急性早幼粒细胞白血病中维甲酸受体α融合基因的研究进展

急性早幼粒细胞白血病(APL)是急性髓系白血病(AML)的一个特殊亚型,常伴有特征性的t(15;17) (q22;q21)易位,形成PML-RARα融合基因.除了特征性的PML-RARα融合基因以外,目前被人们所熟知的RARα融合基因还包括,PLZF-RARα,NPM-RARα,NuMA-RARα和STAT5b-RARα等.虽然这些融合基因的发生率远小于PML-RARα融合基因,但是带有这些融合基因的APL发病机制不同、诊断标准不同、对全反式维甲酸(ATRA)治疗的敏感性亦不同,所以在APL的早期诊断和早期治疗中起到重要作用.笔者就RARα融合基因的一般特点及近期新发现的RARα融合基因的结构、功能、致病机理以及对药物治疗的反应等进行综述.     

维甲酸,维甲酸受体和早幼粒细胞白血病

维甲酸、维甲酸受体和早幼粒细胞白血病董硕综述陈竺王振义审校维甲酸是维生素Ａ的一类衍生物，８０年代末，Ｈｕａｎｇ等［１］发现全反式维甲酸（ＡＴＲＡ）能诱导急性早幼粒细胞白血病（ＡＰＬ）细胞分化成熟并使它们失去增殖能力，从而在临床上取得缓解，完全缓解率达...     

急性早幼粒细胞白血病PML维甲酸受体α融合基因定量检测的应用价值

目的探讨早幼粒细胞白血病PML维甲酸受体α融合基因(PML-RARα)定量检测在急性早幼粒细胞白血病诊断、治疗中的临床应用价值。方法采用实时定量聚合酶链反应对12例急性早幼粒细胞白血病患者初诊、治疗后完全缓解及复发时PML-RARα进行定量检测,分析不同阶段其变化程度,并与同阶段细胞形态学、染色体分析进行比较。结果 12例急性早幼粒细胞白血病患者初发时PML-RARα均为阳性,完全缓解阶段转为阴性或定量结果呈逐渐下降趋势,当复发时PML-RARα再次并早于细胞形态学和染色体分析出现阳性,且定量结果明显高于初发阶段。结论 PML-RARα定量检测可为急性早幼粒细胞白血病诊断、治疗及提示复发提供可靠的依据。     

维甲酸受体α与急性早幼粒细胞白血病PML－RARα融合受体特性研究

作者通过受体的放射配基结合分析方法，研究了ＨＬ－６０细胞中维甲酸受体α（ＲＡＲα）与急性早幼粒细胞白血病（ＡＰＬ）细胞中ＰＭＬ－ＲＡＲα融合受体的一些特性。结果显示：ＲＡＲα在细胞中以单体形式存在，而ＰＭＬ－ＲＡＲα则以复合体形式存在；ＰＭＬ－ＲＡＲα与全反式维甲酸（ＡＴＲＡ）的亲和力比ＲＡＲα与ＡＴＲＡ的亲和力低。提示：ＲＡＲα与ＰＭＬ－ＲＡＲα这些特性的差异可能与ＡＰＬ发病及ＡＴＲＡ治疗作用有关。     

维甲酸受体α与急性早幼粒细胞白血病PML—RARα融合受体特性研究

作者通过受体的放射配基结合分析方法，研究了ＨＬ－６０细胞中维甲酸受体α（ＲＡＲα）与急性早幼粒细胞白血病（ＡＰＬ）细胞中ＰＭＬ－ＲＡＲα融合受体的一些特性。结果显示：ＲＮＡα在细胞中以单体形式存在，ＰＭＬ－ＲＡＲα则以复合体形式存在；ＰＭＬ－ＲＡＲα与全反式维甲酸（ＡＴＲＡ）的亲和力比ＲＡＲα与ＡＴＲＡ的亲和力低。提示：ＲＡＲα与ＰＭＬ－ＲＡＲα这些特性的差异可能与ＡＰＬ发病及ＡＴＲＡ治疗作用有关     

维甲酸融合受体研究现状

急性早幼粒细胞白血病(APL)特有的t(15;17)染色体易位产生特异的维甲酸融合受体以显性负效应方式干扰正常的粒细胞的增殖、分化和死亡,也干扰了正常的PML蛋白的细胞内定位,是急性早幼粒白血病发病和维甲酸诱导分化治疗APL的关键。     

