p15INK4b methylation correlates with thrombocytopenia, blast percentage, and survival in myelodysplastic syndromes in a dose dependent manner: Quantitation using pyrosequencing study

Increased expression of interferon signaling genes in the bone marrow microenvironment of myelodysplastic syndromes

Introduction

The bone marrow (BM) microenvironment plays an important role in the pathogenesis of myelodysplastic syndromes (MDS) through a reciprocal interaction with resident BM hematopoietic cells. We investigated the differences between BM mesenchymal stromal cells (MSCs) in MDS and normal individuals and identified genes involved in such differences.

Materials and Methods

BM-derived MSCs from 7 MDS patients (3 RCMD, 3 RAEB-1, and 1 RAEB-2) and 7 controls were cultured. Global gene expression was analyzed using a microarray.

Result

We found 314 differentially expressed genes (DEGs) in RCMD vs. control, 68 in RAEB vs. control, and 51 in RAEB vs. RCMD. All comparisons were clearly separated from one another by hierarchical clustering. The overall similarity between differential expression signatures from the RCMD vs. control comparison and the RAEB vs. control comparison was highly significant (p = 0), which indicates a common transcriptomic response in these two MDS subtypes. RCMD and RAEB simultaneously showed an up-regulation of interferon alpha/beta signaling and the ISG15 antiviral mechanism, and a significant fraction of the RAEB vs. control DEGs were also putative targets of transcription factors IRF and ICSBP. Pathways that involved RNA polymerases I and III and mitochondrial transcription were down-regulated in RAEB compared to RCMD.

Conclusion

Gene expression in the MDS BM microenvironment was different from that in normal BM and exhibited altered expression according to disease progression. The present study provides genetic evidence that inflammation and immune dysregulation responses that involve the interferon signaling pathway in the BM microenvironment are associated with MDS pathogenesis, which suggests BM MSCs as a possible therapeutic target in MDS.

-7/7q- syndrome in myeloid-lineage hematopoietic malignancies: attempts to understand this complex disease entity

The recurrence of chromosomal abnormalities in a specific subtype of cancer strongly suggests that dysregulated gene expression in the corresponding region has a critical role in disease pathogenesis. -7/7q-, defined as the entire loss of chromosome 7 and partial deletion of its long arm, is among the most frequently observed chromosomal aberrations in myeloid-lineage hematopoietic malignancies such as myelodysplastic syndrome and acute myeloid leukemia, particularly in patients treated with cytotoxic agents and/or irradiation. Tremendous efforts have been made to clarify the molecular mechanisms underlying the disease development, and several possible candidate genes have been cloned. However, the study is still underway, and the entire nature of this syndrome is not completely understood. In this review, we focus on the attempts to identify commonly deleted regions in patients with -7/7q-; isolate the candidate genes responsible for disease development, cooperative genes and the factors affecting disease prognosis; and determine effective and potent therapeutic approaches. We also refer to the possibility that the accumulation of multiple gene haploinsufficiency, rather than the loss of a single tumor suppressor gene, may contribute to the development of diseases with large chromosomal deletions such as -7/7q-.

Azacitidine for myelodysplastic patients aged > 65 years: a review of clinical efficacy

INTRODUCTION

Therapeutic strategies for elderly patients affected by myelodysplastic syndromes (MDS) are scarce and only few patients have an advantage in performing allogeneic bone marrow transplant.

AREAS COVERED

Primary endpoints for treatment of elderly MDS patients were not curative, but rather allowing to maintain a good quality of life through prolongation of overall survival. In this context, azacitidine showed to improve responses in this subset of patients compared to conventional established regimens, such as intensive or low-dose chemotherapy and best supportive care. Good safety profile of the drug was reported either when it was used inside or outside clinical trials. Improved quality of response was observed when the drug was administered beyond the first response, and it is now usually recommended to continue it at the same dose and schedule in responding patients.

EXPERT OPINION

Evaluation of baseline prognostic factors and comorbidities may help to identify patients who can benefit from the prolonged administration of the drug. Real life data regarding efficacy and safety of azacitidine in MDS elderly patients are required in order to confirm the results of clinical trials.

