Epigenomics of leukemia: from mechanisms to therapeutic applications

Digital PCR-based GRHL2 methylation testing in acute myeloid leukemia: diagnosis, prognosis and monitoring

Background: Acute myeloid leukemia (AML) is a challenging disease with high rates of recurrence. The role of the cancer-related gene GRHL2 in AML has not been widely studied. Methods: Peripheral blood samples were collected from 73 AML patients and 68 healthy controls. Droplet digital PCR was used to detect GRHL2 methylation levels to explore the value of GRHL2 methylation in the diagnosis, treatment response and prognosis of AML. Result: GRHL2 methylation was significantly increased in AML patients (p < 0.01), with high diagnostic accuracy (area under the curve: 0.848; p < 0.001). GRHL2 methylation was correlated with chemotherapy response (p < 0.05) and is an independent prognostic factor for AML (p < 0.05). Conclusion: GRHL2 methylation is expected to serve as a biomarker for diagnosing AML patients and predicting prognosis.

Chidamide: Targeting epigenetic regulation in the treatment of hematological malignancy

Epigenetic alterations frequently participate in the onset of hematological malignancies. Histone deacetylases (HDACs) are essential for regulating gene transcription and various signaling pathways. Targeting HDACs has become a novel treatment option for hematological malignancies. Chidamide is the first oral selective HDAC inhibitor for HDAC1, HDAC2, HDAC3, and HDAC10 and was first approved for the treatment of R/R peripheral T-cell lymphoma by the China Food and Drug Administration in 2014. Chidamide was also approved under the name Hiyasta (HBI-8000) in Japan in 2021. In vitro studies revealed that chidamide could inhibit proliferation and induce apoptosis via cell cycle arrest and the regulation of apoptotic proteins. In clinical studies, chidamide was also efficacious in multiple myeloma, acute leukemia and myelodysplastic syndrome. This review includes reported experimental and clinical data on chidamide monotherapy or chidamide treatment in combination with chemotherapy for various hematological malignancies, offering a rationale for the renewed exploration of this drug.

Acetylation stabilizes the signaling protein WISP2 by preventing its degradation to suppress the progression of acute myeloid leukemia

Acute myeloid leukemia (AML) is challenging to treat due to its heterogeneity, prompting a deep understanding of its pathogenesis mechanisms, diagnosis, and treatment. Here, we found reduced expression and acetylation levels of WISP2 in bone marrow mononuclear cells from AML patients and that AML patients with lower WISP2 expression tended to have reduced survival. At the functional level, overexpression of WISP2 in leukemia cells (HL-60 and Kasumi-1) suppressed cell proliferation, induced cell apoptosis, and exerted antileukemic effects in an in vivo model of AML. Our mechanistic investigation demonstrated that WISP2 deacetylation was regulated by the deacetylase histone deacetylase (HDAC)3. In addition, we determined that crosstalk between acetylation and ubiquitination was involved in the modulation of WISP2 expression in AML. Deacetylation of WISP2 decreased the stability of the WISP2 protein by boosting its ubiquitination mediated by NEDD4 and proteasomal degradation. Moreover, pan-HDAC inhibitors (valproic acid and trichostatin A) and an HDAC3-specific inhibitor (RGFP966) induced WISP2 acetylation at lysine K6 and prevented WISP2 degradation. This regulation led to inhibition of proliferation and induction of apoptosis in AML cells. In summary, our study revealed that WISP2 contributes to tumor suppression in AML, which provided an experimental framework for WISP2 as a candidate for gene therapy of AML.

Big Data in Gastroenterology Research

Studying individual data types in isolation provides only limited and incomplete answers to complex biological questions and particularly falls short in revealing sufficient mechanistic and kinetic details. In contrast, multi-omics approaches to studying health and disease permit the generation and integration of multiple data types on a much larger scale, offering a comprehensive picture of biological and disease processes. Gastroenterology and hepatobiliary research are particularly well-suited to such analyses, given the unique position of the luminal gastrointestinal (GI) tract at the nexus between the gut (mucosa and luminal contents), brain, immune and endocrine systems, and GI microbiome. The generation of 'big data' from multi-omic, multi-site studies can enhance investigations into the connections between these organ systems and organisms and more broadly and accurately appraise the effects of dietary, pharmacological, and other therapeutic interventions. In this review, we describe a variety of useful omics approaches and how they can be integrated to provide a holistic depiction of the human and microbial genetic and proteomic changes underlying physiological and pathophysiological phenomena. We highlight the potential pitfalls and alternatives to help avoid the common errors in study design, execution, and analysis. We focus on the application, integration, and analysis of big data in gastroenterology and hepatobiliary research.

Identification of MiRNA–Disease Associations Based on Information of Multi-Module and Meta-Path

Cumulative research reveals that microRNAs (miRNAs) are involved in many critical biological processes including cell proliferation, differentiation and apoptosis. It is of great significance to figure out the associations between miRNAs and human diseases that are the basis for finding biomarkers for diagnosis and targets for treatment. To overcome the time-consuming and labor-intensive problems faced by traditional experiments, a computational method was developed to identify potential associations between miRNAs and diseases based on the graph attention network (GAT) with different meta-path mode and support vector (SVM). Firstly, we constructed a multi-module heterogeneous network based on the meta-path and learned the latent features of different modules by GAT. Secondly, we found the average of the latent features with weight to obtain a final node representation. Finally, we characterized miRNA–disease-association pairs with the node representation and trained an SVM to recognize potential associations. Based on the five-fold cross-validation and benchmark datasets, the proposed method achieved an area under the precision–recall curve (AUPR) of 0.9379 and an area under the receiver–operating characteristic curve (AUC) of 0.9472. The results demonstrate that our method has an outstanding practical application performance and can provide a reference for the discovery of new biomarkers and therapeutic targets.

ACY-1215 suppresses the proliferation and induces apoptosis of chronic myeloid leukemia cells via the ROS/PTEN/Akt pathway

Chronic myeloid leukemia (CML) is a hematological tumor marked by the bcr-abl fusion gene formed by t (9;22) (q34; q11), which translated into the BCR-ABL protein. Tyrosine kinase inhibitors (TKIs) have been widely used to cure CML patients. Nevertheless, the emergence of TKI resistance has become the problem to the outcome of CML patients. Histone deacetylase 6 (HDAC6), a kind of Hsp90α deacetylase, was detected to be overexpressed in chronic myeloid leukemia stem cells. Besides, the loss of HDAC6 enzymatic activity can result in the degradation of Hsp90α's client proteins, such as BCR-ABL, the oncoprotein of CML. Here, we explored the expression of HDAC6 and discovered that it was upregulated compared with control in CML. Then we explored the effect of Rocilinostat (ACY-1215), a specific HDAC6 inhibitor, on CML cells. Our results proved that ACY-1215 could induce apoptosis and cell cycle arrest in a ROS-dependent manner. Moreover, we detected a downregulation of the BCR-ABL signaling pathway in the ACY-1215 treatment group. Mechanistically, we noted that the upregulation of PTEN was induced after being treated by ACY-1215 and its downstream protein p-Akt was decreased. The Akt activator SC79 can partially reverse the influence of ACY-1215 on CML cells. Besides, our results also proved that ACY-1215 can synergize with imatinib to suppress chronic myeloid leukemia in vitro and in vivo. On the whole, our study revealed that HDAC6 is a possible therapeutic target in CML, and the combination therapy of TKI and HDAC6 inhibitor may improve the outcome of CML patients.

