Apoptosis and its significance in MDS: controversies revisited

Identification of novel anti-leishmanials targeting glutathione synthetase of the parasite: a drug repurposing approach

Drug repurposing has emerged as an effective strategy against infectious diseases such as visceral leishmaniasis. Here, we evaluated four FDA-approved drugs-valrubicin, ciclesonide, deflazacort, and telithromycin-for their anti-leishmanial activity on Leishmania donovani parasites, especially their ability to target the enzyme glutathione synthetase (LdGS), which enables parasite survival under oxidative stress in host macrophages. Valrubicin and ciclesonide exhibited superior inhibitory effects compared to deflazacort and telithromycin, inhibiting the promastigotes at very low concentrations, with IC50 values of 1.09 ± 0.09 μm and 2.09 ± 0.09 μm, respectively. Subsequent testing on amastigotes revealed the IC50 values of 1.74 ± 0.05 μm and 3.32 ± 0.21 μm for valrubicin and ciclesonide, respectively. Molecular and cellular level analysis further elucidated the mechanisms underlying the anti-leishmanial activity of valrubicin and ciclesonide.

Hematopoiesis-related microRNA expression in myelodysplastic syndromes

MicroRNAs (miRNAs) are negative regulators of expression of genes involved in hematopoiesis. The present study sought to link hematopoiesis-relevant miRNAs with myelodysplastic syndromes (MDS) and MDS progression to acute myeloid leukemia (AML). We assessed 25 mature miRNAs in total RNA from bone marrow (BM) and peripheral blood (PB) of 25 newly diagnosed patients with MDS and 12 controls. Twelve miRNAs in BM and six in PB were differentially expressed between patients with MDS and controls. Three of these miRNAs, belonging to the cluster 17-92, were overexpressed in both BM and PB. miR-15a in BM ( p = 0.034) and miR-16 in PB ( p = 0.005) were differentially expressed between low-risk and high-risk groups. miR-222 ( p = 0.0023) and miR-181a ( p = 0.014) expression was higher in AML than in MDS in both BM and PB. This study adds further evidence to the role of miRNAs in the pathogenesis of MDS and their transformation into AML.

Cell cycle and apoptosis regulatory gene expression in the bone marrow of patients with de novo myelodysplastic syndromes (MDS)

Deregulation of cell cycle and apoptosis pathways are known contributors to the pathogenesis of myelodysplastic syndromes (MDS). However, the underlying mechanisms are not fully clarified. The aim of our study was to examine mRNA expression levels of cell cycle and apoptosis regulatory genes, as well as the percentage of apoptotic and S phase cells and to correlate the findings with clinical characteristics and prognosis. Sixty patients with MDS, classified according to FAB (17 RA, five RARS, 19 RAEB, nine RAEBT, ten CMML) and WHO (ten RA, three RARS, seven RCMD, two RCMD-RS, 11 RAEBI, eight RAEBII, ten CMML, and nine AML) were included in the study. We found increased expression of anti-apoptotic bclxL and mcl1 genes and decreased expression of p21 gene in MDS patients. Moreover, we found increased expression of anti-apoptotic mcl1 gene in patients with higher than Intermediate-1 IPSS group. Multivariate analysis confirmed that combined expression of apoptotic caspases 8, 3, 6, 5, 2, 7, and Granzyme B was decreased in MDS patients. Regarding cell cycle regulatory genes expression, we demonstrated increased expression of cyclin D1 in patients with CMML Increased combined expression of cyclins B, C, D1, and D2 was found in patients with cytogenetic abnormalities. The two pathways seem to be interconnected as shown by the positive correlation between CDKs 1, 2, 4, p21 and the level of apoptosis and positive correlation between apoptotic caspase 3 expression and the percentage of S phase cells. In conclusion, our study showed altered expression of genes involved in apoptosis and cell cycle in MDS and increased expression of cyclin D1 in patients with CMML.

Serum Levels of CD137 Ligand and CD178 are Prognostic Factors for Progression of Myelodysplastic Syndrome

Excess apoptosis leading to ineffective hematopoiesis is a common feature of myelodysplastic syndrome (MDS). CD178 (Fas ligand/APO-1 ligand) and CD137 ligand (CD137L), 2 molecules involved in the regulation of apoptosis, have previously been found in sera of patients with malignancies and have been hypothesized to participate in the pathogenesis of various diseases. We analyzed sera of patients with MDS and found that while time to progression of MDS correlated with the IPSS score there was no correlation of CD137L or CD178 serum levels with this score or with karyotype, bone marrow blast count or cytopenia. However, when cut-off-values for significant differentiation between cases with higher/lower levels of these molecules were determined we found that high levels of soluble CD137L (sCD137L) and low serum levels of soluble CD178 (sCD178) correlate with statistical significance to rapid progression of disease as estimated by log-rank-test. Conversely, low levels of sCD137L and high levels of sCD178 correlate significantly with prolongation of time to progression of disease. Our results indicate that serum levels of sCD137L and sCD178 represent valuable novel indicators for prognosis and disease progression and may be a useful parameter for treatment decisions in patients with MDS.

