Decitabine

Lymph node myeloid sarcoma with TP53‑associated myelodysplastic syndrome: A case report

Myeloid sarcoma (MS) is a rare extramedullary tumor mass that carries a high risk of progression to acute myeloid leukemia (AML), and patients with MS are commonly treated with the AML regimen. However, MS is frequently misdiagnosed due to its lack of clinical specificity. Patients with MS who harbor tumor protein p53 (TP53) mutations and complex karyotypes are considered to have a poorer prognosis. The present study reports a case of lymph node MS with TP53 (V173G)-related myelodysplastic syndrome (MDS). The mass was first considered to be a lymphoma and treated as such. However, following immunohistochemical analysis, which revealed cells positive for CD43, myeloperoxidase and CD117, the patient was later diagnosed with MS combined with MDS. The patient went into complete remission after the first cycle of chemotherapy, and showed a decrease in platelet, red blood cell and white blood cell counts following the second cycle of chemotherapy. After the third chemotherapy, agranulocytosis occurred, leading to refractory pneumonia and eventually death due to respiratory failure. MS with TP53-related MDS has a low incidence rate, a poor prognosis and a short survival time. The clinical manifestations of MS are non-specific and easy to misdiagnose, leading to delayed diagnosis and treatment, and ultimately worsening the prognosis of the patients. Therefore, a lymph node biopsy should be performed as soon as possible for patients with lymph node enlargement, and early treatment should be carried out to prolong the survival period.

Epigenetic therapy: Research progress of decitabine in the treatment of solid tumors

Decitabine's early successful therapeutic outcomes in hematologic malignancies have led to regulatory approvals from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for addressing myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). These approvals have sparked keen interest in exploring the potential of decitabine for treating solid tumors. Continuous preclinical and clinical trials have proved that low doses of decitabine also bring benefits in treating solid tumors, and various proposed mechanisms attempt to explain the potential efficacy. It is important to note that the application of decitabine in solid tumors is still considered investigational. This article reviews the application mechanism and current status of decitabine in the treatment of solid tumors.

Azacitidine Is Synergistically Lethal with XPO1 Inhibitor Selinexor in Acute Myeloid Leukemia by Targeting XPO1/eIF4E/c-MYC Signaling

Acute myeloid leukemia (AML) is a high-mortality malignancy with poor outcomes. Azacitidine induces cell death and demonstrates treatment effectiveness against AML. Selinexor (KPT-330) exhibited significant benefits in combination with typical induction treatment for AML patients. Here, we explore the antitumor effect of KPT-330 combined with AZA in AML through CCK-8, flow cytometry, RT-qPCR, western blot, and RNA-seq. Our results showed that KPT-330 combined with AZA synergistically reduced cell proliferation and induced apoptosis in AML primary cells and cell lines. Compared to the control, the KPT-330 plus AZA down-regulates the expression of XPO1, eIF4E, and c-MYC in AML. Moreover, the knockdown of c-MYC could sensitize the synergy of the combination on suppression of cell proliferation and promotion of apoptosis in AML. Moreover, the expression of XPO1 and eIF4E was elevated in AML patient cohorts, respectively. XPO1 and elF4E overexpression was associated with poor prognosis. In summary, KPT-330 with AZA exerted synergistic effects by suppressing XPO1/eIF4E/c-MYC signaling, which provided preclinical evidence for further clinical application of the novel combination in AML.

The effect of granulocyte-colony stimulating factor, decitabine, and busulfan-cyclophosphamide versus busulfan-cyclophosphamide conditioning on relapse in patients with myelodysplastic syndrome or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic haematopoietic stem-cell transplantation: an open-label, multicentre, randomised, phase 3 trial

BACKGROUND

Relapse remains high in patients with myelodysplastic syndrome-refractory anaemia with excess blasts (RAEB) or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic haematopoietic stem-cell transplantation (HSCT). We aimed to investigate whether granulocyte-colony stimulating factor (G-CSF) and decitabine plus busulfan-cyclophosphamide conditioning reduced relapse compared with busulfan-cyclophosphamide in this population.

METHODS

We did an open-label, randomised, phase 3 trial at six hospitals in China. Eligible patients (aged 14-65 years) had myelodysplastic syndrome-RAEB or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome, and an Eastern Cooperative Oncology Group performance status of 0-2 and HSCT comorbidity index of 0-2. Patients were randomly assigned (1:1) to receive G-CSF, decitabine, and busulfan-cyclophosphamide conditioning or busulfan-cyclophosphamide conditioning. Randomisation was done with permuted blocks (block size four) with no stratification and was implemented through an interactive web-based response system, which was independent of study site staff and investigators. G-CSF, decitabine, and busulfan-cyclophosphamide conditioning comprised G-CSF 5 μg/kg daily subcutaneously (days -17 to -10), decitabine 20 mg/m² daily intravenously (days -14 to -10), busulfan 3·2 mg/kg daily intravenously (days -7 to -4), and cyclophosphamide 60 mg/kg daily intravenously (days -3 and -2). Busulfan-cyclophosphamide conditioning comprised the same dose and duration of busulfan and cyclophosphamide. The primary endpoint was 2 year cumulative incidence of relapse. All efficacy and safety endpoints were assessed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02744742; the trial is complete.