Potential Approaches Versus Approved or Developing Chronic Myeloid Leukemia Therapy

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of patients with chronic myeloid leukemia (CML). However, continued use of these inhibitors has contributed to the increase in clinical resistance and the persistence of resistant leukemic stem cells (LSCs). So, there is an urgent need to introduce additional targeted and selective therapies to eradicate quiescent LSCs, and to avoid the relapse and disease progression. Here, we focused on emerging BCR-ABL targeted and non-BCR-ABL targeted drugs employed in clinical trials and on alternative CML treatments, including antioxidants, oncolytic virus, engineered exosomes, and natural products obtained from marine organisms that could pave the way for new therapeutic approaches for CML patients.

Genistein-induced Anticancer Effects on Acute Leukemia Cells Involve the Regulation of Wnt Signaling Pathway Through H4K20me1 Rather Than DNA Demethylation

OBJECTIVE

To investigate the effects and mechanisms of genistein on the gene expression in the Wnt pathway in acute leukemia (AL) cells.

METHODS

The expression of Wnt pathway genes and cell cycle-related genes were analyzed in two AL cell lines. Pyrophosphate sequencing was performed to determine the methylation degree. Then, the enrichment of H4K20me1 and H3K9ac was determined using ChIP-qPCR. Flow cytometry was used to analyze the cell cycle.

RESULTS

The IC₅₀ of genistein in the two AL cell lines was lower than that for the bone marrow mesenchymal stem cell line. Genistein upregulated H4K20me1, KMT5A and Wnt suppressor genes, including _Wnt5a, and downregulated the downstream target genes of Wnt, such as c-myc and β-catenin. The methylation degree and H3K9ac enrichment in the _Wnt5a promoter region remained unchanged. However, the enrichment of H4K20me1 in the _Wnt5a promoter and coding regions increased. In addition, genistein upregulated Phospho-cdc2, Myt1, Cyclin A, Cyclin E2, p21 and Phospho-histone H3, but downregulated Phospho-wee1. Cell cycle arrest was induced in the G2/M phase.

CONCLUSION

Genistein inhibits the activation of the Wnt pathway by promoting the expression of _Wnt5a through the activation of KMT5A and enrichment of H4K20me1 in the _Wnt5a gene promoter and coding regions, rather than demethylation. Genistein also blocks the cell cycle in the G2/M phase. Therefore, genistein is a potential anti-leukemia drug.

Tumor-targeted Drug Delivery by Nanocomposites

BACKGROUND

Tumor-targeted delivery by nanoparticles is a great achievement towards the use of highly effective drug at very low doses. The conventional development of tumor-targeted delivery by nanoparticles is based on enhanced permeability and retention (EPR) effect and endocytosis based on receptor-mediated are very demanding due to the biological and natural complications of tumors as well as the restrictions on the design of the accurate nanoparticle delivery systems.

METHODS

Different tumor environment stimuli are responsible for triggered multistage drug delivery systems (MSDDS) for tumor therapy and imaging. Physicochemical properties, such as size, hydrophobicity and potential transform by MSDDS because of the physiological blood circulation different, intracellular tumor environment. This system accomplishes tumor penetration, cellular uptake improved, discharge of drugs on accurate time, and endosomal discharge.

RESULTS

Maximum drug delivery by MSDDS mechanism to target therapeutic cells and also tumor tissues and sub cellular organism. Poorly soluble compounds and bioavailability issues have been faced by pharmaceutical industries, which are resolved by nanoparticle formulation.

CONCLUSION

In our review, we illustrate different types of triggered moods and stimuli of the tumor environment, which help in smart multistage drug delivery systems by nanoparticles, basically a multi-stimuli sensitive delivery system, and elaborate their function, effects, and diagnosis.

Ketogenic Diet in Cancer Prevention and Therapy: Molecular Targets and Therapeutic Opportunities

Although cancer is still one of the most significant global challenges facing public health, the world still lacks complementary approaches that would significantly enhance the efficacy of standard anticancer therapies. One of the essential strategies during cancer treatment is following a healthy diet program. The ketogenic diet (KD) has recently emerged as a metabolic therapy in cancer treatment, targeting cancer cell metabolism rather than a conventional dietary approach. The ketogenic diet (KD), a high-fat and very-low-carbohydrate with adequate amounts of protein, has shown antitumor effects by reducing energy supplies to cells. This low energy supply inhibits tumor growth, explaining the ketogenic diet's therapeutic mechanisms in cancer treatment. This review highlights the crucial mechanisms that explain the ketogenic diet's potential antitumor effects, which probably produces an unfavorable metabolic environment for cancer cells and can be used as a promising adjuvant in cancer therapy. Studies discussed in this review provide a solid background for researchers and physicians to design new combination therapies based on KD and conventional therapies.

MLL5 improves ATRA driven differentiation and promotes xenotransplant engraftment in acute promyelocytic leukemia model

Although the mixed lineage leukemia 5 (MLL5) gene has prognostic implications in acute promyelocyte leukemia (APL), the underlying mechanism remains to be elucidated. Here, we demonstrate the critical role exerted by MLL5 in APL regarding cell proliferation and resistance to drug-induced apoptosis, through mtROS regulation. Additionally, MLL5 overexpression increased the responsiveness of APL leukemic cells to all-trans retinoic acid (ATRA)-induced differentiation, via regulation of the epigenetic modifiers SETD7 and LSD1. In silico analysis indicated that APL blasts with MLL5^high transcript levels were associated with retinoic acid binding and downstream signaling, while MLL5^low blasts displayed decreased expression of epigenetic modifiers (such as KMT2C, PHF8 and ARID4A). Finally, APL xenograft transplants demonstrated improved engraftment of MLL5-expressing cells and increased myeloid differentiation over time. Concordantly, evaluation of engrafted blasts revealed increased responsiveness of MLL5-expressing cells to ATRA-induced granulocytic differentiation. Together, we describe the epigenetic changes triggered by the interaction of MLL5 and ATRA resulting in enhanced granulocytic differentiation.

Recent Clinical Update of Acute Myeloid Leukemia: Focus on Epigenetic Therapies

Acute myeloid leukemia (AML) is a complicated disease characterized by genetic heterogeneity and simultaneous alterations in multiple genes. For decades, its only curative method has been intensive induction chemotherapy with or without allogeneic hematopoietic stem cell transplantation, and this approach cannot be applied to elderly patients, who make up more than 50% of AML patients. Recent advances in genomics facilitated the elucidation of various mutations related to AML, and the most frequent mutations were discovered in epigenetic regulators. Alterations to epigenetic modifications that are essential for normal cell biology, including DNA methylation and histone acetylation, have been identified. As epigenetic dysregulation is an important carcinogenic mechanism and some epigenetic changes are reversible, these epigenetic alterations have become targets for novel drug development against AML. This review summarizes the recent advances in epigenetic therapies for AML and discusses future research directions.

Promoter Methylation Status and Expression Levels of RASSF1A Gene in Different Phases of Acute Lymphoblastic Leukemia (ALL)

Background: Although the precise pathogenesis of acute lymphoblastic leukemia (ALL) remains unclear, studying gene-regulating mechanisms during ALL pathogeneses may shed light on the underlying mechanisms driving malignant behavior. There is some evidence showing the promoter hypermethylation and silencing of RASSF1A tumor suppressor gene in ALL cells; however, there is a lack of evidence for whether the gene indeed alters during different phases of ALL or in response to therapy. Thus, the current study aimed to clarify this issue using groups of adult ALL patients who have been scarcely investigated regarding expression levels and promoter methylation status.

