Epigenetics and Oncology

Effects of valproic acid on wound healing of the abdominal wall musculoaponeurotic layer: an experimental study in rats

INTRODUCTION

valproic acid (VPA), an epigenetic drug, has potential for the treatment of neoplasms. Its effects on the healing of the peritoneal-musculo-aponeurotic plane (PMA) of the abdominal wall are studied.

METHOD

sixty Wistar rats were allocated into two groups: experimental (VPA) and control (0.9% sodium chloride), treated daily, starting three days before the intervention and until euthanasia. Under anesthesia, a median laparotomy was performed and repaired with two synthetic layers. Assessments took place 3, 7 and 14 days after surgery. The integrity of the wounds, the quality of the inflammatory reaction, the intensity of the leukocyte infiltrate, collagen synthesis, the intensity of angiogenesis and the presence of myofibroblasts were studied.

RESULTS

there was dehiscence of the PMA plane in 11 of the 30 animals (p=0.001) in the experimental group. There was no difference in the quality and intensity of the inflammatory reaction. Immunohistochemistry revealed, in the experimental group, less collagen I (p3=0.003, p7=0.013 and p14=0.001) and more collagen III (p3=0.003, p7=0.013 and p14= 0.001). Collagen evaluated by Sirus Supra Red F3BA showed, in the experimental group, less collagen at all three times (p<0.001) with less collagen I and collagen III (p<0.001). A lower number of vessels was found on the 3rd day (p<0.001) and on the 7th day (p=0.001) and did not affect the number of myofibroblasts.

CONCLUSION

VPA showed dehiscence of the PMA plane, with less deposition of total collagen and collagen I, less angiogenic activity, without interfering with the number of myofibroblasts.

Optimization of Epigenetic Modifier Drug Combination for Synergistic Effect against Glioblastoma Multiform Cancer Cell Lines

Glioblastoma multiforme (GBM), is a frequent class of malignant brain tumors. Epigenetic therapy, especially with synergistic combinations is highly paid attention for aggressive solid tumors like GBM. Here, RSM optimization has been used to increase the efficient arrest of U87 and U251 cell lines due to synergistic effects. Cell lines were treated with SAHA, 5-Azacytidine, GSK-126, and PTC-209 individually and then RSM was used to find most effective combinations. Results showed that optimized combinations significantly reduce cell survival and induce cell cycle arrest and apoptosis in both cell lines. Expression of cyclin B1 and cyclin D1 were decreased while caspase3 increased expression.

3-deazaneplanocin A, a histone methyltransferase inhibitor, improved the chemoresistance induced under hypoxia in melanoma cells

One of common characteristics of solid tumors is low O2 level, so-called hypoxia, which plays a critical role in chemoresistance. Epigenetic mechanism such as DNA methylation and histone modification is involved in cancer development and progression. There is ample evidence that epigenetic drugs reversed acquired chemoresistance in cancer cells under normal O2 level, normoxia. However, it remains unknown whether epigenetic drugs improve acquired chemoresistance under hypoxia. The aim of our study was to investigate whether epigenetic drugs can improve the chemoresistance induced under hypoxia in cancer cells. In murine melanoma B16-BL6 (B16) cells, the culture under hypoxia, 1%O2 caused the elevated expression of hypoxia-inducible factor-1α (HIF-1α) and its target genes. The chemoresistance to 7-ethyl-10-hydroxycamptothecin (SN-38, the active metabolite of irinotecan) was also acquired under hypoxia in B16 cells. In addition, as epigenetic mechanisms, the protein expression of the enhancer of zeste homolog 2 (EZH2), histone methyltransferase and its target histone H3 trimethylation at lysine 27 (H3K27Me3) level increased under hypoxia. The induction of H3K27Me3 under hypoxia was suppressed by EZH2 siRNA and 3-deazaneplanocin A (DZNep), an EZH2 inhibitor. Furthermore, both EZH2 siRNA and DZNep significantly reduced the cell viability after SN-38 treatment and improved the chemoresistance to SN-38 under hypoxia. These results indicated that the chemoresistance to SN-38 under hypoxia would arise from epigenetic mechanism, H3K27Me3 elevation due to EZH2 induction. In conclusion, a histone methyltransferase EZH2 inhibitor, DZNep was capable of tackling acquired chemoresistance via the suppression of histone methylation induced under hypoxic tumor microenvironment.