FINDINGS

Between April 18, 2016, and Sept 30, 2019, 297 patients were screened for eligibility, 202 of whom were randomly assigned to G-CSF, decitabine, and busulfan-cyclophosphamide (n=101) or busulfan-cyclophosphamide (n=101) conditioning. 123 (61%) participants were male and 79 (31%) were female. Median follow-up was 32·4 months (IQR 10·0-43·0). The 2-year cumulative incidence of relapse was 10·9% (95% CI 5·8-17·9) in the G-CSF, decitabine, and busulfan-cyclophosphamide group and 24·8% (16·8-33·5) in the busulfan-cyclophosphamide group (hazard ratio 0·39 [95% CI 0·19-0·79]; p=0·011). Within 100 days after transplantation, the most common grade 3-4 adverse events in the G-CSF, decitabine, and busulfan-cyclophosphamide group and the busulfan-cyclophosphamide group were infections (34 [34%] and 32 [32%]), acute graft-versus-host disease (30 [30%] and 30 [30%]), and gastrointestinal toxicity (28 [28%] and 29 [29%]). 11 (11%) patients in the G-CSF, decitabine, and busulfan-cyclophosphamide group and 13 (13%) in the busulfan-cyclophosphamide group died of adverse events. There were no treatment related deaths.

INTERPRETATION

Our results suggest that G-CSF, decitabine, and busulfan-cyclophosphamide conditioning is a better choice than busulfan-cyclophosphamide conditioning for patients with myelodysplastic syndrome-RAEB or secondary acute myeloid leukaemia evolving from myelodysplastic syndrome undergoing allogeneic HSCT. This conditioning could be a suitable therapuetic option for this patient population.

FUNDING

None.

TRANSLATION

For the Chinese translation of the abstract see Supplementary Materials section.

Aptamer nucleotide analog drug conjugates in the targeting therapy of cancers

Aptamers are short single-strand oligonucleotides that can form secondary and tertiary structures, fitting targets with high affinity and specificity. They are so-called "chemical antibodies" and can target specific biomarkers in both diagnostic and therapeutic applications. Systematic evolution of ligands by exponential enrichment (SELEX) is usually used for the enrichment and selection of aptamers, and the targets could be metal ions, small molecules, nucleotides, proteins, cells, or even tissues or organs. Due to the high specificity and distinctive binding affinity of aptamers, aptamer-drug conjugates (ApDCs) have demonstrated their potential role in drug delivery for cancer-targeting therapies. Compared with antibodies which are produced by a cell-based bioreactor, aptamers are chemically synthesized molecules that can be easily conjugated to drugs and modified; however, the conventional ApDCs conjugate the aptamer with an active drug using a linker which may add more concerns to the stability of the ApDC, the drug-releasing efficiency, and the drug-loading capacity. The function of aptamer in conventional ApDC is just as a targeting moiety which could not fully perform the advantages of aptamers. To address these drawbacks, scientists have started using active nucleotide analogs as the cargoes of ApDCs, such as clofarabine, ara-guanosine, gemcitabine, and floxuridine, to replace all or part of the natural nucleotides in aptamer sequences. In turn, these new types of ApDCs, aptamer nucleotide analog drug conjugates, show the strength for targeting efficacy but avoid the complex drug linker designation and improve the synthetic efficiency. More importantly, these classic nucleotide analog drugs have been used for many years, and aptamer nucleotide analog drug conjugates would not increase any unknown druggability risk but improve the target tumor accumulation. In this review, we mainly summarized aptamer-conjugated nucleotide analog drugs in cancer-targeting therapies.

Immune-Related Protein Interaction Network in Severe COVID-19 Patients toward the Identification of Key Proteins and Drug Repurposing

Coronavirus disease 2019 (COVID-19) is still an active global public health issue. Although vaccines and therapeutic options are available, some patients experience severe conditions and need critical care support. Hence, identifying key genes or proteins involved in immune-related severe COVID-19 is necessary to find or develop the targeted therapies. This study proposed a novel construction of an immune-related protein interaction network (IPIN) in severe cases with the use of a network diffusion technique on a human interactome network and transcriptomic data. Enrichment analysis revealed that the IPIN was mainly associated with antiviral, innate immune, apoptosis, cell division, and cell cycle regulation signaling pathways. Twenty-three proteins were identified as key proteins to find associated drugs. Finally, poly (I:C), mitomycin C, decitabine, gemcitabine, hydroxyurea, tamoxifen, and curcumin were the potential drugs interacting with the key proteins to heal severe COVID-19. In conclusion, IPIN can be a good representative network for the immune system that integrates the protein interaction network and transcriptomic data. Thus, the key proteins and target drugs in IPIN help to find a new treatment with the use of existing drugs to treat the disease apart from vaccination and conventional antiviral therapy.

A Novel Cognition of Decitabine: Insights into Immunomodulation and Antiviral Effects

DNA methylation, as one of the major means of epigenesis change, makes a large difference in the spatial structure of chromatin, transposable element activity and, fundamentally, gene transcription. It has been confirmed that DNA methylation is closely related to innate immune responses. Decitabine, the most efficient available DNA methyltransferase inhibitor, has demonstrated exhilarating immune activation and antiviral effects on multiple viruses, including HIV, HBV, HCV, HPV and EHV1. This review considers the role of decitabine in regulating innate immune responses and antiviral ability. Understanding the complex transcriptional and immune regulation of decitabine could help to identify and validate therapeutic methods to reduce pathogen infection-associated morbidity, especially virus infection-induced morbidity and mortality.

