The role of decitabine in the treatment of myelodysplastic syndromes

Epigenetic modifications in obesity-associated diseases

The global prevalence of obesity has reached epidemic levels, significantly elevating the susceptibility to various cardiometabolic conditions and certain types of cancer. In addition to causing metabolic abnormalities such as insulin resistance (IR), elevated blood glucose and lipids, and ectopic fat deposition, obesity can also damage pancreatic islet cells, endothelial cells, and cardiomyocytes through chronic inflammation, and even promote the development of a microenvironment conducive to cancer initiation. Improper dietary habits and lack of physical exercise are important behavioral factors that increase the risk of obesity, which can affect gene expression through epigenetic modifications. Epigenetic alterations can occur in early stage of obesity, some of which are reversible, while others persist over time and lead to obesity-related complications. Therefore, the dynamic adjustability of epigenetic modifications can be leveraged to reverse the development of obesity-associated diseases through behavioral interventions, drugs, and bariatric surgery. This review provides a comprehensive summary of the impact of epigenetic regulation on the initiation and development of obesity-associated cancers, type 2 diabetes, and cardiovascular diseases, establishing a theoretical basis for prevention, diagnosis, and treatment of these conditions.

Immunologic Predictors for Clinical Responses during Immune Checkpoint Blockade in Patients with Myelodysplastic Syndromes

PURPOSE

The aim of this study is to determine immune-related biomarkers to predict effective antitumor immunity in myelodysplastic syndrome (MDS) during immunotherapy (IMT, αCTLA-4, and/or αPD-1 antibodies) and/or hypomethylating agent (HMA).

EXPERIMENTAL DESIGN

Peripheral blood samples from 55 patients with MDS were assessed for immune subsets, T-cell receptor (TCR) repertoire, mutations in 295 acute myeloid leukemia (AML)/MDS-related genes, and immune-related gene expression profiling before and after the first treatment.

RESULTS

Clinical responders treated with IMT ± HMA but not HMA alone showed a significant expansion of central memory (CM) CD8+ T cells, diverse TCRβ repertoire pretreatment with increased clonality and emergence of novel clones after the initial treatment, and a higher mutation burden pretreatment with subsequent reduction posttreatment. Autophagy, TGFβ, and Th1 differentiation pathways were the most downregulated in nonresponders after treatment, while upregulated in responders. Finally, CTLA-4 but not PD-1 blockade attributed to favorable changes in immune landscape.

CONCLUSIONS

Analysis of tumor-immune landscape in MDS during immunotherapy provides clinical response biomarkers.

Synergistic inhibitory effect of Smo inhibitor jervine and its combination with decitabine can target Hedgehog signaling pathway to inhibit myelodysplastic syndrome cell line

OBJECTIVE

Hypomethylating agents (HMAs) have been reported to target the Sonic Hedgehog (Shh) signaling pathway in myelodysplastic syndrome (MDS). However, the synergistic inhibitory effect of Smo inhibitor jervine and its combination with decitabine in MUTZ-1 cell lines remains lacking.

METHODS

We used a CCK-8 assay to detect the in-vitro proliferation rate of MUTZ-1 cell lines. Besides, the Annexin V-FITC/PI double staining flow cytometry was utilized to detect the apoptosis rate and cell cycle changes. The expression levels of mRNA were quantified by using qRT-PCR, and the western blot was employed to detect the expression of proteins.

RESULTS

We found that the single-agent jervine or decitabine can significantly inhibit the proliferation rate of MUTZ-1 cell lines, and this inhibitory effect is time-dependent and concentration-dependent. The combined intervention of the jervine and decitabine can more significantly inhibit cell proliferation, induce cell apoptosis, and block the G1 phase of the cell cycle. The combined intervention of the two drugs significantly reduced Smo and G1i-1 mRNA expression in MUTZ-1 cells. Furthermore, after combining both of the drug treatments, the proteins levels of Smo, G1i-1, PI3K, p-AKT, Bcl2, and Cyclin Dl were significantly downregulated, and Caspase-3 is upregulated, indicating that jervine with its combination of decitabine might be effective for controlling the proliferation, apoptosis, and cell cycle.

CONCLUSION

The Smo inhibitor jervine and its combination with decitabine have a synergistic effect on the proliferation, cell cycle, and apoptosis of MUTZ-1 cells, and its mechanism may be achieved by interfering with the Shh signaling pathway.

