Important features of myelodysplastic syndrome

Identification of defects in the transcriptional program during lineage-specific in vitro differentiation of CD34(+) cells selected from patients with both low- and high-risk myelodysplastic syndrome

OBJECTIVE

Development of myelodysplastic syndrome (MDS) is suggested to follow a multistep pathogenesis and is characterized by accumulation of molecular defects of the hematopoietic stem/progenitor cells, resulting in aberrant differentiation and proliferation.

MATERIALS AND METHODS

To detect alterations within the transcriptional program in MDS-derived CD34(+) cells during lineage-specific differentiation, we performed serial gene expression analysis of in vitro differentiated erythro-, granulo-, and megakaryopoietic cells using oligonucleotide microarrays (HG-U133A, Affymetrix, Santa Clara, CA, USA). For selected genes, expression data were confirmed using real-time polymerase chain reaction.

RESULTS

We identified genes with altered expression during lineage-specific differentiation in either low- or high-risk MDS cells compared to the expression patterns of continuously up- or downregulated genes from the normal transcriptional program of hematopoiesis. In cluster analyses, we could show that MDS samples have a distinct expression pattern of a set of selected genes compared to normal cells, which allows prediction of the affiliation of a sample to one group. Furthermore, this study gives an overview of genes that are differentially expressed in MDS cells compared to normal hematopoiesis.

CONCLUSION

Our data provide the first comprehensive transcriptional analysis of differentiating human CD34(+) cells derived from MDS patients compared to normal individuals. It gives new insights into the alteration of differentiation and proliferation of MDS stem cells.

Aberrant promotor methylation in MDS hematopoietic cells during in vitro lineage specific differentiation is differently associated with DNMT isoforms

Aberrant promoter methylation may contribute to the hematopoietic disturbances in myelodysplastic syndromes (MDS). To explore a possible mechanism, we therefore analyzed expression of DNA methyltransferase (DNMT) subtypes kinetics and aberrant promoter methylation of key regulatory genes during MDS hematopoiesis. An in vitro model of MDS lineage-specific hematopoiesis was generated by culturing CD34+ cells from healthy donors (n=7) and MDS patients (low-risk: RA/n=6, RARS/n=3; high-risk: RAEB/n=4, RAEB-T/n=2) with EPO, TPO and GCSF. Promoter methylation analysis of key genes involved in the control of apoptosis (p73, survivin, DAPK), DNA-repair (hMLH1), differentiation (RARb, WT1) and cell cycle control (p14, p15, p16, CHK2) was performed by methylation specific PCR of bisulfite-treated genomic DNA. Expression of DNMT1, DNMT3a and DNMT3b was analyzed and correlated with gene promoter methylation for each lineage at different time points. DNMT expression (all isoforms) was increased during thrombopoiesis whereas elevated DNMT1 level were seen during erythropoiesis. Associations between aberrant promoter methylation and DNMT expression were found in high-risk MDS for all lineages and during erythropoiesis. Hypermethylation of p15, p16, p73, survivin, CHK2, RARb and DAPK were associated with elevated DNMT isoform expression. No general overexpression of DNMT subtype was detected during MDS hematopoiesis. However a negative association of DNMT3a and 3b expression with MDS disease risk (IPSS) could be observed. Our data indicate that all mammalian DNMT isoforms may be involved in the aberrantly methylated phenotype in MDS but seem also to be essential for the differentiation of normal hematopoietic stem cells. In particular elevated DNMT1 expression may in particular contribute to ineffective erythropoiesis in MDS.

Lack of TP53 and FMS gene mutations in children with myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are rare disorders in children. Molecular mechanisms underlying MDS in children are not yet completely understood. Considering the role of FMS and TP53 gene mutations in adult MDS patients, we analyzed mutations of these genes in a cohort of 35 children with MDS. Single-strand conformation polymorphism polymerase chain reaction analysis performed on FMS codon 969 and TP53 exons 5-9 showed no mutations in the analyzed sequences. Our results suggest that molecular mechanisms of MDS evolution in children are different from those in adults.