Synergistic Inhibitory Effects of 5-Aza-2'-Deoxycytidine and Cisplatin on Urothelial Carcinoma Growth via Suppressing TGFBI-MAPK Signaling Pathways

This study is to reveal the gene transcriptional alteration, possible molecular mechanism, and pathways involved in the synergy of 5-aza-2'-deoxycytidine (DAC) and CDDP in UC. Two UC cell lines, 5637 and T24, were used in the study. A cDNA microarray was carried out to identify critical genes in the synergistic mechanism of both agents against UC cells. The results showed that several key regulatory genes, such as interleukin 24(IL24), fibroblast growth factor 1(FGF1), and transforming growth factor beta-induced (TGFBI), were identified and may play critical roles in the synergy of DAC and CDDP in UC. Pathway enrichment suggested that many carcinogenesis-related pathways, such as ECM-receptor interaction and MAPK signaling pathways, may participate in the synergy of both agents. Our results suggested that TGF-β1 stimulates the phosphorylation levels of ERK1/2 and p38 via increasing TGFBI expression, TGFBI-MAPK signaling pathway plays an important role in the synergy of DAC and CDDP against UC. Therefore, we revealed the synergistic mechanism of DAC and CDDP in UC, several key regulatory genes play critical roles in the synergy of combined treatment, and TGFBI-MAPK signaling pathway may be an important potential target of these two agents.

A Retrospective Observation of Treatment Outcomes Using Decitabine-Combined Standard Conditioning Regimens Before Transplantation in Patients With Relapsed or Refractory Acute Myeloid Leukemia

Hypomethylating agents, decitabine (DAC) and azacitidine, can act as prophylactic and pre-emptive approaches after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and a non-intensive bridging approach before allo-HSCT. However, they are rarely used as a part of conditioning regimens in patients with relapsed or refractory acute myeloid leukemia (AML). This retrospectively study included a total of 65 patients (median, 37; range, 13–63) with relapsed or refractory AML who were treated by allo-HSCT after myeloablative conditioning regimens without or with DAC (high-dose DAC schedule, 75 mg/m² on day −9 and 50 mg/m² on day −8; low-dose DAC schedule, 25 mg/m²/day on day −10 to −8). DAC exerted no impact on hematopoietic reconstitution. However, patients who were treated with the high-dose DAC schedule had significantly higher incidence of overall survival (OS, 50.0%) and leukemia-free survival (LFS, 35.0%), and lower incidence of relapse (41.1%) and grade II–IV acute graft versus host disease (aGVHD, 10.0%) at 3 years, when compared with those treated with standard conditioning regimens or with the low-dose DAC schedule. In conclusion, high-dose DAC combined with standard conditioning regimens before allo-HSCT is feasible and efficient and might improve outcomes of patients with relapsed or refractory AML, which provides a potential approach to treat these patients.

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.

Role of CK2 inhibitor CX-4945 in anti-cancer combination therapy - potential clinical relevance

BACKGROUND

Protein kinase CK2 inhibition has long been considered as an attractive anti-cancer strategy based on the following considerations: CK2 is a pro-survival kinase, it is frequently over-expressed in human tumours and its over-expression correlates with a worse prognosis. Preclinical evidence strongly supports the feasibility of this target and, although dozens of CK2 inhibitors have been described in the literature so far, CX-4945 (silmitasertib) was the first that entered into clinical trials for the treatment of both human haematological and solid tumours. However, kinase inhibitor monotherapies turned out to be effective only in a limited number of malignancies, probably due to the multifaceted causes that underlie them, supporting the emerging view that multi-targeted approaches to treat human tumours could be more effective.

CONCLUSIONS

In this review, we will address combined anti-cancer therapeutic strategies described so far which involve the use of CX-4945. Data from preclinical studies clearly show the ability of CX-4945 to synergistically cooperate with different classes of anti-neoplastic agents, thereby contributing to an orchestrated anti-tumour action against multiple targets. Overall, these promising outcomes support the translation of CX-4945 combined therapies into clinical anti-cancer applications.

GSK-J4 induces cell cycle arrest and apoptosis via ER stress and the synergism between GSK-J4 and decitabine in acute myeloid leukemia KG-1a cells

Background

GSK-J4 is the inhibitor of H3K27me3 demethylase. Recent studies demonstrated that GSK-J4 could affect the proliferation and apoptosis of a variety of cancer cells. However, the effects and underlying mechanisms of GSK-J4 on the proliferation and apoptosis of human acute myeloid leukemia (AML) KG-1a cells have not been explored thoroughly.

Methods

The effect of GSK-J4 on cell proliferation was assessed with CCK8, while cell cycle distribution and apoptosis were analyzed using flow cytometry. The proteins related to cell cycle, cell apoptosis, endoplastic reticulum (ER) stress and PKC-α/p-Bcl2 pathway were detected by Western blotting. The expression level of PKC-α mRNA was measured by quantitative real-time PCR.ER stress inhibitor 4-phenyl butyric acid (4-PBA) was used to explore the role of ER stress in GSK-J4 induced cell-cycle arrest and cell apoptosis. The combination effects of Decitabine and GSK-J4 on KG-1a cells proliferation and apoptosis were also evaluated by CCK8, flow cytometry and immunoblot analysis.

