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PubMed2006

siRNA-mediated AML1/MTG8 depletion affects differentiation and proliferation-associated gene expression in t(8;21)-positive cell lines and primary AML blasts.

The chromosomal translocation t(8;21) is associated with 10-15% of all cases of acute myeloid leukaemia (AML). The resultant fusion protein AML1/MTG8 interferes with haematopoietic gene expression and is an important regulator of leukaemogenesis. We studied the effects of small interfering RNA (siRNA)-mediated AML1/MTG8 depletion on global gene expression in t(8;21)-positive leukaemic cell lines and in primary AML blasts using cDNA arrays, oligonucleotide arrays and real-time reverse transcription-polymerase chain reaction (RT-PCR). Suppression of AML1/MTG8 results in the increased expression of genes associated with myeloid differentiation, such as AZU1, BPI, CTSG, LYZ and RNASE2 as well as of antiproliferative genes such as IGFBP7, MS4A3 and SLA both in blasts and in cell lines. Furthermore, expression levels of several genes affiliated with drug resistance or indicative of poor prognosis AML (BAALC, CD34, PRG2, TSPAN7) are affected by AML1/MTG8 depletion. In conclusion, siRNA-mediated suppression of AML1/MTG8 cause very similar changes in gene expression pattern in t(8;21)-positive cell lines and in primary AML blasts. Furthermore, the results suggest that the specific targeting of AML1/MTG8 function may be a promising approach for complementing existing treatment strategies.

Acute Disease↗

PubMed2003

Biallelic mutations in the CEBPA gene and low CEBPA expression levels as prognostic markers in intermediate-risk AML.

The CCAAT/enhancer binding protein alpha is an essential transcription factor for granulocytic differentiation. Recent studies reported N- and C-terminal CEBPA mutations in approximately 7% of acute myeloid leukaemia (AML) patients. C-terminal mutations are usually in-frame and occur in the basic-leucine zipper (bZIP) domain, resulting in deficient DNA binding. Using a rapid PCR approach, we screened for bZIP mutations and determined the prognostic value of these mutations in a cohort of 277 de novo AMLs. In addition, we set out to quantify CEBPA mRNA levels by 'real-time' PCR using TaqMan technology. In-frame insertions were observed in 12 (4.3%) cases. All cases with mutations carried an intermediate-risk karyotype and all but one belonged to M1 or M2 FAB class. Further sequence analysis revealed that CEBPA C-terminal mutations are associated with frameshift mutations in the N-terminus of CEBPA. These two mutations were always found in different alleles. Event-free survival (EFS) and overall survival (OS) of patients with CEBPA mutations were significantly increased (P=0.02 and 0.03, respectively) in comparison to the patients lacking these mutations. Mutations were associated with a significantly reduced hazard ratio for death (OS: HR=0.35, P=0.04) and failure (EFS: no CR, death in CR or relapse, HR=0.37, P=0.03). This favourable hazard ratio was maintained after adjustment for cytogenetic risk, FLT3-ITD and CEBPA expression levels in multivariable analysis. In contrast, low CEBPA expression in AML with intermediate-risk karyotype (n=6) seemed to be associated with poor prognosis (not significant). By including this newly developed PCR assay, we define a subgroup of good-risk patients within the heterogeneous intermediate-risk group of AML.

Acute Disease↗

PubMed2004

FLT3-activating mutations are associated with poor prognostic features in AML at diagnosis but they are not an independent prognostic factor.