Survivin Expression in Acute Leukemias and Myelodysplastic Syndromes

We analyzed by immunocytochemistry the expression of survivin in bone marrow cells from 36 acute myeloid leukemia (AML) cases, from 98 patients with myelodysplastic syndrome (MDS), and from 41 non hemopathic subjects. Our aim was to evaluate whether abnormalites in survivin expression were associated with peculiar laboratory and clinical findings, altered apoptosis levels or altered proliferative rate. In normal samples survivin was never detectable. It was detected in almost all AML and MDS cases. In AML and in MDS with more than 5% bone marrow blasts survivin levels higher than in RA and RARS were observed (P=0.04). In MDS a tendential inverse correlation between survivin and TUNEL positivity was identified (P=0.08), whereas survivin expression was independent of the proliferative rate. Survivin levels did not predict disease progression in MDS; among AML patients treated with intensive polichemotherapy, survivin expression was significantly higher in resistant cases (P=0.01). Our findings confirm the high incidence of survivin expression in AML. Its abnormal expression also in MDS may play a role in promoting aberrantly increased cell viability and contribute to the altered homeostatic balance between cell growth and cell death.

Impaired differentiation and apoptosis of hematopoietic precursors in a mouse model of myelodysplastic syndrome

Expression of a NUP98-HOXD13 (NHD13) fusion gene, initially identified in a patient with myelodysplastic syndrome, leads to a highly penetrant myelodysplastic syndrome in mice that recapitulates all of the key features of the human disease. Expansion of undifferentiated lineage negative (lin(neg)) hematopoietic precursors that express NHD13 was markedly inhibited (30-fold) in vitro. Decreased expansion was accompanied by decreased production of terminally differentiated cells, indicating impaired differentiation of NHD13 precursors. Rather than differentiate, the majority (80%) of NHD13 lin(neg) precursors underwent apoptotic cell death when induced to differentiate. These findings demonstrate that NHD13 lin(neg) cells provide a tractable in vitro system for studies of myelodysplastic syndrome.

An erythroid differentiation signature predicts response to lenalidomide in myelodysplastic syndrome

BACKGROUND

Lenalidomide is an effective new agent for the treatment of patients with myelodysplastic syndrome (MDS), an acquired hematopoietic disorder characterized by ineffective blood cell production and a predisposition to the development of leukemia. Patients with an interstitial deletion of Chromosome 5q have a high rate of response to lenalidomide, but most MDS patients lack this deletion. Approximately 25% of patients without 5q deletions also benefit from lenalidomide therapy, but response in these patients cannot be predicted by any currently available diagnostic assays. The aim of this study was to develop a method to predict lenalidomide response in order to avoid unnecessary toxicity in patients unlikely to benefit from treatment.

METHODS AND FINDINGS

Using gene expression profiling, we identified a molecular signature that predicts lenalidomide response. The signature was defined in a set of 16 pretreatment bone marrow aspirates from MDS patients without 5q deletions, and validated in an independent set of 26 samples. The response signature consisted of a cohesive set of erythroid-specific genes with decreased expression in responders, suggesting that a defect in erythroid differentiation underlies lenalidomide response. Consistent with this observation, treatment with lenalidomide promoted erythroid differentiation of primary hematopoietic progenitor cells grown in vitro.

CONCLUSIONS

These studies indicate that lenalidomide-responsive patients have a defect in erythroid differentiation, and suggest a strategy for a clinical test to predict patients most likely to respond to the drug. The experiments further suggest that the efficacy of lenalidomide, whose mechanism of action in MDS is unknown, may be due to its ability to induce erythroid differentiation.

Analysis of apoptosis regulatory genes expression in the bone marrow (BM) of adult de novo Myelodysplastic Syndromes (MDS)

The aim of the present study was to examine caspases, granzyme B and bcl-2 family mRNA expression and the degree of apoptosis in the bone marrow (BM) of 46 Myelodysplastic Syndromes (MDS) and to correlate our findings with clinical parameters. The degree of apoptosis was determined by Annexin V, whereas expression of genes was determined using a multiprobe RNase Protection System. A positive correlation was found between caspases 8, 5, 3, 2, 1 and the level of apoptosis. bfl1 and mcl1 levels were significantly higher in patients with BM blasts >5%. Cases with ratio of bid expression >1 compared to normal pool were associated with IPSS values < or =1.

