Immunological detection of myeloperoxidase in poorly differentiated acute leukemia

Abstract: We performed immunocytochemical detection of myeloperoxidase (MPO), using monoclonal antibody MPO-7, in 15 consecutive cases of adult acute leukemia (AL) unclassified by conventional cytological and cytochemical criteria and 7 AML-M, with less than 10% of cytochemically MPO-positive blasts. In AL with negative MPO cytochemistry the anti-MPO reaction was positive in 5 of the 15 patients with 3, 3, 7, 11 and 45% positive blasts respectively. In AML-M₁, immunocytochemistry was positive in a larger percentage of blasts than cytochemistry in 2 cases. Immunological detection of myeloid surface markers was positive in all 15 cases of unclassified AL (including the 10 AL with negative anti-MPO reaction). Eleven of the 22 patients from this study had mixed lymphoid-myeloid phenotype. Discrepancy between immunological MPO detection and light cytochemistry was more frequent in patients with mixed immunophenotype than in patients without lymphoid markers. No relationship between MPO-antigen positivity and clinical or biological features was seen. These findings confirm immunological detection of MPO as useful for the diagnosis of poorly differentiated AL. The high incidence of inactive MPO detectable only by immunocytochemistry in mixed lineage AL needs to be confirmed.     

WT1基因在白血病患者中的表达

目的 研究急性白血病（ＡＬ）患者中ＷＴ１基因的表达情况及其与预后的关系。方法 用逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）的方法,研究ＷＴ１基因在１０２例ＡＬ中的表达。结果 ＲＴ－ＰＣＲ检测ＷＴ１基因的敏感性为１０＾－４。ＷＴ１基因在ＡＬ所有亚型中都有表达,初治和复发的ＡＬ中阳性率为６６．７％,而在５年长期生存者中阳性率只有７．７％（４／５２）。随着完全缓解（ＣＲ）时间的延长,ＷＴ１基因阳性率有所下降,     

DNA methylation-independent loss of RARA gene expression in acute myeloid leukemia

The retinoic acid receptor (RAR) alpha gene (RARA) encodes 2 major isoforms and mediates positive effects of all-trans retinoic acid (ATRA) on myelomonocytic differentiation. Expression of the ATRA-inducible (RARalpha2) isoform increases with myelomonocytic differentiation and appears to be down-regulated in many acute myeloid leukemia (AML) cell lines. Here, we demonstrate that relative to normal myeloid stem/progenitor cells, RARalpha2 expression is dramatically reduced in primary AML blasts. Expression of the RARalpha1 isoform is also significantly reduced in primary AML cells, but not in AML cell lines. Although the promoters directing expression of RARalpha1 and RARalpha2 are respectively unmethylated and methylated in AML cell lines, these regulatory regions are unmethylated in all the AML patient cell samples analyzed. Moreover, in primary AML cells, histones associated with the RARalpha2 promoter possessed diminished levels of H3 acetylation and lysine 4 methylation. These results underscore the complexities of the mechanisms responsible for deregulation of gene expression in AML and support the notion that diminished RARA expression contributes to leukemogenesis.     

Dysregulated gene expression networks in human acute myelogenous leukemia stem cells

We performed the first genome-wide expression analysis directly comparing the expression profile of highly enriched normal human hematopoietic stem cells (HSC) and leukemic stem cells (LSC) from patients with acute myeloid leukemia (AML). Comparing the expression signature of normal HSC to that of LSC, we identified 3,005 differentially expressed genes. Using 2 independent analyses, we identified multiple pathways that are aberrantly regulated in leukemic stem cells compared with normal HSC. Several pathways, including Wnt signaling, MAP Kinase signaling, and Adherens Junction, are well known for their role in cancer development and stem cell biology. Other pathways have not been previously implicated in the regulation of cancer stem cell functions, including Ribosome and T Cell Receptor Signaling pathway. This study demonstrates that combining global gene expression analysis with detailed annotated pathway resources applied to highly enriched normal and malignant stem cell populations, can yield an understanding of the critical pathways regulating cancer stem cells.     

急性白血病BCL-2基因的表达及临床意义

目的：探讨急性白血病患者BCL-2基因的表达及临床意义。方法：应用逆转录-聚合酶链反应（RT-PCR）检测40例急性白血病患者细胞中BCL-2基因的表达。结果：BCL-2基因的表达水平与患者的年龄，性别，淋巴结肿大，肝脾肿大，出血，生化乳酸脱氢酶LDH，白血病分型及初治或复发难治等因素无关，但与患者骨髓中原幼细胞数呈正相关，除7例急性早幼粒细胞白血病患者外，BCL-2基因高表达患者完全缓解率（CR）低于低表达者。结论：BCL-2基因的表达对于预测白血病细胞耐药，判断预后，评估化疗反应及选择化疗方案均有十分重要的意义。     

Classification of pediatric acute lymphoblastic leukemia by gene expression profiling

Contemporary treatment of pediatric acute lymphoblastic leukemia (ALL) requires the assignment of patients to specific risk groups. We have recently demonstrated that expression profiling of leukemic blasts can accurately identify the known prognostic subtypes of ALL, including T-cell lineage ALL (T-ALL), E2A-PBX1, TEL-AML1, MLL rearrangements, BCR-ABL, and hyperdiploid karyotypes with more than 50 chromosomes. As the next step toward developing this methodology into a frontline diagnostic tool, we have now analyzed leukemic blasts from 132 diagnostic samples using higher density oligonucleotide arrays that allow the interrogation of most of the identified genes in the human genome. Nearly 60% of the newly identified subtype discriminating genes are novel markers not identified in our previous study, and thus should provide new insights into the altered biology underlying these leukemias. Moreover, a proportion of the newly selected genes are highly ranked as class discriminators, and when incorporated into class-predicting algorithms resulted in an overall diagnostic accuracy of 97%. The performance of an array containing the identified discriminating genes should now be assessed in frontline clinical trials in order to determine the accuracy, practicality, and cost effectiveness of this methodology in the clinical setting.     