Materials and Methods: In this case/control study, the expression levels and methylation status of the gene promoter was evaluated using quantitative real-time PCR and methylation-specific PCR (MSP), respectively in adults with ALL. The study included peripheral blood of patients with newly diagnosed ALL (n=10), complete remission (CR) (n=10), or relapse (n=10), and 10 control samples from healthy individuals.

Results: MSP results revealed an unmethylated status for almost all patients and control samples, except a case with relapsing ALL, which showed a hemimethylated pattern. RASSF1A also showed no difference in terms of gene expression in the patients compared with the control group (p>0.05).

Conclusion: The results revealed an up-regulation of RASSF1A tumor suppressor in adult ALL patients experiencing CR, suggesting this to be a marker of therapy response. However, further investigations using more sensitive methylation detecting tools with larger sample sizes may better clarify the involvement of the promoter methylation of RASSF1A in these patients. 

Epigenetic regulation of steroidogenic enzymes expressed in peripheral blood mononuclear cells from healthy individuals and from patients with chronic lymphocytic leukemia

Sex hormone synthesis occurs in various organs and tissues besides the gonads, such as adrenal glands, brain, intestines, skin, fat, bone, and cells of the immune system. Regarding the latter, it is still not clear which pathways are active, and if they are modified in case of illness of the immune system. Our goal in this study was to determine mRNA expression of different steroidogenic enzymes in peripheral blood mononuclear cells (PBMCs) from healthy individuals of both sexes and of different ages, and then to compare their expression between healthy individuals and patients with Chronic Lymphocytic Leukemia (CLL). Furthermore, to elucidate possible mechanisms that regulate enzyme expression, we analyzed epigenetic events like promoter methylation. We determined that normal cells of the immune system, regardless of sex and age, expressed P450 side chain cleavage (P450scc), cytochrome P450 17α-hydroxylase/c17,20-lyase (P45017α), 3β-hydroxysteroid dehydrogenase/Δ5-Δ4-isomerase (3β-HSD), steroid 5 α reductase (5α-R) types 1, 2 and 3, 3α-hydroxysteroid dehydrogenase (3α-HSD) type 3, and 17β-hydroxysteroid dehydrogenase (17β-HSD) types 1, 3 and 5. We also established that 5α-R 1, 5α-R 3, 3α-HSD 3, 17β-HSD 1 and 17β-HSD 5 expression was altered in CLL patients, and that promoter regions of 5α-R 1, 17β-HSD 1 and 17β-HSD 5 were diferentially methylated. These results suggest that steroidogenic pathways may be affected in CLL cells, and this could be related to disease pathogenesis.

HMGB1: an important regulator of myeloid differentiation and acute myeloid leukemia as well as a promising therapeutic target

Abstract

High mobility group box 1 (HMGB1) is a non-histone nuclear protein which has been intensively studied in various physiological and pathological processes including leukemia. Here in this study, we further demonstrated that HMGB1 presents higher expression in the bone marrow mononuclear cells of acute myeloid leukemia (AML) patients compared with the normal controls and contributes to the AML pathogenesis and progression by inhibiting apoptosis, facilitating proliferation, and inducing myeloid differentiation blockade of AML cells. Mechanistic investigation revealed that transforming growth factor beta-induced (TGFBI) acts as a potential downstream target of HMGB1 and lentivirus-mediated knockdown of TGFBI expression impaired phorbol-12-myristate-13-acetate (PMA) and all-trans retinoic acid (ATRA)–induced myeloid differentiation of AML cell lines. On the other hand, chidamide, an orally histone deacetylase inhibitor, decreases HMGB1 expression significantly in AML cells with concomitant upregulation of TGFBI expression, and confers therapeutic effect on AML by inducing cell differentiation, apoptosis and inhibiting cell proliferation. In conclusion, our findings provide additional insights that HMGB1 is a promising therapeutic target of AML, and also present experimental evidence for the clinical application of chidamide as a novel agent in AML therapy by downregulating HMGB1 expression.

Key messages

HMGB1 induces cell proliferation and myeloid differentiation blockade and inhibits apoptosis of AML cells.

TGFBI acts as a potential target of HMGB1.

Chidamide, a selective HDAC inhibitor, confers promising therapeutic effect for AML via downregulating HMGB1 expression.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-020-01998-5.

Deciphering the role of Wnt signaling in acute myeloid leukemia prognosis: how alterations in DNA methylation come into play in patients' prognosis

Acute myeloid leukemia (AML) is a malignant clonal disorder affecting myeloid differentiation through mechanisms that include epigenetic dysregulation. Abnormal changes in DNA methylation and gene expression profiles of pathways involved in hematopoietic development, such as Wnt/β-catenin, contribute to the transformation, development, and maintenance of leukemic cells. This review summarizes the alterations of Wnt signaling-related genes at the epigenetic and transcriptional level and their implications for AML prognosis. Among the implications of epigenetic alterations in AML, methylation of Wnt antagonists is related to poor prognosis, whereas their upregulation has been associated with a better clinical outcome. Furthermore, Wnt target genes c-Myc and LEF-1 present distinct implications. LEF-1 expression positively influences the patient overall survival. c-Myc upregulation has been associated with treatment resistance in AML, although c-Myc expression is not exclusively dependent of Wnt signaling. Understanding the signaling abnormalities could help us to further understand leukemogenesis, improve the current risk stratification for AML patients, and even serve to propose novel therapeutic targets.

The HDAC6 inhibitor 7b induces BCR-ABL ubiquitination and downregulation and synergizes with imatinib to trigger apoptosis in chronic myeloid leukemia

Despite the discovery of tyrosine kinase inhibitors (TKIs) for the treatment of breakpoint cluster region-Abelson (BCR-ABL)⁺ cancer types, patients with chronic myeloid leukemia (CML) treated with TKIs develop resistance and severe adverse effects. Combination treatment, especially with a histone deacetylase (HDAC) 6 inhibitor (HDAC6i), appears to be an attractive option to prevent TKI resistance, considering the potential capacity of an HDAC6i to diminish BCR-ABL expression. We first validated the in vivo anti-cancer potential of the compound 7b by significantly reducing the tumor burden of BALB/c mice xenografted with K-562 cells, without notable organ toxicity. Here, we hypothesize that the HDAC6i compound 7b can lead to BCR-ABL downregulation in CML cells and sensitize them to TKI treatment. The results showed that combination treatment with imatinib and 7b resulted in strong synergistic caspase-dependent apoptotic cell death and drastically reduced the proportion of leukemia stem cells, whereas this treatment only moderately affected healthy cells. Ultimately, the combination significantly decreased colony formation in a semisolid methylcellulose medium and tumor mass in xenografted zebrafish compared to each compound alone. Mechanistically, the combination induced BCR-ABL ubiquitination and downregulation followed by disturbance of key proteins in downstream pathways involved in CML proliferation and survival. Taken together, our results suggest that an HDAC6i potentiates the effect of imatinib and could overcome TKI resistance in CML cells.