FLT3: gene alterations (internal tandem duplications - ITDs - and D835 mutations) are thought to be associated with poor-risk acute myeloid leukemia (AML). However, not all studies confirm this association, so it is still a matter of debate. Moreover, their association with other molecular abnormalities is less studied. We have investigated the presence of FLT3-ITD and D835 mutations in AML patients and their correlation with clinical and biological disease characteristics. The presence of ITD was analyzed in diagnostic samples of 176 AML patients and the D835 mutation in 135 of these patients. In all these patients, the presence of four well-known molecular abnormalities were also simultaneously characterized: PML/RARalpha, AML1/ETO, CBFbeta/MYH11 and MLL rearrangements. In all, 41 (23%) patients harbored FLT3 mutations, with 34 (19.3%) of them positive for the ITD, and seven (5%) positive for the D835 mutation. Of the acute promyelocytic leukemia (APL) patients, 16 (27%) showed FLT3 mutations, more frequently in M3 hypogranular cases (62% versus 17%, P=0.001) and cases with the short (bcr3) PML-RARalpha isoform (69%, P=0.002). In contrast, FLT3 was never altered in patients with inv(16), t(8;21) or 11q23 abnormalities. FLT3 mutations were significantly associated with some negative prognostic features at diagnosis (leukocytosis, high blast-cell percentage, and elevated LDH values), but they were not associated with different disease-free or overall survival. Therefore, we confirm a high frequency of FLT3 mutations in APL and in adult AML without recurrent cytogenetic translocations. In addition, they were not found as independent prognostic factors although associated with several adverse features at diagnosis.

Acute Disease↗

PubMed1997

The predominant E2F complex in human primary haemopoietic cells and in AML blasts contains E2F-4, DP-1 and p130.

The E2F family of transcription factors are thought to play an important role in the control of cell cycle progression. There is now also increasing evidence that some family members may act as oncogenes or tumour suppressor genes. The characterization of these proteins in human primary haemopoietic cells and acute myeloid leukaemia (AML) blasts may thus give an insight to the molecular mechanisms governing proliferation and leukaemogenesis in these cells. Therefore we analysed the expression of E2F-DNA binding activity and the constituent proteins found in the complexes in human primary haemopoietic cells of various lineages. We also studied blasts from 18 patients with acute myeloid leukaemia (AML). On electromobility shift assays (EMSA) a single E2F-DNA binding complex was detected in T cells, B cells and monocytes which was shown to contain E2F-4, DP-1 and p130, indicating that all quiescent haemopoietic cells have the same complex. Examination of 18 AML samples by EMSA revealed the presence of E2F binding and no gross abnormalities were detected. An E2F-4/p130 complex was detected in representative samples of all FAB types analysed. Thus abnormalities of E2F function are unlikely to play a primary pathogenic role in AML.

Blotting, Western↗

PubMed1997

Frequency of CBF beta/MYH11 fusion transcripts in patients entered into the U.K. MRC AML trials. The MRC Adult Leukaemia Working Party.

It has been established that cytogenetic findings at diagnosis of acute myeloid leukaemia (AML) are a powerful prognostic indicator. Patients who have the inv(16)(p13q22), closely associated with the FAB subtype M4Eo. are deemed to have good-risk disease. This subtle translocation may be difficult to detect in poor-quality metaphase preparations and if missed could lead to the incorrect assignment of risk group and influence further treatment strategies. We studied 321 patients with AML at diagnosis for the presence of inv(16)(p13q22) and CBF beta/MYH11 fusion transcripts by cytogenetic and RT-PCR techniques respectively. Karyotypic analysis detected 21 cases of inv(16) (p13q22), all of which were PCR positive. A further 12 cases were detected at the molecular level only, in FAB types other than M4Eo. The observed frequencies of CBF beta/MYH11 fusion transcripts in our study have been adjusted for the reported incidence of each FAB subtype and we calculate that 10.1% of all new cases of AMLs have molecular evidence of inv(16)(p13q22). only half of which are of the M4Eo subtype. We conclude that molecular screening for the presence of CBF beta/MYH11 fusion transcripts should be mandatory in all case of AML at diagnosis.

Adolescent↗

PubMed1998

MDR1 gene expression and drug resistance of AML cells.