Effect of aqueous extract of Scorodophloeus zenkeri bark on chronic hyperglycemia and its complications in a diabetic Wistar rat model induced by streptozotocin

Diabetes and its complications represent a real major public health problem in the world because of its high rates of morbidity and mortality. Chronic hyperglycemia, oxidative stress, dyslipidemia and inflammation play a major role in the pathophysiology of diabetes and its vascular complications. The objective of this study was to evaluate the effect of aqueous extract of S. zenkeri on chronic hyperglycemia and its complications in a streptozotocin-induced diabetic Wistar rat model. The barks of S. zenkeri were washed, dried and crushed; the powder was dissolved in distilled water (1:10 weight/volume) then macerated and the filtrate obtained was dried in an oven. Subsequently, after quantification of the bioactive compounds (total polyphenols, flavonoids and alkaloids) present in the extract, an in vivo study was conducted in an animal model of streptozotocin-induced hyperglycemia. For this fact, the rats were divided into four groups of five rats as folow: a normoglycaemia group (NC), an untreated hyperglycaemia group (PC), two hyperglycaemia groups including a test group receiving by esophageal gavage, the aqueous extract of the bark of S zenkerii (AESZ) at a dose of 300 mg/kg body weight and a control group receiving metformin at a dose of 20 mg/kg body weight. During the treatment which lasted 21 days, the weights have been taken every two days and the blood sugar levels every week. At the end of the treatment, the rats were killed under light chloroform anesthesia; the plasma, hemolysate, serum and liver homogenate prepared were used to assay the biochemical parameters of oxidative stress (catalase, MDA), lipid profile (Triglycerides, total cholesterol and HDL-cholesterol) and immunological (CRP and NFS). It emerged that the extract limited weight loss and caused a reduction in blood sugar of -26.59% after 21 days of treatment; the extract caused an increase in the activity of erythrocyte catalase and a reduction in the concentration of hepatic MDA, as well as a very marked reduction in inflammatory cells and CRP. The extract also caused a reduction in dyslipidemiawhich was materialized by a reduction in CRR, AC, AIP and an increase in CPI. These results suggest that this extract contains bioactive compounds capable of reducing chronic hyperglycemia while preventing its complications, thus justifying its traditional use in the management of diabetes.

The effects of valproic acid on skin healing: experimental study in rats

Purpose:

To recognize the effects of valproic acid (VPA), an epigenetic drug, on the skin healing process.

Methods:

Sixty male Wistar rats were divided into two groups: the experiment treated with VPA (100 mg/kg/day); and the control, with 0.9% sodium chloride by gavage. Skin healing was studied in three moments (the third, the seventh, and the 14th day), evaluating the parameters: inflammatory reaction and its intensity (anti-LCA), angiogenesis (anti-CD34), collagen I and III (anti-collagen I, anti-collagen III and Picrosirius-red F3BA) and myofibroblasts (anti-alpha-AMS).

Results:

The inflammatory reaction was acute or sub-acute in both groups on the third day. On the seventh and the 14th day, chronic predominated in the control (p=0.006), and sub-acute in the experiment (p=0.020). There was a greater number of leukocytes in the group treated only on the third day (p=0.036). The number of vessels was lower in the treated group at the three times (p3=0.002, p7<0.001, and p14=0.027). Myofibroblasts were rare in the third day and moderate quantity in the remaining periods. Collagen I density was higher in the control at the three times (p<0.001) and collagen III in the treated group (p<0.001).

Conclusions:

VPA led to a more intense inflammatory reaction, decreased angiogenesis and collagen deposition, especially type I collagen.

Ultrasonic Atomizer-Driven Development of Biocompatible and Biodegradable Poly(d,l-lactide-co-glycolide) Nanocarrier-Encapsulated Suberoylanilide Hydroxamic Acid to Combat Brain Cancer

The path to the discovery of anticancer drugs and investigating their potential activity has remained a quest for several decades. Suberoylanilide hydroxamic acid (SAHA), also known as "Vorinostat", is a well-known histone deacetylase inhibitor (HDACi) and has the potential to act as a therapeutic agent against tumorigenesis. Herein, we have fabricated SAHA incorporated into biocompatible and biodegradable poly(d,l-lactide-co-glycolide) PLGA nanoparticles (NPs) using a facile method of ultrasonic atomization and evaluated their anticancer property. We have explored their characteristics using dynamic light scattering (DLS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), encapsulation efficiency, and in vitro drug release and have investigated their efficacy on U87 glioblastoma (GBM) cells. SAHA-PLGA NPs synthesized were of average mean size of 80 ± 23 and 105 ± 6.0 nm observed through cryo-field-emission gun SEM and HR-TEM with a polydispersity index of 0.068 and a ζ-potential value of -13.26 mV. The encapsulation efficiency was 53%, with a sustained in vitro release up to 48 h. The in vitro assessment of SAHA-PLGA NPs for their anticancer activity on U87 GBM cells showed cellular cytotoxicity with an IC₅₀ of 19.91 μM. SAHA-PLGA NP-treated cells also showed suppression in migration with 8.77 μM concentration, and cell growth inhibition was observed in the wound scratch assay for up to 24 h. The cellular uptake studies have been utilized by time-dependent experiments, revealing their cellular internalization. Taking this into account, our present experimental findings indicate that SAHA-PLGA NPs could play a significant role in enhancing the effectiveness and bioavailability and reducing adverse effects of cancer chemotherapy. It also highlights the inherent potential of these biocompatible entities for chemotherapeutic applications in biomedical and pharmaceutics.