Novel HDAC inhibitor MAKV-8 and imatinib synergistically kill chronic myeloid leukemia cells via inhibition of BCR-ABL/MYC-signaling: effect on imatinib resistance and stem cells

Background

Chronic myeloid leukemia (CML) pathogenesis is mainly driven by the oncogenic breakpoint cluster region-Abelson murine leukemia viral oncogene homolog 1 (BCR-ABL) fusion protein. Since BCR-ABL displays abnormal constitutive tyrosine kinase activity, therapies using tyrosine kinase inhibitors (TKis) such as imatinib represent a major breakthrough for the outcome of CML patients. Nevertheless, the development of TKi resistance and the persistence of leukemia stem cells (LSCs) remain barriers to cure the disease, justifying the development of novel therapeutic approaches. Since the activity of histone deacetylase (HDAC) is deregulated in numerous cancers including CML, pan-HDAC inhibitors may represent promising therapeutic regimens for the treatment of CML cells in combination with TKi.

Results

We assessed the anti-leukemic activity of a novel hydroxamate-based pan-HDAC inhibitor MAKV-8, which complied with the Lipinski’s “rule of five,” in various CML cells alone or in combination with imatinib. We validated the in vitro HDAC-inhibitory potential of MAKV-8 and demonstrated efficient binding to the ligand-binding pocket of HDAC isoenzymes. In cellulo, MAKV-8 significantly induced target protein acetylation, displayed cytostatic and cytotoxic properties, and triggered concomitant ER stress/protective autophagy leading to canonical caspase-dependent apoptosis. Considering the specific upregulation of selected HDACs in LSCs from CML patients, we investigated the differential toxicity of a co-treatment with MAKV-8 and imatinib in CML versus healthy cells. We also showed that beclin-1 knockdown prevented MAKV-8-imatinib combination-induced apoptosis. Moreover, MAKV-8 and imatinib co-treatment synergistically reduced BCR-ABL-related signaling pathways involved in CML cell growth and survival. Since our results showed that LSCs from CML patients overexpressed c-MYC, importantly MAKV-8-imatinib co-treatment reduced c-MYC levels and the LSC population. In vivo, tumor growth of xenografted K-562 cells in zebrafish was completely abrogated upon combined treatment with MAKV-8 and imatinib.

Conclusions

Collectively, the present findings show that combinations HDAC inhibitor-imatinib are likely to overcome drug resistance in CML pathology.

Chidamide induces necroptosis via regulation of c‑FLIPL expression in Jurkat and HUT‑78 cells

T‑cell acute lymphoblastic leukemia (T‑ALL) is a hematopoietic malignancy, which is associated with a poor prognosis. It is difficult to achieve complete remission or long‑term survival with conventional chemotherapy, partly due to decreased apoptosis. However, necroptosis can serve as an alternative pathway to induce cell death. The present study investigated whether the selective histone deacetylase (HDAC) inhibitor chidamide exerted a therapeutic effect on T‑ALL and explored the underlying mechanism. The results revealed that HDAC expression was increased in Jurkat and HUT‑78 cells treated compared with the control cell line (H9), and was accompanied by elevated cellular Fas‑associated death domain‑like interleukin‑1β converting enzyme inhibitory protein long form (c‑FLIPL) levels. Chidamide treatment (2 µmol/l) also induced mitochondrial dysfunction, necroptosis and apoptosis in T‑ALL cells in vitro. Furthermore, necroptosis was increased when apoptosis was blocked in T‑ALL cells. Additionally, chidamide (2 µmol/l) downregulated c‑FLIPL, HDAC1 and HDAC3 expression, and increased receptor‑interacting protein kinase 3 expression and the phosphorylation of mixed lineage kinase domain‑like pseudokinase in Jurkat and HUT‑78 cells. The results obtained in the present study revealed that chidamide may induce necroptosis via regulation of c‑FLIPL expression when apoptosis is inhibited in Jurkat and HUT‑78 cells.

Epigenetic mechanisms underlying the therapeutic effects of HDAC inhibitors in chronic myeloid leukemia

Chronic myeloid leukemia (CML) is a hematological disorder caused by the oncogenic BCR-ABL fusion protein in more than 90% of patients. Despite the striking improvements in the management of CML patients since the introduction of tyrosine kinase inhibitors (TKis), the appearance of TKi resistance and side effects lead to treatment failure, justifying the need of novel therapeutic approaches. Histone deacetylase inhibitors (HDACis), able to modulate gene expression patterns and important cellular signaling pathways through the regulation of the acetylation status of both histone and non-histone protein targets, have been reported to display promising anti-leukemic properties alone or in combination with TKis. This review summarizes pre-clinical and clinical studies that investigated the mechanisms underlying the anticancer potential of HDACis and discusses the rationale for a combination of HDACis with TKis as a therapeutic option in CML.

Redox biology of regulated cell death in cancer: A focus on necroptosis and ferroptosis

Redox changes and generation of reactive oxygen species (ROS) are part of normal cell metabolism. While low ROS levels are implicated in cellular signaling pathways necessary for survival, higher levels play major roles in cancer development as well as cell death signaling and execution. A role for redox changes in apoptosis has been long established; however, several new modalities of regulated cell death have been brought to light, for which the importance of ROS production as well as ROS source and targets are being actively investigated. In this review, we summarize recent findings on the role of ROS and redox changes in the activation and execution of two major forms of regulated cell death, necroptosis and ferroptosis. We also discuss the potential of using modulators of these two forms of cell death to exacerbate ROS as a promising anticancer therapy.

Anticancer potential of naturally occurring immunoepigenetic modulators: A promising avenue?

The immune system represents the major primary defense line against carcinogenesis and acts by identifying and eradicating nascent transformed cells. A growing body of evidence is indicating that aberrant epigenetic reprogramming plays a key role in tumor immune escape through: 1) impaired efficient recognition of neoplastic cells by the immune system, resulting from a downregulation or loss of the expression of tumor-associated antigens, human leukocyte antigens, antigen processing and presenting machinery, and costimulatory molecule genes; 2) aberrant expression of immune checkpoint proteins and their ligands; and 3) modification of cytokine profiles and tumor-associated immune cell populations toward an immunosuppressive state in the tumor microenvironment. Consistent with the inherent reversibility of epigenetic alterations, epigenetic drugs, including DNA methyltransferase and histone deacetylase inhibitors, have the unique potential to favorably modify the tumor microenvironment, restore tumor recognition and stimulate an antitumor immune response. The objective of this review is to highlight selected, naturally occurring epigenetic modulators, namely, butyrate, curcumin, (-)-epigallocatechin-3-gallate, resveratrol, romidepsin, and trichostatin A, with a special focus on their antitumor immune properties.

Clinical Exome Sequencing unravels new disease-causing mutations in the myeloproliferative neoplasms: A pilot study in patients from the state of Qatar

Clinical Exome Sequencing (CES) has increasingly become a popular diagnostic tool in patients suffering from genetic disorders that are clinically and genetically complicated. Myeloproliferative Neoplasms (MPNs) is an example of a heterogeneous disorder. In Qatar, familial cases of MPNs are more frequently seen than described in the literature. In this study, we aimed to use CES to classify six Qatari subjects that were suspected of clinical diagnosis of MPNs, according to the WHO 2008 diagnostic criteria for hematologic malignancies, and identify variants that can potentially explain the phenotypic diversity of MPNs. We sequenced six Qatari subjects using CES, of whom, three probands were unrelated families and three members were from the same family, all probands come from consanguineous families, and had a positive family history of MPNs. CES identified 61 variants in 50 genes; of which, 13 were recurrently mutated in our patients. Ten novel variants were identified in ten known genes related to MPNs and seven variants were identified in seven novel candidate genes. The genotype of the six subjects was due to a combination of different variants in different genes. This study serves as a pilot study to investigate the complexity of the genotype of patients with MPNS in Qatar, and serves as a guide for further well-controlled genetic epidemiological studies for patients with MPNs. CES is a powerful tool to be used in the genetic clinics for differential and definitive diagnosis of patients with MPNs.

