Promoter methylation of DAPK1, E-cadherin and thrombospondin-1 in de novo and therapy-related myeloid neoplasms.

DNA methylation is one of the major epigenetic changes in human cancers, leading to silencing of tumor suppressor genes, with a pathogenetic role in tumor development and progression in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Methylation of key promoter regions, induced by cytotoxic therapy together with complex genetic changes, is important in the biology of therapy-related myeloid neoplasms (t-MN). We were interested in the characterization of the methylation pattern of AML and MDS de novo and therapy-related. We studied 385 patients (179 females, 206 males), of a median age of 66 years (range 16-98 years). There were 105 MDS, 208 de novo AML and 72 t-MN (45 MDS and 27 AML). Using a methylation-specific PCR, we studied the promoter methylation status of E-cadherin (CDH1), TSP1 and DAP-Kinase 1. These genes have been shown to be involved in the malignant transformation, interfering with angiogenesis, interaction with micro-environment, apoptosis and xenobiotic detoxification. We found no associations between promoter hypermethylation and gender or age at the time of initial diagnosis. In patients with MDS, there were no associations between hypermethylation and clinical characteristics, including IPSS score, WHO classification and cytogenetics. DAPK1 was more frequently methylated in t-MDS/AML when compared to de novo MDS and AML (39% vs 15.3% and 24.4%, p=0.0001), while methylation of CDH1 was similar in t-MDS/AML and AML (51% and 53.4%), but less frequent in de novo MDS (29%) (p=0.003). In the t-MDS/AML group, we found that the methylation pattern appeared to be related to the primary tumor, with DAPK1 more frequently methylated in patients with a previous lymphoproliferative disease (75% vs 32%, p=0.006). On the other hand, methylation of CDH1 was associated to radiotherapy for the primary malignancy (84.5% vs 38%, p=0.003). TSP1 hypermethylation was rare and not characteristic of t-MDS/AML. In 177 patients studied for concurrent methylation of several promoters, t-MN and AML de novo were significantly more frequently hypermethylated in 2 or more promoter regions than de novo MDS (20% vs 12.4%, p<0.001). Chemotherapy and individual genetic predisposition have a role in t-MDS/AML development, the identification of specific epigenetic modifications may explain complexity and genomic instability of these diseases and give the basis for targeted-therapy. The significant association with previous malignancy subtypes may underlie a likely susceptibility to methylation of specific targets and a role for constitutional epimutations as predisposing factors for the development of therapy-related myeloid neoplasm.

Association between glutathione S-transferase genotypes and Hodgkin's lymphoma risk and prognosis.

PURPOSE: The interplay between genetic susceptibility and exposure to carcinogens has been shown to be involved in the etiology of many solid tumors. We studied the frequency and clinical correlates of polymorphisms resulting in deletions of two genes involved in the detoxification of potentially carcinogenic agents, glutathione S-transferase (GST)-M1 and GSTT1 in patients with Hodgkin's lymphoma (HL). EXPERIMENTAL DESIGN: The prevalence of gene deletions in 90 patients with HL was compared with a case-matched cohort of 176 normal blood donors. GST gene polymorphisms were studied using a multiplex PCR method, including the BCL2 gene as an internal control. RESULTS: Deletions of the GSTT1 gene were more frequent in cases compared with controls (28.9 versus 17.6%, P = 0.04), resulting in an increased risk for HL in individuals with the GSTT1-null genotype (odds risk, 1.9; 95% confidence interval 1.04-3.46). The GSTT1-null genotype particularly increased the HL risk in females aged <45 years (odds risk 6.1, 95% confidence interval 1.6-23, P = 0.008). Correlating patient characteristics to genotype, we found an association between the GSTT1-null genotype and a limited stage of disease (I/IIA versus IIB-IV, 40.6 versus 19.6%, P = 0.047) and an erythrocyte sedimentation rate of <50 mm/h (P = 0.02). Patients with at least one GST deletion (GSTM1- or GSTT1-) had a significant better disease-free survival when compared with those with undeleted GST genes (GSTM1+/GSTT1+; P = 0.012). CONCLUSIONS: The GSTT1-null genotype may increase the risk for HL and is associated with favorable prognostic factors, and the presence of at least one GST deletion indicates an improved disease-free survival.

In vivo priming with granulocyte colony-stimulating factor possibly enhances the effect of gemtuzumab-ozogamicin in acute myeloid leukemia: results of a pilot study.

Eight elderly patients with relapsed or refractory acute myeloid leukemia were treated sequentially with recombinant human granulocyte colony-stimulating factor with rhG-CSF and Mylotarg. Priming with rhG-CSF in vivo induced an increase in the proportion of CD33+ cycling blasts. Four patients (50% ) achieved a complete remission, 2 patients had a partial remission and the other 2 were resistant.

Polymorphisms of CYP1A1 and glutathione S-transferase and susceptibility to adult acute myeloid leukemia.

