induced invasion of the SH-SY5Y cells. To confirm the involvement of Tgase-2, gene silencing of Tgase-2 was performed in the ATRA-induced invasion of the SH-SH5Y cells. The siRNA of Tgase-2 suppressed the MMP-9 and MMP-2 activity of the SH-SY5Y cells. MMP-2 and MMP-9 are well known target genes of NF-κB. Therefore the relationship of Tgase-2 and NF-κB in the ATRA-induced invasion of the SH-SY5Y cells was examined using siRNA and CTM. ATRA induced the activation of NF-κB in the SH-SY5Y cells and CTM suppressed the activation of NF-κB. Gene silencing of Tgase-2 suppressed the MMP expression by ATRA. These results suggested that Tgase-2 might be a new target for controlling the ATRA-induced invasion of NBs.     

Differential modulation of PI3-kinase/Akt pathway during all-trans retinoic acid- and Am80-induced HL-60 cell differentiation revealed by DNA microarray analysis

All-trans retinoic acid (ATRA) and Am80 are natural and synthetic derivatives of Vitamin A and have been used in the fields of oncology and dermatology for years. Their action was considered to be achieved mainly through binding to nuclear hormone receptors, retinoic acid receptors (RARs), although they have been observed to have different biological effects. For example, the two compounds have similar effects on differentiation but different effects on proliferation in human promyelocytic leukemia cell line HL-60 cells. To elucidate the genes responsible for this and other differences, we attempted for the first time to determine the genes whose expressions were differentially modulated during the time course of HL-60 cell differentiation by ATRA and Am80 treatment up to 72h utilizing DNA microarray and clustering analyses. As a result, the expressions of 204 genes were found to be modulated differentially by ATRA and Am80. Among them, we focused on two components of the PI3-kinase/Akt signal transduction pathway, phosphoinositide-3-kinase, beta-catalytic subunit and ribosomal protein S6 kinase polypeptide 1, which are related to the regulation of cell proliferation and apoptosis. Their expressions were specifically suppressed by ATRA, which coincided with the suppressive effects of ATRA on the HL-60 cell proliferation. Moreover, PI3-kinase inhibitors suppressed the proliferation of Am80-treated cells to the same extent as ATRA did. These results indicated that these gene products play a role in HL-60 cell growth suppression during the late stage of differentiation. The complete data and a list of the genes are available at .     

全反式维甲酸诱导人急性早幼粒白血病HL-60细胞分化的机制

目的研究全反式维甲酸诱导人急性早幼粒白血病HL-60细胞分化机制。方法用流式细胞仪分析维甲酸对HL-60细胞周期变化的影响，用自制的含9 984个已知基因和EST的高密度基因芯片检测HL-60细胞在维甲酸诱导作用下不同时期的基因表达变化。结果HL-60细胞在1 μmol·L^-1维甲酸持续作用2,4和6 d时,流式细胞仪结果显示48%～73%细胞阻断在G0/G1期;基因表达谱分析发现,黏附分子、组织重建蛋白、转运蛋白、核蛋白体蛋白和涉及氧化酶激活途径的基因表达明显升高。结论基因表达谱的研究结果表明,维甲酸作用HL-60细胞与氧化酶激活途径及组织重建蛋白的表达相关联,并揭示了一些已知和未知功能的基因在HL-60细胞分化与细胞凋亡过程中的作用。     

Andrographolide inhibits growth of acute promyelocytic leukaemia cells by inducing retinoic acid receptor‐independent cell differentiation and apoptosis

Objectives The growth inhibiting potential of andrographolide was evaluated in three acute promyelocytic leukaemia cell line models (HL‐60, NB4 and all‐trans retinoic acid (ATRA)‐resistant NB4‐R2). Methods In elucidating the mechanisms of growth inhibition, a special emphasis was placed on assessing the induction of differentiation and apoptosis by andrographolide in the primary acute promyelocytic leukaemia NB4 cells. Key findings The compound was 2‐ and 3‐fold more active in inhibiting the growth of HL‐60 and NB4‐R2 cells compared with NB4 cells, respectively. At IC50 (concentration at which growth of 50% of the cells (compared with medium only treated control cells) is inhibited; 4.5 μM) the compound exhibited strong cell‐differentiating activity in NB4 cells, similar to ATRA (IC50 1.5 μM). In the presence of a pure retinoic acid receptor antagonist AGN193109, the growth inhibition of NB4 cells by ATRA was reversed, whereas the activity of andrographolide was not affected. This clearly suggested that andrographolide's cell differentiating activity to induce growth inhibition of NB4 cells most likely occurred via a retinoic acid receptor‐independent pathway. At higher concentration (2 × IC50), andrographolide was an efficient inducer of apoptosis in NB4 cells. Conclusions Taken together, these results suggest andrographolide and its derivatives, apparently with a novel cell differentiating mechanism and with ability to induce apoptosis, might be beneficial in the treatment of primary and ATRA‐resistant acute promyelocytic leukaemia.     