Promyelocytic leukemia protein in mesenchymal stem cells is essential for leukemia progression

The dynamic interactions between leukemic cells and cells resident within the bone marrow microenvironment are vital for leukemia progression. The lack of detailed knowledge about the cellular and molecular mechanisms involved in this cross-talk restricts the design of effective treatments. Guarnerio et al. (2018) by using state-of-the-art techniques, including sophisticated Cre/loxP technologies in combination with leukemia mouse models, reveal that mesenchymal stem cells via promyelocytic leukemia protein (Pml) maintain leukemic cells in the bone marrow niche. Strikingly, genetic deletion of Pml in mesenchymal stem cells raised survival of leukemic mice under chemotherapeutic treatment. The emerging knowledge from this research provides a novel target in the bone marrow niche for therapeutic benefit in leukemia.

Insight into origins, mechanisms, and utility of DNA methylation in B-cell malignancies

Understanding how tumor cells fundamentally alter their identity is critical to identify specific vulnerabilities for use in precision medicine. In B-cell malignancy, knowledge of genetic changes has resulted in great gains in our understanding of the biology of tumor cells, impacting diagnosis, prognosis, and treatment. Despite this knowledge, much remains to be explained as genetic events do not completely explain clinical behavior and outcomes. Many patients lack recurrent driver mutations, and said drivers can persist in nonmalignant cells of healthy individuals remaining cancer-free for decades. Epigenetics has emerged as a valuable avenue to further explain tumor phenotypes. The epigenetic landscape is the software that powers and stabilizes cellular identity by abridging a broad genome into the essential information required per cell. A genome-level view of B-cell malignancies reveals complex but recurrent epigenetic patterns that define tumor types and subtypes, permitting high-resolution classification and novel insight into tumor-specific mechanisms. Epigenetic alterations are guided by distinct cellular processes, such as polycomb-based silencing, transcription, signaling pathways, and transcription factor activity, and involve B-cell-specific aspects, such as activation-induced cytidine deaminase activity and germinal center-specific events. Armed with a detailed knowledge of the epigenetic events that occur across the spectrum of B-cell differentiation, B-cell tumor-specific aberrations can be detected with improved accuracy and serve as a model for identification of tumor-specific events in cancer. Insight gained through recent efforts may prove valuable in guiding the use of both epigenetic- and nonepigenetic-based therapies.

Discovery and characterization of Isofistularin-3, a marine brominated alkaloid, as a new DNA demethylating agent inducing cell cycle arrest and sensitization to TRAIL in cancer cells

We characterized the brominated alkaloid Isofistularin-3 (Iso-3), from the marine sponge Aplysina aerophoba, as a new DNA methyltransferase (DNMT)1 inhibitor. Docking analysis confirmed our in vitro DNMT inhibition data and revealed binding of Iso-3 within the DNA binding site of DNMT1. Subsequent increased expression of tumor suppressor gene aryl hydrocarbon receptor (AHR) could be correlated to decreased methylation of CpG sites within the essential Sp1 regulatory region of its promoter. Iso-3 induced growth arrest of cancer cells in G0/G1 concomitant with increased p21 and p27 expression and reduced cyclin E1, PCNA and c-myc levels. Reduced proliferation was accompanied by morphological changes typical of autophagy revealed by fluorescent and transmission electron microscopy and validated by LC3I-II conversion. Furthermore, Iso-3 strongly synergized with tumor-necrosis-factor related apoptosis inducing ligand (TRAIL) in RAJI [combination index (CI) = 0.22] and U-937 cells (CI = 0.21) and increased TRAIL-induced apoptosis via a mechanism involving reduction of survivin expression but not of Bcl-2 family proteins nor X-linked inhibitor of apoptosis protein (XIAP). Iso-3 treatment decreased FLIP_L expression and triggered activation of endoplasmatic reticulum (ER) stress with increased GRP78 expression, eventually inducing TRAIL receptor death receptor (DR)5 surface expression. Importantly, as a potential candidate for further anticancer drug development, Iso-3 reduced the viability, colony and in vivo tumor forming potential without affecting the viability of PBMCs from healthy donors or zebrafish development.

The Fungal Metabolite Eurochevalierine, a Sequiterpene Alkaloid, Displays Anti-Cancer Properties through Selective Sirtuin 1/2 Inhibition

NAD⁺-dependent histone deacetylases (sirtuins) are implicated in cellular processes such as proliferation, DNA repair, and apoptosis by regulating gene expression and the functions of numerous proteins. Due to their key role in cells, the discovery of small molecule sirtuin modulators has been of significant interest for diverse therapeutic applications. In particular, it has been shown that inhibition of sirtuin 1 and 2 activities is beneficial for cancer treatment. Here, we demonstrate that the fungal metabolite eurochevalierine from the fungus Neosartorya pseudofischeri inhibits sirtuin 1 and 2 activities (IC₅₀ about 10 µM) without affecting sirtuin 3 activity. The binding modes of the eurochevalierine for sirtuin 1 and 2 have been identified through computational docking analyses. Accordingly, this sequiterpene alkaloid induces histone H4 and α-tubulin acetylation in various cancer cell models in which it induces strong cytostatic effects without affecting significantly the viability of healthy PBMCs. Importantly, eurochevalierine targets preferentially cancer cell proliferation (selectivity factor ≫ 7), as normal human primary CD34⁺ stem/progenitor cells were less affected by the treatment. Finally, eurochevalierine displays suitable drug-likeness parameters and therefore represent a promising scaffold for lead molecule optimization to study the mechanism and biological roles of sirtuins and potentially a basis for development into therapeutics.

Targeting protein-protein interaction between MLL1 and reciprocal proteins for leukemia therapy

The mixed lineage leukemia protein-1 (MLL1), as a lysine methyltransferase, predominantly regulates the methylation of histone H3 lysine 4 (H3K4) and functions in hematopoietic stem cell (HSC) self-renewal. MLL1 gene fuses with partner genes that results in the generation of MLL1 fusion proteins (MLL1-FPs), which are frequently detected in acute leukemia. In the progress of leukemogenesis, a great deal of proteins cooperate with MLL1 to form multiprotein complexes serving for the dysregulation of H3K4 methylation, the overexpression of homeobox (HOX) cluster genes, and the consequent generation of leukemia. Hence, disrupting the interactions between MLL1 and the reciprocal proteins has been considered to be a new treatment strategy for leukemia. Here, we reviewed potential protein-protein interactions (PPIs) between MLL1 and its reciprocal proteins, and summarized the inhibitors to target MLL1 PPIs. The druggability of MLL1 PPIs for leukemia were also discussed.

Aberrant DNA methylation of key genes and Acute Lymphoblastic Leukemia

DNA methylation is a dynamic process influencing gene expression by altering either coding or non-coding loci. Despite advances in treatment of Acute Lymphoblastic Leukemia (ALL); relapse occurs in approximately 20% of patients. Nowadays, epigenetic factors are considered as one of the most effective mechanisms in pathogenesis of malignancies. These factors are reversible elements which can be potentially regarded as therapy targets and disease prognosis. DNA methylation, which primarily serves as transcriptional suppressor, mostly occurs in CpG islands of the gene promoter regions. This was shown as a key epigenetic factor in inactivating various tumor suppressor genes during cancer initiation and progression. We aimed to review methylation status of key genes involved in hematopoietic malignancies such as IKZF1, CDKN2B, TET2, CYP1B1, SALL4, DLC1, DLX family, TP73, PTPN6, and CDKN1C; and their significance in pathogenesis of ALL. The DNA methylation alterations in promoter regions of the genes have been shown to play crucial roles in tumorigenesis. Methylation -based inactivation of these genes has also been reported as associated with prognosis in acute leukemia. In this review, we also addressed the association of gene expression and methylation pattern in ALL patients.

