The percentage of myeloperoxidase-positive blast cells is a strong independent prognostic factor in acute myeloid leukemia, even in the patients with normal karyotype

A Hypochlorite-Activated Theranostic Prodrug for Selective Imaging of High Myeloperoxidase Expression Acute Myeloid Leukemia Cells and Drug Release

Acute myeloid leukemia (AML) is a fatal hematologic disease. Diagnosis and proper treatment are important for prognosis. High myeloperoxidase (MPO) expression AML cells are characterized with high levels of hypochlorite (ClO-). In this study, we report a ClO--activated theranostic agent, FNC, for AML therapy. FNC responds to ClO- specifically in high MPO expression AML cells, resulting in bright fluorescence and chlorambucil release. FNC can be used to quickly distinguish high MPO expression AML cells from other cells, including low MPO expression leukemia and activated inflammatory cells. FNC exhibits selective toxicity to highly MPO expression AML cells and can efficiently inhibit tumor growth. Meanwhile, FNC can be used to indicate differentiation through the detection of ClO-.

Xanthene-Based Dyes for Photoacoustic Imaging and their Use as Analyte-Responsive Probes

Developing imaging tools that can report on the presence of disease-relevant analytes in multicellular organisms can provide insight into fundamental disease mechanisms as well as provide diagnostic tools for the clinic. Photoacoustic imaging (PAI) is a light-in, sound-out imaging technique that allows for high resolution, deep-tissue imaging with applications in pre-clinical and point-of-care settings. The continued development of near-infrared (NIR) absorbing small-molecule dyes promises to improve the capabilities of this emerging imaging modality. For example, new dye scaffolds bearing chemoselective functionalities are enabling the detection and quantification of disease-relevant analytes through activity-based sensing (ABS) approaches. Recently described strategies to engineer NIR absorbing xanthenes have enabled development of analyte-responsive PAI probes using this classic dye scaffold. Herein, we present current strategies for red-shifting the spectral properties of xanthenes via bridging heteroatom or auxochrome modifications. Additionally, we explore how these strategies, coupled with chemoselective spiroring-opening approaches, have been employed to create ABS probes for in vivo detection of hypochlorous acid, nitric oxide, copper (II), human NAD(P)H: quinone oxidoreductase isozyme 1, and carbon monoxide. Given the versatility of the xanthene scaffold, we anticipate continued growth and development of analyte-responsive PAI imaging probes based on this dye class.

Regulation of coagulation activation in newly diagnosed AML by the heme enzyme myeloperoxidase

INTRODUCTION

Patients with acute myeloid leukemia (AML) are at increased risk of thrombohemorrhagic complications. Overexpressed tissue factor (TF) on AML blasts contributes to systemic coagulation activation. We have recently shown that the heme enzyme myeloperoxidase (MPO) negatively regulates TF procoagulant activity (PCA) on myelomonocytic cells in vitro. We now aimed to further characterize the functional interaction of MPO and TF in AML in vivo.

METHODS

We prospectively recruited 66 patients with newly diagnosed AML. TF PCA of isolated peripheral blood mononuclear cells (PBMC) was assessed by single-stage clotting assay in the presence or absence of inhibitors against MPO catalytic activity (ABAH) or against MPO-binding integrins (anti-CD18). MPO in plasma and in AML blasts was measured by ELISA, and plasma D-dimers and prothrombin fragment F1+2 were quantified by automated immunoturbidimetric and chemiluminescence assays, respectively.

RESULTS

Patients with AML had significantly higher MPO plasma levels compared to healthy controls and exhibited increased levels of D-dimers and F1+2. In vivo thrombin generation was mediated by TF PCA on circulating PBMC. Ex vivo incubation of isolated PBMC with ABAH or anti-CD18 antibody resulted in either increased or decreased TF PCA. The strong and robust correlation of F1+2 with TF PCA of circulating PBMC was abrogated at MPO plasma levels higher than 150 ng/mL, indicating a modulatory role for MPO on TF-mediated in vivo thrombin generation above this threshold.

CONCLUSION

Our study indicates that catalytically active MPO released by circulating myeloblasts regulates TF-dependent coagulation in patients with newly diagnosed AML in a CD18-dependent manner.

Correlation Analysis and Prognostic Impacts of Biological Characteristics in Elderly Patients with Acute Myeloid Leukemia

Background

The significant heterogeneity of elderly AML patients’ biological features has caused stratification difficulties and adverse prognosis. This paper did a correlation study between their genetic mutations, clinical features, and prognosis to further stratify them.

Methods

90 newly diagnosed elderly acute myeloid leukemia (AML) patients (aged ≥60 years) who detected genetic mutations by next-generation sequencing (NGS) were enrolled between April 2015 and March 2021 in our medical center.

Results

A total of 29 genetic mutations were identified in 82 patients among 90 cases with a frequency of 91.1%. DNMT3A, BCOR, U2AF1, and BCORL1 mutations were unevenly distributed among different FAB classifications (p < 0.05). DNMT3A, IDH2, NPM1, FLT3-ITD, ASXL1, IDH1, SRSF2, BCOR, NRAS, RUNX1, U2AF1, MPO, and WT1 mutations were distributed differently when an immunophenotype was expressed or not expressed (p<0.05). NPM1 and FLT3-ITD had higher mutation frequencies in patients with normal chromosome karyotypes than abnormal chromosome karyotypes (p<0.001, p=0.005). DNMT3A and NRAS mutations predicted lower CR rates. DNMT3A, TP53, and U2AF1 mutations were related to unfavorable OS. TET2 mutation with CD123+, CD11b+ or CD34- predicted lower CR rate. IDH2+/CD34- predicted lower CR rate. ASXL1+/CD38+ and SRSF2+/CD123- predicted shorter OS.