Results

GSK-J4 reduced cell viability and arrested cell cycle progression at the S phase by decreasing the expression of CyclinD1 and CyclinA2 and increasing that of P21. Moreover, GSK-J4 enhanced the expression of apoptosis-related proteins (cle-caspase-9 and bax) and inhibited PKC-a/p-Bcl2 pathway to promote cell apoptosis. In addition, ER stress-related proteins (caspase-12, GRP78 and ATF4) were increased markedly after exposure to GSK-J4. The effects of GSK-J4 on cell cycle, apoptosis and PKC-a/p-Bcl2 pathway were attenuated after treatment with ER stress inhibitor. Furthermore, decitabine could significantly inhibit the proliferation and induce the apoptosis of KG-1a cells after combined treatment with GSK-J4.

Conclusion

Taken together, this study provided evidence that ER stress could regulate the process of GSK-J4-induced cell cycle arrest, cell apoptosis and PKC-α/p-bcl2 pathway inhibition and demonstrated a potential combinatory effect of decitabine and GSK-J4 on leukemic cell proliferation and apoptosis.

Small Molecule Inhibitor C188-9 Synergistically Enhances the Demethylated Activity of Low-Dose 5-Aza-2'-Deoxycytidine Against Pancreatic Cancer

Aberrant DNA methylation, especially hypermethylation of tumor suppressor genes, has been associated with many cancers' progression. 5-Aza-2′-deoxycytidine (DAC) can reverse hypermethylation-induced gene silencing via regulating DNA methyltransferases (DNMTs) activity, In addition, low-dose of DAC was proved to exert durable antitumor effects against solid tumor cells. Nevertheless, no clinical effect of DAC has been made when fighting against pancreatic cancer. Hence, it is necessary to raise a novel therapeutic strategy that further enhance the efficacy of DAC but not increase side effect, which impede the utilization of DAC. In the present study, we have discovered that C188-9, a novel signal transduction activator of transcription (STAT) inhibitor, could improve the antitumor effects of low-dose DAC in vivo and in vitro. Further study demonstrated that such improvement was attributed to re-expression of Ras association domain family member 1A (RASSF1A), a well-known tumor suppressor gene. Bisulfite sequencing PCR (BSP) assay showed that C188-9 combined with DAC treatment could significantly reverse the hypermethylation status of RASSF1A promoter, which indicated that C188-9 could enhance the demethylation efficacy of DAC. Our data demonstrated that DNA methyltransferase 1 (DNMT1) was the underlying mechanism that C188-9 regulates the demethylation efficacy of DAC. Overall, these findings provide a novel therapeutic strategy combining low-dose DAC and C188-9 to improve therapeutic efficacy by inhibiting DNMT1-inducing promoter methylation.

Identification of key genes by integrating DNA methylation and next-generation transcriptome sequencing for esophageal squamous cell carcinoma

Aberrant DNA methylation leads to abnormal gene expression, making it a significant regulator in the progression of cancer and leading to the requirement for integration of gene expression with DNA methylation. Here, we identified 120 genes demonstrating an inverse correlation between DNA methylation and mRNA expression in esophageal squamous cell carcinoma (ESCC). Sixteen key genes, such as SIX4, CRABP2, and EHD3, were obtained by filtering 10 datasets and verified in paired ESCC samples by qRT-PCR. 5-Aza-dC as a DNA methyltransferase (DNMT) inhibitor could recover their expression and inhibit clonal growth of cancer cells in seven ESCC cell lines. Furthermore, 11 of the 16 genes were correlated with OS (overall survival) and DFS (disease-free survival) in 125 ESCC patients. ChIP-Seq data and WGBS data showed that DNA methylation and H3K27ac histone modification of these key genes displayed inverse trends, suggesting that there was collaboration between DNA methylation and histone modification in ESCC. Our findings illustrate that the integrated multi-omics data (transcriptome and epigenomics) can accurately obtain potential prognostic biomarkers, which may provide important insight for the effective treatment of cancers.

Air pollution and DNA methylation: effects of exposure in humans

Air pollution exposure is estimated to contribute to approximately seven million early deaths every year worldwide and more than 3% of disability-adjusted life years lost. Air pollution has numerous harmful effects on health and contributes to the development and morbidity of cardiovascular disease, metabolic disorders, and a number of lung pathologies, including asthma and chronic obstructive pulmonary disease (COPD). Emerging data indicate that air pollution exposure modulates the epigenetic mark, DNA methylation (DNAm), and that these changes might in turn influence inflammation, disease development, and exacerbation risk. Several traffic-related air pollution (TRAP) components, including particulate matter (PM), black carbon (BC), ozone (O₃), nitrogen oxides (NO_x), and polyaromatic hydrocarbons (PAHs), have been associated with changes in DNAm; typically lowering DNAm after exposure. Effects of air pollution on DNAm have been observed across the human lifespan, but it is not yet clear whether early life developmental sensitivity or the accumulation of exposures have the most significant effects on health. Air pollution exposure-associated DNAm patterns are often correlated with long-term negative respiratory health outcomes, including the development of lung diseases, a focus in this review. Recently, interventions such as exercise and B vitamins have been proposed to reduce the impact of air pollution on DNAm and health. Ultimately, improved knowledge of how exposure-induced change in DNAm impacts health, both acutely and chronically, may enable preventative and remedial strategies to reduce morbidity in polluted environments.