BACKGROUND AND OBJECTIVES: The origin of acute myeloid leukemia (AML) may be explained by a combination of genetic susceptibility factors and environmental exposure. We studied the polymorphisms of cytochrome P450 CYP1A1 and glutathione S-transferase (GST), enzymes involved in the metabolism of carcinogens and anti-cancer drugs, as risk factors for adult AML. DESIGN AND METHODS: The prevalence of CYP1A1*2A, *2B and *4 alleles and of GSTM1 and GSTT1 homozygous deletions was examined in 193 patients with AML and 273 normal individuals using polymerase chain reaction (PCR)-based methods. RESULTS: A higher prevalence of the CYP1A1*4 allele was found in AML patients than in controls (19.1% vs 9.9%, OR =2.2, 95% C.I. 1.3-3.7, p=0.006). GSTT1 homozygous deletions were also more frequent in AML patients (29% vs 19%, OR = 1.7, 95% CI 1.1-2.7, p=0.02). The combination of GSTT1 null genotype and CYP1A1 *2B and *4 alleles further increased the risk of AML (OR =10.2, 95% CI 1.2-83.9, p=0.01, and OR =7.0, 95% CI 2.0-24.8, p=0.001, respectively). INTERPRETATION AND CONCLUSIONS: Polymorphic variants in xenobiotic-metabolism genes, including CYP1A1 and GSTT1, may increase the risk of adult AML, particularly when present together.

Polymorphisms of detoxification and DNA repair enzymes in myelodyplastic syndromes.

The genetic background may modify the individual's risk of developing cancer. We performed a case-control study to test the impact of genomic polymorphisms of 9 genes involved in xenobiotics detoxification and DNA repair in myelodysplastic syndromes (MDS). Frequencies of polymorphic variants of RAD51, XRCC3, NQO1, GSTA1, GSTM1, GSTT1, CYP3A4 and XPD enzymes were similar in patients and controls. On the other hand, the GSTP1-105Val allele was associated to an increased risk of MDS (O.R. 1.66; p=0.04) and to higher probability of overall survival in the low/intermediate-1 IPSS risk group (p=0.008). The GSTP1-Ile105Val polymorphism is likely to influence MDS risk and prognosis.

Aberrant methylation of DAP-kinase in therapy-related acute myeloid leukemia and myelodysplastic syndromes.

Death-associated protein kinase (DAP-kinase), a proapoptotic serine/threonine kinase, is a candidate tumor suppressor gene. We studied the methylation status of DAP-kinase of 194 bone marrow samples from 160 patients with acute myeloid leukemia (AML) and 34 with a myelodysplastic syndrome (MDS) at the time of initial diagnosis by polymerase chain reaction (PCR). Hypermethylation of DAP-kinase was present in 27.5% (44 of 160) of AML and in 47% (16 of 34) of MDS specimens and significantly correlated to loss of DAP-kinase expression (P =.008). It was significantly more frequent in AML secondary to therapy for other malignancies (s-AML; 14 of 29, 48.3%), as compared to de novo AML (30 of 131, 22.9%, P =.01). DAP-kinase hypermethylation in AML was associated with myelodysplastic changes in the bone marrow at the time of the initial diagnosis (P =.002) and with the presence of cytogenetic abnormalities (P =.02). Alteration in the apoptotic response due to the loss of DAP-kinase function may be an early event in the transformation pathway to secondary leukemia via myelodysplasia.

Negative prognostic value of glutathione S-transferase (GSTM1 and GSTT1) deletions in adult acute myeloid leukemia.

Glutathione S-transferases (GSTs) are enzymes involved in the detoxification of several environmental mutagens, carcinogens, and anticancer drugs. GST polymorphisms resulting in decreased enzymatic activity have been associated with several types of solid tumors. We determined the prognostic significance of the deletion of 2 GST subfamilies genes, M1 and T1, in patients with acute myeloid leukemia (AML). Using polymerase chain reactions, we analyzed the GSTM1 and GSTT1 genotype in 106 patients with AML (median age, 60.5 years; range, 19-76 years). The relevance of GSTM1 and GSTT1 homozygous deletions was studied with respect to patient characteristics, response to therapy, and survival. Homozygous deletions resulting in null genotypes at the GSTM1 and GSTT1 loci were detected in 45 (42%) and 30 (28%) patients, respectively. The double-null genotype was present in 19 patients (18%). GST deletions predicted poor response to chemotherapy (P =.04) and shorter survival (P =.04). The presence of at least one GST deletion proved to be an independent prognostic risk factor for response to induction treatment and overall survival in a multivariate analysis including age and karyotype (P =.02). GST genotyping was of particular prognostic value in the cytogenetically defined intermediate-risk group (P =.003). In conclusion, individuals with GSTM1 or GSTT1 deletions (or deletions of both) may have an enhanced resistance to chemotherapy and a shorter survival.