Targeting of epigenetic regulators in neuroblastoma

Encapsulation of 4-oxo-N-(4-hydroxyphenyl) retinamide in human serum albumin nanoparticles promotes EZH2 degradation in preclinical neuroblastoma models

Neuroblastoma is the most prevalent and aggressive solid tumor that develops extracranially in children between the ages of 0-14 years, which accounts for 8-10% of all childhood malignancies and ∼15% of pediatric cancer-related mortality. The polycomb repressive complex 2 (PRC2) protein, EZH2, is overexpressed in neuroblastoma and mediates histone H3 methylation at lysine 27 (K27) positions through its methyl transferase activity and is a potential epigenetic silencer of many tumor suppressor genes in cancer. Phosphorylation of EZH2 decreases its stability and leads to proteasomal degradation. The 4-oxo-N-(4-hydroxyphenyl) retinamide (4O4HPR) promotes EZH2 degradation via activation of PKC-δ, but its limited solubility and physiological instability limit its application. In the current study, the encapsulation of 4O4HPR in Human Serum Albumin Nanoparticles (HSANPs) enhanced the solubility and physiological stability of the nanoformulation, leading to improved therapeutic efficacy through G2-M cell cycle arrest, depolarization of mitochondrial membrane potential, generation of reactive oxygen species and caspase 3 mediated apoptosis activation. The molecular mechanistic approach of 4O4HPR loaded HSANPs has activated caspase 3, which further cleaves PKC-δ into two fragments wherein the cleaved fragment of PKC-δ possesses the kinase activity that phosphorylates EZH2 and decreases the protein stability leading to its further ubiquitination in SH-SY5Y cells. Co-immunoprecipitation experiments revealed the direct interaction between PKC-δ and EZH2 phosphorylation, followed by ubiquitination. Moreover, 4O4HPR loaded HSANPs demonstrated improved in vivo biodistribution, greater dispersibility, and biocompatibility and exhibited enhanced protein instability and degradation of EZH2 in the neuroblastoma xenograft mouse model.

Preclinical spheroid models identify BMX as a therapeutic target for metastatic MYCN nonamplified neuroblastoma

The development of targeted therapies offers new hope for patients affected by incurable cancer. However, multiple challenges persist, notably in controlling tumor cell plasticity in patients with refractory and metastatic illness. Neuroblastoma (NB) is an aggressive pediatric malignancy originating from defective differentiation of neural crest-derived progenitors with oncogenic activity due to genetic and epigenetic alterations and remains a clinical challenge for high-risk patients. To identify critical genes driving NB aggressiveness, we performed combined chromatin and transcriptome analyses on matched patient-derived xenografts (PDXs), spheroids, and differentiated adherent cultures derived from metastatic MYCN nonamplified tumors. Bone marrow kinase on chromosome X (BMX) was identified among the most differentially regulated genes in PDXs and spheroids versus adherent models. BMX expression correlated with high tumor stage and poor patient survival and was crucial to the maintenance of the self-renewal and tumorigenic potential of NB spheroids. Moreover, BMX expression positively correlated with the mesenchymal NB cell phenotype, previously associated with increased chemoresistance. Finally, BMX inhibitors readily reversed this cellular state, increased the sensitivity of NB spheroids toward chemotherapy, and partially reduced tumor growth in a preclinical NB model. Altogether, our study identifies BMX as a promising innovative therapeutic target for patients with high-risk MYCN nonamplified NB.

Histone Deacetylases in Retinoblastoma

Retinoblastoma, a pediatric ocular malignancy, presents significant challenges in comprehending its molecular underpinnings and targeted therapeutic approaches. The dysregulated activity of histone deacetylases (HDACs) has been associated with retinoblastoma pathogenesis, influencing critical cellular processes like cell cycle regulation or retinal ganglion cell apoptosis. Through their deacetylase activity, HDACs exert control over key tumor suppressors and oncogenes, influencing the delicate equilibrium between proliferation and cell death. Furthermore, the interplay between HDACs and the retinoblastoma protein pathway, a pivotal aspect of retinoblastoma etiology, reveals a complex network of interactions influencing the tumor microenvironment. The examination of HDAC inhibitors, encompassing both established and novel compounds, offers insights into potential approaches to restore acetylation balance and impede retinoblastoma progression. Moreover, the identification of specific HDAC isoforms exhibiting varying expression in retinoblastoma provides avenues for personalized therapeutic strategies, allowing for interventions tailored to individual patient profiles. This review focuses on the intricate interrelationship between HDACs and retinoblastoma, shedding light on epigenetic mechanisms that control tumor development and progression. The exploration of HDAC-targeted therapies underscores the potential for innovative treatment modalities in the pursuit of more efficacious and personalized management strategies for this disease.