Megakaryocytic dysfunction in myelodysplastic syndromes and idiopathic thrombocytopenic purpura is in part due to different forms of cell death

Platelet production requires compartmentalized caspase activation within megakaryocytes. This eventually results in platelet release in conjunction with apoptosis of the remaining megakaryocyte. Recent studies have indicated that in low-risk myelodysplastic syndromes (MDS) and idiopathic thrombocytopenic purpura (ITP), premature cell death of megakaryocytes may contribute to thrombocytopenia. Different cell death patterns have been identified in megakaryocytes in these disorders. Growing evidence suggests that, besides apoptosis, necrosis and autophagic cell death, may also be programmed. Therefore, programmed cell death (PCD) can be classified in apoptosis, a caspase-dependent process, apoptosis-like, autophagic and necrosis-like PCD, which are predominantly caspase-independent processes. In MDS, megakaryocytes show features of necrosis-like PCD, whereas ITP megakaryocytes demonstrate predominantly characteristics of apoptosis-like PCD (para-apoptosis). Triggers for these death pathways are largely unknown. In MDS, the interaction of Fas/Fas-ligand might be of importance, whereas in ITP antiplatelet autoantibodies recognizing common antigens on megakaryocytes and platelets might be involved. These findings illustrate that cellular death pathways in megakaryocytes are recruited in both physiological and pathological settings, and that different forms of cell death can occur in the same cell depending on the stimulus and the cellular context. Elucidation of the underlying mechanisms might lead to novel therapeutic interventions.

Thalidomide : mécanismes d'action et indications en hématologie

Purpose. - Thalidomide, a major teratogen drug, was rehabilitated mainly in malignant hemopathy. Current knowledge and key points. - Thalidomide-mechanisms of action are well known, multiple, they combine immunomodulatory, antiangiogenic properties, and the modulation of cytokines, particularly tumour necrosis factor-alpha. Multiple trials are ongoing, however, the main indication remain multiple myeloma with a response rate of 30% in relapsed patients. Future prospects and projects. - New structural analogues of the thalidomide which priviligiate some of the thalidomide-specific mechanisms of action, the selected cytokine inhibitory drugs (SelCIDS) and the immunomodulatory drugs (IMiDs) family are under evaluation. The IMiDs, which mechanism is based on stimulation of T lymphopoiesis rather than inhibition of tumour necrosis factor-alpha, are under clinical trials in multiple myeloma with interesting results.

Limited numbers of apoptotic cells in fresh paraffin embedded bone marrow samples of patients with myelodysplastic syndrome

In myelodysplasia (MDS) the precise mechanism of ineffective erythropoiesis is not fully elucidated, but it is suggested that apoptosis may contribute to this process. We performed TdT-mediated dUTP-nick end labelling (TUNEL) staining of paraffin embedded bone marrow specimens to assess the amount of apoptotic cells in 21 MDS patients (7 RA, 3 RARS, 5 RAEB, 3 RAEB-T, 3 CMML) and five normal controls. In 10 MDS patients the TUNEL assay was performed in combination with immunostaining for Glycophorin-A (GpA) to determine apoptosis in the maturing erythroid compartment. To assess the proliferation of the bone marrow cells the expression of Ki-67 antigen was used as a marker. The mean apoptotic index (AI) in MDS patients was not increased (2.3 +/- 3.0% in MDS versus 4.8 +/- 1.2% in normal controls (P < 0.05)). Moreover, no significant difference in mean AI was observed in the GpA+ compartment between MDS and normal controls (0.8 +/- 0.2% versus 0.6 +/- 0.1%). In addition the different FAB-classifications and the different International Prognostic Scoring System (IPSS)-risk groups showed no significant differences between the subgroups. The expression of Ki-67, as marker for proliferative activity, in the GpA+ compartment from MDS did not differ significantly from normal controls (84.0 +/- 12.2% versus 79.9 +/- 20.2%). Our findings suggest that the observed increased apoptosis in in vitro culture assays is related to the detachment of the cells from the microenvironment leading to an increased susceptibility to apoptosis.

Bone marrow stroma in childhood myelodysplastic syndrome: composition, ability to sustain hematopoiesis in vitro, and altered gene expression

We studied bone marrow stromal cell cultures from patients with childhood myelodysplastic syndromes (MDS, refractory anemia with excess of blasts, RAEB) and from matched normal donors. Stromal cell monolayers were characterized as myofibroblasts by the expression of smooth muscle alpha-actin, collagen IV, laminin and fibronectin. When normal cord blood cells were plated onto myelodysplastic stromas, a pathologic cell differentiation was observed, indicating altered myelosupportive properties. cDNA array analysis showed that patient stromas expressed increased levels of thrombospondin-1, collagen-I alpha2-chain, osteoblast-specific factor-2 and osteonectin, indicating the presence of increased osteoblast content, as confirmed by enhanced alkaline phosphatase synthesis. Alterations in the myelodysplastic stroma environment might contribute to abnormal hematopoiesis in this pathology.

