The immunophenotype of acute myeloid leukemia: is there a relationship with prognosis?

Clinical features of immature leukemias in children

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL), mixed phenotypic acute leukemia (MPAL), and acute myeloid leukemia with minimal differentiation (AML-M0) all originate from immature hematopoietic progenitor cells and have a poor prognosis. We investigated the clinical characteristics of these immature leukemias in 17 children (ETP-ALL: 8, MPAL: 5, AML-M0: 4) at seven institutions. Clinical and laboratory findings were comparable across disease types. Eleven and six patients received ALL- and AML-oriented induction chemotherapy, with six and four achieving complete remission (CR), respectively. Five additional patients achieved CR after salvage with the other type of chemotherapy. Eight patients received hematopoietic cell transplantation (HCT) in first CR, and six survived without relapse. However, six of seven patients who did not receive HCT during first CR relapsed; all underwent HCT later, and only three survived. The 5-year event-free survival (EFS) and overall survival (OS) rate were 37% and 69%, respectively. Patients who achieved CR after induction chemotherapy and received HCT in first CR had favorable EFS and OS. Notably, all patients who received HCT in first CR survived 5 years after diagnosis. Appropriate induction chemotherapy and HCT in first CR could improve the outcome of immature leukemias.

Prevalence and clinical impact of CD56 and T-cell marker expression in acute myeloid leukaemia: A single-centre retrospective analysis

Flow cytometry-based immunophenotyping is a mainstay of diagnostics in acute myeloid leukaemia (AML). Aberrant CD56 and T-cell antigen expression is observed in a fraction subset of AML cases, but the clinical relevance remains incompletely understood. Here, we retrospectively investigated the association of CD56 and T-cell marker expression with disease-specific characteristics and outcome of 324 AML patients who received intensive induction therapy at our centre between 2011 and 2019. We found that CD2 expression was associated with abnormal non-complex karyotype, NPM1 wild-type status and TP53 mutation. CD2 also correlated with a lower complete remission (CR) rate (47.8% vs. 71.6%, p = 0.03). CyTdT and CD2 were associated with inferior 3-year event-free-survival (EFS) (5.3% vs. 33.5%, p = 0.003 and 17.4% vs. 33.1%, p = 0.02, respectively). CyTdT expression was also correlated with inferior relapse-free survival (27.3% vs. 48.8%, p = 0.04). In multivariable analyses CD2 positivity was an independent adverse factor for EFS (HR 1.72, p = 0.03). These results indicate a biological relevance of aberrant T-cell marker expression in AML and provide a rationale to further characterise the molecular origin in T-lineage-associated AML.

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.

A Temporal PROTAC Cocktail-Mediated Sequential Degradation of AURKA Abrogates Acute Myeloid Leukemia Stem Cells

AURKA is a potential kinase target in various malignancies. The kinase-independent oncogenic functions partially disclose the inadequate efficacy of the kinase inhibitor in a Phase III clinical trial. Simultaneously targeting the catalytic and noncatalytic functions of AURKA may be a feasible approach. Here, a set of AURKA proteolysis targeting chimeras (PROTACs) are developed. The CRBN-based dAurA383 preferentially degrades the highly abundant mitotic AURKA, while cIAP-based dAurA450 degrades the lowly abundant interphase AURKA in acute myeloid leukemia (AML) cells. The proteomic and transcriptomic analyses indicate that dAurA383 triggers the "mitotic cell cycle" and "stem cell" processes, while dAurA450 inhibits the "MYC/E2F targets" and "stem cell" processes. dAurA383 and dAurA450 are combined as a PROTAC cocktail. The cocktail effectively degrades AURKA, relieves the hook effect, and synergistically inhibits AML stem cells. Furthermore, the PROTAC cocktail induces AML regression in a xenograft mouse model and primary patient blasts. These findings establish the PROTAC cocktail as a promising spatial-temporal drug administration strategy to sequentially eliminate the multifaceted functions of oncoproteins, relieve the hook effect, and prevent cancer stem cell-mediated drug resistance.

Leukemic Stem Cell: A Mini-Review on Clinical Perspectives

Hematopoietic stem cells (HSCs) are known for their ability to proliferate and self-renew, thus being responsible for sustaining the hematopoietic system and residing in the bone marrow (BM). Leukemic stem cells (LSCs) are recognized by their stemness features such as drug resistance, self-renewal, and undifferentiated state. LSCs are also present in BM, being found in only 0.1%, approximately. This makes their identification and even their differentiation difficult since, despite the mutations, they are cells that still have many similarities with HSCs. Although the common characteristics, LSCs are heterogeneous cells and have different phenotypic characteristics, genetic mutations, and metabolic alterations. This whole set of alterations enables the cell to initiate the process of carcinogenesis, in addition to conferring drug resistance and providing relapses. The study of LSCs has been evolving and its application can help patients, where through its count as a biomarker, it can indicate a prognostic factor and reveal treatment results. The selection of a target to LSC therapy is fundamental. Ideally, the target chosen should be highly expressed by LSCs, highly selective, absence of expression on other cells, in particular HSC, and preferentially expressed by high numbers of patients. In view of the large number of similarities between LSCs and HSCs, it is not surprising that current treatment approaches are limited. In this mini review we seek to describe the immunophenotypic characteristics and mechanisms of resistance presented by LSCs, also approaching possible alternatives for the treatment of patients.