We investigated the cellular drug resistance to aclarubicin (Acla), cytosine arabinoside (Ara-C), daunorubicin (Dau), doxorubicin (Dox), etoposide (Etop) and mitoxantrone (Mitox) using the MTT assay at time of disease presentation in 93 cases of acute myeloid leukaemia (AML). In 31 cases we concomitantly investigated MDR1 (multiple drug resistance 1 gene) expression (semi-quantitative competitive RT-PCR) of the leukaemic cells. Drug resistance towards Dau, Dox and Etop was correlated to the MDR1 expression of the AML cells (P<0.05) with high MDR1 expression being associated with high drug resistance towards these drugs. Although the data did not allow firm conclusions to be drawn on the correlation between MDR1 expression and drug resistance towards Ara-C and Mitox, the drug resistance towards Acla clearly was not correlated to, or dependent on, the MDR1 expression level of the AML blast cells. In addition, when examining the cross-activities among the six drugs distinct patterns emerged. Thus, high to very high degrees of cross-activity were found to exist between Dau, Dox, Etop and Mitox, whereas Ara-C had moderate cross-activity with the other drugs except Acla, which showed absent to moderate cross-activity with the other drugs. We conclude that MDR1 gene expression is of significance for cellular drug resistance towards specific (MDR1-related) drugs in AML, whereas it is not of significance regarding drug resistance towards other drugs, which is the case with the anthracycline Acla. We suggest that in the place of other more or less complicated ways to circumvent MDR1-mediated drug resistance, Acla may be used to replace Dau, Dox and other MDR1-related drugs if proven as potent as the drug it is to substitute.

Aclarubicin↗

PubMed1998

Marked improvements in outcome with chemotherapy alone in paediatric acute myeloid leukemia: results of the United Kingdom Medical Research Council's 10th AML trial. MRC Childhood Leukaemia Working Party.

359 eligible children with acute myeloid leukaemia (AML) entered the MRC AML 10 trial between May 1988 and March 1995. Patients received four courses of intensive induction and consolidation chemotherapy, with or without subsequent autologous (A-BMT) or allogeneic (allo-BMT) bone marrow transplant. There were randomized comparisons of thioguanine versus etoposide in induction and of A-BMT versus not. Allo-BMT was recommended for patients with a HLA-matched sibling and was evaluated by donor versus no donor comparison. The complete remission rate was 92%. In first remission there were 20 deaths during consolidation chemotherapy and 11 after BMT (8/61 allo-BMTs. 1/60 A-BMTs and 2/4 matched unrelated donor transplants). The relapse rate was low, decreasing from 26% in the first year to 2% in the fourth. Long-term outcome was excellent with survival at 7 years from entry of 56% and event-free survival of 48%. There were no significant differences between thioguanine and etoposide, whereas both A-BMT and allo-BMT reduced relapse risk but did not produce a significant survival benefit. It appears that over half the children entered into AML 10 are cured, a result which compares favourably with other reported series. We conclude that four courses of intensive chemotherapy are an effective approach to the treatment of paediatric AML, which avoids the acute toxicity and long-term side-effects of BMT and also avoids the need for prolonged maintenance therapy or cranial irradiation.

Acute Disease↗

PubMed1999

Real-time RT-PCR for the detection and quantification of AML1/MTG8 fusion transcripts in t(8;21)-positive AML patients.

AML1/MTG8 was quantified relative to the expression of the GAPDH housekeeping gene by real-time RT-PCR in 22 patients with t(8;21)-positive acute myeloblastic leukaemia (AML) at initial diagnosis and in seven of these patients also during/after chemotherapy and allogeneic bone marrow transplantation. Real-time PCR was able to specifically detect and quantify AML1/MTG8 over a 5 log range. The detection limit for t(8;21)-positive cells was a dilution of 1:105. The AML1/MTG8 expression varied considerably among the 22 AML patients at intial diagnosis with a ratio AML1/MTG8:GAPDH of 0.5135+/-0.536 (range 0.1-2.14, median 0.318). In six patients with t(8;21)-positive AML a marked decline of AML1/MTG8 could be induced by chemotherapy. These patients are in ongoing complete haematological remission (CR) with a constant low-level AML1/MTG8 expression. In another patient a rapid rise of AML1/MTG8 transcripts could be detected in CR after allogeneic bone marrow transplantation and the patient relapsed 10 weeks later. In conclusion, real-time RT-PCR is a suitable approach for the quantification of AML1/MTG8 transcripts in the monitoring of AML patients with t(8;21) during/after chemotherapy and can provide data of prognostic relevance.