The combination of Decitabine and EPZ-6438 effectively facilitate adipogenic differentiation of induced pluripotent stem cell-derived mesenchymal stem cells

As a novel type of mesenchymal stem cell, induced pluripotent stem cell-derived mesenchymal stem cells (iPMSCs) have huge potential for cell therapy. iPMSCs exhibited the typical characteristics of MSCs, whereas the tri-lineage differentiation potential is limited, especially the adipogenic propensity. Here, to reveal the molecular mechanism we carried out the epigenetic comparisons between the iPMSCs and the bone marrow-derived mesenchymal stem cells (BMSCs) and embryonic stem cell-derived mesenchymal stem cells (EMSCs). We found that the iPMSCs was significantly higher than the BMSCs in terms of genome-wide DNA methylation. Meanwhile, the adipogenic gene PPARγ promoter region existed hypermethylation. In addition, compared with EMSCs and BMSCs, iPMSCs had significant differences in the histones epigenetic modification of methylation and acetylation, especially high levels of histone 27 lysine trimethylation (H3K27me3). Furthermore, the epigenetic modifiers Decitabine and EPZ6438 effectively upregulated the gene expression of PPARγ and promoted the adipogenic differentiation of iPMSCs via chromatin remodeling. Taken together, our findings set new metrics to the applications for improving the efficiency and the therapeutic potential of iPMSCs.

Establishment and molecular characterization of decitabine-resistant K562 cells

The clinical activity of decitabine (5‐aza‐2‐deoxycytidine, DAC), a hypomethylating agent, has been demonstrated in acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) patients. However, secondary resistance to this agent often occurs during treatment and leads to treatment failure. It is important to clarify the mechanisms underlying the resistance for improving the efficacy. In this study, by gradually increasing concentration after a continuous induction of DAC, we established the DAC‐resistant K562 cell line (K562/DAC) from its parental cell line K562. The proliferation and survival rate of K562/DAC was significantly increased, whereas the apoptosis rate was remarkably decreased than that of K562 after DAC treatment. In K562/DAC, a total of 108 genes were upregulated and 118 genes were downregulated by RNA‐Seq. In addition, we also observed aberrant expression of DDX43/H19/miR‐186 axis (increased DDX43/H19 and decreased miR‐186) in K562/DAC cells. Ectopic expression of DDX43 in parental K562 cells rendered cells resistant to the DAC. Taken together, we successfully established DAC‐resistant K562 cell line which can serve as a good model for investigating DAC resistance mechanisms, and DDX43/H19/miR‐186 may be involved in DAC resistance in K562.

5-aza-2'-deoxycytidine in the regulation of antioxidant enzymes in retinal endothelial cells and rat diabetic retina

AIM

To investigate the roles of a DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) in the regulation of antioxidant enzymes in diabetic retinopathy (DR) models.

METHODS

DNMTs expressions and activity, and changes of two key antioxidant enzymes in DR, MnSOD (encoded by SOD2 gene) and glutathione S-transferase theta 1 (GSTT1), were quantified in the isolated human retinal endothelial cells (HRECs) exposed to high glucose (HG) with or without 5-aza-dC treatment. The downstream exacerbating factors including vascular endothelial growth factor (VEGF), intercellular adhesion molecule 1 (ICAM-1) and matrix metalloproteinase 2 (MMP2), which are implicated in the pathogenesis of DR and closely related to oxidative stress were also analyzed. The key parameters were confirmed in the retina from streptozotocin (STZ) diabetic rats.

RESULTS

DNMTs expression and DNMT activity was induced in HRECs exposed to HG. Hyperglycemia decreased MnSOD and GSTT1 expression. 5-aza-dC administration effectively suppressed DNMTs expression and activity and reversed the MnSOD and GSTT1 expression under HG condition. VEGF, ICAM-1 and MMP2 induced by HG were also suppressed by 5-aza-dC treatment. Similar results were observed in the retina from STZ diabetic rats.

CONCLUSION

Our findings suggest that DNA methylation may serves as one of the mechanisms of antioxidant defense system disruption in DR progression. Modulation of DNA methylation using pharmaceutic means such as DNMT inhibitors could help maintain redox homeostasis and prevent further progression of DR.

Addressing the elephant in the room, therapeutic resistance in non-small cell lung cancer, with epigenetic therapies

Like Chinese boxes nesting inside each other, the classification of non-small cell lung cancer (NSCLC) is subdivided into smaller and smaller subtypes on the basis of histological and molecular attributes. The latter characterizes NSCLC by its molecular alterations and the identification of inhibitors that target these cancer-specific "driver" mutations. Despite the initial promise of precision-guided therapies to inhibit a finer and finer array of molecular subcategories, despite even the curative potential of immunotherapeutic checkpoint blockade, in particular, casualties still abound and true clinical success stories are few and far between; the ever-present, if sometimes unmentioned, "elephant in the room", is the acquisition of resistance, which, sooner or later, rears its ugly head to undermine treatment success and shorten survival. Emerging data suggests that epigenetic therapies are able to reprogram the aberrant tumor-associated epigenome and 'tame the beast of resistance', thereby prolonging survival. This article reviews the role of epigenetic dysregulation in NSCLC, explores PFS2 as a possible surrogate endpoint, briefly mentions possible biomarkers and highlights combinatorial treatment epigenetic strategies to "prime" tumors and reverse resistance.