Prognostic Significance of CD56 Antigen Expression in Patients with De Novo Non-M3 Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous group of disorders with distinct characteristics and prognoses. Although cytogenetic changes and gene mutations are associated with AML prognosis, there is a need to identify further factors. CD56 is considered a prognostic factor for AML, which is abnormally expressed in leukemia cells. However, a clear consensus for this surface molecule is lacking, which has prompted us to investigate its prognostic significance. Bone marrow samples of de novo non-M3 AML were collected to detect CD56 expression using multiparameter flow cytometry (FCM). As a result, the CD56 expression in de novo non-M3 AML was found to be significantly higher than that in acute lymphoma leukemia (ALL, P = 0.017) and healthy controls (P = 0.02). The X-Tile program produced a CD56 cutoff point at a relative expression level of 24.62%. Based on this cutoff point, high CD56 expression was observed in 29.21% of de novo non-M3 AML patients. CD56-high patients had a poor overall survival (OS, P = 0.015) compared to CD56-low patients. Bone marrow transplantation (BMT) improved OS (P = 0.004), but a poor genetic risk was associated with an inferior OS (P = 0.002). Compared with CD56-low patients, CD56-high patients had lower peripheral blood platelet (PLT) counts (P = 0.010). Our research confirmed that high CD56 expression is associated with adverse clinical outcomes in de novo non-M3 AML patients, indicating that CD56 could be used as a prognostic marker for a more precise stratification of de novo non-M3 AML patients.

Long noncoding RNA HOXA-AS2 functions as an oncogene by binding to EZH2 and suppressing LATS2 in acute myeloid leukemia (AML)

Acute myeloid leukemia (AML) is the most common hematological malignancy in the world. Long noncoding RNAs (lncRNAs) play an important role in the development of physiology and pathology. Many reports have shown that lncRNA HOXA cluster antisense RNA 2 (HOXA-AS2) is a carcinogen and plays an important role in many tumors, but little is known about its role in AML. The aim of this study was to explore the potential mechanism and role of HOXA-AS2 in AML. HOXA-AS2 was upregulated in AML cell lines and tissues, and the overexpression of HOXA-AS2 is negatively correlated with the survival of patients. Silencing HOXA-AS2 can inhibit the proliferation and induce differentiation of AML cells in vitro and in vivo. Overexpressing HOXA-AS2 showed the opposite result. Moreover, more in-depth mechanism studies showed that carcinogenicity of HOXA-AS2 exerted mainly through binding with the epigenetic inhibitor Enhancer of zeste homolog 2 (EZH2) and then inhibiting the expression of Large Tumor Suppressor 2 (LATS2). Taken together, our findings highlight the important role of HOXA-AS2 in AML, suggesting that HOXA-AS2 may be an effective therapeutic target for patients with AML.

LncRNA NR-104098 Inhibits AML Proliferation and Induces Differentiation Through Repressing EZH2 Transcription by Interacting With E2F1

Abundant evidence has illustrated that long non-coding RNA (lncRNA) plays a vital role in the regulation of tumor development and progression. Most lncRNAs have been proven to have biological and clinical significance in acute myeloid leukemia (AML), but further investigation remains necessary. In this study, we investigated lncRNA NR-104098 in AML and its specific mechanism. The microarray analysis was performed on NB4 cells. Based on the related analysis results, we identified that lncRNA NR-104098 is a suppressor gene that is significantly upregulated in AML cells. LncRNA NR-104098 could inhibit proliferation and induce differentiation in AML cells in vitro and also play main role in the mouse xenografts. Mechanically, it was confirmed that lncRNA NR-104098 may effectively inhibit EZH2 transcription by directly binding to E2F1 and recruiting E2F1 to the EZH2 promoter. In addition, ATPR can significantly increase the expression of lncRNA NR-104098, whereas knocking down NR104098 can inhibit the inhibitory effect of ATPR on the proliferation and induction differentiation of AML cells. Taken together, these results lead to deeper insight into the mechanism of ATPR-induced AML differentiation and prevent proliferation by inhibiting EZH2 on the transcriptional level.

