High expression of EDAG and its significance in AML

Abstract

ReferencesThe expression of EDAG mRNA in the leukemia cell lines and other samples were detected by semiquantitative RT-PCR. The PCR conditions and the numbers of cycles were chosen according to preliminary experiments in which the amount of product was directly proportional to the quantity of starting cDNA. In summary, total cellular RNA was extracted with the use of Trizol Reagent (Invitrogen). mRNA from 1 mg of total cellular RNA was reverse transcribed using an M-MLV reverse transcriptase commercial kit (Invitrogen). cDNA (2 ml) was amplified by PCR at 941C for 30 s, X1C for 30 s, 721C for 60 s with 30 cycles. X refers to the annealing temperature (Table 1). The results showed that a high level of EDAG transcripts was detected in K562, KG-1a, Jurkat, Namalva and cord blood CD34 þ cells. A low level of expression was found in Raji, EBV transformed lymphoblastoid cell line LCL-H, hepatoma cell line SMMC-7721, U937 and normal adult bone marrow. However, no expression was detected in HL-60, NB4, J6-1 (derived from a myelomonocytic leukemia patient in 1976) 3 cells.The different expression patterns of EDAG in various leukemia cell lines suggest that EDAG mRNA levels may vary in different leukemia patients. In this study, we also analyzed EDAG mRNA expression in the bone marrow of 75 AML patients (65 with de novo AML and 10 with complete remission (CR) at the time of sample collection) and 15 normal donors. The patients' clinical characteristics are summarized in Table 2. The diagnosis was based on FAB by standard morphological, cytochemical and immunophenotypic criteria. For statistical analysis, Wilcoxon rank-sum test (Mann-Whitney U test) was used for two-group means comparison; Kruskal-Wallis test (ANOVA) was used for more than two means comparison. EDAG mRNA was expressed in BMMC of all cases detected. In de novo AML patients, its relative expression averaged 0.6470.28, which was significantly higher than that in the normal donors (0.3570.11). We did not detect a marked difference between the CR AML patients (0.3870.16) and the normal donors. We further investigated whether EDAG expression related to the leukemia patients' clinical characteristics. No significant differences were found when the patients were divided into different groups regarding age, sex, initial WBC count, FAB subtype and CD34 expression (Table 2). Of the 65 de novo AML patients, 53 received therapy in our hospital. A total of 35 patients achieved CR within two courses of standard induction therapies. Interestingly, we found

The GATA site-dependent hemogen promoter is transcriptionally regulated by GATA1 in hematopoietic and leukemia cells

“…A recent study has reported an inverse relationship between HEMGN/EDAG expression and the chemotherapy response for AML patients 6 and our own results strongly suggest a causal relationship between GATA1 and EDAG in primary AMLs. Since mutation of GATA1 has been shown to contribute to the chemotherapy sensitivity of AML in Down's syndrome patients, 12 it is conceivable that the downregulation of HEMGN may be involved in molecular mechanisms of the remarkable chemotherapy sensitivity of this unique group of AML patients.…”

“…6 To further confirm that EDAG is a downstream target of GATA1, we performed the real time RT-PCR to quantify EDAG and GATA1 transcript levels in primary myeloblast specimens. As shown in Figure 6c, both EDAG and GATA1 transcripts varied over a substantial range (for EDAG: 0.06 to 19.85 with a mean of 0.6325; for GATA1: 0.016 to 3.988 with a mean of 0.1350).…”

“…More recently, assocaition of overexpression of EDAG and no remission in de novo AML has been reported: this result suggests that EDAG may play a modulator role in AML and could be a new target in the treatment of AML. 6 A number of hematopoietic-specific transcription factors are found to regulate the molecular pathways of hematopoiesis through direct binding to regulatory elements of key hematopoietic genes. 7 For instance, GATA proteins bind to the consensus sequence WGATAR in the promoter regions of a variety of erythroid genes.…”

Hemgn is a direct transcriptional target of HOXB4 and induces expansion of murine myeloid progenitor cells

“…Overexpression of Hemgn in a transgenic mouse model caused an expansion of myeloid hematopoiesis, most particularly in the spleen, 23 and overexpression of the human homolog, EDAG, has been found in acute human leukemia. 24 Based on these findings, we decided to pursue the role of Hemgn in mediating the HOXB4 phenotype.…”

Chicken hemogen homolog is involved in the chicken-specific sex-determining mechanism

“…EDAG shows similar expression patterns. EDAG expression is high in the BM cells in acute myeloid leukemia, suggesting that EDAG may play a modulator role in acute myeloid leukemia (8). Overexpression of Hemgn in hematopoietic cells suppresses lymphopoiesis and enhances myelopoiesis in transgenic mice, suggesting that Hemgn regulates the proliferation and differentiation of hematopoietic cells (9).…”