Frequent loss of heterozygosity in the region of D1S450 at 1p36.2 in myelodysplastic syndromes

To understand the underlying mechanisms in myelodysplastic syndromes (MDS) by identifying target tumor suppressor genes, we performed a detailed deletional mapping of the short arm of chromosome 1 in 38 paired samples of bone marrow and peripheral blood obtained from individuals with MDS by PCR amplification of a total of 23 highly informative microsatellite sequences. We identified the commonly deleted region between D1S508 and D1S244. LOH of this region was found in five patients (13%). In addition, LOH at 1p was associated with a poor clinical outcome, suggesting that the deletion of a gene in this region may be involved in the course of this disease. By analyzing the chromosomal map of this region, we found TNFRSF12 as a candidate tumor suppressor gene. However, our search for mutations in this gene did not identify somatic mutations in MDS. Our findings are consistent with the possible existence of an as-yet unknown tumor suppressor gene in this region that is altered in MDS.

AC133 expression on acute myeloid leukemia blasts: correlation to FAB and to CD34 expression and possible implications for peripheral blood progenitor cell purging in AML

AC133 is an antigen expressed on CD34+ hematopoietic progenitor cells. In acute myeloid leukemia (AML) it is expressed on leukemic blasts of most FAB subtypes. However, few data are available regarding coexpression of other surface antigens. We measured AC133 expression on AML blasts from 28 consecutive patients at initial diagnosis (n=26) or at diagnosis of first relapse (n=2) and on 26 leukapheresis products from 14 patients. In AML AC133 correlated with CD34 expression (Spearman r=0.4711, P=0.0114) and even stronger with combined CD34/CD33 expression (Spearman r=0.5083, P=0.0068). In leukapheresis products AC133 expression correlated with CD34 expression (Spearman r=0.7495, P=0.002) and the yield of the obtained amount of CD34+ cells (Spearman r=0.6484, P=0.0121). In conclusion AC133 expression is closely related to CD34 expression in AML. In leukapheresis products AC133 provides an additional marker for selection of PBPC autografts in AC133- AML.

Deregulated expression of prostate apoptosis response gene-4 in less differentiated lymphocytes and inverse expressional patterns of par-4 and bcl-2 in acute lymphocytic leukemia

INTRODUCTION

Prostate apoptosis response gene-4, known as par-4, is a new proapoptotic factor functionally required but not sufficient for apoptosis. Since there is evidence from prostate cancer cells that par-4 is involved in regulation of bcl-2 we assessed expression of par-4 and bcl-2 in different populations of normal and neoplastic lymphocytes.

MATERIALS AND METHODS

Expression of par-4 mRNA and protein in different subpopulations of normal and neoplastic lymphocytes was assessed by reverse transcription polymerase chain reaction and Western blot.

RESULTS

Par-4 mRNA was not detectable in lymphocytes of healthy volunteers (n = 10), but was present in the majority of samples of chronic lymphocytic leukemia (n = 30), chronic lymphocytic leukemia/prolymphocytic leukemia (n = 6) and acute lymphocytic leukemia (n = 10). Par-4 protein was expressed unanimously in samples of mononuclear cells from healthy volunteers and patients with CLL, but less frequently in immature lymphocytes, including neoplastic cells of CLL/PLL and ALL. The decreased frequency of par-4 expression in immature subpopulations was confirmed by results on lymphocytic cell lines at various stages of maturation. Comparing the expressional patterns of par-4 and bcl-2 there was an inverse relationship of both proteins in ALL and different lymphocytic cell lines, indicating a functional relationship of par-4 and bcl-2.

CONCLUSIONS

This study establishes par-4 as a factor expressed in the majority of normal and neoplastic lymphocytic cells, demonstrating a decreased frequency of protein expression in less differentiated lymphocytes and an inverse expressional pattern of par-4 and bcl-2 in lymphocytic cell lines and ALL.

