Methylation profiling in acute myeloid leukemia

Aberrant methylation of multiple CpG islands has been described in acute myeloid leukemia (AML), but it is not known whether these are independent events or whether they reflect specific methylation defects in a subset of cases. To study this issue, the methylation status of 14 promoter-associated CpG islands was analyzed in 36 cases of AML previously characterized for estrogen-receptor methylation (ERM). Cases with methylation density of 10% or greater were considered positive. Seventeen cases (47%) were ERM(+) while 19 cases were ERM(-). Hypermethylation of any of the following, p15, p16, CACNA1G, MINT1, MINT2, MDR1, THBS1, and PTC1 (2 promoters), was relatively infrequent (6% to 31% of patients). For each of these CpG islands, the methylation density was positively correlated with ERM density (rank order correlation coefficients, 0.32-0.59; 2-tailed P < or = .058 for each gene). Hypermethylation of MYOD1, PITX2, GPR37, and SDC4 was frequently found in AML (47% to 64% of patients). For each of these genes as well, methylation density was positively correlated with ERM density (correlation coefficients 0.43 to 0.69, P < or = .0087 for each gene). MLH1 was unmethylated in all cases. Hypermethylation of p15, MDR1, and SDC4 correlated with reduced levels of expression. There was an inverse correlation between age and the number of genes methylated (P = .0030). It was concluded that CpG-island methylation in AML results from methylation defects in subsets of cases. These results have potential implications for the classification and prognosis of AML and for the identification of patients who may benefit from treatment with methylation inhibitors.     

Array-based DNA methylation profiling in acute myeloid leukaemia

Methylation in the promoter region of many genes is involved in regulating gene expression patterns. Using the Illumina GoldenGate^© methylation assay, we examined the methylation status of 1505 CpG‐sites from 807 genes in 32 samples from patients with acute myeloid leukaemia (AML) at diagnosis, nine at relapse and 15 normal controls and performed additional pyrosequencing and semiquantitative methylation specific polymerase chain reaction (MSP) of the GNMT promoter in 113 diagnostic AML samples. We found a gain of overall methylation in AML samples with a further increase at relapse. Regional hypermethylation as assessed by array analysis could be confirmed by both MSP and pyrosequencing. Additionally, large‐scale methylation analysis identified interesting candidate genes. Cluster analysis indicated that cytogenetic subgroups seemed to be characterized by additional distinct epigenetic modifications and that basic DNA methylation patterns remain at relapse. Therefore, promoter hypermethylation is a frequent event in AML and is accentuated at relapse. Array‐based methylation analysis determined distinct methylation profiles for non‐malignant controls and AML samples with specific chromosomal aberrations and can identify target genes for further evaluation.     

Gene expression profiling in acute myeloid leukemia

PURPOSE OF REVIEW: This review deals with the emerging promises of gene expression profiling (GEP) and the currently accumulating knowledge about the classification and the discovery of novel disease entities in clinical acute myeloid leukemia (AML). RECENT FINDINGS: Gene expression profiling studies in AML have shown that known and novel classes of disease can be recognized by unsupervised analyses. Prognostically informative molecular signatures can be deduced. Supervised analyses show that particular clinically relevant subsets of AML can be predicted with high accuracy with minimal sets of genes. SUMMARY: The AML GEP studies published to date show a remarkable level of concordance in findings, especially for similar GEP platforms. This confirms the robustness of the methodology and the promise for future applicability of GEP in clinical diagnostics. For the time being, certain technical hurdles remain to be overcome. These relate, for instance, to the conversion of data between different GEP platforms, the effect of differences between various statistical clustering methods, and the still incomplete understanding of the effect of biologic (eg, morphology) and genetic factors on the expression signature. GEP analyses, perhaps in combination with high-throughput mutation analysis and proteomic approaches, may ultimately result in the establishment of a comprehensive diagnostic approach that will yield a key to the precise pathobiologic nature of AML.     