Conclusion

The study showed specific correlations between elderly AML patients’ genetic mutations and clinical features, some of which may impact prognosis.

NADH dehydrogenase subunit 1/4/5 promotes survival of acute myeloid leukemia by mediating specific oxidative phosphorylation

Acute myeloid leukemia (AML) is a type of hematological malignancy caused by uncontrolled clonal proliferation of hematopoietic stem cells. The special energy metabolism mode of AML relying on oxidative phosphorylation is different from the traditional ‘Warburg effect’. However, its mechanism is not clear. In the present study, it was demonstrated that the mRNA expression levels of NADH dehydrogenase subunit 1, 4 and 5 (ND1, ND4 and ND5) were upregulated in AML samples from The Cancer Genome Atlas database using the limma package in the R programming language. Reverse transcription-quantitative PCR and ELISA were used to verify the upregulation of ND1, ND4 and ND5 in clinical samples. Pan-cancer analysis revealed that the expression of ND1 was upregulated only in AML, ND2 was upregulated only in AML and thymoma, and ND4 was upregulated only in AML and kidney chromophobe. In the present study, it was demonstrated that silencing of ND1/4/5 could inhibit the proliferation of AML cells in transplanted tumor of nude mice. Additionally, it was found that oxidative phosphorylation and energy metabolism of AML cells were decreased after silencing of ND1/4/5. In conclusion, the present study suggested that ND1/4/5 may be involved in the regulation of oxidative phosphorylation metabolism in AML as a potential cancer-promoting factor.

Residual disease is a strong prognostic marker in patients with acute lymphoblastic leukaemia with chemotherapy-refractory or relapsed disease prior to allogeneic stem cell transplantation

Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is one of the curative treatment options for acute lymphoblastic leukaemia (ALL). However, the outcomes in patients transplanted without complete remission (non-CR) have not yet been fully reported, and detailed analyses are required to identify subgroups in which optimal prognosis is expected and to optimize pre-transplant therapeutic strategies. Hence, we performed a multicentred retrospective cohort study including a total of 663 adult ALL patients transplanted at non-CR status; the median bone marrow (BM) blast counts at HSCT was 13·2%, and 203 patients (30·6%) were treated at primary induction failure status. The overall survival (OS) was 31·1% at two years, and the multivariate analyses identified five prognostic risk factors, including older age (≥50 years), increased BM blasts (≥10%), poor performance status, high haematopoietic cell transplantation (HCT)-comorbidity index, and relapsed disease status, among which BM blast was the most significantly related. A predictive scoring system composed of these risk factors clearly stratified OS (15·6-59·5% at two years). In conclusion, this is the first large-scale study to analyze the correlation of patient characteristics with post-transplant prognosis in ALL transplanted at non-CR status. The importance of blast control before HSCT should be focused on for better patient prognosis.

Bioinformatics Analysis Identifies Key Genes and Pathways in Acute Myeloid Leukemia Associated with DNMT3A Mutation

Background

DNA methyltransferase 3 alpha (DNMT3A) mutation was one of the most frequent genetic alterations in acute myeloid leukemia (AML), which was associated with poor prognosis and appeared to be a potential biomarker. Herein, we aimed to identify the key genes and pathways involved in adult AML with DNMT3A mutations and to find possible therapeutic targets for improving treatment.

Methods

The RNA sequencing datasets of 170 adult AML patients were obtained from The Cancer Genome Atlas (TCGA) database. EdgeR of the R platform was used to identify the differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed by Metascape and DAVID. And protein-protein interaction (PPI) network and clustering modules were analyzed with the STRING database and Cytoscape software.

Results

Mutated DNMT3A resulted in a shorter overall survival (OS) in AML patients and obviously associated with age, blast percentage in peripheral blood, and FLT3 mutation. A total of 283 DEGs were detected, of which 95 were upregulated and 188 were downregulated. GO term analysis showed that DEGs were significantly enriched in neutrophil degranulation, myeloid cell differentiation, stem cell proliferation, positive regulation of neurological system process, leukocyte migration, and tissue morphogenesis. KEGG pathway enrichment analysis indicated that the pathway of cancer, PI3K-Akt signaling pathway, and transcriptional misregulation in cancer may play a crucial role in DNMT3A mutation AML. Seven hub genes (BMP4, MPO, THBS1, APP, ELANE, HOXA7, and VWF) had a significant prognostic value.

Conclusion

Bioinformatics analysis in the present study provided novel targets for early diagnosis and new strategies for treatment for AML with DNMT3A mutation.

Weighted General Group Lasso for Gene Selection in Cancer Classification

Relevant gene selection is crucial for analyzing cancer gene expression datasets including two types of tumors in cancer classification. Intrinsic interactions among selected genes cannot be fully identified by most existing gene selection methods. In this paper, we propose a weighted general group lasso (WGGL) model to select cancer genes in groups. A gene grouping heuristic method is presented based on weighted gene co-expression network analysis. To determine the importance of genes and groups, a method for calculating gene and group weights is presented in terms of joint mutual information. To implement the complex calculation process of WGGL, a gene selection algorithm is developed. Experimental results on both random and three cancer gene expression datasets demonstrate that the proposed model achieves better classification performance than two existing state-of-the-art gene selection methods.