Flow cytometric analysis of the expression of Fas/Fasl in bone marrow CD34+ cells in myelodysplastic syndromes: relation to disease progression

The role of apoptosis in the pathobiology of myelodysplastic syndromes (MDS) remains controversial. We studied the expression of CD95 and CD95L in CD34+ cells of patients with newly diagnosed MDS by flow cytometry, and examined the relation between this expression and FAB and WHO types, total number of CD34+ bone marrow (BM) cells and the degree of peripheral cytopenias. The patients with refractory anemia (RA) and sideroblastic anemia showed CD34+ cells in numbers comparable to normal donors, but had a higher percentage of CD95/CD34 and CD95L/CD34 positive cells. An inverse correlation was found between these cells and the total CD34+ cells. This was also observed when only patients with RA were analyzed. In RAEB, however, CD95/CD95L expression correlated with CD34+ cells but not with the percentage of BM blasts. After classification by the WHO proposal, the patients with refractory cytopenias with multilineage dysplasia showed features intermediary between RA and RAEB. No significant correlation was seen between the expression of CD95/CD95L and the peripheral blood counts. These results are in keeping with the hypothesis that, as the number of MDS precursors increases during disease progression they become less succeptible to apoptosis.

Myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are characterized by hemopoietic insufficiency associated with cytopenias leading to serious morbidity plus the additional risk of leukemic transformation. Therapeutic dilemmas exist in MDS because of the disease's multifactorial pathogenetic features, heterogeneous stages, and the patients' generally elderly ages. Underlying the cytopenias and evolutionary potential in MDS are innate stem cell lesions, cellular/cytokine-mediated stromal defects, and immunologic derangements. This article reviews the developing understanding of biologic and molecular lesions in MDS and recently available biospecific drugs that are potentially capable of abrogating these abnormalities. Dr. Peter Greenberg's discussion centers on decision-making approaches for these therapeutic options, considering the patient's clinical factors and risk-based prognostic category. One mechanism underlying the marrow failure present in a portion of MDS patients is immunologic attack on the hemopoietic stem cells. Considerable overlap exists between aplastic anemia, paroxysmal nocturnal hemoglobinuria, and subsets of MDS. Common or intersecting pathophysiologic mechanisms appear to underlie hemopoietic cell destruction and genetic instability, which are characteristic of these diseases. Treatment results and new therapeutic strategies using immune modulation, as well as the role of the immune system in possible mechanisms responsible for genetic instability in MDS, will be the subject of discussion by Dr. Neal Young. A common morphological change found within MDS marrow cells, most sensitively demonstrated by electron microscopy, is the presence of ringed sideroblasts. Such assessment shows that this abnormal mitochondrial iron accumulation is not confined to the refractory anemia with ring sideroblast (RARS) subtype of MDS and may also contribute to numerous underlying MDS pathophysiological processes. Generation of abnormal sideroblast formation appears to be due to malfunction of the mitochondrial respiratory chain, attributable to mutations of mitochondrial DNA, to which aged individuals are most vulnerable. Such dysfunction leads to accumulation of toxic ferric iron in the mitochondrial matrix. Understanding the broad biologic consequences of these derangements is the focus of the discussion by Dr. Norbert Gattermann.

Pathogenesis, classification, and treatment of myelodysplastic syndromes (MDS)

Myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal myeloid disorders characterized by morphologic dysplasia in one or more cell lineages. Dysplasia in MDS is associated with insufficient production of blood cells and consecutive cytopenia(s). The natural course and prognosis of MDS vary among patients and depend on genetic defects that occur during clonal evolution. In a significant group of patients (roughly 30%) progression to secondary leukemia is observed. These patients appear to have a grave prognosis. The treatment of patients with MDS has to be adjusted to the individual situation and age in each case. In many patients, control of blast cell production by palliative cytoreduction, continuous support with red blood cells, as well as other supportive measures, seem appropriate. In other patients, however, curative therapy (chemotherapy, stem cell transplantation) should be considered. The final decision to offer curative therapy must be based on many different factors including age and the overall situation of the patient. Recently established scoring systems aimed at predicting survival and evolution of leukemia in MDS may be helpful in this regard.