Chromosomes, Human, Pair 21↗

PubMed1999

Clonal selection of CD56+ t(8;21) AML blasts: further suggestion of the adverse clinical significance of this biological marker?

Although patients with acute myelogenous leukaemia (AML) and t(8;21)(q22;q22) have a favourable prognosis, a subset die despite receiving appropriate treatment. Recent reports suggest that expression of the CD56 antigen might predict for both extramedullary disease and poor outcome in these patients. We describe a patient who presented with CD56-negative t(8;21) AML who achieved a complete remission and was subsequently treated with three consolidative courses of high-dose cytarabine therapy. She relapsed 9 months later with extramedullary and bone marrow involvement of CD56-positive t(8;21) AML. This case demonstrates clonal evolution and provides further support that blast expression of CD56 might be an unfavourable prognostic factor in t(8;21) AML.

Adult↗

PubMed2000

Asparagine synthetase activity in paediatric acute leukaemias: AML-M5 subtype shows lowest activity.

Lack of sufficient cellular activity of asparagine synthetase (AS) in blast cells compared with normal tissue is thought to be the basis of the antileukaemic effect of L-asparaginase in acute lymphoblastic leukaemia (ALL). Although L-asparaginase is routinely used in ALL, its role and value in the treatment of acute myelogenous leukaemia (AML) is still being discussed. To evaluate the pharmacological basis for L-asparaginase treatment, we established pretreatment monitoring of the intracellular AS activity in blast cells of patients with AML and ALL. There was no general difference in AS activity between ALL and AML samples. Significantly lower AS activity, however, was found in the B-lineage ALL subgroups as well as AML-M5.

Adolescent↗

PubMed2001

Acute myeloid leukaemia (AML): treatment of the older patient.

Undertreatment of the older patients with acute myeloid leukaemia (AML) can explain, in part, their inferior outcome when compared with that of younger patients. Corresponding to the benefit to patients under the age of 60 from high-dose Ara-C there are also dose effects in those over 60 years old, in particular for daunorubicin in the induction treatment, and for the quantity in terms of duration of postremission treatment. The use of these effects can partly overcome the mostly unfavourable disease biology seen in older age AML patients, which is expressed by the absence of favourable and the over-representation of adverse chromosomal abnormalities as well as by the expression of drug resistance. We recommend an adequate dosage of 60 mg/m(2)daunorubicin for 3 days in combination with standard dose Ara-C and 6-thioguanine given for induction and consolidation, followed by a prolonged monthly maintenance chemotherapy for a duration of at least 1 year. Further improvements in supportive care may help in delivering additional anti-leukaemic cytotoxicity. As a novel approach, non-myeloablative preparative regimens may open up the field of allogeneic transplantation for older patients with AML. Given that the actual median age in this disease is more than 60 years the management of older age AML remains as the major challenge.

Acute Disease↗

PubMed2000

Treatment, long-term outcome and prognostic variables in 214 unselected AML patients in Sweden.

With the aim of describing an unselected series of acute myeloid leukaemias (AML) in adults, patients diagnosed 1987-1992 in the Orebro region of central Sweden were reviewed by investigating hospital records. By utilizing: (1) The Swedish Cancer Registry, (2) The Cause of Death Registry, (3) listings of pathology bone marrow reports and (4) listings of inpatient discharge diagnoses, we attempted to find all patients. Among secondary AML, only blast-crises of CML were excluded. A total of 214 cases of AML with a median age of 69.5 years were verified corresponding to a mean yearly incidence in adults of 5.4/100 000. Of all patients, 56% had received 'high-dose' induction treatment, 28% 'low-dose' treatment and 16% no cytostatic treatment. Median survival for all patients was 5.8 months and the probability of survival at 5 years was 9.3%. The 120 'high-dose' treated patients had a total CR rate of 67%, median CR duration 10.1 months and median survival 11.4 months. Age, LDH and kidney function were found to be independent prognostic variables for survival. The inclusion of patients unreferred from district hospitals makes this study unique as an example of unselected AML.

Acute Disease↗

PubMedDate not supplied

[Treatment of recurrence of acute myeloid leukemia in childhood. A retrospective analysis of recurrence in the AML-BFM-83 study].