Decitabine inhibits the proliferation of human T-cell acute lymphoblastic leukemia molt4 cells and promotes apoptosis partly by regulating the PI3K/AKT/mTOR pathway

T cell acute lymphoblastic leukemia (T-ALL) is a highly aggressive hematological cancer; however, there is a lack of effective chemotherapeutic or targeted drugs for the treatment of T-ALL. Decitabine is a DNA demethylation agent but it has not been used for T-ALL treatment. Therefore, the present study aimed to assess the inhibitory effect of decitabine on T-ALL molt4 cells and determine its regulatory role in the PI3K/AKT/mTOR pathway. Molt4 cells were stimulated with decitabine in vitro, after which cell proliferation, apoptosis and cell cycle analyses were performed to assess cell viability. Subcellular morphology was observed using transmission electron microscopy. Expression levels of phosphate and tension homology (PTEN), genes involved in the PI3K/AKT/mTOR pathway and the corresponding downstream genes were analyzed using reverse transcription-quantitative PCR and western blotting. The results showed that decitabine induced apoptosis, inhibited proliferation and arrested molt4 cells in the G₂ phase. Following decitabine intervention, an increase in the number of lipid droplets, autophagosomes and mitochondrial damage was observed. At concentrations of 1 and 10 µM, decitabine downregulated the expression of PI3K, AKT, mTOR, P70S6 and eukaryotic initiating factor 4E-binding protein 1, which in turn upregulated PTEN expression; however, 50 µM decitabine downregulated PTEN levels. Overall, these results demonstrated that decitabine reduced the viability of molt4 cells partly by inhibiting the PI3K/AKT/mTOR pathway via PTEN, especially at low decitabine concentrations.

Identification of antiviral compounds against equid herpesvirus-1 using real-time cell assay screening: Efficacy of decitabine and valganciclovir alone or in combination

Equid herpesvirus-1 infections cause respiratory, neurological and reproductive syndromes. Despite preventive treatments with vaccines, resurgence of EHV-1 infection still constitutes a major threat to equine industry. However, no antiviral compound is available to treat infected horses. In this study, 2891 compounds were screened against EHV-1 using impedance measurement. 22 compounds have been found to be effective in vitro against EHV-1. Valganciclovir, ganciclovir, decitabine, aphidicolin, idoxuridine and pritelivir (BAY 57-1293) are the most effective compounds identified, and their antiviral potency was further assessed on E. Derm, RK13 and EEK cells and against 3 different field strains of EHV-1 (ORF30 2254 A/G/C). We also provide evidences of synergistic interactions between valganciclovir and decitabine in our in vitro antiviral assay as determined by MacSynergy II, isobologramm and Chou-Talalay methods. Finally, we showed that deoxycytidine reverts the antiviral effect of decitabine, thus supporting some competition at the level of nucleoside phosphorylation by deoxycytidine kinase and/or DNA synthesis. Deoxycitidine analogues, like decitabine, is a family of compounds identified for the first time with promising antiviral efficacy against herpesviruses.

The Roles of Human DNA Methyltransferases and Their Isoforms in Shaping the Epigenome

A DNA sequence is the hard copy of the human genome and it is a driving force in determining the physiological processes in an organism. Concurrently, the chemical modification of the genome and its related histone proteins is dynamically involved in regulating physiological processes and diseases, which overall constitutes the epigenome network. Among the various forms of epigenetic modifications, DNA methylation at the C-5 position of cytosine in the cytosine–guanine (CpG) dinucleotide is one of the most well studied epigenetic modifications. DNA methyltransferases (DNMTs) are a family of enzymes involved in generating and maintaining CpG methylation across the genome. In mammalian systems, DNA methylation is performed by DNMT1 and DNMT3s (DNMT3A and 3B). DNMT1 is predominantly involved in the maintenance of DNA methylation during cell division, while DNMT3s are involved in establishing de novo cytosine methylation and maintenance in both embryonic and somatic cells. In general, all DNMTs require accessory proteins, such as ubiquitin-like containing plant homeodomain (PHD) and really interesting new gene (RING) finger domain 1 (UHRF1) or DNMT3-like (DNMT3L), for their biological function. This review mainly focuses on the role of DNMT3B and its isoforms in de novo methylation and maintenance of DNA methylation, especially with respect to their role as an accessory protein.