NOD/SCID mice transplanted with marrow from patients with myelodysplastic syndrome (MDS) show long-term propagation of normal but not clonal human precursors

Sublethally irradiated NOD/SCID mice were transplanted with hematopoietic progenitor cells obtained from the marrow of patients with myelodysplastic syndromes (MDS). Engraftment of MDS cells, as determined by flow cytometry, was delayed compared to marrow from normal donors. Human CD38(+)CD34(-) cells were prominent in marrows and spleens of MDS chimeras. CD34(+)CD38(-), CD34(+)CD38(+) and T cells were also easily detected. Human myeloid cells (CD33(+); CD15(+)) were present in low proportions. No clonal precursors were identified by fluorescent in situ hybridization (FISH) or by molecular analysis of polymorphic X-linked markers in mice with documented engraftment of human cells more than 2 months after transplantation. These data indicate that human cells present in murine MDS chimeras, at the levels of sensitivity of our assays, were derived from residual normal cells in human MDS marrow, and suggest that the NOD/SCID environment was not conducive to the expansion of clonal MDS precursors. This model may allow identification of factors relevant for sustaining or expanding clonal precursors.

Apoptosis in relation to CD34 antigen expression in normal and myelodysplastic bone marrow

An increased bone marrow (BM) apoptosis is one of the mechanisms responsible for the ineffective hematopoiesis of myelodysplastic syndromes (MDS). It is controversial whether the excessive apoptosis in myelodysplasia predominantly involves the subset of progenitor cells or of maturing cells. We investigated the degree of apoptosis in MDS BM and its differences from normal marrow in relation to CD34 antigen expression. A double-labelling technique that combined the Tdt-mediated dUTP nick end labelling (TUNEL) method with immunocytochemistry for CD34 antigen was used on BM slides of 18 MDS patients and 11 controls. The apoptotic rate (AR) appeared significantly higher in CD34-negative than in CD34-positive cell subsets both in myelodysplastic and in normal BM. When MDS and normal CD34-negative cell populations were compared, a greater AR in MDS CD34-negative cells was found, while no statistical difference in AR resulted from the comparison between MDS and normal CD34-positive cell populations. Our results suggest that in myelodysplastic as well as in normal BM the apoptotic phenomenon predominantly involves the maturing cells. The increase in apoptotic levels which can be observed in myelodysplastic compared to normal BM seems to be mainly due to an increase in apoptosis in the differentiated cell population.

Effects of cyclosporine on hematopoietic and immune functions in patients with hypoplastic myelodysplasia: in vitro and in vivo studies

BACKGROUND

Immunosuppression may benefit some patients with hypoplastic myelodysplasia (HMDS) and refractory anemia (RA), but its mechanism of action is still obscure.

METHODS

Using flow cytometry, we studied Fas-receptor (Fas-R), Fas-ligand (Fas-L), and interferon-gamma (IFN-gamma) expression in CD34(+) cells and lymphocytes obtained from 11 HMDS and 20 RA patients. In colony assays and long-term cultures, the effects of Fas triggering, IFN-gamma blockade, or cyclosporine(CsA) on the growth of hematopoietic progenitors (colony-forming cells [CFC]) were determined. The effects of CsA at daily doses of 1-3 mg/kg for at least 3 months in HMDS patients were also studied.

RESULTS

In basal conditions, committed and immature progenitor cells were found decreased in myelodysplastic (MDS) patients. No significant differences between HMDS and RA patients were detected. IFN-gamma-expressing CD4(+) cells were significantly increased in HMDS patients, whereas intracytoplasmic Fas-L expression was only borderline elevated in CD3(+) MDS cells. Increased numbers of CD34(+) cells expressing Fas-R were found in HMDS and RA patients. CFC and secondary CFC showed higher susceptibility to Fas-L-mediated inhibition and the blockade of IFN-gamma improved marrow primary, but not secondary, CFC growth. CsA added in vitro to patient's lymphocytes significantly decreased the number of IFN-gamma-expressing CD4(+) cells, but not Fas-L production. These effects were associated with increased colony formation. Similar to IFN-gammablockade, production of secondary CFC was not enhanced by CsA. Administration of CsA to patients resulted in prolonged partial hematologic improvement in 8 of 11 HMDS patients.

CONCLUSIONS

Increased frequency of IFN-gamma producing CD4(+) cells supports the involvement of lymphocyte-mediated suppression of hematopoiesis in the development of cytopenia in MDS patients. The ability of CsA to decrease in vitro IFN-gamma production may improve hematopoietic function, explaining the beneficial effect of this agent in HMDS patients.

Significance of fetal hemoglobin-containing erythroblasts (F blasts) and the F blast/F cell ratio in myelodysplastic syndromes

To investigate the relationship between the fetal hemoglobin-containing erythroblasts (F blasts) and apoptosis in myelodysplastic syndromes (MDS), we immunohistochemically assessed F blasts, F cells, and apoptosis in 137 patients with MDS. A marked increase in the number of F blasts in the bone marrow was identified in 116 of 137 patients (84.7%), and the number of F cells was elevated in 54 patients (39.4%). Among the erythroblasts stained by anti-glycophorin C antibody, the mean percentage of F blasts was 14.63 +/- 9.17% in MDS, which was significantly higher than that in non-MDS patients with stress erythropoiesis (4.82 +/- 3.35%, P < 0.01), although there were no significant differences in the number of F cells between these groups. In particular, 62 of the 137 MDS patients (45.3%) had an apparent increase in F blasts but no elevation of F cells. The apoptotic rate was significantly higher in the patients with a F blast/F cell (Fb/Fc) ratio >or=5.0 than in those with a Fb/Fc ratio <1.0 (P < 0.01). The results indicate that F cell precursors are incapable of maturing into functioning end-stage F cells, presumably owing to apoptotic cell death. The measurement of F blasts in the bone marrow is needed for the precise evaluation of fetal-type erythropoiesis in MDS.