A randomized study of imipenem compared to cefotaxime plus piperacillin as initial therapy of infections in granulocytopenic patients

The objective of the presented, randomized study was to compare the efficacy of antimicrobial monotherapy with imipenem (3 x 0.5g/d) to a combination therapy with cefotaxime (3 x 2g/d) plus piperacillin (3 x 4g/d) for empirical treatment of infections in neutropenic patients. In 165 patients, 237 infectious episodes were evaluable. The overall response rate of patients treated with cefotaxime plus piperacillin was 67/115 (58%), of those treated with imipenem 66/122 (54%). In patients not responding to the initial therapy regimen within 2 or 3 days, the antimicrobial therapy was modified. After therapy modification 85/100 patients were cured. Fever of unknown origin (FUO) showed the most favourable course compared to other infection types, with a response in 46/59 (78%) and in 35/50 (70%) cases, respectively. In comparison, pneumonias were successfully treated in only 3/21 (14%) and 7/37 (19%) cases. Even including patients with modified therapy, only 66% (21/32) of pneumonia episodes responded. The unfavourable results in pneumonias is mainly due to the high rate of 13 systemic mycoses in this group (22%). Overall, a similar response was observed in patients treated with cefotaxime plus piperacillin in comparison with imipenem. In primary bacteremias however, an advantage was observed in patients treated with imipenem (20/27; 74%) compared with cefotaxime plus piperacillin (11/23; 48%).

Cytokine therapy for myelodysplastic syndrome

The myelodysplastic syndromes are a heterogeneous family of hematologic disorders characterized by ineffective hematopoiesis. Because of the interpatient variability regarding prognosis and morbidity, management of myelodysplastic syndromes continues to be a challenge to clinical hematologists. Pancytopenia and defective function of neutrophils and platelets carry a high risk of infectious or hemorrhagic complications. Erythropoietin is perhaps the most commonly used therapeutic option, second only to transfusion; improvement of erythropoiesis is seen in approximately 20% of patients, mainly in those with relatively preserved erythroid function and no or low transfusion requirements. Coadministration of erythropoietin with either granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor may increase the response rate up to 50%. Although prophylactic administration of granulocyte- or granulocyte-macrophage colony-stimulating factor cannot be recommended, treatment of febrile neutropenia might benefit from administration of granulocyte- or granulocyte-macrophage colony-stimulating factor in addition to antibiotics.

Comparison of toxicity and outcome in patients with acute myeloid leukemia treated with high-dose cytosine arabinoside consolidation after induction with a regimen containing idarubicin or daunorubicin

The toxicity and outcome after high-dose ara-C/daunorubicin (HDara-C/DNR) consolidation therapy in de novo AML was compared in 11 patients who received an idarubicin-containing induction therapy (IDA; from June 1995 to March 1997) and 16 patients pretreated with daunorubicin (DNR; from July 1990 to May 1995) for induction. The DNR group consisted of two cohorts, one (n = 6) of patients who had received, as had the IDA group, two induction and one intermediate-dose ara-C consolidation courses, and another (n = 10) of patients who had been pretreated with one induction and one consolidation course prior to HDara-C/DNR. There was no difference in the relative dose between the three cohorts. Following HDara-C/DNR, the IDA-pretreated patients experienced a more prolonged myelosuppression during consolidation therapy compared with the DNR group. Duration of neutropenia (< 500 neutrophils/microl) following HDara-C/DNR was 31.2 +/- 16 days (mean +/- SEM) in the IDA group compared with 18.7 +/- 5 days in the DNR group (p < .001 Mann-Whitney U-test). The duration 'of thrombocytopenia (platelets < 25000/microl) was 34.8 +/- 20 days in the IDA group vs. 18.5 +/- 6 days in the DNR group (p < .005). The more prolonged myelosupression was associated with a longer duration of fever (18.9 +/- 24 vs. 6.9 +/- 5.2 days). A greater incidence, length (11 +/- 8 vs. 1.2 +/- 2 days), and severity of diarrhea were observed in the IDA-pretreated group. Three of 11 IDA patients experienced WHO grade III-IV diarrhea. In the IDA group two patients developed severe enterocolitis with Candida septicemia, and one of these patients died. One patient in the IDA group died during prolonged aplasia. In the DNR group 6/16 patients experienced grade I-II diarrhea. Two patients in each group died during consolidation therapy. The CR rate was 87% in the IDA group and 79% in the DNR group. Relapse-free survival after HDara-C is 50% at a median follow-up of 60 months in the DNR group and 45% after a median follow-up of 17 months in the IDA group. Whether the advantage of the superior response rate in the IDA-treated patients may be lost during HDara-C consolidation treatment due to increased toxicity remains to be proven in larger trials.