Targeting Myeloperoxidase Disrupts Mitochondrial Redox Balance and Overcomes Cytarabine Resistance in Human Acute Myeloid Leukemia

Chemotherapies alter cellular redox balance and reactive oxygen species (ROS) content. Recent studies have reported that chemoresistant cells have an increased oxidative state in hematologic malignancies. In this study, we demonstrated that chemoresistant acute myeloid leukemia (AML) cells had a lower level of mitochondrial and cytosolic ROS in response to cytarabine (AraC) and overexpressed myeloperoxidase (MPO), a heme protein that converts hydrogen peroxide to hypochlorous acid (HOCl), compared with sensitive AML cells. High MPO-expressing AML cells were less sensitive to AraC in vitro and in vivo. They also produced higher levels of HOCl and exhibited an increased rate of mitochondrial oxygen consumption when compared with low MPO-expressing AML cells. Targeting MPO expression or enzyme activity sensitized AML cells to AraC treatment by triggering oxidative damage and sustaining oxidative stress, particularly in high MPO-expressing AML cells. This sensitization stemmed from mitochondrial superoxide accumulation, which impaired oxidative phosphorylation and cellular energetic balance, driving apoptotic death and selective eradication of chemoresistant AML cells in vitro and in vivo. Altogether, this study uncovers a noncanonical function of MPO enzyme in maintaining redox balance and mitochondrial energetic metabolism, therefore affecting downstream pathways involved in AML chemoresistance. SIGNIFICANCE: These findings demonstrate the role of myeloperoxidase in the regulation of ROS levels and sensitivity of AML cells to cytarabine, an essential chemotherapeutic backbone in the therapy of AML.

Cellular immunotherapy for acute myeloid leukemia: How specific should it be?

Significant improvements in the survival of patients with hematological cancers following hematopoietic stem cell transplantation provide evidence supporting the potency of immune cell-mediated anti-leukemic effects. Studies focusing on immune cell-based cancer therapies have made significant breakthroughs in the last few years. Adoptive cellular therapy (ACT), and chimeric antigen receptor (CAR) T cell therapy, in particular, has significantly increased the survival of patients with B cell acute lymphoblastic leukemia and aggressive B cell lymphoma. Despite antigen-negative relapses and severe toxicities such as cytokine release syndrome after treatment, CAR-T cell therapies have been approved by the FDA in some conditions. Although a number of studies have tried to achieve similar results for acute myeloid leukemia (AML), clinical outcomes have not been as promising. In this review, we summarize recent and ongoing studies on cellular therapies for AML patients, with a focus on antigen-specific versus -nonspecific approaches.

[Correlation between myeloperoxidase expression and gene alterations and prognosis in acute myeloid leukemia]

Objective: To analyze the percentage of myeloperoxidase (MPO)-positive acute myeloid leukemia (AML) blast cells, and to explore the correlation of MPO expression with the clinical features, gene alterations, therapeutic response and prognosis of AML. Methods: The expressions of MPO in BM blasts cells of 233 newly diagnosed AML were retrospectived analyzed, they were divided into two groups using the percentage of MPO-positive blast [low (≤70%) and high (>70%)], clinical features, gene alterations, chemotherapy efficacy and prognosis were compared between the two groups. Results: ①Of the 233 patients, 121(51.9%) were in the low MPO group, and the rest 112(48.1%) in the high MPO group. Favorable-risk group according NCCN guidelines of AML was always MPO-high (χ(2)=32.773, P<0.001), while MPO-low was closely related to poor-risk (χ(2)=7.078, P=0.008); ②DNMT3A mutation (χ(2)=6.905, P=0.009), spliceosome genes mutation (SF3B1/SRSF2/U2AF1) (χ(2)=5.246, P=0.022), RUNX1 mutation (χ(2)=4.577, P=0.032), ASXL1 mutation (χ(2)=7.951, P=0.005) and TP53 mutation (P=0.004) were more likely to be seen in the low MPO group, while C-KIT mutation (χ(2)=8.936, P=0.003) and CEBPA mutation (χ(2)=12.340, P<0.001) were more frequent in the high MPO group, especially CEBPA double mutation; ③The rates of first complete remission in the low MPO group were significantly lower than that in the high MPO group (38.8% vs 68.1%, χ(2)=15.197, P<0.001). Multivariate analysis showed that low MPO positivity significantly affected the CR(1) unfavourably. ④The overall survival (OS) and the progression-free survival (PFS) were significantly worse in the low MPO group (18.0% vs 89.4% for OS, and 11.5% vs 56.7% for PFS, P<0.001). Multivariate analysis disclosed that the low number of MPO was significantly unfavourable prognostic factor. ⑤The low MPO group still showed a worse survival even when restricted to the patients with normal karyotype, the OS and the PFS were 31.1% and 18.8% respectively. Conclusions: AML with different MPO expression percentage had a unique gene mutation spectrum. Low expression of MPO was an independent risk factor for CR(1), OS and PFS in AML patients, which may be a simple and highly significant factor for AML patients when evaluating the therapeutic efficacy and prognosis.