Long Noncoding RNA (lncRNA) Small Nucleolar RNA Host Gene 5 (SNHG5) Regulates Proliferation, Differentiation, and Apoptosis of K562 Cells in Chronic Myeliod Leukemia

Background

Human chronic myelogenous leukemia (CML) is a hematopoietic stem cell disorder with high malignant and invasive activity. lncRNA SNHG5 has been reported to be upregulated in CML. However, whether it affects the proliferation, differentiation, and apoptosis in CML cells is still unknown. This study investigated the role of SNHG5 in CML and revealed the potential mechanism.

Material/Methods

K562 cells were transfected with shRNA, and the expression level of SNHG5 was assessd by quantitative RT-PCR. The proliferation ability was determined by CCK-8 assay. Western blot analysis was performed to detect protein expressions related to cell proliferation, differentiation, and apoptosis. Cell apoptosis rate was analyzed by flow cytometry. The DNA methylation level was determined by methylation-specific PCR (MSP).

Results

Our results show that inhibition of SNHG5 induced by RNA interference significantly inhibits K562 cells proliferation and induces cell differentiation with the increased expression of CD42b, CD11b, CD14, GATA-1, and β-globin. Flow cytometry analysis indicated that inhibition of SNHG5 significantly induced cell apoptosis with decreased expression of Bcl-2 and increased expression of Bax and cleaved capase-3. Additionally, Western blot and MSP analyses confirmed that inhibition of SNHG5 increased the expression of DR4 gene through suppressing its methylation.

Conclusions

Inhibition of SNHG5 suppressed K562 cell proliferation through inducing the differentiation and apoptosis by inhibiting methylation of DR4. Therefore, downregulated SNHG5 could play a key role in CML progression, and might provide a new strategy for the treatment of CML.

Immunophenotype Discovery, Hierarchical Organization, and Template-Based Classification of Flow Cytometry Samples

We describe algorithms for discovering immunophenotypes from large collections of flow cytometry samples and using them to organize the samples into a hierarchy based on phenotypic similarity. The hierarchical organization is helpful for effective and robust cytometry data mining, including the creation of collections of cell populations’ characteristic of different classes of samples, robust classification, and anomaly detection. We summarize a set of samples belonging to a biological class or category with a statistically derived template for the class. Whereas individual samples are represented in terms of their cell populations (clusters), a template consists of generic meta-populations (a group of homogeneous cell populations obtained from the samples in a class) that describe key phenotypes shared among all those samples. We organize an FC data collection in a hierarchical data structure that supports the identification of immunophenotypes relevant to clinical diagnosis. A robust template-based classification scheme is also developed, but our primary focus is in the discovery of phenotypic signatures and inter-sample relationships in an FC data collection. This collective analysis approach is more efficient and robust since templates describe phenotypic signatures common to cell populations in several samples while ignoring noise and small sample-specific variations. We have applied the template-based scheme to analyze several datasets, including one representing a healthy immune system and one of acute myeloid leukemia (AML) samples. The last task is challenging due to the phenotypic heterogeneity of the several subtypes of AML. However, we identified thirteen immunophenotypes corresponding to subtypes of AML and were able to distinguish acute promyelocytic leukemia (APL) samples with the markers provided. Clinically, this is helpful since APL has a different treatment regimen from other subtypes of AML. Core algorithms used in our data analysis are available in the flowMatch package at www.bioconductor.org. It has been downloaded nearly 6,000 times since 2014.

Independent prognostic impact of CD15 on complete remission achievement in patients with acute myeloid leukemia

The prognostic role of CD15 in acute myeloid leukemia (AML) has been tested in different studies with conflicting results. To address this issue, we retrospectively evaluated a cohort of 460 AML patients of all ages with the exclusion of acute promyelocytic leukemia (M/F 243/217, median age 50.6 years [range 0.9-81.2]) intensively treated at our institute between January 1999 and December 2010. CD15 positivity was found in 171 of 406 evaluable patients (42.1%). Complete remission (CR) was achieved by 334 patients (72.6%), while 82 (17.8%) were resistant and 44 (9.6%) died during induction: the median CR duration was 15.5 months (range 0.6-176.0), with 2-year disease-free survival rate of 45.1% (95% confidence interval 39.6-50.6). The median overall survival was 14.4 months (range 0.3-177.0), with 2-year overall survival rate of 42.2% (95% confidence interval 37.5-46.9). At univariate analysis for CR achievement, age < 60 years (P < .001), World Health Organization classification (P = .045), low-risk karyotype (P < .001), no high-risk karyotype (P = .006), positivity for AML-ETO (P = .004)/CBFβ-MYH11 (P = .003)/CD15 (P = .006)/CD11b (P = .013), negativity for FLT3-ITD (P = .001), Hb > 8 g/dL (P = .020), and white blood cell < 50 × 10⁹ /L (P = .034) had a favorable impact. At a multivariate logistic regression model, CD15 positivity (P = .002), age < 60 years (P = .008), white blood cell < 50 × 10⁹ /L (P = .017), and low-risk/no high-risk karyotype (P = .026/P = .025) retained an independent prognostic role on CR achievement. The baseline assessment of CD15 positivity appears to have a role in the risk evaluation for CR achievement in AML patients undergoing intensive chemotherapy and should be assessed in prospective studies together with other clinical and biologic features already reported.