急性早幼粒细胞白血病的维甲酸治疗

自 1 986年我国首次报导用全反式维甲酸(ATRA)诱导急性早幼粒细胞白血病 (APL)成功以来 ,ATRA诱导APL细胞分化治疗的显著疗效已得到公认 ,完全缓解率 (CR)达到90 %以上[1 ] 。同时ATRA大大地增加了APL患者的无病生存期及生存率 ,降低复发率[2 ] 。现将ATRA治疗APL的机制、方法、并发症等综述于下。1　APL的特征APL是急性髓系白血病的一个特殊类型 ,它具有下述 4个方面特征 :(1 )细胞形态学 ;表现为粒系分化停滞在早幼粒细胞阶段 ;(2 )细胞免疫表型 :CD9+ 、CD33+ 、CD1 3+ 、HLA-DR- 为APL的特征 ,而CD34、CD7、CD1 …     

一种新的早幼粒细胞白血病/维甲酸受体α融合基因S亚型变异易位

目的：逆转录聚合酶链反应（RT－PCR）检测早幼粒细胞白血病／维甲酸受体α（PML／RARα）融合基因，筛查变异易位并对变异易位产物测序，以进一步了解变异易位的特点及临床意义。方法：取急性早幼粒细胞白血病（APL）患者骨髓，RT－PCR检测L亚型和S亚型，发现的变异易位经全自动测序仪测定其碱基序列。结果：11例PML／RARα融合基因表达的患者中，S亚型1例、L亚型8例、变异S亚型合并L亚型2例；变异S亚型产物测序得到206bp的碱基序列，检索证实是一种新的变异易位。结论：发现了一种新的S亚型变异易位，证实同一个体可有S和L二种不同亚型并存；提示PML／RARα融合基因的RT－PCR检测中，识别变异易位有重要意义。     

维甲酸融合受体研究现状

急性早幼粒细胞白血病（ＡＰＬ）特有的ｔ（１５：１７）染色体易位产生特异的维甲酸融合受体以显性负效应方式干扰正常的粒细胞的增殖、分化和死亡，也干扰了正常的ＰＭＬ蛋白的细胞内定位，是急性早幼粒白血病发病和维甲酸诱导分化治疗ＡＰＬ的关键。     

急性早幼粒细胞白血病全反式维甲酸治疗时IL—8及其受体表达 …

目的：探讨白细胞介素８（ＩＬ－８）及其Ａ型受体（ＩＬ－８ＲＡ）的表达在全反式维甲酸（ＡＴＲＡ）诱导治疗急性早幼粒细胞白血病（ＡＰＬ）中的临床意义。方法：动态检测ＡＰＬ患者１８例ＡＴＲＡ治疗中血浆ＩＬ－８水平（ＥＬＩＳＡ法）取３例骨髓单个核细胞（ＭＮＣ）加ＡＴＲＡ（１０＾－６ｍｍｏｌ／Ｌ）体外诱导，流式细胞仪动态检测ＭＮＣ膜Ｌ－８ＲＡ的表达。结果：ＭＮＣ加入ＡＴＲＡ诱导７２小时，上清ＩＬ－８水平明显     

CNS relapses of acute promyelocytic leukemia after all-trans retinoic acid

OBJECTIVE: To review the role of all-trans retinoic acid (ATRA) and arsenic trioxide in central nervous system (CNS) relapses of acute promyelocytic leukemia (APL). CASE SUMMARY: A 69-year-old white man diagnosed with APL presented with bleeding diathesis. His molecular and cytogenetic studies were positive for promyelocytic leukemia-retinoic acid receptoralpha (PML-RARalpha) and t(15;17) transformation. Complete molecular and cytogenetic remission was achieved with ATRA, daunorubicin, and cytarabine. Within 6 months, the patient was readmitted for investigation of severe global headaches and an ataxic gait. His peripheral blood and cerebral spinal fluid were positive for PML-RARalpha fusion protein. Intrathecal chemotherapy and radiation, as well as ATRA, were the main treatment modalities provided. Molecular and cytogenetic remission was again obtained. Three months later, a second relapse occurred in the CNS and the peripheral blood. DISCUSSION: APL is typically treated with anthacycline-based chemotherapy and ATRA. Approximately 85-95% of patients achieve complete remission (CR); however, the relapse rate has been reported to be about 30-40%. A thorough literature search (MEDLINE, EMBASE, CANCERLIT, 1966-January 2002) revealed only 54 cases of extramedullary disease, of which 35 involved the CNS. CONCLUSIONS: The introduction of ATRA has improved patient survival dramatically. APL relapse, in general, has been in part attributable to repetitive or prolonged exposure to ATRA and the possibility of additional chromosomal changes, making the disease more refractory to treat. Given the evidence, one could argue that, with repeated ATRA treatment, CR duration may be shortened. However, limited data are available to guide the appropriate management of APL relapsed to the CNS with either ATRA, chemotherapy, or arsenic trioxide. In our opinion, treatment using arsenic trioxide is an unconventional option worthy of exploring.     