Novel Epigenetic Eight-Gene Signature Predictive of Poor Prognosis and MSI-Like Phenotype in Human Metastatic Colorectal Carcinomas

Simple Summary

The global methylation profile of two human metastatic colorectal carcinoma subgroups with significantly different outcomes (primary-resistant versus drug-sensitive tumors) was analyzed and compared with the gene expression and methylation data from The Cancer Genome Atlas COlon ADenocarcinoma (TCGA COAD) metastatic colorectal carcinoma dataset with the aim to identify a prognostic signature of functionally methylated genes. A novel epigenetic eight-gene signature, with hypermethylation of the promoter regions, was identified and validated for its capacity to predict poor outcome, which had a CpG-island methylator phenotype (CIMP)-high status and microsatellite instability (MSI)-like phenotype.

Abstract

Epigenetics is involved in tumor progression and drug resistance in human colorectal carcinoma (CRC). This study addressed the hypothesis that the DNA methylation profiling may predict the clinical behavior of metastatic CRCs (mCRCs). The global methylation profile of two human mCRC subgroups with significantly different outcome was analyzed and compared with gene expression and methylation data from The Cancer Genome Atlas COlon ADenocarcinoma (TCGA COAD) and the NCBI GENE expression Omnibus repository (GEO) GSE48684 mCRCs datasets to identify a prognostic signature of functionally methylated genes. A novel epigenetic signature of eight hypermethylated genes was characterized that was able to identify mCRCs with poor prognosis, which had a CpG-island methylator phenotype (CIMP)-high and microsatellite instability (MSI)-like phenotype. Interestingly, methylation events were enriched in genes located on the q-arm of chromosomes 13 and 20, two chromosomal regions with gain/loss alterations associated with adenoma-to-carcinoma progression. Finally, the expression of the eight-genes signature and MSI-enriching genes was confirmed in oxaliplatin- and irinotecan-resistant CRC cell lines. These data reveal that the hypermethylation of specific genes may provide prognostic information that is able to identify a subgroup of mCRCs with poor prognosis.

Ketotherapy as an epigenetic modifier in cancer

Epigenetic alterations in cancer play a variety of roles. Aberrant DNA methylation, as one of the epigenetic mechanisms, has been widely studied in both tumor and liquid biopsies and provide a useful bench mark for treatment response in cancer. Recently, several studies have reported an association between the type of diet and epigenetic modifications. Whereby there is a growing interest in finding the "anti-cancer diet formula", if such a thing exists. In this sense, ketogenic diets (KD) have reported potentially beneficial effects, which were able to prevent malignancies and decrease tumor growth. Some studies have even shown increased survival in cancer patients, reduced side effects of cytotoxic treatments, and intensified efficacy of cancer therapies. Although the biological mechanisms of KD are not well understood, it has been reported that KD may affect DNA methylation by modulating the expression of crucial genes involved in tumor survival and proliferation. However, there are many considerations to take into account to use ketotherapy in cancer, such as epigenetic mark, type of cancer, immunological and metabolic state or microbiota profile. In this review, we argue about ketotherapy as a potential strategy to consider as coadjuvant of cancer therapy. We will focus on mainly epigenetic mechanisms and dietary approach that could be included in the current clinical practice guidelines.

Evodiamine-inspired dual inhibitors of histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) with potent antitumor activity

A great challenge in multi-targeting drug discovery is to identify drug-like lead compounds with therapeutic advantages over single target inhibitors and drug combinations. Inspired by our previous efforts in designing antitumor evodiamine derivatives, herein selective histone deacetylase 1 (HDAC1) and topoisomerase 2 (TOP2) dual inhibitors were successfully identified, which showed potent in vitro and in vivo antitumor potency. Particularly, compound 30a was orally active and possessed excellent in vivo antitumor activity in the HCT116 xenograft model (TGI = 75.2%, 150 mg/kg, p.o.) without significant toxicity, which was more potent than HDAC inhibitor vorinostat, TOP inhibitor evodiamine and their combination. Taken together, this study highlights the therapeutic advantages of evodiamine-based HDAC1/TOP2 dual inhibitors and provides valuable leads for the development of novel multi-targeting antitumor agents.

Stress and Feline Health

In the health sciences, stress often is defined in terms of stressors; events that are perceived as threats to one's perception of control. From this perspective, a stressor is anything that activates the central threat response system (CTRS). Recent research shows that the CTRS can be sensitized to environmental events through epigenetic modulation of gene expression. When CTRS activation is chronic, health and welfare may be harmed. Environmental modification can mitigate the harmful effects of chronic CTRS activation by reducing the individual's perception of threat and increasing its perception of control, which improves health and welfare.

Epigenetics mechanisms mediate the miR-125a/BRMS1 axis to regulate invasion and metastasis in gastric cancer

Purpose

Altered expression of breast cancer metastasis suppressor 1 (BRMS1), is a tumor suppressor, which is found in many types of cancers, including gastric cancer (GC), but the mechanism by which BRMS1 inhibits invasion and metastasis in GC is unknown. The aim of the study was to investigate the molecular mechanisms of miR-125a/BRMS1 in GC.