Vindesine in the treatment of leukaemia

Despite lack of cross-resistance with vincristine and a somewhat different toxicity spectrum, the semi-synthetic vinca alkaloid, vindesine, has not yet achieved its expected potential in the treatment of acute leukaemias. The ability of vindesine to induce remissions in vincristine-resistant and relapsed ALL is of particular interest for the development of potentially curative second-line regimens. Vindesine may also have a role in consolidation strategies for de novo ALL, although it will be difficult to demonstrate specific advantages for this agent as part of a multidrug treatment approach. In myeloid leukaemias, while vindesine appears to have a limited role in ANLL, it may be useful for the palliative treatment of CML blast crisis. In the future, new synergistic combinations, incorporating vindesine with for example, methotrexate or edatrexate, may be developed.

Re-entry of resting leukaemic blood cells into proliferation in human acute leukaemia during diffusion chamber culture

From 17 patients with different forms of acute leukaemia, mononuclear blood cells were cultured in diffusion chambers (DC) implanted intraperitoneally into pre-irradiated mice. In 14 patients, growth of blast cells could be observed during the culture period of up to 21 days. To question whether this growth of blast cells was due only to proliferation of the initially proliferating fraction or whether a re-entry of resting leukaemic cells into proliferation was involved, various 3H-thymidine (3H-TdR) labelling studies were carried out. The absolute increase of blast cells in EC showed no correlation with the fraction of leukaemic blast cells in DNA-synthesis in the implanted cell suspension as measured by 3H-TdR labelling in vitro. Furthermore, in 2 patients where the kinetic behaviour of initially labelled leukaemic blast cells was followed during DC culture, the increase in total blast cells could only be attributed to a small extent to proliferation of those cells initially in the cell cycle. Lastly, "in vivo" labelling during the culture period showed that in one case 25% and in another case 60% of the blast cells in DC were proliferating. The conclusion is that, owing to the stimulation of the diffusion chamber milieu and possibly also due to removal of an in vivo inhibition, in most cases of acute leukaemia resting leukaemic blast cells can apparently re-enter the active cell cycle. This has relevance for an understanding of the self-maintenance of the leukaemic cell population and may also be a reason for relapse of leukaemia after the usual cytostatic drug treatment which affects mainly the proliferating leukaemic cells.

Iron-overload and genotypic expression of HFE mutations H63D/C282Y and transferrin receptor Hin6I and BanI polymorphism in german patients with hereditary haemochromatosis

Gene variations of HFE, a HLA-class I like molecule, are highly associated with hereditary haemochromatosis (HH). Functional as well as molecular studies of the HFE protein have indicated that the molecule is involved in iron metabolism and that the HFE gene variations observed among HH patients affect its interaction with the transferrin receptor (TfR). In the present study, we have therefore analysed the relationship between the HFE gene variants, C282Y and H63D, and body iron status among 85 German HH patients. In addition, two TfR gene polymorphism, TfR-Hin6I and TfR-BanI, were typed that have been reported to define ethnically distinct haplotypes. As controls we used 251/159 healthy German blood donors. Seventy-eight (92%) patients were C292Y homozygous, the H63D mutation was present in five (6%) patients with none of the patients being H63D homozygous. Serum transferrin, transferrin saturation and liver iron content were determined prior to therapeutic intervention. Among C282Y homozygous patients serum ferritin levels (2294 +/- 3174 vs. 463 +/- 224 microg L-1, P < 0.0001) and transferrin saturation (86 +/- 18% vs. 62 +/- 25%, P = 0.048) were elevated significantly compared with C282Y and/or H63D heterozygous patients. In addition, the liver iron content (291 +/- 165 vs. 138 +/- 95 micromol g-1, P = 0.028) and liver iron index (6.4 +/- 2.8 vs. 3.2 +/- 2.3, P = 0.019) were increased among C282Y homozygotes compared with C282Y heterozygotes. In contrast, no difference was observed between patients and controls regarding the distribution of TfR-Hin6I and TfR-BanI alleles. These data indicate that the iron intake is higher among C282Y homozygous patients compared with C282Y heterozygous or C282Y/H63D compound heterozygous individuals and supports the functional role of the HFE protein in iron metabolism whereas the TfR gene variants seem to have no influence on iron uptake.