苦参碱对急性早幼粒细胞白血病细胞维甲酸耐药的逆转作用研究

目的 探讨苦参碱逆转急性早幼粒细胞白血病(APL)全反式维甲酸(ATRA)耐药的作用及可能的机制.方法 以ATRA敏感的APL细胞系NB4及其ATRA耐药株NB4-R1、NIM-R2作为研究对象.用MTT法明确苦参碱低毒性剂量,进一步计算ATRA联合100μmoL/L苦参碱作用前后细胞ATRA IC50值,明确苦参碱的逆转耐药倍数;用NBT还原实验分析不同浓度(10、8、6、4、2、1、mmol/L,100、10、1μmol/L)苦参碱联用1μmol/L ATRA对耐药细胞分化能力的影响,并观察细胞形态变化;Annexin V/PI染色流式细胞术检测不同浓度苦参碱联用1 μmol/L ATRA作用下细胞凋亡率.结果 ①苦参碱对NB4、NB4-R1、NB4-R2细胞的增殖抑制作用随浓度增加而增强,IC50值分别为(0.661±0.035)、(0.673±0.132)、(0.329±0.020)mmol/L;②联用100 μmol/L苦参碱能显著逆转NB4-R1细胞的耐药性(逆转耐药倍数为4.96±1.15),但不能增强NB4-R2细胞对ATRA的敏感性,甚至增强其耐药性(逆转耐药倍数为0.66±0.17);③苦参碱与1 μmol/L ATRA联用时,NB4、NB4-R1细胞的分化能力随苦参碱作用浓度的增大而增强,且在苦参碱为100 μmol/L时达到峰值(P<0.05),但对NB4-R2细胞无明显影响;④1 μmol/L ATRA联合苦参碱能显著提高NB4、NB4-R1细胞凋亡率(P<0.05和P<0.01),但对NB4-R2细胞同样无明显作用.结论 苦参碱能有效逆转NB4-R1细胞的ATRA耐药,可能与其协同ATRA诱导分化及促进细胞凋亡有关.苦参碱与ATRA联用非但不能缓解NB4-R2细胞的ATRA耐药,甚至可能加重耐药、阻断耐药细胞的凋亡过程.     

BCL-2 cooperates with promyelocytic leukemia retinoic acid receptor alpha chimeric protein (PMLRARalpha) to block neutrophil differentiation and initiate acute leukemia

The promyelocytic leukemia retinoic acid receptor alpha (PMLRARalpha) chimeric protein is associated with acute promyelocytic leukemia (APL). PMLRARalpha transgenic mice develop leukemia only after several months, suggesting that PMLRARalpha does not by itself confer a fully malignant phenotype. Suppression of apoptosis can have a central role in tumorigenesis; therefore, we assessed whether BCL-2 influenced the ability of PMLRARalpha to initiate leukemia. Evaluation of preleukemic animals showed that whereas PMLRARalpha alone modestly altered neutrophil maturation, the combination of PMLRARalpha and BCL-2 caused a marked accumulation of immature myeloid cells in bone marrow. Leukemias developed more rapidly in mice coexpressing PMLRARalpha and BCL-2 than in mice expressing PMLRARalpha alone, and all mice expressing both transgenes succumbed to leukemia by 7 mo. Although both preleukemic, doubly transgenic mice and leukemic animals had abundant promyelocytes in the bone marrow, only leukemic mice exhibited thrombocytopenia and dissemination of immature cells. Recurrent gain of chromosomes 7, 8, 10, and 15 and recurrent loss of chromosome 2 were identified in the leukemias. These chromosomal changes may be responsible for the suppression of normal hematopoiesis and dissemination characteristic of the acute leukemias. Our results indicate that genetic changes that inhibit apoptosis can cooperate with PMLRARalpha to initiate APL.     