Distinct gene alterations with a high percentage of myeloperoxidase-positive leukemic blasts in de novo acute myeloid leukemia

The myeloperoxidase (MPO)-positivity of blasts in bone marrow smears is an important marker for not only the diagnosis, but also the prognosis of acute myeloid leukemia (AML). To investigate the relationship between genetic alterations and MPO-positivity, we performed targeted sequencing for 51 genes and 10 chimeric gene transcripts in 164 newly diagnosed de novo AML patients; 107 and 57 patients were classified as AML with >50% MPO-positive blasts (MPO-high group) and ≤50% MPO-positive blasts, (MPO-low group), respectively. The univariate analysis revealed that RUNX1-RUNX1T1 (P < 0.001), the KIT mutation (P < 0.001), and CEBPA double mutation (P = 0.001) were more likely to be found in the MPO-high group, while the DNMT3A mutation (P = 0.001), FLT3 tyrosine kinase domain mutation (P = 0.004), and TP53 mutation (P = 0.020) were more likely to be present in the MPO-low group. Mutations in genes related to DNA hypermethylation signatures (IDH1, IDH2, TET2, and WT1 genes) were more frequent in the MPO-high group (P = 0.001) when patients with fusion genes of core-binding factors were excluded from the analysis. Our results suggest that MPO-positivity of blasts was related with the distinct gene mutation patterns among de novo AML patients.

Circulating cytokines and small molecules follow distinct expression patterns in acute myeloid leukaemia

Background:

Although aberrant expression of cytokines and small molecules (analytes) is well documented in acute myeloid leukaemia (AML), their co-expression patterns are not yet identified. In addition, plasma baselines for some analytes that are biomarkers for other cancers have not been previously reported in AML.

Methods:

We used multiplex array technology to simultaneously detect and quantify 32 plasma analyte (22 reported analytes and 10 novel analytes) levels in 38 patients.

Results:

In our study, 16 analytes are found to be significantly deregulated (13 higher, 3 lower, Mann–Whitney U-test, P-value <0.005), where 5 of them have never been reported before in AML. We predicted a seven-analyte-containing multiplex panel for diagnosis of AML and, among them, MIF could be a possible therapeutic target. In addition, we observed that circulating analytes show five co-expression signatures.

Conclusions:

Circulating analyte expression in AML significantly differs from normal, and follow distinct expression patterns.

biosigner: A New Method for the Discovery of Significant Molecular Signatures from Omics Data

High-throughput technologies such as transcriptomics, proteomics, and metabolomics show great promise for the discovery of biomarkers for diagnosis and prognosis. Selection of the most promising candidates between the initial untargeted step and the subsequent validation phases is critical within the pipeline leading to clinical tests. Several statistical and data mining methods have been described for feature selection: in particular, wrapper approaches iteratively assess the performance of the classifier on distinct subsets of variables. Current wrappers, however, do not estimate the significance of the selected features. We therefore developed a new methodology to find the smallest feature subset which significantly contributes to the model performance, by using a combination of resampling, ranking of variable importance, significance assessment by permutation of the feature values in the test subsets, and half-interval search. We wrapped our biosigner algorithm around three reference binary classifiers (Partial Least Squares—Discriminant Analysis, Random Forest, and Support Vector Machines) which have been shown to achieve specific performances depending on the structure of the dataset. By using three real biological and clinical metabolomics and transcriptomics datasets (containing up to 7000 features), complementary signatures were obtained in a few minutes, generally providing higher prediction accuracies than the initial full model. Comparison with alternative feature selection approaches further indicated that our method provides signatures of restricted size and high stability. Finally, by using our methodology to seek metabolites discriminating type 1 from type 2 diabetic patients, several features were selected, including a fragment from the taurochenodeoxycholic bile acid. Our methodology, implemented in the biosigner R/Bioconductor package and Galaxy/Workflow4metabolomics module, should be of interest for both experimenters and statisticians to identify robust molecular signatures from large omics datasets in the process of developing new diagnostics.

[Expression of cMPO in 502 cases of acute myeloid leukemia (AML) and its diagnosis significance in AML subtypes]

目的

探讨髓过氧化物酶（cMPO）在急性髓系白血病（AML）患者中的表达及其在诊断分型中的意义。

方法

采用CD45/SSC双参数散点图设门方法对502例AML患者进行八色流式细胞术免疫表型分析，观察患者白血病细胞cMPO表达的阳性率和阳性强度。

结果

502例AML患者cMPO总体阳性率为58.0%，其中阳性占21.5%，弱阳性占34.1%，部分阳性占2.4%；阴性占42.0%。各亚型中，AML伴t(15;17）（q22;q12）/PML-RARα的cMPO阳性率最高，为100%，阳性强度多数接近正常粒细胞水平；其次为AML伴t(8;21）（q22;q22）/RUNX1-RUNX1T1，阳性率为91.4%，阳性强度多为弱阳性；AML微分化型和急性巨核细胞白血病患者cMPO表达皆为阴性；余各亚型阳性率在22.7%~76.2%。

结论

各亚型AML cMPO的阳性率及阳性强度存在显著差异。

Association of -463G/A MPO gene polymorphism and risk of cervical intraepithelial neoplasia

PURPOSE

The MPO system plays an important role in the control of infections and the deletion of malignant cells. Nevertheless, alternations in the MPO system can lead to DNA damage and carcinogenesis. Polymorphisms in the MPO Gene have been associated with an increased expression of MPO and a higher risk for development of cancer. This study evaluates the association between -463G/A MPO gene polymorphism and the risk for CIN.

METHODS

The MPO gene polymorphism (-463G/A) was investigated in 616 women with cervical intraepithelial neoplasia and in 206 healthy women. Association between MPO gene polymorphism and risk of cervical intraepithelial neoplasia were analyzed by univariate and multivariable models.