Decitabine Inhibits Gamma Delta T Cell Cytotoxicity by Promoting KIR2DL2/3 Expression

Gamma delta (γδ) T cells, which possess potent cytotoxicity against a wide range of cancer cells, have become a potential avenue for adoptive immunotherapy. Decitabine (DAC) has been reported to enhance the immunogenicity of tumor cells, thereby reinstating endogenous immune recognition and tumor lysis. However, DAC has also been demonstrated to have direct effects on immune cells. In this study, we report that DAC inhibits γδ T cell proliferation. In addition, DAC increases the number of KIR2DL2/3-positive γδ T cells, which are less cytotoxic than the KIR2DL2/3-negative γδ T cells. We found that DAC upregulated KIR2DL2/3 expression in KIR2DL2/3-negative γδ T cells by inhibiting KIR2DL2/3 promoter methylation, which enhances the binding of KIR2DL2/3 promoter to Sp-1 and activates KIR2DL2/3 gene expression. Our data demonstrated that DAC can inhibit the function of human γδ T cells at both cellular and molecular levels, which confirms and extrapolates the results of previous studies showing that DAC can negatively regulate the function of NK cells and αβ T cells of the immune system.

Decitabine Improves the Clinical Manifestations of Rats With l-NAME-Induced Pre-eclampsia: A Potential Approach to Studying Pre-eclampsia

OBJECTIVE

Pre-eclampsia is a major cause of maternal mortality and morbidity. Conditions with low oxygen tension are regarded as a key factor. Decitabine can partly attenuate the effects of hypoxia. This research was designed to investigate the effects of decitabine in rats with NG-Nitro-L-arginine Methyl Eater (L-NAME) induced pre-eclampsia and to explore the molecular mechanisms.

METHODS

A Wistar rat model of pre-eclampsia was established by intraperitoneal injection of L-NAME, and the intervention reagent was decitabine. Blood pressure (BP) and 24-h urinary protein were monitored. The expression of Mammary Serine Protease Inhibitor (SERPINB5, maspin) in the placenta was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

Systolic BP in the tail artery of pregnant rats was increased by more than 30 mm Hg, and 24-h urinary protein was significantly increased after L-NAME was added. After decitabine treatment, blood pressure and 24-h urinary protein were significantly decreased. The expression of SERPINB5 in the placenta significantly increased after L-NAME was added. Decitabine significantly elevated the expression of SERPINB5 in the placenta of rats with L-NAME-induced preeclampsia.

CONCLUSION

Decitabine reduced 24-h urinary protein and partly decreased blood pressure of pre-eclampsia in late pregnancy in rats with L-NAME-induced pre-eclampsia and increased the expression of SERPINB5, but the molecular mechanism of decitabine's effect remains unknown. This research provided a potential approach to studying the pathogenesis, treatment and prevention of pre-eclampsia.

Decitabine represses translocated MYC oncogene in Burkitt lymphoma

Burkitt lymphoma (BL) is caused by translocation of the MYC gene to an immunoglobulin locus resulting in its constitutive expression depending on the activity of the immunoglobulin (Ig) enhancer elements. Treatment of BL cell lines with epigenetic modifiers is known to repress B-cell-specific genes and to up-regulate B-cell-inappropriate genes including the transcription repressor ID2 expression. We found that the DNA methyltransferase inhibitor decitabine/5-aza-2-deoxycytidine (5-aza-dC) represses the MYC oncogene on RNA and protein levels by inducing ID2. Down-regulation of MYC was associated with repression of transcriptional activity of the Ig locus and with inhibition of proliferation. The induction of ID2 can be in part explained by activation of the transcription factor NF-κB. We conclude that up-regulation of ID2 contributes to anti-tumour activity of 5-aza-dC via repression of Ig locus activity and consequently MYC expression.

Pharmacokinetic and pharmacodynamic analysis of 5-aza-2'-deoxycytidine (decitabine) in the design of its dose-schedule for cancer therapy