Impact of Natural Compounds on DNA Methylation Levels of the Tumor Suppressor Gene RASSF1A in Cancer

Epigenetic inactivation of tumor suppressor genes (TSG) is a fundamental event in the pathogenesis of human cancer. This silencing is accomplished by aberrant chromatin modifications including DNA hypermethylation of the gene promoter. One of the most frequently hypermethylated TSG in human cancer is the Ras Association Domain Family 1A (RASSF1A) gene. Aberrant methylation of RASSF1A has been reported in melanoma, sarcoma and carcinoma of different tissues. RASSF1A hypermethylation has been correlated with tumor progression and poor prognosis. Reactivation of epigenetically silenced TSG has been suggested as a therapy in cancer treatment. In particular, natural compounds isolated from herbal extracts have been tested for their capacity to induce RASSF1A in cancer cells, through demethylation. Here, we review the treatment of cancer cells with natural supplements (e.g., methyl donors, vitamins and polyphenols) that have been utilized to revert or prevent the epigenetic silencing of RASSF1A. Moreover, we specify pathways that were involved in RASSF1A reactivation. Several of these compounds (e.g., reseveratol and curcumin) act by inhibiting the activity or expression of DNA methyltransferases and reactive RASSF1A in cancer. Thus natural compounds could serve as important agents in tumor prevention or cancer therapy. However, the exact epigenetic reactivation mechanism is still under investigation.

Role and mechanism of decitabine combined with tyrosine kinase inhibitors in advanced chronic myeloid leukemia cells

Patients with advanced chronic myeloid leukemia (CML) have a poor prognosis, with the use of tyrosine kinase inhibitors (TKIs) to treat CML demonstrating poor results. The results of the present study revealed that, following Cell Counting Kit-8 analysis, treatment of K562 cells with decitabine (DAC) combined with TKIs exhibits synergic effects. Co-immunoprecipitation indicated that tyrosine-protein phosphatase non-receptor type 6 (SHP-1) and BCR-ABL fusion protein (BCR-ABL) (p210) form a complex in the K562 cell line, and in the primary cells derived from patients with CML. These results suggested that SHP-1 serves a role in regulating the tyrosine kinase activity of BCR-ABL (p210). In addition, SHP-1 expression increased, while BCR-ABL expression decreased in the group treated with DAC and TKIs combined group compared with the TKI monotherapy group. Treatment with imatinib (IM) demonstrated no effect on SHP-1 methylation in the K562 cell line; however, the methylation of SHP-1 was not determined in the combined IM and DAC therapy group. Treatment with DAC demonstrated the ability to activate the expression of silenced SHP-1 through demethylation, thus decreasing BCR-ABL tyrosine kinase activity, resulting in an improved therapeutic effect on CML.

In vitro analysis of factors influencing CYP1A2 expression as potential determinants of interindividual variation

Individual differences in drug metabolism contribute to interindividual variation that characterizes responses to drugs and risk in exposure to foreign chemicals. Large individual differences are found in expression levels of CYP1A2, a major drug-metabolizing enzyme. Underlying causes for this variation are not well understood. Several factors, including tobacco smoking, consumption of cruciferous vegetables, and sex, have been associated with modulating CYP1A2 expression. To understand factors regulating expression of CYP1A2 in establishing a causal relationship, this study examined effects of cigarette smoke condensate (CSC), indole-3-carbinol (I3C), and 17β-estradiol (estradiol) on CYP1A2 expression in in vitro systems using human liver and lung cells. Treatment with CSC (2-25 μg/mL) significantly increased levels of CYP1A2 in six cell lines examined, in a concentration- and time-dependent manner. Fold changes in expression levels relative to controls varied among cell lines. CYP1A2 enzymatic activity also increased with CSC exposure. Treatment of H1299 and HepB3 cells with dietary agent I3C (50 and 100 μmol/L) increased CYP1A2 expression. In human cell lines H1299 and H1395, treatment with estradiol (10 and 100 nmol/L) significantly reduced expression of CYP1A2. Using ChIP assays, effects of CSC on histone modifications were analyzed. Increases in H3K4me3 and H4K16ac were observed at several segments in the CYP1A2 gene, whereas H3K27me3 decreased, following CSC treatment. These results suggest that CYP1A2 expression is affected epigenetically by CSC. Additional studies will be needed to further establish regulatory mechanisms underlying effects of various environmental, dietary, and endogenous factors on CYP1A2 expression in better predicting individual variation.

Epigenetic DNA Demethylation Causes Inner Ear Stem Cell Differentiation into Hair Cell-Like Cells

The DNA methyltransferase (DNMT) inhibitor 5-azacytidine (5-aza) causes genomic demethylation to regulate gene expression. However, it remains unclear whether 5-aza affects gene expression and cell fate determination of stem cells. In this study, 5-aza was applied to mouse utricle sensory epithelia-derived progenitor cells (MUCs) to investigate whether 5-aza stimulated MUCs to become sensory hair cells. After treatment, MUCs increased expression of hair cell genes and proteins. The DNA methylation level (indicated by percentage of 5-methylcytosine) showed a 28.57% decrease after treatment, which causes significantly repressed DNMT1 protein expression and DNMT activity. Additionally, FM1-43 permeation assays indicated that the permeability of 5-aza-treated MUCs was similar to that of sensory hair cells, which may result from mechanotransduction channels. This study not only demonstrates a possible epigenetic approach to induce tissue specific stem/progenitor cells to become sensory hair cell-like cells, but also provides a cell model to epigenetically modulate stem cell fate determination.