Clinical and biological effects of treatment with amifostine in myelodysplastic syndromes

We treated six patients with primary myelodysplastic syndrome (MDS) with amifostine (200 mg/m(2) i.v./three times a week for three consecutive weeks). Neutrophil counts were more frequently increased than platelet and reticulocyte counts, but no reduction of the transfusion requirement was observed. Significant reduction of the marrow blasts was observed in one case of refractory anaemia with excess of blasts. In vitro stimulation of haematopoiesis was observed in five cases. The apoptotic rate of marrow cells was significantly diminished even after the first course. Our findings show fairly good clinical and biological response to amifostine in MDS.

The clinical and biological effects of thalidomide in patients with myelodysplastic syndromes

Thirty patients with myelodysplastic syndromes (MDS) were treated with thalidomide at 100 mg/d p.o., increased as tolerated to 400 mg/d for 12 weeks. Levels of apoptosis, macrophage number, microvessel density (MVD), tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), interleukin 6 (IL-6), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were determined in the serum, bone marrow (BM) plasma and BM biopsies before and after therapy. Pretherapy biological characteristics of MDS patients were compared with similar studies performed in 11 normal volunteers. Ten patients demonstrated haematological improvement in the erythroid series, six becoming transfusion independent. Responders had a higher pretherapy platelet count (P < 0.048) and lower BM blasts (P < 0.013). Median time to response was 10 weeks, and four remain in remission beyond a year. Pretherapy MDS BMs showed higher MVD (P < 0.001) and TGF-beta (P < 0.03) and higher serum TNF-alpha (P < 0.008) compared with normal control subjects. After therapy, only BM TGF-beta decreased significantly (P < 0.002). Pretherapy haemoglobin was directly related to serum VEGF (P < 0.001) in responders and inversely related in non-responders (P < 0.05), suggesting the possibility that angiogenesis may be a primary pathology in the former and a consequence of anaemia-induced hypoxia in the latter. We conclude that thalidomide has important clinical and biological effects in at least a subset of MDS patients, but the precise mechanism of its action remains unknown and requires further study including a larger number of patients.

Transcription patterning of uncoupled proliferation and differentiation in myelodysplastic bone marrow with erythroid-focused arrays

Because abnormal erythroid differentiation is the most common manifestation of the myelodysplastic syndromes (MDS), it was hypothesized that erythroid gene expression may be used to illustrate myelodysplastic transcription patterns. Ten normal bone marrow aspirates (NBM) were first analyzed using an erythroid-focused cDNA array to define steady-state transcription levels. Proliferation and differentiation gene subsets were identified by statistically significant differences between NBM and erythroleukemia gene expression. Next, cDNAs from 5 separate MDS aspirates were studied: refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess blasts, refractory anemia with excess blasts in transformation (RAEB-T), and RAEB-T/secondary MDS. A distinct pattern of significantly increased proliferation-associated and reduced differentiation-associated gene activity was established for MDS.

Telomere dynamics in myelodysplastic syndromes and acute leukemic transformation

Myelodysplastic syndromes (MDS) are characterized by cytopenias in the blood and dysplastic features in the hematopoietic cells. Although the impact of cytogenetic abnormalities is considerable for prognosis, the exact genetic mechanism of MDS remains undetermined. In this study we assessed cytogenetic changes, microsatellite alterations, and telomere dynamics in order to obtain further insight into the pathogenesis of MDS. Thirty-three percentage of MDS patients and 60% of post-MDS acute leukemia (post-MDS AML) had de novo microsatellite changes. In the MDS phase, however, > 60% of patients showed reduction of telomere lengths without microsatellite changes, indicating that telomere reduction in most MDS patients does not seem to be directly linked to genome instability, or that reduction of telomere length does not induce microsatellite changes in the MDS phase. Some MDS patients had microsatellite changes without telomerase elevation, indicating that genome instability might accumulate during the disease progression in some MDS patients, and this condition (cellular senescence) may be related to ineffective hemopoiesis in MDS patients. In contrast, 40% of post-MDS AML patients had elevated telomerase activity with microsatellite changes, indicating that approximately 40% of patients with post-MDS AML patients had accumulation of genome instability resulting in elevated telomerase activity in an attempt to obtain genetic stability. However, the remaining MDS patients had microsatellite changes without telomerase up-regulation, suggesting that some MDS had genome instability even after leukemic transformation. Most MDS patients with elevated telomerase activity in the AML phase had elevated telomerase activity even in the MDS phase without apparent change in telomere length before and after leukemic transformation. These findings indicate that telomerase activity in the MDS phase may be independent of telomere length, although telomere shortening seems to be related to genomic instability, and this process may be linked to apoptosis of MDS cells.