Older patients with acute myeloid leukemia

Outcomes for older patients with acute myeloid leukemia have not improved over the last three decades, with only a small proportion of patients achieving long-term disease-free survival with standard induction chemotherapy. Older patients are more likely to have comorbidities, diminished functional reserve and other age-related issues, which decrease their tolerability to chemotherapy. Furthermore, the disease is frequently associated with poor-risk features, such as unfavorable cytogenetic abnormalities, antecedent hematologic disorders and expression of the multidrug resistant P-glycoprotein, which are associated with chemoresistant disease. Therefore, is it not only important to develop newer treatment modalities, but also to develop and validate prognostic models to help select the patients who are likely to benefit from and be suitable for intensive therapy, and reproducibly risk-stratify (based on disease biology) a relatively uniform group of older patients onto trials, so that the clinical significance of new therapeutic agents can be evaluated.     

Updates on DNA methylation modifiers in acute myeloid leukemia

Annals of Hematology - Acute myeloid leukemia (AML)&nbsp;is the most common acute leukemia in adults. Chemotherapy with cytotoxic agents is the standard of care, but is associated with a high...     

Genome-wide genotype-based risk model for survival in core binding factor acute myeloid leukemia patients

The present study attempted to build a single nucleotide polymorphism (SNP)-based risk model for predicting overall survival (OS) and event-free survival (EFS) in patients with core binding factor acute myeloid leukemia (CBF-AML). Adopting genome-wide SNP array using Affymetrix SNP array 6.0, we analyzed 868,157 SNPs with respect to OS and EFS in 104 patients with CBF-AML. Significant SNPs were identified from single SNP analysis. The risk model was constructed with incorporation of six SNPs and three clinical factors (age, c-kit exon 17 mutation, and LDH) for OS and six SNPs and three clinical factors (age, WBC, and LDH) for EFS. The model was further defined into low- and high-risk groups based on risk scores. The median age was 39 years, and the subgroup of t(8;21) and inv(16) or t(16;16) was assessed in 68 (65.4%) and 36 patients (34.6%). Finally, six SNPs per each OS (rs4353685, rs4908185, rs7709207, rs12034, rs1554844, and rs17241868) and EFS (rs13385610, rs11210617, rs11169282, rs7709207, rs4438401, and rs16894846) were incorporated into the risk model. OS was significantly different in favor of the low risk group (80.4?±?8.4%) compared to the high-risk group (22.0?±?7.3% at 3 years; p?=?8.75?×?10^??13; HR 8.67). For EFS, there was also a significant difference between the low- (75.0?±?5.8%) versus high-risk group (17.1?±?6.3% at 3 years; p?=?5.95?×?10^??13; HR 7.67). A genome-wide SNP-based risk model can stratify CBF-AML patients according to their OS and EFS in 104 patients.     

Intestinal permeability in patients with acute myeloid leukemia

Intestinal permeability was studied in patients with acute myeloid leukemia (AML) before, during and after chemotherapy. Intestinal permeability was determined by the lactulose (La)/mannitol (Ma) absorption test in 16 adult patients with de novo AML. The hydrogen breath test was used to disclose bacterial fermentation of the test substances in the small intestine. The permeability was found significantly increased (p<0.02) in the patients before induction chemotherapy treatment. During induction treatment and throughout the cytopenic period the intestinal permeability was constantly and significantly increased, compared with controls. In patients with abnormally increased permeability, no increase in hydrogen breath test result was noted. From our results it can be concluded that increased intestinal permeability is present in AML patients before commencing chemotherapy. Factors other than chemotherapy would seem to be more important regarding the occurrence of intestinal disturbances in these patients.     