High resolution physical mapping of human HDAC3, a potential tumor suppressor gene in the 5q31 region

Histone deacetylases have been described as crucial cofactors of mammalian transcriptional complexes. We have recently identified human histone deacetylase HDAC3 on chromosome 5q31 by fluorescence in situ hybridization (FISH) in a region commonly deleted in malignant myeloid disease. Since HDAC3 carries strong potential to be a tumor suppressor gene, we report herein its exact position between the CD14 and GRIA1 genes within the 5q31.1 subband.

The efficiency of strict reverse isolation and antimicrobial decontamination in remission induction therapy of acute leukemia

The efficiency of strict reverse isolation and antimicrobial decontamination in remission induction therapy of acute leukemia was studied retrospectively in 47 patients who were treated with a standardized aggressive chemotherapy of daunorubicin and cytosine arabinoside. Twenty-two patients were treated in strict reverse isolation with antimicrobial decontamination and 25 patients in the open ward without any measures against infections. In the patients in isolation the incidence of new infections per patient was 0.77 compared to 1.42 in the control group. The rate of complete remissions was 77% in the patients in isolation vs. 56% in the control patients.

Chromosomal organization and localization of the human histone deacetylase 5 gene (HDAC5)

Histone deacetylases (HDACs) are important participants in the remodeling of chromatin structure and in the regulation of eukaryotic proliferation and differentiation. We have isolated and characterized the human HDAC5 genomic sequence, which spans a region of 39,138 bp and which has one single chromosomal locus. Determination of the exon-intron splice junctions established that HDAC5 is encoded by 26 exons ranging in size from 22 bp (exon 1) to 285 bp (exon 12). Characterization of the 5' flanking genomic region revealed that the human HDAC5 promoter lacks both the canonical TATA and CCAAT boxes. The human HDAC5 mRNA encodes a 1122 aa protein with a predictive molecular mass of 121.9 kDa and an isoelectric point of 5.84. Fluorescence in situ hybridization analysis localized the human HDAC5 gene to chromosome 17q21, a region which is characterized by frequent gains and losses of chromosomal material in several types of cancer.

Megakaryocytic cells in mixed haemopoietic colonies (CFU-GEMM) from the peripheral blood of normal individuals

The cellular composition of mixed haemopoietic colonies CFU-GEMM from the peripheral blood of normal individuals was investigated using both an improved in vitro culture assay and a monoclonal antibody reactive with the earliest megakaryocytic precursor cells. The frequency of CFU-GEMM was found to be 22 +/- 7/ml blood (mean +/- SE; n = 8) and 4.9 +/- 1.8/10(6) mononuclear cells. Double-labelling of single colonies with monoclonal antibodies against megakaryocytic as well as granulocytic cells revealed that only 18% of mixed colonies from the peripheral blood contained megakaryocytic cells as compared to 87% of mixed colonies from the bone marrow, while no difference existed with regard to granulocytic cells. It is concluded that circulating multilineage progenitor cells either require different culture conditions to express their megakaryocytic component or, alternatively, that the circulating pluripotent stem cell pool mainly consists of bipotent rather than multipotent progenitor cells.