Anti-cancer effects of naturally derived compounds targeting histone deacetylase 6-related pathways

Alterations of the epigenetic machinery, affecting multiple biological functions, represent a major hallmark enabling the development of tumors. Among epigenetic regulatory proteins, histone deacetylase (HDAC)6 has emerged as an interesting potential therapeutic target towards a variety of diseases including cancer. Accordingly, this isoenzyme regulates many vital cellular regulatory processes and pathways essential to physiological homeostasis, as well as tumor multistep transformation involving initiation, promotion, progression and metastasis. In this review, we will consequently discuss the critical implications of HDAC6 in distinct mechanisms relevant to physiological and cancerous conditions, as well as the anticancer properties of synthetic, natural and natural-derived compounds through the modulation of HDAC6-related pathways.

Whole-genome DNA methylation characteristics in pediatric precursor B cell acute lymphoblastic leukemia (BCP ALL)

In addition to genetic alterations, epigenetic abnormalities have been shown to underlie the pathogenesis of acute lymphoblastic leukemia (ALL)—the most common pediatric cancer. The purpose of this study was to characterize the whole genome DNA methylation profile in children with precursor B-cell ALL (BCP ALL) and to compare this profile with methylation observed in normal bone marrow samples. Additional efforts were made to correlate the observed methylation patterns with selected clinical features. We assessed DNA methylation from bone marrow samples obtained from 38 children with BCP ALL at the time of diagnosis along with 4 samples of normal bone marrow cells as controls using Infinium MethylationEPIC BeadChip Array. Patients were diagnosed and stratified into prognosis groups according to the BFM ALL IC 2009 protocol. The analysis of differentially methylated sites across the genome as well as promoter methylation profiles allowed clear separation of the leukemic and control samples into two clusters. 86.6% of the promoter-associated differentially methylated sites were hypermethylated in BCP ALL. Seven sites were found to correlate with the BFM ALL IC 2009 high risk group. Amongst these, one was located within the gene body of the MBP gene and another was within the promoter region- PSMF1 gene. Differentially methylated sites that were significantly related with subsets of patients with ETV6-RUNX1 fusion and hyperdiploidy. The analyzed translocations and change of genes’ sequence context does not affect methylation and methylation seems not to be a mechanism for the regulation of expression of the resulting fusion genes.

Clinical Pharmacokinetics and Pharmacodynamics of Bosutinib

Chronic myeloid leukemia (CML) is a clonal myeloproliferative stem cell disorder. Bosutinib is an oral, once-daily SRC/ABL tyrosine kinase inhibitor with very potent inhibitory activity. Bosutinib is effective against all phases of intolerant or resistant Philadelphia chromosome-positive CML that do not harbor the T315I or V299LABL kinase domain mutations. Peak plasma concentrations of bosutinib occur at 4-6 h following oral administration, and dose-proportional increases in exposure are observed at doses ranging from 200 to 800 mg. Absorption of bosutinib increases with food. Bosutinib is distributed extensively into the tissues. It is highly plasma protein bound (94 %) and is primarily metabolized in the liver by cytochrome P450 3A4. Bosutinib is well tolerated overall and has a unique but manageable toxicity profile. This article provides a review of the available clinical pharmacokinetic, pharmacodynamic, and drug-drug interaction data on bosutinib in healthy subjects, patients with CML, and special populations.

DNA Methylation Events as Markers for Diagnosis and Management of Acute Myeloid Leukemia and Myelodysplastic Syndrome

During the onset and progression of hematological malignancies, many changes occur in cellular epigenome, such as hypo- or hypermethylation of CpG islands in promoter regions. DNA methylation is an epigenetic modification that regulates gene expression and is a key event for tumorigenesis. The continuous search for biomarkers that signal early disease, indicate prognosis, and act as therapeutic targets has led to studies investigating the role of DNA in cancer onset and progression. This review focuses on DNA methylation changes as potential biomarkers for diagnosis, prognosis, response to treatment, and early toxicity in acute myeloid leukemia and myelodysplastic syndrome. Here, we report that distinct changes in DNA methylation may alter gene function and drive malignant cellular transformation during several stages of leukemogenesis. Most of these modifications occur at an early stage of disease and may predict myeloid/lymphoid transformation or response to therapy, which justifies its use as a biomarker for disease onset and progression. Methylation patterns, or its dynamic change during treatment, may also be used as markers for patient stratification, disease prognosis, and response to treatment. Further investigations of methylation modifications as therapeutic biomarkers, which may correlate with therapeutic response and/or predict treatment toxicity, are still warranted.

The effects of SAHA on radiosensitivity in pancreatic cancer cells by inducing apoptosis and targeting RAD51

Suberoyl anilide hydroxamic acid (SAHA) is one of the most promising Histone deacetylases(HDAC) inhibitors which has shown significant anti-tumor activity for many malignancies. We explored the potential mechanism of the radiosensitivity effect of SAHA in Panc-1 cells and attempted to develop SAHA as a systemic treatment strategy for pancreatic cancer. Growth inhibition was detected by CCK-8 assay. Radiosensitizing enhancement ratio was determined by clonogenic assay. The cell cycle and apoptosis assay was detected using flow cytometry and annexin-V/PI. The level of Bax, Bcl-2, Ku70, Ku86, RAD51, RAD54 protein expression were detected using Western blot analysis. Gene silencing was processed by lentiviral vector and qRT-PCR was performed to detect mRNA expression. The results revealed that SAHA inhibited the proliferation of Panc-1 cells. SAHA enhanced the radiosensitivity with a sensitization enhancement ratio(SER) of 1.10 of the Panc-1 cells. SAHA induced G2-M phase arrest and apoptosis of Panc-1 cells with radiation. SAHA upregulated Bax and downregulated Bcl-2, Ku70, Ku86, RAD51, RAD54 protein expression of irradiated Panc-1 cells. SAHA enhanced the radiosensitivity of Panc-1 cells by modulating RAD51 expression. SAHA enhanced radiosensitivity to pancreatic carcinoma Panc-1 cells. It was associated with the G2-M phase arrest and apoptosis via modulation of Bax and Bcl-2 expression. Downregulation of Ku70, Ku86, RAD51 and RAD54 expression caused suppression of HR-mediated DNA repair. SAHA is a good radiosensitizer for pancreatic cancer treatment.

ADAMTSL5 and CDH11: putative epigenetic markers for therapeutic resistance in acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

DNA hypermethylation has been linked to poor treatment outcome in childhood acute lymphoblastic leukemia (ALL). Genes differentially methylated in the chemoresponsive pre-B-ALL compared to chemoresistant pre-B-ALL cases provide potential prognostic markers.

METHODS

DNA methylation profiles of five B-ALL childhood patients who achieved morphological complete remission (chemoresponsive) and five B-ALL patients who did not (chemoresistant) after induction treatments as well as four normal controls were compared on 27 000 CpG sites microarray chips. Subsequently, methylation-specific polymerase chain reaction (MSP) on selected hypermethylated genes was conducted on an additional 37 chemoresponsive and 9 chemoresistant B-ALL samples and 2 normal controls.