Materials and methods

The expression of BRMS1 and miR-125a were detected by quantitative real-time PCR (qRT-PCR) and analyzed by bioinformatics. BSP and MSP were used to detecte the methylation status of miR-125a and BRMS1 which was treated by 5-Aza or not. Western Blot and qRT-PCR were used to analyze the expression of BRMS1 and EZH2. Transwell was performed to explore the invasion and metastasis ability of GC cells. The nude mice were used for the tumor formation assay.

Results

BRMS1 may be regulated by copy number variation (CNV), methylation and miR-125a-5p. As one of the essential components of PRC2, EZH2 is an important regulatory factor resulting in the low expression of miR-125a. An epigenetic mechanism mediates the miR-125a/BRMS1 axis to inhibit the invasion and metastasis of GC cells. In vivo experiments, it is also showed that BRMS1 is involved in invasion and metastasis but not the proliferation in GC.

Conclusion

These studies shed light on the mechanism of BRMS1 inhibition of GC invasion and metastasis and the development of new drugs targeting the miR-125a/BRMS1 axis, which will be a promising therapeutic strategy for GC and other human cancers.

Combined Acylselenourea-Diselenide Structures: New Potent and Selective Antitumoral Agents as Autophagy Activators

A series of 16 new diselenide-acylselenourea conjugates have been designed following the fragment-based drug strategy. Compound in vitro cytotoxic potential was evaluated against six human cancer cell lines and two nonmalignant derived cell lines with the aim of determining their potency and selectivity. Nine derivatives exhibited GI₅₀ values under 10 μM in at least four cancer cell lines. A clear gap situated phenyl substitution over heterocyclic moieties in terms of selectivity. Among carbocyclic compounds, derivatives 2 and 7 significantly inhibited cell growth of breast adenocarcinoma cells with GI₅₀ values of 1.30 and 0.15 nM, respectively, with selectivity indexes 12 and 121 times higher than those obtained for doxorubicin. Preliminary mechanistic studies indicated that compounds 2 and 7 induce cell cycle arrest and autophagy-dependent cell death evidenced by the blockage of cell death with pretreatment with wortmannin or chloroquine and confirmed by the upregulation of the markers Beclin1 and LC3B in MCF-7 cells.

Optimization Of Cancer Treatment Through Overcoming Drug Resistance

Cancer Drug resistance is a medical concern that requires extensive research and a thorough understanding in order to overcome. Remarkable achievements related to this field have been accomplished and further work is needed in order to optimize the cure for cancer and serve as the basis for precise medicine with few or no side effects.

IFN-α potentiates the direct and immune-mediated antitumor effects of epigenetic drugs on both metastatic and stem cells of colorectal cancer

Epigenetic alterations, including dysregulated DNA methylation and histone modifications, govern the progression of colorectal cancer (CRC). Cancer cells exploit epigenetic regulation to control cellular pathways, including apoptotic and metastatic signals. Since aberrations in epigenome can be pharmacologically reversed by DNA methyltransferase and histone deacetylase inhibitors, epigenetics in combination with standard agents are currently envisaged as a new therapeutic frontier in cancer, expected to overcome drug resistance associated with current treatments. In this study, we challenged this idea and demonstrated that the combination of azacitidine and romidepsin with IFN-α owns a high therapeutic potential, targeting the most aggressive cellular components of CRC, such as metastatic cells and cancer stem cells (CSCs), via tight control of key survival and death pathways. Moreover, the antitumor efficacy of this novel pharmacological approach is associated with induction of signals of immunogenic cell death. Of note, a previously undisclosed key role of IFN-α in inducing both antiproliferative and pro-apoptotic effects on CSCs of CRC was also found. Overall, these findings open a new frontier on the suitability of IFN-α in association with epigenetics as a novel and promising therapeutic approach for CRC management.

Epigenetic actions of environmental factors and promising drugs for cancer therapy

Carcinogenesis is known to be primarily associated with gene mutations. Recently, increasing evidence has suggested that epigenetic events also serve crucial roles in tumor etiology. Environmental factors, including nutrition, toxicants and ethanol, are involved in carcinogenesis through inducing epigenetic modifications, such as DNA methylation, histone deacetylase and miRNA regulation. Studying epigenetic mechanisms has facilitated the development of early diagnostic strategies and potential therapeutic avenues. Modulation at the epigenetic level, including reversing epigenetic modifications using targeted drugs, has demonstrated promise in cancer therapy. Therefore, identifying novel epigenetic biomarkers and therapeutic targets has potential for the future of cancer therapy. The present review discusses the environmental factors involved in epigenetic modifications and potential drug candidates for cancer therapy.