Oral 9-cis retinoic acid (Alitretinoin) in the treatment of myelodysplastic syndromes: results from a pilot study

A multicenter phase II study was initiated to investigate the efficacy, toxicity and tolerability of an oral regimen of 9-cis retinoic acid (9CRA) as a differentiation-inducing agent stimulating both retinoic acid receptor (RAR) and retinoic X receptor (RXR). Thirty patients with myelodysplastic syndromes (MDS) were enrolled into the study. The MDS subtypes were distributed as follows: 14 refractory anaemia (RA), four refractory anaemia with ringed sideroblasts (RARS), and 12 refractory anaemia with excess blasts (RAEB). The age ranged from 40 to 81 years (median 70). None of these had previously received treatment for MDS other than supportive therapy. 9CRA (Alitretinoin capsules, kindly provided by Allergan-Ligand Retinoid Therapeutics) was given daily at 60 mg/m2 p.o. for 1 week, followed by an intra-patient escalation to 100 mg/m2 during the second week, up to a maximum of 140 mg/m2. The planned treatment duration was 48 weeks. Twenty-five were available for assessment. One patient (4%) with RA achieved complete hematological remission. Four (16%), two with RA, two with RAEB, had minor responses resulting in decreased transfusion requirements or increased neutrophils. Thus, the overall response rate was 20% in evaluable patients with MDS and 17% in the study group on an intention-to-treat basis. The most frequent side-effects included headache (77%), dry skin (57%), arthralgias (30%), and rash (23%). In conclusion, although modest responses were noted in this study, the treatment tolerability was suboptimal. It is conceivable that a lower dosage schedule may be efficacious and better tolerated so enabling prolonged exposure which may be required to induce a differentiation effect.

TGF beta-induced SMAD2 phosphorylation predicts inhibition of thymidine incorporation in CD34+ cells from healthy donors, but not from patients with AML after MDS

Cells from patients with MDS-derived AML display heterogeneous proliferative responses to transforming growth factor beta (TGF beta). We analyzed growth inhibition and SMAD2 phosphorylation by TGF beta in CD34+ cells from nine patients, as compared to normal controls. While TGF beta consistently inhibited thymidine incorporation of normal cells (41% of control, P < 0.05), cells from patients with AML were growth-inhibited in only four of seven cases (40%), whereas TGF beta stimulated thymidine incorporation in the three other samples (166%). Remarkably, TPO reverted the stimulatory effect of TGF beta to profound growth inhibition. Upon exposure to TGF beta, SMAD2 protein was phosphorylated in normal CD34+ cells (n = 3), CD34+ leukemic blasts from all examined patients with AML (n = 4), and in the myeloid leukemic cell lines M-07e and HEL. TGF beta inhibited TPO-mediated thymidine incorporation, cell proliferation and survival in all samples analyzed. In M-07e cells and CD34+ cells from healthy donors, this inhibition was enhanced by an antagonist of JAK2 (AG490), but not a MEK-1 antagonist (PD098059). Conversely, in CD34+ cells from a patient with AML, both AG490 and PD098059 significantly enhanced TGF beta-mediated suppression of TPO-induced thymidine incorporation. Thus, in MDS-derived AML, altered responses to TGF beta may be due to defects downstream of SMAD2 and may involve MAPK activation.

Chronic myelocytic leukaemia: cytogenetical studies on haemopoietic colonies and diffusion chamber cultures

In 20 patients with chronic myelocytic leukaemia in the chronic phase or in blast crisis, several in vitro (CFU-C, BFU-E) and in vivo (diffusion chamber) culture techniques were used to demonstrate the existence of a still diploid cell clone. In 4 out of 12 patients in the chronic phase, Ph1-negative metaphases were found in the various cultures for haemopoietic progenitor cells but not in the standard suspension cultures used for cytogenetics. However, all the 8 patients investigated during blast crisis had only Ph1-positive and other abnormal clones, indicating the loss of the diploid clone during progression of the disease.