High-Dimensional Analysis of Acute Myeloid Leukemia Reveals Phenotypic Changes in Persistent Cells during Induction Therapy

The plasticity of AML drives poor clinical outcomes and confounds its longitudinal detection. However, the immediate impact of treatment on the leukemic and non-leukemic cells of the bone marrow and blood remains relatively understudied. Here, we conducted a pilot study of high dimensional longitudinal monitoring of immunophenotype in AML. To characterize changes in cell phenotype before, during, and immediately after induction treatment, we developed a 27-antibody panel for mass cytometry focused on surface diagnostic markers and applied it to 46 samples of blood or bone marrow tissue collected over time from 5 AML patients. Central goals were to determine whether changes in AML phenotype would be captured effectively by cytomic tools and to implement methods for describing the evolving phenotypes of AML cell subsets. Mass cytometry data were analyzed using established computational techniques. Within this pilot study, longitudinal immune monitoring with mass cytometry revealed fundamental changes in leukemia phenotypes that occurred over time during and after induction in the refractory disease setting. Persisting AML blasts became more phenotypically distinct from stem and progenitor cells due to expression of novel marker patterns that differed from pre-treatment AML cells and from all cell types observed in healthy bone marrow. This pilot study of single cell immune monitoring in AML represents a powerful tool for precision characterization and targeting of resistant disease.

Complex measurements may be required to establish the prognostic impact of immunophenotypic markers in AML

OBJECTIVES

The prognostic impact of immunophenotypic markers in acute myeloid leukemia (AML) is controversial.

METHODS

We retrospectively analyzed the value of CD34, CD117, CD7, and CD123 expression in a consecutive series of 592 adult patients with de novo AML.

RESULTS

CD34+ measured as a percentage (≥2.88%) and CD34 mean fluorescence intensity (MFI) (≥146.79, arbitrary units [AU]) expression had a prognostic impact in terms of overall survival (OS; P = .005, P = .003), leukemia-free survival (LFS; P = .011, P < .001), and cumulative incidence of relapse (CIR; P = .014, P =. 001). The percentage of CD117+ cells (61.29%) was associated with shorter LFS (P =. 043), and CD117 MFI (≥284.01 AU) was associated with a shorter OS (P =. 033) and LFS (P =. 028). In the multivariate analysis, high CD34 MFI retained the independent value as predictor of LFS and CIR (P =. 012; hazard ratio [HR], 1.59; 95% confidence interval [CI], 1.11-2.28 and P =. 045; HR, 1.58; 95% CI, 1.01-2.46).

CONCLUSIONS

CD34 positivity threshold with prognostic relevance is low (3% positive cells). Immunophenotypic findings in AML probably could only be fully exploited after a complex analysis that takes into account unconventional thresholds and the MFI.

Correlation of CD11b and CD56 expression in adult acute myeloid leukemia with cytogenetic risk groups and prognosis

Among other phenotypic markers, CD11b expression has been considered as an unfavorable prognostic factor, both in terms of overall survival (OS), disease-free survival (DFS), and attainment and duration of complete remissions (CRs) in adult patients with acute myeloid leukemia (AML). Recently, some groups have restricted its prognostic impact to poor prognostic karyotypic risk groups. The aim of this study was to retrospectively analyze the prevalence of CD11b and of CD56 expression in blast cells of 158 AML patients [excluding those with t(15;17)] stratified according to their cytogenetic risk and to correlate these phenotypic characteristics with OS, DFS, and CR. CD11b was more frequently expressed in intermediate and unfavorable cytogenetic prognostic groups (38.9 and 35.5 %, respectively) than in the favorable group (9.5 %). No differences were observed in CD56 expression according to the cytogenetic risk groups. When OS, DFS, and CR were analyzed according to these two markers, no statistical differences were recorded in any cytogenetic risk group. In conclusion, although CD11b was more frequently expressed in blast cells of patients with intermediate and unfavorable cytogenetic risk groups, this feature did not translate into different clinical outcome. Similarly, CD56 positivity did not have any influence on the prognosis of these patients.