CRABP-II- and FABP5-independent responsiveness of human glioblastoma cells to all-trans retinoic acid

Glioblastomas respond differently to all-trans retinoic acid (RA) for unknown reasons. Because CRABP-II and FABP5 mediate RA intracellular signaling respectively and lead to distinct biological consequences, their expression patterns in different grades of astrocytomas and the glioblastoma cells lines LN18, LN428 and U251 were examined to identify potential correlations with RA sensitivities. The response of glioblastoma cells to RA, decitabine or the FABP5 competitive inhibitor, BMS309403, was analyzed. CRABP-II and FABP5 were expressed to varying degrees by the 84-astrocytoma cases examined. Treatment of LN428, U251 and LN18 cells with RA failed to suppress their growth; however, U251 proliferation was inhibited by decitabine. The combination of decitabine and RA suppressed the growth of all three cell lines and induced significant apoptosis of LN428 and U251 cells. Both CRABP-II and FABP5 were transcribed in the three cell lines but FABP5 proteins were undetectable in U251 cells. The ratio of CRABP-II to FABP5 was not altered after RA, decitabine or RA and decitabine treatment and the resistance of cells to RA was not reversed by BMS309403 treatment. In conclusion, CRABP-II and FABP5 expression patterns are neither related to the tumor grades nor correlated with RA sensitivity. Additional molecular factors may be present that determines the sensitivity of glioblastoma cells to RA. Dicitabine may improve the sensitivity of glioblastoma cells to RA, however, its underlying mechanism and its in vivo feasibility need to be investigated.

A genome-wide search for epigenetically [corrected] regulated genes in zebra finch using MethylCap-seq and RNA-seq

Learning and memory formation are known to require dynamic CpG (de)methylation and gene expression changes. Here, we aimed at establishing a genome-wide DNA methylation map of the zebra finch genome, a model organism in neuroscience, as well as identifying putatively epigenetically regulated genes. RNA- and MethylCap-seq experiments were performed on two zebra finch cell lines in presence or absence of 5-aza-2′-deoxycytidine induced demethylation. First, the MethylCap-seq methodology was validated in zebra finch by comparison with RRBS-generated data. To assess the influence of (variable) methylation on gene expression, RNA-seq experiments were performed as well. Comparison of RNA-seq and MethylCap-seq results showed that at least 357 of the 3,457 AZA-upregulated genes are putatively regulated by methylation in the promoter region, for which a pathway analysis showed remarkable enrichment for neurological networks. A subset of genes was validated using Exon Arrays, quantitative RT-PCR and CpG pyrosequencing on bisulfite-treated samples. To our knowledge, this study provides the first genome-wide DNA methylation map of the zebra finch genome as well as a comprehensive set of genes of which transcription is under putative methylation control.

Mining the epigenetic landscape of tissue polarity in search of new targets for cancer therapy

The epigenetic nature of cancer encourages the development of inhibitors of epigenetic pathways. Yet, the clinical use for solid tumors of approved epigenetic drugs is meager. We argue that this situation might improve upon understanding the coinfluence between epigenetic pathways and tissue architecture. We present emerging information on the epigenetic control of the polarity axis, a central feature of epithelial architecture created by the orderly distribution of multiprotein complexes at cell-cell and cell-extracellular matrix contacts and altered upon cancer onset (with apical polarity loss), invasive progression (with basolateral polarity loss) and metastatic development (with basoapical polarity imbalance). This information combined with the impact of polarity-related proteins on epigenetic mechanisms of cancer enables us to envision how to guide the choice of drugs specific for distinct epigenetic modifiers, in order to halt cancer development and counter the consequences of polarity alterations.

Epigenetic-based therapy: From single- to multi-target approaches

The treatment of cancer has traditionally been based on the identification of a single molecule and/or enzymatic function (target) responsible for a particular phenotype, and therefore on the ability to stimulate, attenuate or inhibit its activity through the use of selective compounds. However, cancer is no longer considered a disease caused by a single factor, but is now recognized as a multi-factorial disorder. Genetic, epigenetic and metabolic factors all contribute to neoplasia, causing significant changes in molecular networks that govern cell growth, development, death and specialization. Consequently, many antitumor therapies are no longer directed against a single target but the biological system as a whole, in which functions determining the onset and maintenance of a physio-pathological state are modulated. The field of epi-drug discovery is currently in a transitional phase where the search for putative anticancer drugs is shifting from single-target-oriented molecules to network-active compounds and to epi-drugs used in combination with other epi-agents and with traditional chemotherapeutics. This review illustrates the pros and cons of each therapeutic option, providing examples in support of single-target and multi (network)-target epi-drug approaches.