Hypermethylation of p15 gene in diffuse - large B-cell lymphoma: association with less aggressiveness of the disease

In this study, methylation-specific polymerase chain reaction was used to investigate the potential prognostic significance of the methylation status of p15, p16, MGMT, and DAPK genes in 51 specimens of diffuse large B-cell lymphoma (DLBCL). Hypermethylation of p15 gene was significantly more prevalent in patients without relapse (p = 0.001) and there was a trend toward more frequent presence of p15 methylation in patients without death outcome within 5-year follow-up period (p = 0.086) Also, there was a trend toward accumulation of p15 methylation with favorable clinicopathological parameters including: age ≤ 60 years (p = 0.091), normal levels of lactate dehydrogenase (p = 0.090), Eastern Cooperative Oncology Group performance status < 2 (p = 0.095), and low/intermediate low International Prognostic Index (p = 0.076). In the female group and group of the patients without bulky tumor mass, treated with chemotherapeutic regimens including rituximab, methylation of p15 was significantly related to longer overall survival (p = 0.036 and 0.027, respectively). Our results suggest that promoter methylation of p15 gene could have prognostic value in DLBCL patients treated with rituximab when used in combination with gender and tumor size.

Quantitative comparison of CDKN2B methylation in pediatric and adult myelodysplastic syndromes

BACKGROUND/AIMS

Transcriptional repression of tumor suppressor genes is determined by the quantity of promoter hypermethylation. We analyzed the methylation quantity of CDKN2B in pediatric myelodysplastic syndromes (MDS).

METHODS

Quantitative measurement of CDKN2B methylation was performed in 25 pediatric MDS patients and 12 controls using pyrosequencing, and the result was compared with those from 74 adult MDS cases and 31 adult controls. The association between CDKN2B methylation quantity and factors related to prognosis including bone marrow blast percentage and karyotype was analyzed.

RESULTS

Pediatric MDS patients showed a higher methylation level (MtL) of CDKN2B than pediatric controls (2.94 vs. 1.62; p = 0.031) but a lower level than adult MDS patients (8.76; p < 0.001). MtL was higher in pediatric MDS cases with >5% blasts than in pediatric controls (3.78 vs. 1.62; p = 0.052). Pediatric MDS cases with abnormal karyotype showed a higher MtL than pediatric controls (5.95 vs. 1.62; p = 0.045).

CONCLUSIONS

We confirmed that methylation of CDKN2B is associated with the pathogenesis and prognosis in pediatric MDS. The difference in MtLs between pediatric and adult MDS might be related to the physiological hypermethylation of tumor suppressor genes in aging.

Using peripheral blood circulating DNAs to detect CpG global methylation status and genetic mutations in patients with myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a hematopoietic stem cell disorder. Several genetic/epigenetic abnormalities are deeply associated with the pathogenesis of MDS. Although bone marrow (BM) aspiration is a common strategy to obtain MDS cells for evaluating their genetic/epigenetic abnormalities, BM aspiration is difficult to perform repeatedly to obtain serial samples because of pain and safety concerns. Here, we report that circulating cell-free DNAs from plasma and serum of patients with MDS can be used to detect genetic/epigenetic abnormalities. The plasma DNA concentration was found to be relatively high in patients with higher blast cell counts in BM, and accumulation of DNA fragments from mono-/di-nucleosomes was confirmed. Using serial peripheral blood (PB) samples from patients treated with hypomethylating agents, global methylation analysis using bisulfite pyrosequencing was performed at the specific CpG sites of the LINE-1 promoter. The results confirmed a decrease of the methylation percentage after treatment with azacitidine (days 3-9) using DNAs from plasma, serum, and PB mono-nuclear cells (PBMNC). Plasma DNA tends to show more rapid change at days 3 and 6 compared with serum DNA and PBMNC. Furthermore, the TET2 gene mutation in DNAs from plasma, serum, and BM cells was quantitated by pyrosequencing analysis. The existence ratio of mutated genes in plasma and serum DNA showed almost equivalent level with that in the CD34+/38- stem cell population in BM. These data suggest that genetic/epigenetic analyses using PB circulating DNA can be a safer and painless alternative to using BM cells.

Effect of etafenone on total and regional myocardial blood flow

The distribution of blood flow to the subendocardial, medium and subepicardial layers of the left ventricular free wall was studied in anaesthetized dogs under normoxic (A), hypoxic (B) conditions and under pharmacologically induced (etafenone) coronary vasodilation (C). Regional myocardial blood flow was determined by means of the particle distribution method. In normoxia a transmural gradient of flow was observed, with the subendocardial layers receiving a significantly higher flow rate compared with the subepicardial layers. In hypoxia induced vasodilation this transmural gradient of flow was persistent. In contrast a marked redistribution of regional flow was observed under pharmacologically induced vasodilation. The transmural gradient decreased. In contrast to some findings these experiments demonstrate that a considerable vasodilatory capacity exists in all layers of the myocardium and can be utilized by drugs. The differences observed for the intramural distribution pattern of flow under hypoxia and drug induced vasodilation support the hypothesis that this pattern reflects corresponding gradients of regional myocardial metabolism.