Expression of p53, bcl-2 and ras oncoproteins and apoptosis levels in acute leukaemias and myelodysplastic syndromes

We analysed by immunocytochemistry the expression of p53, bcl-2 and ras proteins in bone marrow blasts from 59 patients with acute leukaemia (AL), 36 myeloid (AML) and 23 lymphoid (ALL), and from 22 patients with myelodysplastic syndrome (MDS); our aim was to examine if abnormalities in their expression were associated with peculiar biological and clinical findings, or with an altered apoptosis rate, as measured by TUNEL technique. The oncoproteins were expressed with extreme variability, without significant differences among the various morphological or immunological AL subtypes. The mean percentages of bcl-2+ blasts were significantly higher in AML than in MDS (p = 0.01), and in MDS with bone marrow blastosis than in the forms without excess of blasts (p = 0.007). The lowest percentages of apoptotic cells were observed in ALL (mean 1%, p = 0.006), whereas in MDS the apoptotic index was higher (16.7%) than in AML (8.6%) and than in the normal controls (10.8%). but the difference tended to be statistically significant only for cases of refractory anaemia. Whereas in AML and MDS the apoptotic rate was independent of the oncoprotein expression, in ALL there was a significant linear relationship between TUNEL and ras positivity (p = 0.01). Among AML patients treated with intensive polychemotherapy, no differences were observed in oncoprotein expression and apoptotic rate between responders and resistant cases. In conclusion, our data are in agreement with the hypothesis that decreased apoptosis and enhanced cell survival are associated with AL, whereas a high level of apoptosis may be responsible for the ineffective hematopoiesis in MDS; abnormal expression of oncoproteins, even if not strictly related to apoptosis level, may influence disease behaviour.

Granulocyte colony-stimulating factor inhibits Fas-triggered apoptosis in bone marrow cells isolated from patients with refractory anemia with ringed sideroblasts

Treatment with granulocyte colony-stimulating factor (G-CSF) plus erythropoietin may synergistically improve hemoglobin levels and reduce bone marrow apoptosis in patients with refractory anemia with ringed sideroblasts (RARS). Fas-induced caspase activity is increased in RARS bone marrow cells. We showed that G-CSF significantly reduced Fas-mediated caspase-8 and caspase-3-like activity and the degree of nuclear apoptotic changes in bone marrow from nine RARS patients. A decrease in mitochondrial membrane potential and an increase in intracellular reactive oxygen species occurred in Fas-treated cells, but became significant only 24 h after changes in caspase activity and decrease in proliferation. G-CSF also reduced the magnitude of these late apoptotic changes. In CD34-selected normal cells, G-CSF induced myeloid colony growth, and an overall small decrease in the number of erythroid colonies. By contrast, G-CSF induced a 33-263% increase of erythroid colony formation in CD34+ cells from four of five RARS patients with severely reduced erythroid growth, while the normal or slightly reduced erythroid growth of three other patients was not influenced by G-CSF. This study suggests that G-CSF may reduce the pathologically increased caspase activity and concomitant apoptotic changes, and promote erythroid growth and differentiation of stem cells from RARS patients. Our data support the clinical benefit of G-CSF in this subgroup of myelodysplastic syndromes.

Is myelodysplastic related acute myelogenous leukemia a distinct entity from de novo acute myelogenous leukemia? Potential for targeted therapies

Acute myelogenous leukemia (AML) can be separated by whether the presentation was proceeded by a myelodysplastic (MDS related AML) or developed de novo (dAML). Clinically, MDS related AML (mAML) has been considered to have a worse prognosis that dAML. The objective of this literature review was to identify unique biologic features of mAML. Compared to dAML, mAML is characterized by an altered immunophenotype (increased frequency of CD34, CD11b and CD25), lack of leukemic progenitor cell suppression due to TGFbeta1, increased bcl-2 expression, presence of inducible nitric oxide synthase, lower levels or mrp transcripts and increased expression of p53. Possible interpretations of these differences between mAML and dAML are presented. Implications for mAML directed therapy are discussed.