Promoter hypermethylation of p15INK4B, HIC1, CDH1, and ER is frequent in myelodysplastic syndrome and predicts poor prognosis in early-stage patients

The propensity of myelodysplastic syndrome (MDS) to transform into acute myeloid leukemia (AML) suggests the existence of common pathogenic components for these malignancies. Here, four genes implicated in the development of AML were examined for promoter CpG island hypermethylation in cells from 37 patients with different stages of MDS. Aberrant methylation was detected by polymerase chain reaction amplification of bisulfite-treated DNA followed by denaturing gradient gel electrophoresis. The highest rate of methylation was found for p15INK4B (51%), followed by HIC1 (32%), CDH1 (27%), and ER (19%). Concurrent hypermethylation of > or = 3 genes was more frequent in advanced compared with early-stage MDS (P < or = 0.05), and hypermethylation of p15INK4B was associated with leukemic transformation in early MDS (P < or = 0.05). The median overall survival was 17 months for cases showing hypermethylation of > or = 1 genes vs. 67 months for cases without hypermethylation (P = 0.002). Specifically, promoter hypermethylation identified a subgroup of early MDS with a particularly poor prognosis (median overall survival 20 months vs. 102 months; P = 0.004). In multivariate analysis including stage and thrombocyte count, hypermethylation of > or = 1 genes was an independent negative prognostic factor (P < 0.05). These data suggest that hypermethylation of p15INK4B, HIC1, CDH1, and ER contribute to the development and outcome of MDS.

Successful treatment of oral lichen planus-like chronic graft-versus-host disease with topical tacrolimus: a case report

BACKGROUND

Bone marrow transplantation (BMT) is a common treatment used for deficiencies of host marrow or in the control of blood malignancies. Post-allogeneic BMT complications include graft-versus-host disease (GVHD). GVHD occurs when immunologically active T lymphocytes are transplanted into an immunosuppressed recipient who is genetically disparate from the donor. In this case report we describe the occurrence of oral lichen planus-like lesions as the first manifestation of chronic GVHD (c-GVHD) and the subsequent management of this disease with topical tacrolimus.

METHODS

Diagnostic aids included routine histology and direct immunofluorescence studies to rule out immunobullous diseases and to confirm the c-GVHD. Treatment consisted of topical application of 0.1% tacrolimus ointment three times a day.

RESULTS

Routine histology confirmed the clinical diagnosis of oral lichen planus-like c-GVHD. Treatment with tacrolimus ointment completely resolved the oral lesions after 2 months of therapy.

CONCLUSIONS

Topical tacrolimus at low concentrations (0.1%) shows promise in the management of oral lichen planus-like c-GVHD. Controlled studies are necessary to assess the efficacy, the duration of therapy required for effective results, and the safety of this treatment over the long-term.

Update on myelodysplastic syndromes: New approaches to classification and therapy

Myelodysplastic syndromes have long provided hematologists with difficult therapeutic challenges, and until recently treatment options beyond supportive care were limited. Recent advances in our understanding of hematopoiesis, immunology, and genetics have led to a better understanding of the natural history of these disorders and have facilitated development of more rational and targeted treatment approaches. A number of promising agents are in various phases of study, including arsenic trioxide, CC5013, the farnesyltransferase inhibitors, and DNA methyltransferase inhibitors. In addition, less intensive strategies for allogeneic stem cell transplantation now permit us to offer potentially curative therapy to a larger proportion of patients. Optimal management of an individual patient requires consideration of the disease and its expected course, available treatment options, the patient's age and condition, and an ongoing assessment of the goals of therapy.

Treatment of acute promyelocytic leukemia and other hematologic malignancies with arsenic trioxide: review of clinical and basic studies

Acute promyelocytic leukemia (APL) is now the most potentially curable subtype of acute myeloid leukemia in adults because of the introduction of novel approaches in the management of this disease. All-trans-retinoic acid (ATRA)-based therapy is now the first-choice treatment of patients presenting with de novo APL, and clinical studies have shown that nearly all patients who receive ATRA therapy achieve complete remission. However, approximately 20% to 30% of APL patients eventually have relapses with resistance to further ATRA treatment. Arsenic trioxide (As2O3 [ATO]) has been established as highly effective therapy for patients with APL, even for those with disease refractory to ATRA. Furthermore, results of recent studies have suggested a broad therapeutic potential for ATO in the treatment of hematologic malignancies beyond APL. In this review, we discuss the clinical activity and multiple mechanisms of ATO therapy in the management of APL and other hematologic neoplasms.