RESULTS

No significant difference in genotype distribution of the MPO gene polymorphism was observed in women with CIN and controls (p = 0.4; OR 1.2, 95 % CI 0.8-1.6). A subgroup analysis only including women with CIN did not show an association between -463G/A MPO gene polymorphism and risk for high-grade CIN (CIN 2/3) (p = 0.09; OR 1.5, 95 % CI 0.9-2.3).

CONCLUSIONS

The investigated MPO gene polymorphism is not associated with risk for the development of cervical intraepithelial neoplasia.

Mitoxantrone, More than Just Another Topoisomerase II Poison

Mitoxantrone is a synthetic anthracenedione originally developed to improve the therapeutic profile of the anthracyclines and is commonly applied in the treatment of breast and prostate cancers, lymphomas, and leukemias. A comprehensive overview of the drug's molecular, biochemical, and cellular pharmacology is presented here, beginning with the cardiotoxic nature of its predecessor doxorubicin and how these properties shaped the pharmacology of mitoxantrone itself. Although mitoxantrone is firmly established as a DNA topoisomerase II poison within mammalian cells, it is now clear that the drug interacts with a much broader range of biological macromolecules both covalently and noncovalently. Here, we consider each of these interactions in the context of their wider biological relevance to cancer therapy and highlight how they may be exploited to further enhance the therapeutic value of mitoxantrone. In doing so, it is now clear that mitoxantrone is more than just another topoisomerase II poison.

Expression of myeloperoxidase in acute myeloid leukemia blasts mirrors the distinct DNA methylation pattern involving the downregulation of DNA methyltransferase DNMT3B

Myeloperoxidase (MPO) has been associated with both a myeloid lineage commitment and favorable prognosis in patients with acute myeloid leukemia (AML). DNA methyltransferase inhibitors (decitabine and zeburaline) induced MPO gene promoter demethylation and MPO gene transcription in AML cells with low MPO activity. Therefore, MPO gene transcription was directly and indirectly regulated by DNA methylation. A DNA methylation microarray subsequently revealed a distinct methylation pattern in 33 genes, including DNA methyltransferase 3 beta (DNMT3B), in CD34-positive cells obtained from AML patients with a high percentage of MPO-positive blasts. Based on the inverse relationship between the methylation status of DNMT3B and MPO, we found an inverse relationship between DNMT3B and MPO transcription levels in CD34-positive AML cells (P=0.0283). In addition, a distinct methylation pattern was observed in five genes related to myeloid differentiation or therapeutic sensitivity in CD34-positive cells from AML patients with a high percentage of MPO-positive blasts. Taken together, the results of the present study indicate that MPO may serve as an informative marker for identifying a distinct and crucial DNA methylation profile in CD34-positive AML cells.

Myeloperoxidase expression in acute myeloid leukemia helps identifying patients to benefit from transplant

PURPOSE

Despite extensive study, the use of allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia (AML) vary considerably. The decision of which of these options to choose is complex and depends on both clinical and molecular variables as well as the availability and histocompatability of donor stem cells. So far there is no clear explanation on whether the expression of myeloperoxidase (MPO) relates to the prognosis of AML.

MATERIALS AND METHODS

We retrospectively analyzed the prognostic significance of the MPO expression in the 140 patients with diagnosed AML treated at a single institution.

RESULTS

In our study, MPO expression was associated with disease-free survival (DFS) and transplant was beneficial to overcome a negative prognostic effect of MPO-negative at diagnosis based upon the result that the DFS in patients received transplants are not significant between the MPO-positive group and MPO-negative group although DFS in all patients was different according to MPO expression.

CONCLUSION

MPO expression at diagnosis helps to choose therapy for each AML patient and can differentiate AML patients who need transplantation.

Myeloperoxidase expression as a potential determinant of parthenolide-induced apoptosis in leukemia bulk and leukemia stem cells

Given that parthenolide (PTL) is an effective antileukemic agent, identifying molecular markers that predict response to PTL is important. We evaluated the role of myeloperoxidase (MPO) in determining the sensitivity of leukemia cells to PTL-induced apoptosis. In this study, the level of PTL-induced generation of reactive oxygen species (ROS) and apoptosis was significantly higher in the MPO-high leukemia cell lines compared with the MPO-low leukemia cell lines. Pretreatment of MPO-high leukemia cells with a MPO-specific inhibitor, 4-aminobenzoic acid hydrazide, or a MPO-specific small interfering RNA (siRNA) abrogated the PTL-induced ROS generation and apoptosis, indicating that MPO plays a crucial role in PTL-induced apoptosis in leukemia cells. PTL-induced apoptosis was accompanied by down-regulation of nuclear factor-κB, Bcl-xL, Mcl-1, X-linked inhibitor of apoptosis protein, and survivin and selectively observed in primary acute myeloid leukemia (AML) cells expressing higher levels of MPO (≥50%) while sparing both AML cells with lower MPO and normal CD34-positive (CD34+) normal bone marrow cells. The extent of PTL-induced apoptosis of the CD34+CD38- cell fraction was significantly greater in the MPO-high AML cases, compared with the MPO-low AML (P < 0.01) and normal CD34+ marrow cells (P < 0.01). Nonobese diabetic/severe combined immunodeficient human leukemia mouse model also revealed that PTL preferentially targets the MPO-high AML cells. Our data suggest that MPO plays a crucial role in determining the susceptibility of leukemia cells to PTL-induced apoptosis. PTL can be considered a promising leukemic stem cell-targeted therapy for AML expressing high levels of MPO.

Prognostic significance of myeloperoxidase expression in childhood acute myeloid leukemia

BACKGROUND

The percentage of myeloperoxidase (MPO)-positive blast cells is associated with prognosis in adult acute myeloid leukemia (AML), but this association is unsubstantiated in pediatric AML.