CD56 expression is an independent prognostic factor for relapse in acute myeloid leukemia with t(8;21)

We investigated the significance of surface antigen expression for prognosis by focusing on a specific subtype, AML with t(8;21). The investigation included 144 patients with AML with t(8;21) in the JALSG AML97 study. AML with t(8;21) expressed CD19 (36%), CD34 (96%), and CD56 (65%) more frequently than did other subtypes of AML. CD19 expression had a significant favorable effect on CR (95.7% vs. 83.8%; P=0.049). Univariate analysis showed that increased white blood cell (WBC) counts (WBC ≥ 20 × 10(9)/L), CD19 negativity, and CD56 positivity were critical adverse factors for relapse after CR; multivariate analysis revealed that WBC count and CD56 expression were independent adverse risk factors (HR 2.18; P=0.045, HR 2.30; P=0.011, respectively). We concluded that CD56 expression has a possible role in risk stratification for patients with AML with t(8;21).

Hierarchical cluster analysis of immunophenotype classify AML patients with NPM1 gene mutation into two groups with distinct prognosis

Background

The prognostic implication of immunophenotyping in acute myeloid leukemia (AML) patients with NPM1 mutation remains unclear.

Methods

Ninety-four of 543 AML patients diagnosed with NPM1 mutation between 1987 and 2007 were studied. The expression of surface antigens on leukemic cells was evaluated with respect to clinical manifestations and outcomes. In order to validate the prognostic effect of the immunophenotypic cluster, another 36 patients with NPM1 mutation diagnosed between 2008 and 2010 were analyzed.

Results

Ninety-four patients with NPM1 mutations and complete immunophenotyping data were enrolled for a hierarchical cluster analysis and the result was correlated with clinico-laboratory characteristics. Clustering analysis divided the patients with NPM1 mutations into the following two groups: group I, CD34(−)/CD7(−), but with variable expression of HLA-DR; and group II, HLA DR(+)/CD34(+)/CD7(+). With a median follow-up of 53 months, the group II patients had a significantly shorter relapse-free survival (RFS, median: 3 vs. 23 months, p = 0.006) and overall survival (OS, median: 11 vs. 40 months, p = 0.02) than group I patients. Multivariate analysis of variables, including clinico-laboratory data and other gene mutations revealed that the immunophenotypic cluster is an independent prognostic factor (RFS, p = 0.002; OS, p = 0.024). In order to confirm the prognostic effect of the immunophenotypic cluster, another 36 patients with NPM1 mutation diagnosed between 2008 and 2010 were validated. Hierarchical cluster analysis also showed two distinct clusters, group I patient showed significant better RFS (p = 0.021), and OS (p = 0.055). In total, we stratified 130 NPM1-mutant patients, by FLT3-ITD mutation and immunophenotypic cluster into distinct prognostic groups (RFS, p < 0.001 and OS, p = 0.017).

Conclusions

Among NPM1-mutated AML, the antigen expression pattern of HLADR(+) CD34(+) CD7(+) is associated with a poor prognosis, independent to the FLT3-ITD mutation.

CD11b expression correlates with monosomal karyotype and predicts an extremely poor prognosis in cytogenetically unfavorable acute myeloid leukemia

Several cytogenetic features, including monosomal karyotype (MK), have been associated with unfavorable prognosis in acute myeloid leukemia (AML). However, little is known about the prognostic significance of immunophenotypes in AML patients with unfavorable-risk cytogenetics. We evaluated immunophenotypes, cytogenetics, clinical features and survival outcomes in 233 uniformly treated AML patients who harbored unfavorable cytogenetics. CD11b expression was observed in 145 (70%) of 208 patients and emerged as an independent prognostic factor for inferior overall survival in multivariate analysis (p=0.024). MK and age ≥ 60 years were predictors for lower complete remission rate (p=0.017, p<0.0001, respectively) and shorter overall survival (p=0.024, p<0.0001), while complex karyotype (CK) predicted a shorter overall survival (p=0.013). CD11b expression was strongly correlated with MK and identified a subset of patients with MK who had extremely poor overall survival. We proposed a prognostic scoring model using CD11b positivity, age ≥ 60 years, the presence of MK and the presence of CK to classify the patients into distinct risk groups. We identified the poor prognosis of CD11b expression and validated the adverse influence of MK, CK and age ≥ 60 years in cytogenetically unfavorable AML patients. Our proposed scoring model may be adapted in clinical practice to further the stratification of this high-risk population.