Tailored temozolomide therapy according to MGMT methylation status for elderly patients with acute myeloid leukemia

Temozolomide sensitivity is determined by methylation of the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter. This study assessed whether the temozolomide dose can be tailored by MGMT promoter status and whether protracted, low-dose temozolomide can "prime" blasts in patients with unmethylated MGMT (unMGMT). Elderly patients with high-risk AML were stratified by MGMT methylation. Patients with methylated MGMT (mMGMT) received temozolomide 200 mg/m(2) orally for 7 days every 4 weeks, while patients with unMGMT received temozolomide 100 mg/m(2) orally for 14 days followed by 200 mg/m(2) orally for 7 days every 6weeks. Of 36 patients (median age, 75 years), 31 (86%) had an unMGMT promoter. Overall response rate for the entire cohort was 36%. Patients with mMGMT and unMGMT had similar response rates (40% vs. 29%). Median duration of response and overall survival (OS) among responders were 29 and 35 weeks, respectively. Induction deaths (ID) occurred in 25% of patients, mostly caused by disease progression. Hematological toxicities were the most common adverse event. Toxicities were similar between patients on conventional versus protracted schedules. High HCT-CI scores were predictive of lower CR rate, higher ID, and shorter OS, while bone marrow blast count <50% at screening predicted for improved responses. Temozolomide, dosed according to MGMT methylation status, demonstrated modest clinical activity in elderly patients with AML, especially in those presenting with fewer comorbidities and low disease burden. The trial was registered on www.ClinicalTrials.gov as #NCT00611247.     

急性髓系白血病患者线粒体DNA的D-loop区存在突变

目的研究线粒体DNA的D-loop区突变与白血病发生、发展的关系。方法应用盐析法对8例初治的成人急性髓系白血病患者及其生母和正常无关对照者的外周血基因组DNA提取、线粒体基因D-loop区PCR扩增、序列测定,对比分析白血病患者的线粒体基因D-loop区序列与其生母和健康无关对照者的线粒体基因D-loop区序列与标准剑桥线粒体基因D-loop区序列的差异。结果8例白血病患者中6例存在突变(突变率75%),共查出突变位点11个,突变类型均为D-loop区的T-C、A-C、G-A碱基替代突变。结论线粒体DNA的D-loop区在白血病患者中的突变率较高,D-loop区的突变在白血病发生发展过程中可能起作用。     

Circulating endothelial cells in patients with acute myeloid leukemia

OBJECTIVES: The circulating endothelial cells (CEC) are proposed to be a non-invasive marker of angiogenesis. The level of CEC in peripheral blood (PB) of acute myeloid leukemia (AML) patients has not been investigated prior to this study. We evaluated the count of resting (rCEC), activated (aCEC) and endothelial progenitor cells (CEPC) in the PB of AML and healthy subjects. In addition we correlated the levels of CEC with disease status, known prognostic factors and response to treatment. METHODS: CEC were quantified by utilizing four-color flow cytometry procedures in 48 AML patients at the time of diagnosis and 29 healthy controls. Additionally, measurements were again taken after the first course of induction treatment in 12 of the patients. RESULTS: The numbers of aCEC, rCEC and CEPC were significantly higher in the AML patients than in the controls (P < 0.0001, P < 0.0001 and P < 0.001, respectively). The CEC count was significantly higher in the AML patients with white blood cell count (WBC) >15 G/L, elevated lactic dehydrogenase (LDH) levels and a higher (over median) absolute blasts count (ABC) in PB than in the group with WBC <15 G/L (P < 0.03), a normal LDH level (P < 0.03) and a lower (相似文献   

Monitoring of methylation changes in 9p21 region in patients with myelodysplastic syndromes and acute myeloid leukemia