PROCEDURE

We retrospectively compared cytochemical MPO results with outcome in 154 patients younger than 21 years treated on three consecutive institutional protocols for newly diagnosed AML (1987-2001). Patients with FAB M0 and M7 AML (no MPO expression) or M3 AML (100% MPO expression) and Down's syndrome were excluded.

RESULTS

Median MPO expression was higher in FAB M2 subtype than in other subtypes (P < 0.0001) and differed significantly across cytogenetic risk groups (P = 0.002) with highest MPO expression among those with favorable karyotypes. The percentage of MPO-positive blasts was not significantly associated with the probability of complete remission (P = 0.97), event-free survival (P = 0.72), or survival (P = 0.76) in multivariate analyses that accounted for age, FAB subtype, presenting WBC count, cytogenetic and protocol treatment risk group. In analysis limited to patients with intermediate-risk cytogenetics, higher MPO expression appeared to be associated with improved EFS (P = 0.06) but was not associated with remission induction rate (P = 0.16) or overall survival (P = 0.38).

CONCLUSIONS

The percentage of MPO-positive blast cells is related to FAB subtype in pediatric AML but has limited prognostic relevance.

Expression of myeloperoxidase enhances the chemosensitivity of leukemia cells through the generation of reactive oxygen species and the nitration of protein

Myeloperoxidase (MPO), a pivotal lineage marker for acute myeloid leukemia (AML), has been also shown to have a prognostic value: a high percentage of MPO-positive blasts correlates to favorable prognosis. To understand the relationship between the expression of MPO in leukemia cells and the response to chemotherapeutic agents, we established MPO-expressing K562 leukemia cell lines and then treated them with cytosine arabinocide (AraC). Cells expressing wild-type MPO, but not mutant MPO that could not mature, died earlier of apoptosis than control K562 cells. Reactive oxygen species (ROS) were generated more in leukemia cells expressing MPO, and the generation was abrogated by MPO inhibitors or antioxidants. Tyrosine nitration of cellular protein also increased more in MPO-expressing K562 cells than control cells after treatment with AraC. In clinical samples, CD34-positive AML cells from high-MPO cases showed a tendency to be sensitive to AraC in the colony-formation assay, and the generation of ROS and the nitration of protein were observed only when the percentage of MPO-expressing cells was high. These data suggest that MPO enhances the chemosensitivity of AML through the generation of ROS and the nitration of proteins.

Diagnosis of acute myeloid leukemia according to the WHO classification in the Japan Adult Leukemia Study Group AML-97 protocol

We reviewed and categorized 638 of 809 patients who were registered in the Japan Adult Leukemia Study Group acute myeloid leukemia (AML)-97 protocol using morphological means. Patients with the M3 subtype were excluded from the study group. According to the WHO classification, 171 patients (26.8%) had AML with recurrent genetic abnormalities, 133 (20.8%) had AML with multilineage dysplasia (MLD), 331 (51.9%) had AML not otherwise categorized, and 3 (0.5%) had acute leukemia of ambiguous lineage. The platelet count was higher and the rate of myeloperoxidase (MPO)-positive blasts was lower in AML with MLD than in the other WHO categories. The outcome was significantly better in patients with high (≥50%) than with low (<50%) ratios of MPO-positive blasts (P < 0.01). The 5-year survival rates for patients with favorable, intermediate, and adverse karyotypes were 63.4, 39.1, and 0.0%, respectively, and 35.5% for those with 11q23 abnormalities (P < 0.0001). Overall survival (OS) did not significantly differ between nine patients with t(9;11) and 23 with other 11q23 abnormalities (P = 0.22). Our results confirmed that the cytogenetic profile, MLD phenotype, and MPO-positivity of blasts are associated with survival in patients with AML, and showed that each category had the characteristics of the WHO classification such as incidence, clinical features, and OS.

The cell growth, morphology and immunocytochemistry of novel cell line established from a bone marrow of the patient with therapy-related myelodysplastic syndrome, entitled PC-MDS

We report on cell growth, morphology, and immunocytochemistry of the first human cell line, PC-MDS, derived from a bone marrow of a patient with therapy-related myelodysplastic syndrome who had no overt leukemia post-MDS phase. This cell population consisted of fast-growing mononuclear cells. Standard cytochemistry methods for detection of MPO, lipids, glycogen and ANAE gave results as follows: MPO and SBB negative while PAS and ANAE positive. Positive cytochemical staining and immunophenotype analyses indicated that PC-MDS cells have some characteristics of the early myeloid precursor cell. As the first t-MDS derived cell line it could be a new tool in evaluation of complex biology of MDS and also serves as a model for diverse in-vitro research.

Myeloperoxidase Is a Key Regulator of Oxidative Stress–Mediated Apoptosis in Myeloid Leukemic Cells

PURPOSE

We reported previously that reactive oxygen species (ROS) are key mediators of apoptosis induced by a polyphenol, (-)-epigallocatechin-3-gallate (EGCG), in myeloid leukemic cells. This study aimed to further examine the mechanism of ROS-mediated apoptosis induced by EGCG and its relationship to the heme enzyme myeloperoxidase (MPO).

EXPERIMENTAL DESIGN

We established stably transfected K562 cells expressing wild-type and mutant MPO. Then, sensitivity against EGCG and other ROS-inducing agent was examined and further investigated the detailed molecular mechanism of ROS-inducing apoptosis in MPO-positive leukemic cells.