Prognostic factors in adult acute leukemia

The prognostic factors in acute leukemia have undergone a major change over the past decade and are likely to be further refined in the coming years. While age is the single most important prognostic factor in both AML and in ALL, recurring cytogenetic abnormalities and molecular markers have become crucial for the prognosis of patients and for new directions in the development of targeted therapies. No less important is the development of a personalized approach for therapy as determined by the response to therapy using increasingly sensitive technologies. The assessment of MRD is rapidly superseding other prognostic factors in ALL and, somewhat lacking behind, coming into its own in AML. The next decade should see further refinement of response-driven prognostication, to include epigenetics as well as pharmacogenetics and pharmacodynamics of individual drugs used and the responses to them. It is hoped that these refinements and better predictors of response will also lead to a significantly improved overall outcome of patients with both AML and ALL.

Hyperforin inhibits Akt1 kinase activity and promotes caspase-mediated apoptosis involving Bad and Noxa activation in human myeloid tumor cells

BACKGROUND

The natural phloroglucinol hyperforin HF displays anti-inflammatory and anti-tumoral properties of potential pharmacological interest. Acute myeloid leukemia (AML) cells abnormally proliferate and escape apoptosis. Herein, the effects and mechanisms of purified HF on AML cell dysfunction were investigated in AML cell lines defining distinct AML subfamilies and primary AML cells cultured ex vivo.

METHODOLOGY AND RESULTS

HF inhibited in a time- and concentration-dependent manner the growth of AML cell lines (U937, OCI-AML3, NB4, HL-60) by inducing apoptosis as evidenced by accumulation of sub-G1 population, phosphatidylserine externalization and DNA fragmentation. HF also induced apoptosis in primary AML blasts, whereas normal blood cells were not affected. The apoptotic process in U937 cells was accompanied by downregulation of anti-apoptotic Bcl-2, upregulation of pro-apoptotic Noxa, mitochondrial membrane depolarization, activation of procaspases and cleavage of the caspase substrate PARP-1. The general caspase inhibitor Z-VAD-fmk and the caspase-9- and -3-specific inhibitors, but not caspase-8 inhibitor, significantly attenuated apoptosis. HF-mediated apoptosis was associated with dephosphorylation of active Akt1 (at Ser(473)) and Akt1 substrate Bad (at Ser(136)) which activates Bad pro-apoptotic function. HF supppressed the kinase activity of Akt1, and combined treatment with the allosteric Akt1 inhibitor Akt-I-VIII significantly enhanced apoptosis of U937 cells.

SIGNIFICANCE

Our data provide new evidence that HF's pro-apoptotic effect in AML cells involved inhibition of Akt1 signaling, mitochondria and Bcl-2 members dysfunctions, and activation of procaspases -9/-3. Combined interruption of mitochondrial and Akt1 pathways by HF may have implications for AML treatment.

Allium compounds, dipropyl and dimethyl thiosulfinates as antiproliferative and differentiating agents of human acute myeloid leukemia cell lines

Epidemiologic studies support the premise that Allium vegetables may lower the risk of cancers. The beneficial effects appear related to the organosulfur products generated upon processing of Allium. Leukemia cells from patients with acute myeloid leukemia (AML) display high proliferative capacity and have a reduced capacity of undergoing apoptosis and maturation. Whether the sulfur-containing molecules thiosulfinates (TS), diallyl TS (All(2)TS), dipropyl TS (Pr(2)TS) and dimethyl TS (Me(2)TS), are able to exert chemopreventative activity against AML is presently unknown. The present study was an evaluation of proliferation, cytotoxicity, differentiation and secretion of AML cell lines (U937, NB4, HL-60, MonoMac-6) in response to treatment with these TS and their related sulfides (diallylsulfide, diallyl disulfide, dipropyl disulfide, dimethyl disulfide). As assessed by flow cytometry, ELISA, gelatin zymogaphy and RT-PCR, we showed that Pr(2)TS and Me(2)TS, but not All(2)TS and sulfides, 1) inhibited cell proliferation in dose- and time-dependent manner and this process was neither due to cytotoxicity nor apoptosis, 2) induced macrophage maturation, and 3) inhibited the levels of secreted MMP-9 (protein and activity) and TNF-alpha protein, without altering mRNA levels. By establishing for the first time that Pr(2)TS and Me(2)TS affect proliferation, differentiation and secretion of leukemic cell lines, this study provides the opportunity to explore the potential efficiency of these molecules in AML.