Altered self-reactive antibody repertoires are a general feature of patients with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is characterized by an acquired clonal disorder of haematopoietic progenitor cells that results in inhibition of normal haematopoiesis and contributes to the development of haematological malignancies. Autoimmune syndromes may occur in MDS, but they are not a major clinical feature of the disease. In the present study, we have analysed the global antibody repertoires of IgM and IgG in plasma of 10 patients with MDS toward self- and non-self-antigens by quantitative immunoblotting. Myelodysplastic syndrome patients included in this study did not exhibit autoimmune symptoms nor secondary haematological neoplastic disease. Data were compared by means of multiparametric statistical analysis. We demonstrate that the antibody repertoires of self-reactive IgM and IgG of patients with MDS exhibit significantly altered patterns of reactivity, as compared to those of healthy individuals. In contrast, reactivity patterns of IgM in plasma of patients and of healthy controls toward non-self-antigens were similar, whereas reactivity patterns of IgG of patients and healthy subjects toward non-self-antigens were discriminated by multiparametric statistical analysis. These observations indicate that a broad disturbance of self-recognition mechanisms is a general feature of patients with MDS. A failure in the regulation of self-reactivity may contribute to the pathogenesis of MDS.

Freezing induces artificial cleavage of apoptosis-related proteins in human bone marrow cells

The aim of this study was to investigate whether freeze-thawing of freshly isolated human mononuclear bone marrow cells (MNC) influences the integrity of apoptosis-related proteins as determined by immunoblot analyses. Our results show that bone marrow is more sensitive to this process than either myelomonocytoid leukemic P39 or Jurkat T-lymphocyte cell lines. Specifically, bone marrow cells displayed a high level of intrinsic proteolytic activity in response to a single freeze-thaw cycle, which led to the cleavage of various proteins involved in apoptosis cell signaling. This effect was completely blocked by the inclusion of broad-spectrum protease inhibitors in the freezing medium and subsequently thawing the cells on ice. Since differences in the freezing conditions (-80 degrees C vs. liquid nitrogen) did not alter the proteins of interest, we suggest that the thawing process is the critical point when proteolytic enzyme activity is elevated.

P53 overexpression in bone marrow biopsies in refractory anemia and aplastic anemia: impact of antibody selection

There is a growing interest in studying cell cycle and apoptosis in the myelodysplastic syndromes (MDS). p53 has been a major target of several studies. We examined the impact of antibody selection on p53 overexpression in bone marrow (BM) biopsies of 28 patients with refractory anemia (RA) in addition to 10 cases of aplastic anemia (AA) using three antibodies DO-7, PAb 1801, and PAb 240. DO-7 was positive in 68%, PAb 1801 in 18% and PAb240 in 4% of RA patients. All three antibodies were negative in AA. We conclude that antibody selection is an important variable in studying p53 in MDS regardless of the method of fixation or decalcification of BM trephine biopsies.

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.

Dyshaemopoiesis in adults: a practical classification for diagnosis and management

Dyshaemopoiesis is a heterogeneous disease that may be classified into non-clonal and clonal dyshaemopoiesis. Non-clonal dyshaemopoiesis comprises reversible disorders with DNA synthesis impairment in dividing cells of the bone marrow by avitaminosis through various mechanisms or direct DNA damage from multiple causes. Complete haematologic recovery is obtained after vitamin supplementation or suppression of a myelotoxic agent. On the contrary, clonal dyshaemopoiesis is a group of chronic and usually irreversible diseases that may culminate in acute leukaemia (AL). These so called myelodysplastic syndromes (MDS) and their variants may be classified as primary, secondary and other diseases with doubtful clonality. A detailed classification of dyshaemopoiesis in adults may offer partial help in the diagnosis and management of dyshaemopoiesis. Pathobiological studies in progress allow better understanding of MDS and consequently the establishment of new modalities of treatment.

Detection of TNFalpha expression in the bone marrow and determination of TNFalpha production of peripheral blood mononuclear cells in myelodysplastic syndrome

TNFalpha is a highly active cytokine which plays an important role in the regulation of apoptotic cell death, a mechanism involved in the pathophysiology of myelodysplastic syndrome (MDS). In this study we investigated the expression of TNFalpha of the bone marrow trephine biopsies by immunohistochemical method and the TNFalpha production of peripheral blood mononuclear cells by ELISA method in 15 patients affected by MDS. Five of seven patients without excess of blasts showed high or intermediate TNFalpha expression in the bone marrow biopsies, whereas two patients with excess of blasts were negative and one had low expression. The five CMML patients revealed low or intermediate expression. The production of TNFalpha by the PBMC was analysed in 10 patients, four patients with RA and two with CMML produced higher level of TNFalpha which increased after stimulation with phorbol myristic acetate, but none of the RAEB patients revealed increase in TNFalpha production. In conclusion we suppose that increased TNFalpha expression and production by PBMC may be an indirect evidence of the role of increased apoptosis in low risk MDS patients.