RESULTS

EGCG rapidly induced apoptosis in MPO-positive leukemia cells. Preincubation of myeloid leukemic cells with the MPO-specific inhibitor, 4-aminobenzoic acid hydrazide, and the heme biosynthesis inhibitor, succinylacetone, resulted in inhibition of the intracellular MPO activity, ROS production, and induction of apoptosis following addition of EGCG. Overexpression of MPO sensitized EGCG-resistant K562 cells to apoptosis induced by EGCG. In contrast, an enzymatically inactive MPO mutant-expressing K562 cell could not respond to EGCG, suggesting that MPO is important for determining the sensitivity to EGCG-induced oxidative stress. Hypochlorous acid scavengers and the hydroxyl radical (.OH) scavenger inhibited EGCG-induced apoptosis in myeloid leukemic cells. The fluorescence intensity of both aminophenyl fluorescein- and hydroxyphenyl fluorescein-loaded myeloid leukemic cells significantly increased on stimulation with EGCG, indicating that EGCG generated highly toxic ROS in myeloid leukemic cells.

CONCLUSIONS

These results indicated that highly toxic ROS such as .OH generated via the hydrogen peroxide/MPO/halide system induce apoptosis and that ROS may be the direct mediators of EGCG-induced apoptosis in MPO-positive leukemic cells.

Characteristics of novel myeloid precursor cell line, PC-MDS, established from a bone marrow of the patient with therapy-related myelodysplastic syndrome

We report on characteristics of the first human cell line, PC-MDS, derived from a bone marrow of a patient with therapy-related myelodysplastic syndrome (t-MDS) who had no overt post-MDS leukemia. Classic cytology analyses, immunophenotyping, cytogenetic and molecular genetic procedures were used for characterization of the cell line. PC-MDS cells are positive for the expression of CD13, CD15, CD30, CD33, and CD45 antigen. Positive cytochemical staining and immunophenotype analyses indicated that PC-MDS cells have some characteristics of the early myeloid precursor cell. The karyotype analysis of PC-MDS cell line revealed various numerical and structural changes including those typically associated with t-MDS: del(5)(q13)[7], der(5)t(5;11)(p11;q11)[13], -7[6], del(7)(q31)[2], +20[3], -20[4]. Evaluation of methylation status in a promoter region of p15, p16 and MGMT genes showed biallelic hypermethylation pattern of 5' promoter region only in MGMT gene. PC-MDS is the first t-MDS derived cell line, and based on its immunological, cytogenetic and molecular characterization could be a new tool in evaluation of complex biology of MDS and a model for methylation studies.

Expression of the myeloperoxidase gene in AC133 positive leukemia cells relates to the prognosis of acute myeloid leukemia

We previously reported that the percentage of myeloperoxidase (MPO) positive blasts had a prognostic impact on survival of patients with acute myeloid leukemia (AML). To extend this observation, we quantitatively measured the level of the MPO gene in AC133 positive leukemia cells that would contain a putative AML stem/progenitor compartment. AML cases were divided into the MPO gene high (MPOg-H) and MPO gene low (MPOg-L) groups. Only patients belonging to the MPOg-H group had a favorable chromosomal translocation, t(8;21), and having no morphological dysplasia that was associated with MPOg-L. The difference in the survival of MPOg-H and MPOg-L was statistically meaningful, demonstrating the possible prognostic impact of the expression of MPO gene in AC133 positive leukemia cells.

Histone deacetylase inhibitor depsipeptide (FK228) induces apoptosis in leukemic cells by facilitating mitochondrial translocation of Bax, which is enhanced by the proteasome inhibitor bortezomib

Histone deacetylase (HDAC) inhibitors are promising candidates for molecular-targeted therapy for leukemia. In this study, we investigated the mechanisms of cytotoxic effects of depsipeptide (FK228), one of the most effective HDAC inhibitors against leukemia, using human myeloid leukemic cell lines HL-60 and K562. We found that FK228 activated caspase-9 and a subsequent caspase cascade by perturbing the mitochondrial membrane to release cytochrome c, which was almost completely blocked by overexpression of Bcl-2. The mitochondrial damage was caused by the translocation of Bax but not other pro-apoptotic Bcl-2 family proteins to the mitochondria. FK228 did not affect the interaction between Bax and Bax adaptor proteins such as 14-3-3theta and Ku70. FK228-induced apoptosis and mitochondrial translocation of Bax were markedly enhanced by the proteasome inhibitor bortezomib. The synergistic action of FK228 and bortezomib was at least partly mediated through conformational changes in Bax, which facilitate its translocation to the mitochondria. These results suggest that the combination of HDAC inhibitors and proteasome inhibitors is useful in the treatment of leukemia especially in the context of molecular-targeted therapy. The status of Bcl-2 and Bax may influence the sensitivity of tumors to this combination and thus can be a target of further therapeutic intervention.

CD34 expression in native human acute myelogenous leukemia blasts: differences in CD34 membrane molecule expression are associated with different gene expression profiles

BACKGROUND

The stem cell marker CD34 is expressed by leukemia blasts only for a subset of patients with acute myelogenous leukemia (AML). It is still controversial as to whether CD34 expression (defined as at least 10-20% positive cells) has any prognostic effect in patients with AML who receive intensive chemotherapy. The present study investigated whether gene expression profiling could be used to further subclassify CD34(+) AML cell populations.

METHODS

AML blasts derived from 25 patients were examined; these patients were randomly selected from a larger consecutive group of patients. CD34 protein expression was determined by flow cytometry and expressed as the percentage of positive cells. Gene expression profiles were determined by complementary DNA microarrays.