Redox-Related Epigenetic Mechanisms in Glioblastoma: Nuclear Factor (Erythroid-Derived 2)-Like 2, Cobalamin, and Dopamine Receptor Subtype 4

Glioblastoma is an exceptionally difficult cancer to treat. Cancer is universally marked by epigenetic changes, which play key roles in sustaining a malignant phenotype, in addition to disease progression and patient survival. Studies have shown strong links between the cellular redox state and epigenetics. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a redox-sensitive transcription factor that upregulates endogenous antioxidant production, and is aberrantly expressed in many cancers, including glioblastoma. Methylation of DNA and histones provides a mode of epigenetic regulation, and cobalamin-dependent reactions link the redox state to methylation. Antagonists of dopamine receptor subtype 4 (D₄ receptor) were recently shown to restrict glioblastoma stem cell growth by downregulating trophic signaling, resulting in inhibition of functional autophagy. In addition to stimulating glioblastoma stem cell growth, D₄ receptors have the unique ability to catalyze cobalamin-dependent phospholipid methylation. Therefore, D₄ receptors represent an important node in a molecular reflex pathway involving Nrf2 and cobalamin, operating in conjunction with redox status and methyl group donor availability. In this article, we describe the redox-related effects of Nrf2, cobalamin metabolism, and the D₄ receptor on the regulation of the epigenetic state in glioblastoma.

Epigenetic control of the tumor microenvironment

Stromal cells of the tumor microenvironment have been shown to play important roles in both supporting and limiting cancer growth. The altered phenotype of tumor-associated stromal cells (fibroblasts, immune cells, endothelial cells etc.) is proposed to be mainly due to epigenetic dysregulation of gene expression; however, only limited studies have probed the roles of epigenetic mechanisms in the regulation of stromal cell function. We review recent studies demonstrating how specific epigenetic mechanisms (DNA methylation and histone post-translational modification-based gene expression regulation, and miRNA-mediated translational regulation) drive aspects of stromal cell phenotype, and discuss the implications of these findings for treatment of malignancies. We also summarize the effects of epigenetic mechanism-targeted drugs on stromal cells and discuss the consideration of the microenvironment response in attempts to use these drugs for cancer treatment.

ATP-binding cassette transmembrane transporters and their epigenetic control in cancer: an overview

INTRODUCTION

Members of the ATP-binding cassette (ABC) transmembrane transporters control the passage of several substrates across cell membranes, including drugs. This means that ABC transporters may exert a significant influence on the kinetics and dynamics of pharmacological agents, being responsible for the occurrence of multidrug-resistant (MDR) phenotype. Pharmacogenetic analyses have shed light on gene expression and polymorphisms as possible markers predictive of transporter activity. However, a non-negligible part of the variability in drug pharmacokinetics and pharmacodynamics still remains. Further research has demonstrated that different epigenetic mechanisms exert a coordinated control over ABC genes, and on the corresponding MDR phenotype. Areas covered: DNA methylation and histone modifications (namely acetylation, methylation, phosphorylation, etc.) significantly impact gene expression, as well as noncoding RNA molecules that are involved in the post-transcriptional control of the ABC transporters ABCB1, ABCC1 and ABCG2. We describe the epigenetic mechanisms of gene expression control for ABC transporters and their relevant association with the MDR phenotype in human cancer. Expert opinion: The clinical meaning of those observations is discussed in the review, highlighting the importance of the epigenetic control of the ABC transporters for the clinical therapeutic outcomes that despite their effects and applications, requires further investigation.

How do tumor cells respond to HDAC inhibition?

It is now well recognized that mutations, deregulated expression, and aberrant recruitment of epigenetic readers, writers, and erasers are fundamentally important processes in the onset and maintenance of many human tumors. The molecular, biological, and biochemical characteristics of a particular class of epigenetic erasers, the histone deacetylases (HDACs), have been extensively studied and small-molecule HDAC inhibitors (HDACis) have now been clinically approved for the treatment of human hemopoietic malignancies. This review explores our current understanding of the biological and molecular effects on tumor cells following HDACi treatment. The predominant responses include induction of tumor cell death and inhibition of proliferation that in experimental models have been linked to therapeutic efficacy. However, tumor cell-intrinsic responses to HDACi, including modulating tumor immunogenicity have also been described and may have substantial roles in mediating the antitumor effects of HDACi. We posit that the field has failed to fully reconcile the biological consequences of exposure to HDACis with the molecular events that underpin these responses, however progress is being made. Understanding the pleiotrophic activities of HDACis on tumor cells will hopefully fast track the development of more potent and selective HDACi that may be used alone or in combination to improve patient outcomes.

Novel cinnamohydroxamic acid derivatives as HDAC inhibitors with anticancer activity in vitro and in vivo

A novel series of cinnamohydroxamic acid derivatives were synthesized and their biological activities against HDAC were assessed. Our results showed that the compound with more strong inhibitory activity to HDAC would exhibited more significant anti-proliferative effect on tumor cells. Among these compounds, 7e displayed clearly inhibitory effects on HDAC and tumor cell growth. Furthermore, HDAC isoforms enzyme data indicated that, compared to HDAC pan-inhibitor SAHA, 7e owned an enhanced inhibitory effect on HDAC1, 3 and 6 isoforms. Meanwhile, it also significantly suppressed cell growth of lung cancer cells compared to SAHA, but with lower toxicity in normal cells. Mechanistically, 7e prompted acetylation of histone3 and histone4, led to up-regulation of p21, and then mediated cell cycle arrest and pro-apoptosis. Moreover, the in vivo study indicated that compound 7e could retard tumor growth of A549 xenograft models. These findings support the further investigation on the anti-tumor potential of this class of compounds as HDAC inhibitor.