Aminopeptidase-N/CD13 is a potential proapoptotic target in human myeloid tumor cells

The transmembrane metalloprotease aminopeptidase‐N (APN)/CD13 is overexpressed in various solid and hematological malignancies in humans, including acute myeloid leukemia (AML) and is thought to influence tumor progression. Here, we investigated the contribution of APN/CD13 to the regulation of growth and survival processes in AML cells in vitro. Anti‐CD13 monoclonal antibodies MY7 and SJ1D1 (which do not inhibit APN activity) and WM15 (an APN‐blocking antibody) inhibited the growth of the AML cell line U937 and induced apoptosis, as evidenced by cell accumulation in the sub‐G₁ phase, DNA fragmentation, and phosphatidylserine externalization. Isotype‐matched IgG1 and the APN/CD13 enzymatic inhibitors bestatin and 2' ,3‐dinitroflavone‐8‐acetic acid, were ineffective. Internalization of CD13‐MY7 complex into cells was followed by mitochondrial membrane depolarization, Bcl‐2 and Mcl‐1 down‐regulation, Bax up‐regulation, caspase‐9, caspase‐8, and caspase‐3 activation, and cleavage of the caspase substrate PARP‐1. The broad‐spectrum caspase inhibitor Z‐VAD‐fmk and the caspase‐9‐ and caspase‐8‐specific inhibitors significantly attenuated apoptosis. CD13 ligation also induced apoptosis and PARP‐1 cleavage in primary AML blasts, whereas normal blood cells were not affected. Overall, these data provide new evidence that CD13 can serve as a target for inducing caspase‐dependent apoptosis in AML (independently of its APN activity). These findings may have implications for tumor biology and treatment.—Piedfer, M., Dauzonne, D., Tang, R., N'Guyen, J., Billard, C., Bauvois, B. Aminopeptidase‐N/CD13 is a potential proapoptotic target in human myeloid tumor cells. FASEB J. 25, 2831‐2842 (2011). http://www.fasebj.org

Expression of the leukemic prognostic marker CD7 is linked to epigenetic modifications in chronic myeloid leukemia

Background

Expression levels of the cell surface glycoprotein, CD7, and the serine protease, elastase 2 (ELA2), in the leukemic cells of patients with chronic myeloid leukemia (CML) have been associated with clinical outcome. However, little is known about the mechanisms that underlie the variable expression of these genes in the leukemic cells.

Results

To address this question, we compared the level of their expression with the DNA methylation and histone acetylation status of 5' sequences of both genes in leukemic cell lines and primitive (lin^-CD34⁺) leukemic cells from chronic phase CML patients. DNA methylation of the ELA2 gene promoter did not correlate with its expression pattern in lin^-CD34⁺ cells from chronic phase CML patient samples even though there was clear differential DNA methylation of this locus in ELA2-expressing and non-expressing cell lines. In contrast, we found a strong relation between CD7 expression and transcription-permissive chromatin modifications, both at the level of DNA methylation and histone acetylation with evidence of hypomethylation of the CD7 promoter region in the lin^-CD34⁺ cells from CML patients with high CD7 expression.

Conclusion

These findings indicate a link between epigenetic modifications and CD7 expression in primitive CML cells.

Expression patterns of CD33 and CD15 predict outcome in patients with acute myeloid leukemia

Expression patterns of CD33 and CD15 in normal/reactive bone marrow (n = 13) and in leukemic blasts from patients with acute myeloid leukemia (n = 129) were determined using multiparameter flow cytometry and a standard panel of triple antibody combinations. Five patterns, corresponding to the consecutive stages of myeloid differentiation, were identified [I: CD33-/CD15- (n = 18), II: CD33+/CD15- (n = 43), III: CD33+/CD15 heterogeneous (n = 10), IV: CD33+/CD15+ (n = 50), V: CD33-/CD15+ (n = 8)]. Patients with pattern II had the highest relapse rate and shortest median overall survival (OS, 8 months), but they were also the oldest (median age 72 years) and had the highest frequency of unfavorable cytogenetic aberrations. Pattern V patients had a short OS (median 14 months) even though they were the youngest (median age 50 years), had high remission rate and did not have unfavorable cytogenetics. In multivariate analysis, age, cytogenetics, CD15 expression and the presented immunophenotypic classification were significant for OS (age p = 0.004, cytogenetics p = 0.011, immunophenotype pattern p = 0.024, CD15 p = 0.031). Age (p = 0.001) and immunophenotypic classifications (p = 0.015) were significant for disease-free survival in patients who achieved complete remission.

MN1 affects expression of genes involved in hematopoiesis and can enhance as well as inhibit RAR/RXR-induced gene expression

The oncoprotein meningioma 1 (MN1) is overexpressed in several subtypes of acute myeloid leukemia (AML) and overexpression was associated with a poor response to chemotherapy. MN1 is a cofactor of retinoic acid receptor/retinoic x receptor (RAR/RXR)-mediated transcription and this study identified genes in the promonocytic cell line U937 that were regulated by MN1. We found that MN1 can both stimulate and inhibit transcription. Combining MN1 expression with all-trans retinoic acid (ATRA), the ligand of the RAR/RXR dimer, showed that MN1 could both enhance and repress ATRA effects. Many of the identified genes are key players in hematopoiesis and leukemogenesis (e.g. MEIS1 and BMI1). Another interesting target is DHRS9. DHRS9 is involved in the synthesis of ATRA from vitamin A. MN1 inhibited DHRS9 expression and completely abolished its induction by ATRA. MN1 is also the target of a rare AML-causing translocation encoding the MN1-TEL protein. MN1-TEL induces expression of only a few genes and its most pronounced effect is inhibition of a large group of ATRA-induced genes including DHRS9. In conclusion, both MN1 and MN1-TEL interfere with the ATRA pathway and this might explain the differentiation block in leukemias in which these genes are involved.