Clinical significance of low levels of myeloperoxidase positivity in childhood acute nonlymphoblastic leukemia

The clinical significance of a low percentage of myeloperoxidase- positive blast cells in childhood acute nonlymphoblastic leukemia was determined. Of 155 consecutive cases studied by cytochemical staining methods, 14 were characterized by 4% to 15% (median 6%) myeloperoxidase- positive blasts. All 14 cases showed reactivity to Sudan black B stain, and 7 had Auer rods. The morphological subtypes of leukemia were M1 (8 cases), M2 (3), M4 (1), and M5 (2). Immunological marker studies disclosed the lymphoid-associated T11 antigen on cells from 8 of the 11 cases tested. Other lymphoid-related findings in these 8 cases included the T3 antigen and E rosette formation in 1 case each. Among cases that were prospectively studied for the expression of lymphoid-associated markers, 6 of 8 with low levels of myeloperoxidase positivity compared with only 1 of 44 with higher levels (greater than 15%) possessed such features (P less than 0.001). We conclude that low levels of myeloperoxidase reactivity distinguish cases of acute leukemia in which the blast cells coexpress lymphoid (T11 antigen) and myeloid markers.     

Distinct gene expression profiles determine molecular treatment response in childhood acute lymphoblastic leukemia

Treatment resistance, as indicated by the presence of high levels of minimal residual disease (MRD) after induction therapy and induction consolidation, is associated with a poor prognosis in childhood acute lymphoblastic leukemia (ALL). We hypothesized that treatment resistance is an intrinsic feature of ALL cells reflected in the gene expression pattern and that resistance to chemotherapy can be predicted before treatment. To test these hypotheses, gene expression signatures of ALL samples with high MRD load were compared with those of samples without measurable MRD during treatment. We identified 54 genes that clearly distinguished resistant from sensitive ALL samples. Genes with low expression in resistant samples were predominantly associated with cell-cycle progression and apoptosis, suggesting that impaired cell proliferation and apoptosis are involved in treatment resistance. Prediction analysis using randomly selected samples as a training set and the remaining samples as a test set revealed an accuracy of 84%. We conclude that resistance to chemotherapy seems at least in part to be an intrinsic feature of ALL cells. Because treatment response could be predicted with high accuracy, gene expression profiling could become a clinically relevant tool for treatment stratification in the early course of childhood ALL.     

PTTG蛋白在急性白血病患者中表达的研究

目的:研究垂体瘤转化基因(pituitary tumor transforming gene, PTTG)蛋白在急性白血病(acuteleukemia,AL)患者中的表达,探讨其与白血病发生的关系。方法:采用SABC免疫组织化学方法测定47 例初诊患者及10例骨髓象正常患者骨髓单个核细胞(BMMNC)中PTTG蛋白的表达。结果:AL初诊患者BMMNC中PTTG蛋白表达水平显著高于正常对照(P<0.05);异常染色体核型组高于无异常染色体核型组(P<0.05);治疗后达完全缓解(CR)组其PTTG蛋白表达低于未完全缓解(NR)组。结论:AL患者中PTTG蛋白的异常表达和AL的发生相关,其表达水平可反映患者的预后。     

急性白血病患者Survivin基因表达与耐药的关系

目的　探讨急性白血病 (AL)患者Survivin基因表达及其与临床耐药的关系。方法　应用半定量RT PCR方法检测 71例急性白血病患者 ,10例健康人的Survivin、mdr1基因mRNA表达水平 ,并分析其临床意义。结果　AL患者Survivin、mdr1mRNA表达阳性率分别为 67.61%和 49.3 0 %。急性淋巴细胞白血病 (ALL)和急性非淋巴细胞白血病 (ANLL)患者SurvivinmRNA表达阳性率均高于对照组 (分别为P <0 .0 1,P <0 .0 5 )。半定量后进行方差分析 ,ANLL和ALL患者SurvivinmRNA表达水平 (分别为 0 .64± 0 .2 1,0 .63± 0 .15 )均高于对照组 ( 0 .3 3± 0 .0 1,P <0 .0 5 )。耐药组患者SurvivinmRNA表达阳性率高于敏感组 (P <0 .0 5 )。Survivin阳性mdr1阳性患者耐药比例 ( 73 .0 8% )明显高于Survivin阴性mdr1阴性患者 ( 3 1.2 5 % ,P <0 .0 1)。在 61例初治和复发AL患者Sur vivinmRNA表达水平和mdr1mRNA表达水平呈高度正相关 (r =0 .75 4,P <0 .0 0 1)与骨髓白血病细胞百分比呈正相关 (r =0 .3 89,P =0 .0 0 5 )。结论　Survivin基因在AL患者呈高表达 ,与临床耐药密切相关 ,有望成为AL靶向治疗的一个潜在靶点     

Acute lymphoblastic leukemia with myeloperoxidase activity

The French-American-British (FAB) classification of acute leukemias is based on the light microscopic detection of myeloperoxidase (MPO) activity in blast cells. Cells with MPO activity in >3% of cells are classified as acute myeloid leukemia (AML) and usually express myeloid cell surface antigens. We describe a case of acute leukemia in which the blast cells have lymphoid morphology, ultrastructure, immunophenotype, and molecular rearrangements, but express significant amounts of MPO. We discuss the incidence, features, and outcome of MPO-positive acute lymphoblastic leukemia (ALL). © 1996 Wiley-Liss, Inc.