Polyphenols as Modulator of Oxidative Stress in Cancer Disease: New Therapeutic Strategies

Cancer onset and progression have been linked to oxidative stress by increasing DNA mutations or inducing DNA damage, genome instability, and cell proliferation and therefore antioxidant agents could interfere with carcinogenesis. It is well known that conventional radio-/chemotherapies influence tumour outcome through ROS modulation. Since these antitumour treatments have important side effects, the challenge is to develop new anticancer therapeutic strategies more effective and less toxic for patients. To this purpose, many natural polyphenols have emerged as very promising anticancer bioactive compounds. Beside their well-known antioxidant activities, several polyphenols target epigenetic processes involved in cancer development through the modulation of oxidative stress. An alternative strategy to the cytotoxic treatment is an approach leading to cytostasis through the induction of therapy-induced senescence. Many anticancer polyphenols cause cellular growth arrest through the induction of a ROS-dependent premature senescence and are considered promising antitumour therapeutic tools. Furthermore, one of the most innovative and interesting topics is the evaluation of efficacy of prooxidant therapies on cancer stem cells (CSCs). Several ROS inducers-polyphenols can impact CSCs metabolisms and self-renewal related pathways. Natural polyphenol roles, mainly in chemoprevention and cancer therapies, are described and discussed in the light of the current literature data.

Reversal of microRNA-150 silencing disadvantages crizotinib-resistant NPM-ALK(+) cell growth

The regulatory microRNA miR-150 is involved in the development of hemopathies and is downregulated in T-lymphomas, such as anaplastic large-cell lymphoma (ALCL) tumors. ALCL is defined by the presence or absence of translocations that activate the anaplastic lymphoma kinase (ALK), with nucleophosmin-ALK (NPM-ALK) fusions being the most common. Here, we compared samples of primary NPM-ALK(+) and NPM-ALK(-) ALCL to investigate the role of miR-150 downstream of NPM-ALK. Methylation of the MIR150 gene was substantially elevated in NPM-ALK(+) biopsies and correlated with reduced miR-150 expression. In NPM-ALK(+) cell lines, DNA hypermethylation-mediated miR-150 repression required ALK-dependent pathways, as ALK inhibition restored miR-150 expression. Moreover, epigenetic silencing of miR-150 was due to the activation of STAT3, a major downstream substrate of NPM-ALK, in cooperation with DNA methyltransferase 1 (DNMT1). Accordingly, miR-150 repression was turned off following treatment with the DNMT inhibitor, decitabine. In murine NPM-ALK(+) xenograft models, miR-150 upregulation induced antineoplastic activity. Treatment of crizotinib-resistant NPM-ALK(+) KARPAS-299-CR06 cells with decitabine or ectopic miR-150 expression reduced viability and growth. Altogether, our results suggest that hypomethylating drugs, alone or in combination with other agents, may benefit ALK(+) patients harboring tumors resistant to crizotinib and other anti-ALK tyrosine kinase inhibitors (TKIs). Moreover, these results support further work on miR-150 in these and other ALK(+) malignancies.

Long Term Exposure to Polyphenols of Artichoke (Cynara scolymus L.) Exerts Induction of Senescence Driven Growth Arrest in the MDA-MB231 Human Breast Cancer Cell Line

Polyphenolic extracts from the edible part of artichoke (Cynara scolymus L.) have been shown to be potential chemopreventive and anticancer dietary compounds. High doses of polyphenolic extracts (AEs) induce apoptosis and decrease the invasive potential of the human breast cancer cell line, MDA-MB231. However, the molecular mechanism underlying AEs antiproliferative effects is not completely understood. We demonstrate that chronic and low doses of AEs treatment at sublethal concentrations suppress human breast cancer cell growth via a caspases-independent mechanism. Furthermore, AEs exposure induces a significant increase of senescence-associated β-galactosidase (SA-β-gal) staining and upregulation of tumour suppressor genes, p16^INK4a and p21^Cip1/Waf1 in MDA-MB231 cells. AEs treatment leads to epigenetic alterations in cancer cells, modulating DNA hypomethylation and lysine acetylation levels in total proteins. Cell growth arrest correlates with increased reactive oxygen species (ROS) production in AEs treated breast cancer cells. Inhibition of ROS generation by N-acetylcysteine (NAC) attenuates the antiproliferative effect. These findings demonstrate that chronic AEs treatment inhibits breast cancer cell growth via the induction of premature senescence through epigenetic and ROS-mediated mechanisms. Our results suggest that artichoke polyphenols could be a promising dietary tool either in cancer chemoprevention or/and in cancer treatment as a nonconventional, adjuvant therapy.

The implication of cancer progenitor cells and the role of epigenetics in the development of novel therapeutic strategies for chronic myeloid leukemia

SIGNIFICANCE

Chronic myeloid leukemia (CML) involves the malignant transformation of hematopoietic stem cells, defined largely by the Philadelphia chromosome and expression of the breakpoint cluster region-Abelson (BCR-ABL) oncoprotein. Pharmacological tyrosine kinase inhibitors (TKIs), including imatinib mesylate, have overcome limitations in conventional treatment for the improved clinical management of CML.