Prognostic value of immunophenotyping in elderly patients with acute myeloid leukemia: a single-institution experience

BACKGROUND

The poor prognosis for elderly patients with acute myeloid leukemia (AML) raises questions regarding the benefit of treating them with intensive chemotherapy. The impact of initial characteristics on prognosis has been addressed previously in elderly patients; however, very few data are available regarding the prognostic value of immunophenotypic characteristics in this setting.

METHODS

The authors investigated expression of the membrane antigens CD13, CD15, CD33, and CD34 by flow cytometry in elderly patients with newly diagnosed AML and analyzed whether these parameters had clinical or prognostic relevance to help physicians in their choice of therapy.

RESULTS

Immunophenotyping was performed in 273 patients aged > or =60 years (median age, 69 years). CD13 was expressed in 73% of patients, CD15 was expressed in 43% of patients, CD33 was expressed in 64% of patients, and CD34 was expressed in 66% of patients. Complete remission was obtained in 157 patients (58%). The median overall survival was 8.1 months, and the 3-year survival rate was 14%. Three risk groups were defined based on CD34 and CD33 antigen expression: The poor-risk group included patients with CD34-positive/CD33-positive or CD34-negative/CD33-negative disease, the intermediate-risk group included patients with CD34-positive/CD33-negative disease, and the favorable-risk group included patients with CD34-negative/CD33-positive disease. After cytogenetic analyses, immunophenotype was the most significant prognostic factor in terms of survival in a multivariate analysis (P = .03 and P < .0001, respectively). When immunophenotypic and cytogenetic parameters were combined, patients were classified into 4 prognostic groups: Group A (3-year survival rate, 33%) included patients with favorable and normal karyotypes who had a favorable immunophenotype, Group B (3-year survival rte, 28%) included patients with normal karyotypes who had an intermediate immunophenotype, Group C (3-year survival rate, 8%) included patients with intermediate or normal karyotypes who had an unfavorable immunophenotype, and Group D (3-year survival rate, 2%) included all patients who had unfavorable cytogenetics.

CONCLUSIONS

Immunophenotypic characteristics appeared to be a major prognostic factor in this population of elderly patients with AML. By using 2 simple parameters assessed at the time of diagnosis, the authors devised a prognostic system of immediate clinical utility for prognostic stratification and risk-adapted therapeutic choices.

Identification of distinct prognostic subgroups in low- and intermediate-1-risk myelodysplastic syndromes by flow cytometry

The World Health Organization (WHO) classification contributes to refined classification and prognostication of myelodysplastic syndromes (MDSs). Flow cytometry might add significantly to diagnostic and prognostic criteria. Our analysis of bone marrow samples from 50 patients with MDS showed aberrant expression of differentiation antigens in the myelomonocytic lineage. This also accounted for refractory anemia (RA) with or without ringed sideroblasts (RS), indicating multilineage dysplasia. In 38% of patients, CD34(+) myeloid blasts expressed CD5, CD7, or CD56. Flow cytometry data were translated into a numerical MDS flow-score. Flow-scores increased significantly from RA with or without RS, refractory cytopenia with multilineage dysplasia (RCMD) with or without RS up to refractory anemia with excess of blasts-1 (RAEB-1) and RAEB-2. No significant differences were observed between WHO cytogenetic subgroups. Flow-scores were highly heterogeneous within International Prognostic Scoring System (IPSS) subgroups. Patients in progression to advanced MDS or acute myeloid leukemia had a significantly higher flow-score compared with non-transfusion-dependent patients. In 60% of patients with transfusion dependency or progressive disease, myeloid blasts expressed CD7 or CD56, in contrast to only 9% of non-transfusion-dependent patients. Moreover, all patients with pure RA with or without RS with aberrant myeloid blasts showed an adverse clinical course. In conclusion, flow cytometry in MDS identified aberrancies in the myelomonocytic lineage not otherwise determined by cytomorphology. In addition, flow cytometry identified patients at risk for transfusion dependency and/or progressive disease independent of known risk groups, which might have impact on treatment decisions and the prognostic scoring system in the near future.