RESULTS

Both methods were found to be highly correlated. Unsupervised principal component analysis showed that the chemotherapy-responsive and -resistant B-ALL patients could be segregated from one another. Selection of segregated genes at high stringency identified two potential genes (CDH11 and ADAMTSL5). MSP analysis on the larger cohort of samples (42 chemoresponsive, 14 chemoresistant B-ALL samples and 6 normal controls) revealed significantly higher rates of hypermethylation in chemoresistant samples for ADAMTSL5 (93 vs. 38%; p = 0.0001) and CDH11 (79% vs. 40%, p < 0.01). All control cases remained unmethylated.

CONCLUSION

Chemoresistant B-ALL patients are associated with increased methylation in ADAMTSL5 and CDH11. These findings need to be validated in a larger group of patients, and the functional biological and prognostic significance of differential methylation needs to be studied further.

Harmine, a Novel DNA Methyltransferase 1 Inhibitor in the Leukemia Cell Line

DNA methylation followed by tumor suppressor gene repression plays a critical role in the leukemia development. So, DNA methyl transferase inhibitors have great importance in treatment of theses malignancies. Harmine, A beta carboline alkaloid derivative of Peganum harmala, had shown anti- proliferative effects on leukemic cell line. This study aimed to evaluate the effect of Harmine on DNMT1 (DNA methyl transferase 1) expression in a leukemic cell line. Cell proliferation and cell cycle analysis were studied in NB4 cell line after treatment with Harmine for 72 h. DNMT1 expression in treated cells was analyzed by real time PCR. Tumor suppressor gene hypometylation and reactivation was evaluated via MSP analysis and also real time PCR. Harmine reduced cell proliferation in NB4 cell line in a time and dose-dependent manner. 102 µg/ml of Harmine was increased amount of cells in G1 Phase of cell cycle (p < 0.05). Anti proliferative doses of Harmine, has suppressed DNMT1 gene in NB4 cell line. Down-regulated DNMT1 induced p15 tumor suppressor promoter hypomethylation and reactivation. Our data indicate that Harmine can be considered as a potential treatment for AML (Acute Myeloid Leukemia), and future studies are required to test the clinical efficacy of Harmine-whether used as a single agent or as an adjuvant-for AML treatment.

Expression of DNA methyltransferases and target microRNAs in human tissue samples related to sporadic colorectal cancer

Tissue microenvironment functions as a pivotal mediator in colorectal carcinogenesis, and its alteration can cause some important cellular responses including epigenetic events. The present study examined histologically altered tissue structure, DNA methyltransferases (DNMTs) and their corresponding expression of target microRNAs (miRNA). Tissues resected by surgery were from primary colorectal carcinoma. These samples were from three locations: and were ≥10, 5 and ≤2 cm away from the proximal lesion of colon cancer, and marked as no. 1, no. 2 and no. 3, respectively. Histological alteration was assessed by H&E staining, expression of DNMT1, DNMT3A, and DNMT3B was detected by immunohistochemistry and western blotting, microarray chip was used to screen distinguishable miRNAs and miRNAs targeting DNMTs whose validation assay was performed by quantitative real-time polymerase chain reaction (qRT-PCR). Our results revealed that normal crypt structure was shown in no. 1, while many aberrant crypt foci appeared in no. 3. Significant upregulation of DNMT1, DNMT3A, and DNMT3B expression was found in para-carcinoma tissues, compared with the histopathologically unchanged tissues (P<0.05), furthermore, distinguishable expression profiling was observed of target miRNAs in tissues with different distance. Our results provide additional insights for future research of colorectal carcinogenesis by introducing the tissue microenvironment.

Epigenetic regulation of cell signaling pathways in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous cancer that is characterized by rapid and uncontrolled proliferation of immature B- or T-lymphoid precursors. Although ALL has been regarded as a genetic disease for many years, the crucial importance of epigenetic alterations in leukemogenesis has become increasingly evident. Epigenetic mechanisms, which include DNA methylation and histone modifications, are critical for gene regulation during many key biological processes. Here, we review the cell signaling pathways that are regulated by DNA methylation or histone modifications in ALL. Recent studies have highlighted the fundamental role of these modifications in ALL development, and suggested that future investigation into the specific genes and pathways that are altered by epigenetic mechanisms can contribute to the development of novel drug-based therapies for ALL.

DNA methylation dynamics during B cell maturation underlie a continuum of disease phenotypes in chronic lymphocytic leukemia

Charting differences between tumors and normal tissue is a mainstay of cancer research. However, clonal tumor expansion from complex normal tissue architectures potentially obscures cancer-specific events, including divergent epigenetic patterns. Using whole-genome bisulfite sequencing of normal B cell subsets, we observed broad epigenetic programming of selective transcription factor binding sites coincident with the degree of B cell maturation. By comparing normal B cells to malignant B cells from 268 patients with chronic lymphocytic leukemia (CLL), we showed that tumors derive largely from a continuum of maturation states reflected in normal developmental stages. Epigenetic maturation in CLL was associated with an indolent gene expression pattern and increasingly favorable clinical outcomes. We further uncovered that most previously reported tumor-specific methylation events are normally present in non-malignant B cells. Instead, we identified a potential pathogenic role for transcription factor dysregulation in CLL, where excess programming by EGR and NFAT with reduced EBF and AP-1 programming imbalances the normal B cell epigenetic program.

Growth-suppressive effect of suberoylanilide hydroxamic acid (SAHA) on human oral cancer cells

PURPOSE

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has been reported to exhibit anticancer activities in various cancer cell types, but as yet there are few reports on the anticancer effects of SAHA in oral squamous cell carcinoma (OSCC)-derived cells and xenograft models.

METHODS

The anti-proliferative and apoptotic activities of SAHA were assessed in human HSC-3 and HSC-4 (OSCC)-derived cell lines and JB6 normal mouse skin-derived epidermal cells using histone acetylation, soft agar colony formation, trypan blue exclusion, 4'-6-diamidino-2-phenylindole (DAPI) staining, Live/Dead viability/cytotoxicity and Western blot analyses.

RESULTS

We found that SAHA treatment resulted in hyperacetylation of histones H2A and H3 and a concomitant decrease in the viability of HSC-3 and HSC-4 cells. SAHA also significantly inhibited the neoplastic transformation of JB6 cells treated with TPA, whereas the viability of these cells was not affected by this treatment. Additionally, we found that SAHA suppressed the anchorage-independent growth (colony forming capacity in soft agar) of HSC-3 and HSC-4 cells. DAPI staining, Live/Dead and Western blot analyses revealed that SAHA can induce caspase-dependent apoptosis in HSC-3 and HSC-4 cells. We also found that SAHA treatment led to inhibition of ERK phosphorylation, and that two MEK inhibitors potentiated SAHA-mediated apoptosis. Okadaic acid treatment inhibited SAHA-mediated apoptosis in both the HSC-3 and HSC-4 cell lines, wheras SAHA induced a profound in vivo inhibition of tumor growth in HSC-3 xenografts.

CONCLUSIONS

Our results indicate that the ERK signaling pathway may constitute a critical denominator of SAHA-induced apoptosis in OSCC-derived cells and that SAHA may have therapeutic potential for OSCC.