RECENT ADVANCES

Accumulated evidence has led to the identification of a subpopulation of quiescent leukemia progenitor cells with stem-like self renewal properties that may initiate leukemogenesis, which are also shown to be present in residual disease due to their insensitivity to tyrosine kinase inhibition.

CRITICAL ISSUES

The characterization of quiescent leukemia progenitor cells as a unique cell population in CML pathogenesis has become critical with the complete elucidation of mechanisms involved in their survival independent of BCR-ABL that is important in the development of novel anticancer strategies. Understanding of these functional pathways in CML progenitor cells will allow for their selective therapeutic targeting. In addition, disease pathogenesis and drug responsiveness is also thought to be modulated by epigenetic regulatory mechanisms such as DNA methylation, histone acetylation, and microRNA expression, with a capacity to control CML-associated gene transcription.

FUTURE DIRECTIONS

A number of compounds in combination with TKIs are under preclinical and clinical investigation to assess their synergistic potential in targeting leukemic progenitor cells and/or the epigenome in CML. Despite the collective promise, further research is required in order to refine understanding, and, ultimately, advance antileukemic therapeutic strategies.

Dietary Sulforaphane in Cancer Chemoprevention: The Role of Epigenetic Regulation and HDAC Inhibition

SIGNIFICANCE

Sulforaphane, produced by the hydrolytic conversion of glucoraphanin after ingestion of cruciferous vegetables, particularly broccoli and broccoli sprouts, has been extensively studied due to its apparent health-promoting properties in disease and limited toxicity in normal tissue. Recent Studies: Recent identification of a sub-population of tumor cells with stem cell-like self-renewal capacity that may be responsible for relapse, metastasis, and resistance, as a potential target of the dietary compound, may be an important aspect of sulforaphane chemoprevention. Evidence also suggests that sulforaphane may target the epigenetic alterations observed in specific cancers, reversing aberrant changes in gene transcription through mechanisms of histone deacetylase inhibition, global demethylation, and microRNA modulation.

CRITICAL ISSUES

In this review, we discuss the biochemical and biological properties of sulforaphane with a particular emphasis on the anticancer properties of the dietary compound. Sulforaphane possesses the capacity to intervene in multistage carcinogenesis through the modulation and/or regulation of important cellular mechanisms. The inhibition of phase I enzymes that are responsible for the activation of pro-carcinogens, and the induction of phase II enzymes that are critical in mutagen elimination are well-characterized chemopreventive properties. Furthermore, sulforaphane mediates a number of anticancer pathways, including the activation of apoptosis, induction of cell cycle arrest, and inhibition of NFκB.

FUTURE DIRECTIONS

Further characterization of the chemopreventive properties of sulforaphane and its capacity to be selectively toxic to malignant cells are warranted to potentially establish the clinical utility of the dietary compound as an anti-cancer compound alone, and in combination with clinically relevant therapeutic and management strategies.

In vitro radical scavenging and cytotoxic activities of novel hybrid selenocarbamates

Novel selenocyanate and diselenide derivatives containing a carbamate moiety were synthesised and evaluated in vitro to determine their cytotoxic and radical scavenging properties. Cytotoxic activity was tested against a panel of human cell lines including CCRF-CEM (lymphoblastic leukaemia), HT-29 (colon carcinoma), HTB-54 (lung carcinoma), PC-3 (prostate carcinoma), MCF-7 (breast adenocarcinoma), 184B5 (non-malignant, mammary gland derived) and BEAS-2B (non-malignant, derived from bronchial epithelium). Most of the compounds displayed high antiproliferative activity with GI50 values below 10μM in MCF-7, CCRF-CEM and PC-3 cells. Radical scavenging properties of the new selenocompounds were confirmed testing their ability to scavenge DPPH and ABTS radicals. Based on the activity of selenium-based glutathione peroxidases (GPxs), compounds 1a, 2e and 2h were further screened for their capacity to reduce hydrogen peroxide under thiol presence. Results suggest that compound 1a mimics GPxs activity. Cytotoxic parameters, radical scavenging activity and ADME profile point to 1a as promising drug candidate.

Biochemical, biological and structural properties of romidepsin (FK228) and its analogs as novel HDAC/PI3K dual inhibitors