RESULTS

By unsupervised hierarchical clustering our patients could be grouped into two or three major subsets depending on the methodologic approach before clustering analysis (filtering or flooring of data, respectively). However, both approaches identified a cluster characterized by high gene expression and membrane molecule level of CD34. When using the floored expression profiles, the patient cluster characterized by increased CD34 gene expression was also characterized by a high percentage of CD34(+) cells (median 82%, range 56-100%) compared with the two other major clusters (median 19%, range <1-55%), but three of four outpatients also showed a high percentage of CD34(+) cells.

CONCLUSION

A major proportion of patients with AML and high CD34 expression (usually >80% CD34(+) cells; nearly all patients had >50% positive cells) showed similarities in gene expression profile. In contrast, patients with lower CD34 expression often had a profile similar to those of patients regarded as CD34(-) according to conventional criteria. Our results suggest that the possible prognostic effect of CD34 expression should be reevaluated in clinical studies using additional or alternative cutoff values to describe CD34 expression.

Induction of gene expression by 5-Aza-2'-deoxycytidine in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) but not epithelial cells by DNA-methylation-dependent and -independent mechanisms

The methylation inhibitor 5-Aza-2'-deoxycytidine (5-Aza-CdR, decitabine) has therapeutic efficacy in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Using microarray analysis, we investigated global changes in gene expression after 5-Aza-CdR treatment in AML. In the AML cell line OCI-AML2, Aza-CdR induced the expression of 81 out of 22 000 genes; 96 genes were downregulated (> or =2-fold change in expression). RT-PCR analysis of 10 randomly selected genes confirmed the changes of expression in AML cells. Similar results were obtained with primary AML and MDS cells after treatment with 5-Aza-CdR ex vivo and in vivo, respectively. In contrast, significantly fewer changes in gene expression and cytotoxicity were detected in normal peripheral blood mononuclear and bone marrow cells or transformed epithelial cells treated with 5-Aza-CdR. Interestingly, only 50.6% of the induced genes contain putative CpG islands in the 5' region. To further investigate the significance of promoter methylation in the induced genes, we analyzed the actual methylation status of randomly selected 5-Aza-CdR-inducible genes. We detected hypermethylation exclusively in the 5' region of the myeloperoxidase (MPO) gene. DNA methylation inversely correlated with MPO expression in newly diagnosed untreated AML patients (P< or =0.004). In contrast, all other analyzed 5-Aza-CdR-inducible genes revealed no CpG methylation in the promoter region, suggesting a methylation-independent effect of 5-Aza-CdR.

Polymorphisms in Genes Related to Oxidative Stress (MPO, MnSOD, CAT) and Survival After Treatment for Breast Cancer

The proximate cause of cancer cell death by radiation therapy and a number of therapeutic agents is through generation of reactive oxygen species, resulting in DNA damage as well as mitochondrial membrane disruption, triggering the apoptotic cascade. Because mitochondrial manganese superoxide dismutase catalyzes conversion of superoxide radicals to H2O2, with catalase neutralizing H2O2 and myeloperoxidase converting H2O2 to highly reactive hypochlorous acid, we hypothesized that gene variants could impact the efficacy of treatment for breast cancer and improve survival. Women who were treated with radiation and/or chemotherapy for incident breast cancer at the Arkansas Cancer Research Center from 1985 to 1996 were identified. DNA was extracted from paraffin-embedded normal tissue (n = 279), and MnSOD, CAT, and MPO genotypes were determined using mass spectrometry. Cox proportional hazards models were adjusted for age, race, stage with node status, and estrogen receptor and progesterone receptor status. Women who were homozygous for MPO G alleles, associated with increased transcription, had better survival (hazard ratio, 0.60; 95% confidence interval, 0.38-0.95; P = 0.03) than those with common alleles. Both CAT TT and MnSOD CC genotypes were associated with nonsignificant reduced hazard of death. When we combined genotypes associated with higher levels of reactive oxygen species for MnSOD and MPO, women with MnSOD CC and MPO GG genotypes had a 3-fold decrease in hazard of death (hazard ratio, 0.33; 95% confidence interval, 0.13-0.80; P = 0.01). These data indicate that gene variants that impact oxidative stress modify prognosis after treatment for breast cancer.

CEBPα mutations in childhood acute myeloid leukemia

CEBPalpha: mutations have been described in adult acute myeloid leukemia (AML) and conferred a favorable prognosis. However, CEBPalpha mutation has not been reported in children. We investigated 117 children with de novo AML using DNA PCR assay followed by sequencing for each PCR product. CEBPalpha mutations were detected in seven patients, four had FAB M2, two M1 and one M4. CEBPalpha mutations only occurred in patients with intermediate cytogenetics and not in 56 children with AML1-ETO, CBFbeta-MYH11, PML-RARalpha or MLL rearrangements. Five patients had mutations occurred in both N-terminal part and basic-leucine zipper (bZIP) domain, one had an N-terminal frameshift mutation and the remaining one had an inframe insertion in the bZIP domain. Cloning analysis on five samples carrying more than one mutations demonstrated one homozygous combined mutations and four heterozygous biallelic mutations. Four of seven CEBPalpha mutation(+) patients had cooperating mutations with FLT3-ITD or N-ras mutations compared to 27 in 109 CEBPalpha mutation(-) patients. Our results showed that CEBPalpha mutations occurred in 6% of childhood AML and most exhibited combined mutations in both N-terminal part and bZIP domain.