Complete remission (CR) rates of 80% are achieved with the AML-BFM protocols but one third of patients relapse within the first three years. There are few reports of treatment of relapsed childhood AML, and these deal with the evaluation of new drugs for frontline therapy. We performed a retrospective analysis to investigate how patients previously treated with the AML-BFM-83 protocol were treated after relapse and how many long term remissions were achieved. 48 of 139 patients relapsed after having achieved complete remission with the AML-BFM-83 protocol which consists of continous infusion of ARA-C 100 mg/m2 day 1-2, ARA-C 200 mg/m2 day 3-8, Daunorubicin 60 mg/m2 day 3, 4, and 5, and VP-16 150 mg/m2 day 6, 7, and 8, and an 8 week consolidation therapy consisting of Prednisolone, Thioguanine, Vincristine, ADR, ARA-C, Cyclophosphamide, intrathecal ARA-C and cranial irradiation followed by maintenance therapy. Duration of first remission ranged from 1.5 months to 66.3 months. Excluding 5 children with either isolated or combined extramedullary relapses and another 4 patients for missing data, 39 children were evaluable. 20 children received no therapy or palliative therapy while 16 patients received chemotherapy and another 3 children were transplanted in relapse. Although 9 different intensive chemotherapy regimens were used for reinduction, a high number (12 of 16 = 75%) of second complete remissions was achieved. Several therapeutic options were used to maintain a second remission: regular maintenance therapy (7 patients), allogeneous bone marrow transplantation (BMT) (2 patients), autologous BMT (3 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Stem cell transplantation as consolidation therapy for children in first-remission AML: a single-center report.

A large number of patients affected by acute myeloid leukemia (AML) achieve complete remission following induction chemotherapy based on high-dose aracytin and anthracyclines. However, a postremission consolidation treatment appears to be essential to maintain the remission status. Sixteen patients with newly diagnosed AML received induction chemotherapy according to the AIEOP LAM 92P/Mod protocol. All patients were HLA-typed, and if no donor was identified within the family, patients underwent autologous stem cell transplantation (autoSCT) with mafosfamide-purged bone marrow. Patients with very high-risk AML (cytogenetics with t(9;22), hyperleukocytosis (540x10(9)/L), and AML-M7 with trilineage myelodysplasia) underwent unrelated donor transplantation. One patient relapsed before autoSCT. Eleven patients underwent autoSCT with purged bone marrow, 3 patients underwent unrelated donor transplantation (UD), and 1 patient underwent HLA-identical, matched familiar donor transplantation (MFD). All patients achieved complete remission following one course. No treatment-related deaths occurred during first-line treatment. The median interval between diagnosis and transplant was 175 days (129-277). Three patients relapsed following autoSCT; none relapsed after alloSCT. Taking stem cell transplantation as the starting point, overall survival was 93%, disease-free survival (according to the chosen treatment) was 80%, the relapse rate was 20%, and transplant-related mortality was 0%.

Adolescent↗

PubMed2005

Soluble VEGF/sFLt1 ratio is an independent predictor of AML patient out come.

Angiogenesis is the formation of new blood vessels and is controlled by a balance between positive and negative angiogenic regulatory factors. Soluble vascular endothelial growth factor receptors 1,2 (Flt-1, KDR) are the negative counterpoint to the vascular endothelial growth factor (VEGF) signaling pathway, which has been characterized as one of the most important endothelial regulator in human angiogenesis. In the present work, we tested the differential prognostic relevance of soluble vascular endothelial growth factor (VEGF), their receptors 1 (Flt-1), 2 (KDR), and the ratio between sVEGF/sFlt-1 in 43 patients with acute myeloid leukemia (AML). sVEGF and its soluble receptors were assessed using an ELISA. Soluble VEGF, sFLT-1 and sKDR concentration levels were significantly higher in AML patients at diagnosis when compared to the levels in normal controls. sVEGF, sFlt1 and the sVEGF/sFlt1 ratio were significantly higher in non responders when compared to responders (P < 0.001 for all). However, there was no significant difference regarding sKDR levels (P > 0.05). sVEGF, the sVEGF/sFlt1 ratio but not sFlt1 and sKDR levels were significantly elevated in those who did not survive, when compared to survivors. sVEGF, sFlt1 levels were significantly correlated to WBC counts (R = 0.93, P = 0.000, R = 0.56, P = 0.000, respectively); bone marrow blast cell counts (R = 0.92, P = 0.000; R = 56, P = 0.000, respectively); peripheral blood blast cell counts (R = 0.91, P = 0.000; R = 0.52, P = 0.000, respectively); sKDR was only correlated to peripheral blood blast cell counts(R=0.37,P=0.014). Cox regression analysis results with sVEGF, sFlt1, sKDR, sVEGF/sFlt1 ratio suggest that the most important predictor for AML outcome is the sVEGF/sFlt1 ratio. In conclusion, sVEGF/sVEGF ratio is independent predictor of AML patient out come, and its significance should be assessed when considering antiangiogenic therapy.