Romidepsin (FK228, depsipeptide) is a potent histone deacetylase (HDAC) inhibitor that has FDA approval for the treatment of cutaneous and peripheral T-cell lymphomas. We have previously reported that FK228 and its analogs have an additional activity as phosphatidylinositol 3-kinase (PI3K) inhibitors, and are defined as HDAC/PI3K dual inhibitors. Because a combination of an HDAC inhibitor and a PI3K inhibitor induces apoptosis in human cancer cells in a synergistic manner, development of an HDAC/PI3K dual inhibitor will provide an attractive novel drug for cancer therapy. Using structure-based optimization of the analogs, FK-A11 was identified as the most potent analog. FK-A11 inhibited phosphorylation of AKT and accelerated histone acetylation at lower concentrations, resulting in stronger cytotoxic effects than FK228 and the other analogs in human cancer cells. In this study, we have characterized the biochemical, biological and structural properties of FK228 analogs as PI3K inhibitors. First, FK-A11 is an ATP competitive PI3K inhibitor. Second, FK-A11 is a pan-p110 isoform inhibitor. Third, FK-A11 selectively inhibits PI3K among 22 common cellular kinases. Fourth, conformational changes of FK228 analogs by reduction of an internal disulfide bond have no effect on PI3K inhibitory activity, unlike HDAC inhibitory activity. Finally, molecular modeling of PI3K-FK228 analogs and analyses of the binding affinities identified the structure that defines potency for PI3K inhibitory activity. These results prove our concept that a series of FK228 analogs are HDAC/PI3K dual inhibitors. These findings should help in the development of FK228 analogs as novel HDAC/PI3K dual inhibitors.

The methylation of a panel of genes differentiates low-grade from high-grade gliomas

Epigenetic changes play an important role in the pathogenesis of gliomas and have the potential to become clinically useful biomarkers. The aim of this study was the evaluation of the profile of promoter methylation of 13 genes selected based on their anticipated diagnostic and/or prognostic value. Methylation-specific PCR (MSP) was used to assess the methylation status of MGMT, ERCC1, hMLH1, ATM, CDKN2B (p15INK4B), p14ARF, CDKN2A (p16INK4A), RASSF1A, RUNX3, GATA6, NDRG2, PTEN, and RARβ in a subset of 95 gliomas of different grades. Additionally, the methylation status of MGMT and NDRG2 was analyzed using pyrosequencing (PSQ). The results revealed that the methylation index of individual glioma patients correlates with World Health Organization (WHO) tumor grade and patient's age. RASSF1A, RUNX3, GATA6, and MGMT were most frequently methylated, whereas the INK4B-ARF-INK4A locus, PTEN, RARβ, and ATM were methylated to a lesser extent. ERCC1, hMLH1, and NDRG2 were unmethylated. RUNX3 methylation correlated with WHO tumor grade and patient's age. PSQ confirmed significantly higher methylation levels of MGMT and NDRG2 as compared with normal, non-cancerous brain tissue. To conclude, DNA methylation of a whole panel of selected genes can serve as a tool for glioma aggressiveness prediction.

Histone methylations in heart development, congenital and adult heart diseases

Heart development comprises myocyte specification, differentiation and cardiac morphogenesis. These processes are regulated by a group of core cardiac transcription factors in a coordinated temporal and spatial manner. Histone methylation is an emerging epigenetic mechanism for regulating gene transcription. Interplay among cardiac transcription factors and histone lysine modifiers plays important role in heart development. Aberrant expression and mutation of the histone lysine modifiers during development and in adult life can cause either embryonic lethality or congenital heart diseases, and influences the response of adult hearts to pathological stresses. In this review, we describe current body of literature on the role of several common histone methylations and their modifying enzymes in heart development, congenital and adult heart diseases.

Epigenetic regulation of persistent pain

Persistent or chronic pain is tightly associated with various environmental changes and linked to abnormal gene expression within cells processing nociceptive signaling. Epigenetic regulation governs gene expression in response to environmental cues. Recent animal model and clinical studies indicate that epigenetic regulation plays an important role in the development or maintenance of persistent pain and possibly the transition of acute pain to chronic pain, thus shedding light in a direction for development of new therapeutics for persistent pain.

Enhancer of zeste homolog 2 is widely expressed in T-cell neoplasms, is associated with high proliferation rate and correlates with MYC and pSTAT3 expression in a subset of cases

Enhancer of zeste homolog 2 (EZH2), an epigenetic regulator and H3k27-specific histone methyltransferase, is important for transcriptional regulation. EZH2 has been found to be overexpressed in B-cell lymphomas, as well as some T-cell lymphomas. Here we investigated the expression of EZH2 by immunohistochemical staining in a wide range of T-cell neoplasms. We found that EZH2 is highly expressed in all categories of T-cell neoplasia studied, and its expression strongly correlates with a high proliferation rate. Although up-regulation of EZH2 has been reported to be modulated by the pSTAT3-MYC pathway, our data indicate that EZH2 expression is correlated with MYC and/or pSTAT3 expression in only a subset of T-cell lymphomas, and that other mechanisms may control the overexpression of EZH2 in many T-cell lymphomas. The high level of EZH2 expression in T cell lymphomas suggest that these neoplasms may benefit from targeted treatment with a small molecule inhibitor of EZH2 currently in use in clinical trials.

On the meaning of the word 'epimutation'

The word 'epimutation' is often used in a manner that can be misinterpreted. The strict definition of epimutation is a heritable change in gene activity that is not associated with a DNA mutation but rather with gain or loss of DNA methylation or other heritable modifications of chromatin. Unfortunately, there is a growing tendency in the cancer field to use the word in situations in which underlying DNA sequence changes have occurred.