A practical strategy to subcutaneous administered in-situ gelling co-delivery system of arsenic and retinoic acid for the treatment of acute promyelocytic leukemia

Arsenic trioxide (ATO) combined with all trans retinoic acid (ATRA) is the first choice for the treatment of low and medium risk acute promyelocytic leukemia (APL). Clinical studies reported that the combination of ATO and ATRA could achieve a significant curative effect. However, the retinoic acid syndrome, serious drug resistance and the short half-life in vivo which lead to frequent and large dose administration limit the application of ATRA. In addition, the preparations of arsenic are conventional injections and tablets in clinic, which has poor patients' compliance caused by frequent long-term administration and serious side effects. In order to overcome the above limitations, a phospholipid phase separation gel (PPSG) loaded with ATO and ATRA was developed. ATO+ATRA-PPSG (AAP), as a biodegradable sustained-release delivery system, was the first achievement of co-delivery of hydrophilic ATO and lipophilic ATRA with high drug loading which is the main problem in the application of nano preparation. The prepared PPSG displayed high safety and biocompatibility. The drug in PPSG was released slowly and continuously in vivo and in vitro for up to 10 d, which could reduce the side effects caused by the fluctuation of blood drug concentration and solve the problem of the long treatment cycle and frequent administration. In vivo pharmacokinetics depicted that PPSG could improve the bioavailability, decrease the peak concentration, and prolong the t_1/2 of ATO and ATRA. Particularly, AAP significantly inhibited the tumor volume, extended the survival period of tumor-bearing mice, and promoted the differentiation of APL cells into normal cells. Therefore, ATO+ATRA-PPSG not only could co-load hydrophilic ATO and lipophilic ATRA according to the clinical dosage, but also possessed the sustained-release and long-acting treatment effect which was expected to reduce administration time and ameliorate compliance of patients. Thus, it had great potential for clinical transformation and application.     

三氧化二砷治疗急性早幼粒细胞白血病疗效观察

目的 :观察三氧化二砷 (As2 O3)治疗急性早幼粒细胞白血病的完全缓解率、高白细胞发生率、肝功损害及融合基因转阴率 ,并与维甲酸 (ATRA )的治疗情况进行比较。方法 :随机分为两组 ,As2 O3组 17例 ,ATRA组 2 1例 ,分别选用 0 .1% As2 O310 m L/ d,静脉滴注 ;ATRA2 5 mg· m- 2 · d- 1 ,分 3次服用。分别观察两组的完全缓解率 (CR)、不良反应以及融合基因转阴率。结果 :As2 O3组 15 / 17例 (88.2 % )获 CR,获得 CR时间为 (2 8.1± 4 .6 ) d;ATRA组 19/2 1例 (90 .4 % )获 CR,获得 CR时间为 (39.4± 8.6 ) d,两组之间 CR无明显差别 ,但 As2 O3组获得 CR时间明显缩短。高白细胞发生率 As2 O3组 10 / 15例 (6 6 .7% ) ,ATRA组 18/ 19例 (94 .7% ) ,P<0 .0 5。肝功能异常 ,As2 O3组 11/ 17例(6 4 .7% ) ,ATRA组 13/ 19例 (6 8.4 % ) ,P>0 .0 5。所有患者治疗前 PML- RARα融合基因阳性。 As2 O3组 CR时 ,2 /14例 (14 % )转阴 ,ATRA组 2 / 19例 (10 .5 % )转阴 ,P<0 .0 5。CR后 1a,As2 O3组 5 / 8例 (6 2 .5 % )转阴 ,ATRA组 4 /11例 (36 .3% )转阴 ,P<0 .0 5。As2 O3组 15例获 CR者 ,无 1例复发。ATRA组 19例获 CR者 ,4例 (2 1% )复发。结论 :与 ATRA相比 As2 O3获得 CR时间缩短 ,高白细胞发生率低 ,CR及 CR     

Pathogenesis and treatment of leukemia: an Asian perspective

INTRODUCTION: Leukemias occur worldwide, but there are important geographic differences in incidences. AREAS COVERED: Three leukemias with special Asian perspectives, acute promyelocytic leukemia (APL), T-cell large granular lymphocyte (T-LGL) leukemia and NK-cell leukemia. EXPERT OPINION: In APL, China has made contributions in discovering the efficacy of all-trans retinoic acid (ATRA) and arsenic trioxide. Some APL patients are potentially curable after treatment with ATRA or arsenic trioxide as a single agent. Combined treatment of APL with ATRA and arsenic trioxide induces remission with deeper molecular response. An oral formulation of arsenic trioxide is available, making outpatient treatment feasible. Future regimens for APL should examine how ATRA and arsenic trioxide can be optimally combined with other synergistic drugs. Asian patients with T-LGL leukemia present more frequently with pure red cell aplasia, but less frequently with neutropenia, recurrent infection, splenomegaly and rheumatoid arthritis as compared with Western patients. These differences have potential effects on treatment and disease pathogenesis. NK-cell leukemia is rapidly fatal and occurs almost exclusively in Asian and South American patients. Conventional anthracycline-based chemotherapy designed for B-cell lymphomas do not work in NK-cell leukemias. Novel therapeutic approaches targeting cellular signaling pathways or preferentially upregulated genes are needed to improve outcome.     

急性早幼粒细胞白血病21例临床分析

目的 探讨急性早幼粒细胞白血病(acute promyelocytic leukemia,APL)合并出血的临床特点和防治方法.方法 回顾性分析21例APL患者的临床特点及疗效.结果 初诊时合并出血症状20例(95.2%),合并弥漫性血管内凝血(DIC)10例(47.6%),早期死亡5例(23.8%),经全反式维A酸等治疗及血小板及凝血因子输注后完全缓解13例(61.9%).结论 APL出血发生率高,全反式维A酸(ATRA)的应用、血小板及凝血因子输注等治疗可以减少早期出血病死率.     

Granulomatous tubulointerstitial nephritis induced by all-trans retinoic acid

We report the first case of granulomatous tubulointerstitial nephritis induced by all-trans retinoic acid (ATRA) in a patient with acute promyelocytic leukemia (APL). Acute renal failure during treatment with ATRA has been previously reported as a part of an ATRA syndrome or a thrombotic complication of a hypercoagulable state. This case indicates an alternative mechanism of acute renal failure occurring during ATRA therapy.