Tackling the Cytotoxic Effect of a Marine Polycyclic Quinone-Type Metabolite: Halenaquinone Induces Molt 4 Cells Apoptosis via Oxidative Stress Combined with the Inhibition of HDAC and Topoisomerase Activities

A marine polycyclic quinone-type metabolite, halenaquinone (HQ), was found to inhibit the proliferation of Molt 4, K562, MDA-MB-231 and DLD-1 cancer cell lines, with IC₅₀ of 0.48, 0.18, 8.0 and 6.76 μg/mL, respectively. It exhibited the most potent activity against leukemia Molt 4 cells. Accumulating evidence showed that HQ may act as a potent protein kinase inhibitor in cancer therapy. To fully understand the mechanism of HQ, we further explored the precise molecular targets in leukemia Molt 4 cells. We found that the use of HQ increased apoptosis by 26.23%–70.27% and caused disruption of mitochondrial membrane potential (MMP) by 17.15%–53.25% in a dose-dependent manner, as demonstrated by Annexin-V/PI and JC-1 staining assays, respectively. Moreover, our findings indicated that the pretreatment of Molt 4 cells with N-acetyl-l-cysteine (NAC), a reactive oxygen species (ROS) scavenger, diminished MMP disruption and apoptosis induced by HQ, suggesting that ROS overproduction plays a crucial rule in the cytotoxic activity of HQ. The results of a cell-free system assay indicated that HQ could act as an HDAC and topoisomerase catalytic inhibitor through the inhibition of pan-HDAC and topoisomerase IIα expression, respectively. On the protein level, the expression of the anti-apoptotic proteins p-Akt, NFκB, HDAC and Bcl-2, as well as hexokinase II was inhibited by the use of HQ. On the other hand, the expression of the pro-apoptotic protein Bax, PARP cleavage, caspase activation and cytochrome c release were increased after HQ treatment. Taken together, our results suggested that the antileukemic effect of HQ is ROS-mediated mitochondrial apoptosis combined with the inhibitory effect on HDAC and topoisomerase activities.

The DNA hypomethylating agent, 5-aza-2'-deoxycytidine, enhances tumor cell invasion through a transcription-dependent modulation of MMP-1 expression in human fibrosarcoma cells

In diseases such as cancer, cells need to degrade the extracellular matrix (ECM) and therefore require high protease levels. Thus, aberrant tissue degradation is associated to matrix metalloproteinases (MMPs) overexpression resulting from different mechanisms including epigenetic events. One of the most characterized epigenetic mechanisms is DNA methylation causing changes in chromatin conformation, thereby decreasing the accessibility to the transcriptional machinery and resulting in a robust gene silencing. Modulation of DNA methylation by DNA hypomethylating agents such as 5-aza-2'-deoxycytidine (5-azadC) is widely used in epigenetic anticancer treatments. Here, we focus on the effects of this drug on the expression level of MMP-1, -2, and -9 in human HT1080 fibrosarcoma cells. We demonstrate that 5-azadC increases MMP expression at both mRNA and protein levels, and promotes invasion potential of HT1080 cells. Using broad-spectrum and specific MMP inhibitors, we establish that MMP-1, but not MMP-2 and -9, plays a key role in 5-azadC-enhanced cell invasion. We show that 5-azadC induces MMP-1 expression through a transcriptional mechanism without affecting MMP-1 promoter methylation status. Finally, we demonstrate that 5-azadC treatment increases the nuclear levels of Sp1 and Sp3 transcription factors, and modulates their recruitment to the MMP-1 promoter, resulting in chromatin remodeling associated to 5-azadC-induced MMP-1 expression. All together, our data indicate that the hypomethylating agent 5-azadC modulates, mainly via Sp1 recruitment, MMP-1 expression resulting in an increased invasive potential of HT1080 cells.

Epigenetic roots of immunologic disease and new methods for examining chromatin regulatory pathways

The ability to accurately quantitate and experimentally examine epigenetic modifications across the human genome has exploded in the past decade. This has given rise to a wealth of new information concerning the contributions of epigenetic regulatory networks to the pathogenesis of human disease. In particular, immunological disorders have strong developmental roots in chromatin regulatory pathways. In this review, we focus on the epigenetic signatures and new discoveries revealing the epigenetic compositions of specific immunological cancers and autoimmune diseases. We also comment on the conserved epigenetic roots among diverse immunological disorders and suggest inhibition strategies that may be relevant for future treatment. Finally, we highlight emerging experimental tools with the capability to examine the mechanisms of chromatin regulatory enzymes with a high level of temporal control. The knowledge of genetic and epigenetic defects in immunological disease combined with new experimental approaches will elucidate the contribution of individual enzymes in complex epigenetic regulatory networks. This could lead to new diagnostic and therapeutic approaches for some very diverse and difficult to treat human diseases.

HDAC1 and Klf4 interplay critically regulates human myeloid leukemia cell proliferation

Acute myeloid leukemia (AML) is recognized as a complex disease of hematopoietic stem cell disorders, but its pathogenesis mechanisms, diagnosis, and treatment remain unclear. General histone deacetylase (HDAC) inhibitors have been used in blood cancers including AML, but the lack of gene specificity greatly limits their anti-cancer effects and clinical applications. Here, we found that HDAC1 expression was negatively correlated with that of Krüppel-like factor 4 (Klf4) and that AML patients with lower HDAC1 level had better prognosis. Further, knockdown of HDAC1 in leukemia cells K562, HL-60, and U937 significantly increased Klf4 expression and inhibited cell cycle progression and cell proliferation, similar results were found for HDAC inhibitors (VPA and mocetinostat). Moreover, overexpression or knockdown of Klf4 could markedly block the effects of HDAC1 overexpression or knockdown on leukemia cells in vitro and in vivo, respectively. Mechanistic analyses demonstrated that HDAC1 and Klf4 competitively bound to the promoter region of Klf4 and oppositely regulated Klf4 expression in myeloid leukemia. We identified HDAC1 as a potential specific target for repressing cell proliferation and inducing cell cycle arrest through interplay and modulation of Klf4 expression, suggests that HDAC1 and Klf4 are potential new molecular markers and targets for clinical diagnosis, prognosis, and treatment of myeloid leukemia.

Safety and clinical activity of 5-aza-2'-deoxycytidine (decitabine) with or without Hyper-CVAD in relapsed/refractory acute lymphocytic leukaemia

To test the safety and activity of 5-aza-2'-deoxycytidine (decitabine) in patients with relapsed/refractory acute lymphocytic leukaemia (ALL), we conducted a phase 1 study with two parts: administering decitabine alone or in combination with Hyper-CVAD (fractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone alternating with high-dose methotrexate and cytarabine). Patients participated in either part of the study or in both parts sequentially. In the initial part, decitabine was administered intravenously at doses of 10-120 mg/m(2) per d for 5 d every other week in cycles of 28 d. In the combination part, patients were treated on the first 5 d of Hyper-CVAD with intravenous decitabine at 5-60 mg/m(2) per d. A total of 39 patients received treatment in the study: 14 in the first part only, 16 sequentially in both parts and 9 in the second part only. Decitabine was tolerated at all doses administered, and grade 3 or 4 toxic effects included non-life-threatening hepatotoxicity and hyperglycaemia. Induction of DNA hypomethylation was observed at doses of decitabine up to 80 mg/m(2) . Some patients who had previously progressed on Hyper-CVAD alone achieved a complete response when decitabine was added. Decitabine alone or given with Hyper-CVAD is safe and has clinical activity in patients with advanced ALL.