5-Aza-2′-deoxycytidine (5-AZA-CdR, decitabine), an epigenetic drug that inhibits DNA methylation, is currently used to treat myelodysplastic syndrome (MDS), and is under investigation for treating acute myeloid leukemia (AML) and other malignancies. 5-AZA-CdR can reactivate tumor suppressor genes silenced by aberrant DNA methylation, a frequent event in all types of cancer. Because this epigenetic change is reversible, it is a good target for 5-AZA-CdR therapy. We have reviewed the preclinical data of 5-AZA-CdR to analyze the concentrations and exposure times required to eradicate cancer stem cells. We analyzed the dose-schedules used in animal models that show potent antineoplastic activity of 5-AZA-CdR. We attempted to correlate the preclinical data with the responses obtained in clinical trials of 5-AZA-CdR in patients with cancer. The pharmacokinetics and drug distribution of 5-AZA-CdR are key parameters because adequate therapeutic drug levels are required to eliminate cancer stem cells in all anatomic compartments. The plasma half-life of 5-AZA-CdR in humans is approximately 20 minutes due to the high levels in the liver of cytidine deaminase, the enzyme that inactivates this analogue. This provides a rationale to use an inhibitor of cytidine deaminase in combination with 5-AZA-CdR. Low-dose 5-AZA-CdR is effective for MDS and AML and can induce complete remissions (CR). However, maintenance of CR with low-dose 5-AZA-CdR is difficult. Based on analyses of preclinical and clinical data, low dose 5-AZA-CdR has the potential to be an effective form of therapy in some patients with cancer. For patients who do not respond to low dose therapy we recommend dose-intensive treatment with 5-AZA-CdR. Patients who are candidates for intensive dose 5-AZA-CdR should have a good bone marrow status so as to permit adequate recovery from myelosuppression, the major toxicity of 5-AZA-CdR. Solid tumors are also interesting targets for therapy with 5-AZA-CdR. Both low dose and intensive therapy with 5-AZA-CdR can reduce the proliferative potential of tumor stem cells in animal models. We propose novel dose schedules of 5-AZA-CdR for investigation in patients with cancer. The full chemotherapeutic potential of 5-AZA-CdR to treat cancer merits further clinical investigation and can only be realized when its optimal dose-schedule is determined.

Increased PRAME antigen-specific killing of malignant cell lines by low avidity CTL clones, following treatment with 5-Aza-2'-Deoxycytidine

The cancer testis antigen Preferentially Expressed Antigen of Melanoma (PRAME) is overexpressed in many solid tumours and haematological malignancies whilst showing minimal expression in normal tissues and is therefore a promising target for immunotherapy. HLA-A0201-restricted peptide epitopes from PRAME have previously been identified as potential immunogens to drive antigen-specific autologous CTL responses, capable of lysing PRAME expressing tumour cells. CTL lines, from 13 normal donors and 10 melanoma patients, all of whom were HLA-A0201 positive, were generated against the PRAME peptide epitope PRA(100-108). Specific killing activity against PRA(100-108) peptide-pulsed targets was weak compared with CTL lines directed against known immunodominant peptides. Moreover, limiting dilution cloning from selected PRAME-specific CTL lines resulted in the generation of a clone of only low to intermediate avidity. Addition of the demethylating agent 5-aza-2'-Deoxycytidine (DAC) increased PRAME expression in 7 out of 11 malignant cell lines including several B lineage leukaemia lines and also increased class I expression. Pre-treatment of target cells was associated with increased sensitivity to antigen-specific killing by the low avidity CTL. When CTL, as well as of the target cells, were treated, the antigen-specific killing was further augmented. Interestingly, one HLA-A0201-negative DAC-treated line (RAJI) showed increased sensitivity to killing by clones despite a failure of expression of PRAME or HLA-A0201. Together these data point to a general increased augmentation of cancer immunogenocity by DAC involving both antigen-specific and non-specific mechanisms.

Pharmacokinetic evaluation of decitabine for the treatment of leukemia

INTRODUCTION

Acute myeloid leukemia (AML) is a life-threatening malignancy that primarily afflicts an elderly population. Treatment of elderly patients with intensive chemotherapy is associated with high treatment-related morbidity and mortality. Therefore, less toxic approaches involving low-dose decitabine-based regimens are being explored in this patient population.

AREAS COVERED

This drug evaluation article discusses the rationale for targeting aberrant DNA methylation in hematologic malignancies, in particular the myelodysplastic syndromes (MDS) and AML. The authors review the pharmacokinetic data gained from low-dose decitabine, as well as the clinical progress of decitabine in the treatment of hematologic malignancies. Published manuscripts in English were selected from PubMed using a combination of the following search terms: acute myeloid leukemia, pharmacokinetics, decitabine, 5-aza-2'-deoxycytidine, DNA methylation, DNA methyltransferase, myelodysplastic syndrome and leukemia.

EXPERT OPINION

Decitabine has established efficacy in MDS and shown promising activity in AML at low doses. Given decitabine’s favorable toxicity profile and emerging clinical efficacy, decitabine may be a low intensity therapeutic option for elderly patients with AML who are considered unfit for aggressive chemotherapy.

Current and future management options for myelodysplastic syndromes

The management of the myelodysplastic syndromes (MDS) requires insight into the complex biology of the disease. Despite this challenge, two recent developments have contributed significantly to advancements in the treatment of MDS: (i) improvements in classification systems and prognostic models; and (ii) the emergence of US FDA-approved agents such as lenalidomide, azacitidine and decitabine. Prior to these developments, supportive care measures consisting of blood and platelet transfusions, haematopoietic growth factors and antimicrobials remained standard of care for the treatment of MDS. As a result of these developments, clinicians are able to provide patient-tailored therapy for specific MDS subgroups. Clinical trials addressing combination therapies with multiple investigational agents as well as novel combination regimens are ongoing. This review focuses on supportive care modalities, the approved agents indicated for the treatment of MDS and future directions for the treatment of MDS, including agents under clinical investigation.