All-trans retinoic acid (ATRA) therapeutical effect in acute promyelocytic leukemia.

All-trans retinoic acid (ATRA) is able to specifically differentiate acute promyelocytic leukemic cells (APL) in short-term culture. Patients with APL achieved complete remission within 1-3 months by a progressive maturation of leukemic cells. The advantages of this differentiation therapy are the rapid disappearance of the bleeding disorders and the absence of aplastic phase avoiding the early deaths occurring in 15-30% of patients with conventional chemotherapy. However, relapses occurred when ATRA alone was maintained. For this reason, a chemotherapy is added after complete remission obtained by ATRA. A pilot study on 27 patients was proposed with the sequential combination of ATRA and chemotherapy. A European trial randomizes conventional therapy to the sequential ATRA-chemotherapy protocol. Retinoic acid receptor (RAR alpha) is rearranged by the specific translocation t(15;17) of APL; a PCR technique was developed in order to ensure the diagnosis and to follow the minimal residual disease. Transfection experiment of the chimaeric gene inhibits the transactivation of the natural RAR. ATRA is able to revert the arrest of maturation perhaps through an increase of the expression of the normal allele of RAR, which could overpass the impairment induced by the chimaeric protein on target responsive elements. One of the steps of the repair is the modulation of programmed cell death (PCD). Bcl-2, a gene involved in the PCD, is modulated in in vitro studies, arguing for the engagement of the cell in the natural death. The beneficial effect of differentiation therapy is probably due to the induction of the natural death of the malignant cell.     

Rearrangements of the retinoic acid receptor alpha and promyelocytic leukemia zinc finger genes resulting from t(11;17)(q23;q21) in a patient with acute promyelocytic leukemia.

Cytogenetic study of a patient with acute promyelocytic leukemia (APL) showed an unusual karyotype 46,xy,t(11;17) (q23;21) without apparent rearrangement of chromosome 15. Molecular studies showed rearrangements of the retinoic acid receptor alpha (RAR alpha) gene but no rearrangement of the promyelocytic leukemia gene consistent with the cytogenetic data. Similar to t(15;17) APL, all-trans retinoic acid treatment in this patient produced an early leukocytosis which was followed by a myeloid maturation, but the patient died too early to achieve remission. Further molecular analysis of this patient showed a rearrangement between the RAR alpha gene and a newly discovered zinc finger gene named PLZF (promyelocytic leukemia zinc finger). The fusion PLZF-RAR alpha gene found in this case, was not found in DNA obtained from the bone marrow of normals, APL with t(15;17) and in one patient with AML-M2 with a t(11;17). Fluorescence in situ hybridization using a PLZF specific probe localized the PLZF gene to chromosomal band 11q23.1. Partial exon/intron structure of the PLZF gene flanking the break point on chromosome 11 was also established and the breakpoint within the RAR alpha gene was mapped approximately 2 kb downstream of the exon encoding the 5' untranslated region and the unique A2 domain of the RAR alpha 2 isoform.     

急性早幼粒细胞白血病基因分析

目的：分析急性早幼粒细胞白血病（ＡＰＬ）患者经全反式维甲酸（ＡＴＲＡ）联合细胞毒药物及异基因骨髓移植（ａｌｏ－ＢＭＴ）治疗后融合基因的变化。方法：采用逆转录－多聚酶链反应（ＲＴ－ＰＣＲ）对２２例ＡＰＬ患者治疗前后ＲＡＲα／ＰＭＬ融合基因进行检测。其中１２例患者为单纯化疗，１０例接受了ａｌｏ－ＢＭＴ，９例患者于第１次完全缓解（ＣＲ１）期、１例于第１次复发（ＲＲ１）期接受了ａｌｏ－ＢＭＴ。结果：单纯维甲酸诱导完全缓解时，７５％ＡＰＬ患者融合基因仍然阳性；继用强化疗后８３％患者融合基因转为阴性，ＲＴ－ＰＣＲ转阴时间为发病后１～３９个月；ａｌｏ－ＢＭＴ后４个月内及４个月后，分别有６２．５％及８５．７％患者融合基因转阴。结论：化疗及ＢＭＴ均可使患者融合基因转阴，ａｌｏ－ＢＭＴ似乎能更快地清除体内白血病细胞