Biomarkers, Tumor↗

PubMed2003

A complex variant t(8;21) involving chromosome 3 in a child with acute myeloblastic leukemia with eosinophilia (AML M4Eo).

Although the classic t(8;21) has been reported in 10 pediatric patients with acute myeloid leukemia with eosinophilia (AML M4Eo), no complex variant t(8;21) in children with AML M4Eo has been previously described. In our analysis of leukemic blasts from a 4-year-old boy with AML M4Eo, conventional cytogenetics revealed that 95% of the cells had a hypodiploid line containing 45 chromosomes and a complex karyotype involving chromosomes 3, 8, and 21. Fluorescence in situ hybridization using whole chromosome painting probes for these chromosomes confirmed the cytogenetic findings. The presence of a CBFA2-ETO fusion gene was established by fluorescence in situ hybridization and reverse-transcriptase polymerase chain reaction analysis. Thus, this report illustrates the first description of a complex variant t(8;21) involving chromosome band 3q27 in a child with AML M4Eo.

Bone Marrow Transplantation↗

PubMed2004

Bone marrow microvessel density (MVD) in adult acute myeloid leukemia (AML): therapy induced changes and effects on survival.

Based on the strong evidence in favor of an increase in microvessel density (MVD) in hematological malignancies, we evaluated VEGF immunoreactivity and MVD measurement in bone marrow biopsies of 36 AML patients at diagnosis and following therapy. MVD assessment was based on CD31, CD34 expressing vessels. The values were calculated for only one marker if the other vascular marker was positive on blasts, otherwise both markers were used. VEGF immunoreactivity was also scored. Comparison of MVD values of 36 AML patients with 18 non-malignant controls showed a significantly higher MVD in AML (CD31: P = 0.004, CD34: P < 0.001), which is independent of other variables such as cellularity or blast percentage. Following induction chemotherapy, the responders showed a significant decrease in blast counts (P < 0.001), cellularity (P = 0.001) and MVD (P = 0.050) quantification with CD31. Higher baseline MVD (CD34) values were associated with shorter overall survival (P = 0.0027). These results are encouraging for inclusion of MVD enumeration in bone marrow examinations of AML patients at diagnosis as an additional prognostic factor.

Acute Disease↗

PubMed2005

Evidence for complex multigenic inheritance of radiation AML susceptibility in mice revealed using a surrogate phenotypic assay.

The mapping of genes which affect individual cancer risk is an important but complex challenge. A surrogate assay of susceptibility to radiation-induced acute myeloid leukaemia (AML) in the mouse based on chromosomal radiosensitivity has been developed and validated. This assay was applied to the mapping of radiation-induced AML risk modifier loci by association with microsatellite markers. A region on chromosome (chr) 18 with strong association is identified and confirmed by backcross analysis. Additional loci on chrs 8 and 13 show significant association. A key candidate gene Rbbp8 on chr18 is identified. Rbbp8 is shown to be upregulated in response to X-irradiation in the AML sensitive CBA strain but not AML resistant C57BL/6 strain. This study demonstrates the strength of utilizing surrogate endpoints of cancer susceptibility in the mapping of mouse loci and identifies additional loci that may affect radiation cancer risk.

Acute Disease↗