Transgelin gene is frequently downregulated by promoter DNA hypermethylation in breast cancer

Background

CpG hypermethylation in gene promoters is a frequent mechanism of tumor suppressor gene silencing in various types of cancers. It usually occurs at early steps of cancer progression and can be detected easily, giving rise to development of promising biomarkers for both detection and progression of cancer, including breast cancer. 5-aza-2′-deoxycytidine (AZA) is a DNA demethylating and anti-cancer agent resulting in induction of genes suppressed via DNA hypermethylation.

Results

Using microarray expression profiling of AZA- or DMSO-treated breast cancer and non-tumorigenic breast (NTB) cells, we identified for the first time TAGLN gene as a target of DNA hypermethylation in breast cancer. TAGLN expression was significantly and frequently downregulated via promoter DNA hypermethylation in breast cancer cells compared to NTB cells, and also in 13/21 (61.9 %) of breast tumors compared to matched normal tissues. Analyses of public microarray methylation data showed that TAGLN was also hypermethylated in 63.02 % of tumors compared to normal tissues; relapse-free survival of patients was worse with higher TAGLN methylation; and methylation levels could discriminate between tumors and healthy tissues with 83.14 % sensitivity and 100 % specificity. Additionally, qRT-PCR and immunohistochemistry experiments showed that TAGLN expression was significantly downregulated in two more independent sets of breast tumors compared to normal tissues and was lower in tumors with poor prognosis. Colony formation was increased in TAGLN silenced NTB cells, while decreased in overexpressing BC cells.

Conclusions

TAGLN gene is frequently downregulated by DNA hypermethylation, and TAGLN promoter methylation profiles could serve as a future diagnostic biomarker, with possible clinical impact regarding the prognosis in breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0138-5) contains supplementary material, which is available to authorized users.

Aberrant expression of the CHFR prophase checkpoint gene in human B-cell non-Hodgkin lymphoma

Checkpoint with FHA and Ring Finger (CHFR) is a checkpoint protein that reportedly initiates a cell cycle delay in response to microtubule stress during prophase in mitosis, which has become an interesting target for understanding cancer pathogenesis. Recently, aberrant methylation of the CHFR gene associated with gene silencing has been reported in several cancers. In the present study, we examined the expression of CHFR in B-cell non-Hodgkin lymphoma (B-NHL) in vitro and in vivo. Our results showed that the expression level of CHFR mRNA and protein was reduced in B-NHL tissue samples and B cell lines. Furthermore, CHFR methylation was detected in 39 of 122 B-NHL patients, which was not found in noncancerous reactive hyperplasia of lymph node (RH) tissues. CHFR methylation correlated with the reduced expression of CHFR, high International Prognostic Index (IPI) scores and later pathologic Ann Arbor stages of B-NHL. Treatment with demethylation reagent, 5-Aza-dC, could eliminate the hypermethylation of CHFR, enhance CHFR expression and cell apoptosis and inhibit the cell proliferation of Raji cells, which could be induced by high expression of CHFR in Raji cells. Our results indicated that aberrant methylation of CHFR may be associated with the pathogenesis, progression for B-NHL, which might be a novel molecular marker as prognosis and treatment for B-NHL.

tp53-dependent G2 arrest mediator candidate gene, Reprimo, is down-regulated by promoter hypermethylation in pediatric acute myeloid leukemia

Reprimo (RPRM) is a novel tumor suppressor. However, the expression and molecular function of RPRM in pediatric acute myeloid leukemia (AML) is still unknown. We observed hypermethylation of the RPRM promoter in 8/11 leukemia cell lines and in 44.8% (47/105) of pediatric AML samples compared with 6.7% (2/30) of control samples. Bisulfite genomic sequencing analysis showed that the RPRM promoter was methylated in the majority of AML samples (66.2-83.1%), whereas RPRM was almost unmethylated in normal bone marrow samples (20.0-27.7%). Kaplan-Meier survival analysis revealed poor survival outcomes in samples with RPRM promoter methylation (p < 0.001). Proliferation of AML cells was inhibited in a dose-dependent manner (p < 0.05) after RPRM overexpression with lentivirus transfection. Apoptosis was up-regulated in RPRM-overexpressing AML cells. Real-time polymerase chain reaction array analysis revealed 50 dysregulated genes that might be implicated in apoptosis of RPRM-induced AML cells. RPRM may be a putative tumor suppressor in pediatric AML.

Synergistic effects of combined DNA methyltransferase inhibition and MBD2 depletion on breast cancer cells; MBD2 depletion blocks 5-aza-2'-deoxycytidine-triggered invasiveness

5-Aza-2'-deoxycytidine (5-azaCdR) not only inhibits growth of non-invasive breast cancer cells but also increases their invasiveness through induction of pro-metastatic genes. Methylated DNA binding protein 2 (MBD2) is involved in silencing methylated tumor suppressor genes as well as activation of pro-metastatic genes. In this study, we show that a combination of MBD2 depletion and DNA methyltransferases (DNMT) inhibition in breast cancer cells results in a combined effect in vitro and in vivo, enhancing tumor growth arrest on one hand, while inhibiting invasiveness triggered by 5-azaCdR on the other hand. The combined treatment of MBD2 depletion and 5-azaCdR suppresses and augments distinct gene networks that are induced by DNMT inhibition alone. These data point to a potential new approach in targeting the DNA methylation machinery by combination of MBD2 and DNMT inhibitors.