Epigenetic de novo methylation of CpG islands is an important event in malignant transformation. Two genes are frequently methylated: cyclin-dependent kinase inhibitor 2B (CDKN2B) and cyclin-dependent kinase inhibitor 2A (CDKN2A). In our study methylation of these genes was studied in 63 patients with myelodysplastic syndromes (MDS), 2 with myelodysplastic/myeloproliferative neoplasms (MDS/MPN) and 13 with acute myeloid leukemia (AML). Five patients were monitored during 5-azacytidine treatment. Twenty-six healthy donors were tested in a control group. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) method with all associated techniques was used for detection. Aberrant methylation was present in the CDKN2A gene in 38% and in the CDKN2B gene in 77% of the patients in MDS group. The level of methylation was higher in the group of AML patients - 77% in CDKN2A gene and 100% in CDKN2B gene. In MDS patients, an aberrant methylation was associated with a tendency to disease progression towards more advanced forms according to the World Health Organization (WHO) classification and the International Prognostic Scoring System (IPSS). Significant differences in methylation level were observed between early and advanced forms of MDS in CDKN2B gene (P value < 0.05) but not for CDKN2A gene. The trend of methylation in patients treated with azacitidine was analyzed in CDKN2B gene and correlated with the course of the disease. Increased methylation was connected with disease progression. We concluded that the methylation level of CDKN2B gene might be used as a marker of leukemic transformation in MDS. Our study indicates the role of hypermethylation as an important event in the progression of MDS to AML.     

Aberrant methylation of multiple tumor suppressor genes in acute myeloid leukemia

Hypermethylator phenotype, a propensity of tumors to incur nonrandom concurrent methylation, has been described in several tumors, including acute myeloid leukemia (AML). More recent studies identified methylation of other tumor suppressor genes, DAP-kinase and SOCS1, singly in AML. We therefore assessed the methylation status of these genes concurrently with other known targets of methylation. We used methylation-specific PCR or COBRA to determine the extent of methylation of 10 genes in 28 AML samples from Turkey. In addition to DAP-kinase and SOCS1, we included ER, p15, and E-cadherin (reported to be frequently methylated) as well as p16, GSTP1, and HIC1 (reported as rarely methylated). We also included RARbeta and p73 for which only minimal data in AML is available. All samples were methylated at least in one locus and all except one demonstrated methylation of DAP-kinase, SOCS1, p15, and/or ER. DAP-kinase is the most frequently methylated gene in both pediatric (70%) and adult AML (55%). RARbeta is methylated in 18% and p73 in 10% of AMLs. Methylation of E-cadherin and RARbeta occurs preferentially in AMLs with high methylation index (MI), while epigenetic lesions in SOCS1, DAP-kinase, and p15 appear to be independent. MI may be age-dependent, with a peak in young adults. FAB M3 demonstrated a higher extent of methylation than M2/M4. This study provides an impetus for larger studies to define if the extent and pattern of methylation in subgroups of AML are clinically relevant.     

急性髓细胞性白血病和急性早幼粒细胞性白血病的治疗进展

2003年12月5～9日第45届美国血液学年会(ASH) 在美国召开,与会代表2万多人,我国有100多位代表参加了会议.上海第二医科大学瑞金医院王振义院士(the first speaker from Asia to serve as the Ham-Wasserman Lecturer)在大会上作了"Treatment of Acute Leukemia by Inducing Differentiation and Apoptosis"的专题发言,引发了热烈的讨论.现将该次年会中有关急性髓细胞性白血病(AML)和急性早幼粒细胞性白血病(APL)治疗的进展作一介绍.     

The SOCS-1 gene methylation in chronic myeloid leukemia patients

SOCS-1, an important protein in the JAK/STAT pathway, has a role in the down stream of BCR-ABL protein kinase. We investigated 56 CML patients and 16 controls for the methylation status of SOCS-1 gene promoter and Exon 2 regions. Exon 2 was found to be methylated in 58.9% of the patients and 93.8% of the controls [P = 0.020, OR = 0.121(0.015-0.957)%95CI]. The promoter region was found unmethylated in all patient samples and controls. Although previous studies revealed a relation between SOCS1 gene Exon-2 hypermethylation and CML development or progression, the results of this study showed no such correlation. On the contrary, our results might be indicating hypomethylation in CML patients, this hypothesis need to be studied in larger study population.