Additive effects of 5-aza-2'-deoxycytidine and irradiation on clonogenic survival of human medulloblastoma cell lines

BACKGROUND AND PURPOSE

In recent years, epigenetic modulators were introduced into tumor therapy. Here, the authors investigated the antitumor effect of 5-aza-2'-deoxycytidine-(5-aza-dC-)induced demethylation combined with irradiation on human medulloblastoma (MB) cells, which form the most common malignant brain tumor in children.

MATERIAL AND METHODS

Three MB cell lines were treated with 5-aza-dC in a low-dose (0.1 microM, 6 days) or high-dose (3/5 microM, 3 days) setting and irradiated with 2, 4, 6, or 8 Gy single dose on an X-ray unit. Methylation status and mRNA expression of three candidate genes were analyzed by methylation-specific PCR (polymerase chain reaction) and quantitative real-time RT-PCR. Cell survival and mortality were determined by trypan blue exclusion test. Proliferation was analyzed by BrdU incorporation assay, and long-term cell survival was assessed by clonogenic assay.

RESULTS

5-aza-dC treatment resulted in partial promoter demethylation and increased expression of hypermethylated candidate genes. A significant decrease of vital cell count, proliferation inhibition and increase of mortality was observed in 5-aza-dC-treated as well as in irradiated MB cells, whereby combination of both treatments led to additive effects. Although high-dose 5-aza-dC treatment was more effective in terms of demethylation, clonogenic assay revealed no differences between high- and low-dose settings indicating no relevance of 5-aza-dC-induced demethylation for decreased cell survival. MB cells pretreated with 5-aza-dC showed significantly lower plating efficiencies than untreated cells at all irradiation doses investigated. Analysis of surviving curves in irradiated MB cells, however, revealed no significant differences of alpha-, beta-values and 2-Gy surviving fraction with or without 5-aza-dC treatment.

CONCLUSION

5-aza-dC did not enhance radiation sensitivity of MB cells but significantly reduced the clonogenicity versus irradiation alone, which merits further investigation of its potential clinical application in MB possibly by combination with other chemotherapeutic agents.

Role of epigenetic therapy in myelodysplastic syndrome

Myelodysplastic syndrome, characterized by ineffective hematopoiesis and cytopenias, remains a lethal disease. Until recently, patients with myelodysplastic syndrome have been managed supportively with blood product transfusions and growth factors, until they succumb to infections, bleeding complications or transformation to acute leukemia. The discovery that epigenetic factors play an important role in cancer, and specifically in myelodysplastic syndrome, has led to the recent approval of several new therapies that will make a significant impact on this disease. Epigenetics refers to a number of biochemical modifications to chromatin that do not alter the primary DNA sequence, but play an important role in genomic regulation at the level of gene transcription. Epigenetic factors can be passed on from a cell to its progeny and can mimic traditional genetic lesions that are implicated in cancer. Unlike genetic abnormalities, however, epigenetic changes, such as DNA methylation or histone deacetylation, can be manipulated pharmacologically. Recently developed hypomethylating agents and histone deacetylase inhibitors have shown significant biological and clinical activity in myelodysplastic syndrome. These drugs have been well-tolerated by patients and have been shown to alter the course of this disease. In order to use these drugs optimally, however, we need to better understand the role of these epigenetic changes: how they contribute to the disease process, how we can use them to better select patients and how we can use combinations to target them more effectively.

Potentiation of reactive oxygen species is a marker for synergistic cytotoxicity of MS-275 and 5-azacytidine in leukemic cells

Epigenetic modifiers are currently in clinical use for various tumor types. Recently, numerous studies supporting the combination of histone deacetylase inhibitors (HDACi) and DNA methyltransferase inhibitors have emerged, encouraging early clinical trials of these agents together. Here we show that MS-275, an HDACi, and 5-azacytidine, a methyltransferase inhibitor, display synergistic cytotoxicity and apoptosis in AML and ALL cells. Intracellular production of reactive oxygen species (ROS), such as superoxide and hydrogen peroxide, is a novel marker for this synergism in ALL cells. These data suggest that assessment of oxidative stress can serve as a marker of the concerted action of MS-275 and 5-azacytidine.