UBE4B interacts with the ITCH E3 ubiquitin ligase to induce Ku70 and c-FLIPL polyubiquitination and enhanced neuroblastoma apoptosis

Expression of the UBE4B ubiquitin ligase is strongly associated with neuroblastoma patient outcomes, but the functional roles of UBE4B in neuroblastoma pathogenesis are not known. We evaluated interactions of UBE4B with the E3 ubiquitin ligase ITCH/AIP4 and the effects of UBE4B expression on Ku70 and c-FLIPL ubiquitination and proteasomal degradation by co-immunoprecipitation and Western blots. We also evaluated the role of UBE4B in apoptosis induced by histone deacetylase (HDAC) inhibition using Western blots. UBE4B binding to ITCH was mediated by WW domains in the ITCH protein. ITCH activation led to ITCH-UBE4B complex formation and recruitment of Ku70 and c-FLIPL via ITCH WW domains, followed by Ku70 and c-FLIPL Lys48/Lys63 branched polyubiquitination and proteasomal degradation. HDAC inhibition induced Ku70 acetylation, leading to release of c-FLIPL and Bax from Ku70, increased Ku70 and c-FLIPL Lys48/Lys63 branched polyubiquitination via the ITCH-UBE4B complex, and induction of apoptosis. UBE4B depletion led to reduced polyubiquitination and increased levels of Ku70 and c-FLIPL and to reduced apoptosis induced by HDAC inhibition via stabilization of c-FLIPL and Ku70 and inhibition of caspase 8 activation. Our results have identified novel interactions and novel targets for UBE4B ubiquitin ligase activity and a direct role for the ITCH-UBE4B complex in responses of neuroblastoma cells to HDAC inhibition, suggesting that the ITCH-UBE4B complex plays a critical role in responses of neuroblastoma to therapy and identifying a potential mechanism underlying the association of UBE4B expression with neuroblastoma patient outcomes.

Discovery of Novel Oxazepine Derivatives as Akt/ROCK Inhibitors for Growth Arrest and Differentiation Induction in Neuroblastoma Treatment

Patients with high-risk neuroblastoma face limited treatment choices, typically involving a combination of cytotoxic and differentiation maintenance therapies due to a scarcity of drugs. Evidence suggests that targeted inhibitors may provide opportunities for inducing neuroblastoma differentiation while inhibiting proliferation. Here, we demonstrate the synergistic effect of inhibiting Akt and ROCK in antineuroblastoma and present the design and discovery of a new Akt/ROCK inhibitor, B12. It displays strong antiproliferative effects and excellent differentiation inducing activity against Neuro2a cells. Treatment with B12 results in the arrest of G0/G1 cell cycles, a significant decrease in N-myc protein level, and an increase in differentiation markers. The administration of B12 effectively suppresses xenograft tumor growth and promotes differentiation. Overall, the discovery of B12 based on the Akt/ROCK dual inhibition strategy may provide hope for the development of more effective and targeted therapies for this challenging disease.

Target therapy for high-risk neuroblastoma treatment: integration of regulatory and scientific tools is needed

Introduction

Several new active substances (ASs) targeting neuroblastoma (NBL) are under study. We aim to describe the developmental and regulatory status of a sample of ASs targeting NBL to underline the existing regulatory gaps in product development and to discuss possible improvements.

Methods

The developmental and regulatory statuses of the identified ASs targeting NBL were investigated by searching for preclinical studies, clinical trials (CTs), marketing authorizations, pediatric investigation plans (PIPs), waivers, orphan designations, and other regulatory procedures.

Results

A total of 188 ASs were identified. Of these, 55 were considered 'not under development' without preclinical or clinical studies. Preclinical studies were found for 115 ASs, of which 54 were associated with a medicinal product. A total of 283 CTs (as monotherapy or in combination) were identified for 70 ASs. Of these, 52% were at phases 1, 1/2, and 2 aimed at PK/PD/dosing activity. The remaining ones also included efficacy. Phase 3 studies were limited. Studies were completed for 14 ASs and suspended for 11. The highest rate of ASs involved in CTs was observed in the RAS-MAPK-MEK and VEGF groups. A total of 37 ASs were granted with a PIP, of which 14 involved NBL, 41 ASs with a waiver, and 18 ASs with both PIPs and waivers, with the PIP covering pediatric indications different from the adult ones. In almost all the PIPs, preclinical studies were required, together with early-phase CTs often including efficacy evaluation. Two PIPs were terminated because of negative study results, and eight PIPs are in progress. Variations in the SmPC were made for larotrectinib sulfate/Vitrakvi® and entrectinib/Rozlytrek® with the inclusion of a new indication. For both, the related PIPs are still ongoing. The orphan designation has been largely adopted, while PRIME designation has been less implemented.

Discussion

Several ASs entered early phase CTs but less than one out of four were included in a regulatory process, and only two were granted a pediatric indication extension. Our results confirm that it is necessary to identify a more efficient, less costly, and time-consuming "pediatric developmental model" integrating predictive preclinical study and innovative clinical study designs. Furthermore, stricter integration between scientific and regulatory efforts should be promoted.

A light-operated dual-mode method for neuroblastoma diagnosis based on a Tb-MOF: from biometabolite detection to logic devices

Tb-DBA can not only serve as a light-operated dual-mechanism driven platform to detect VMA (an early pathological feature of neuroblastoma), but can also produce a different fluorescence response to epinephrine (EP, the metabolic precursor of VMA).

Epigenetic modulation of neuroblastoma enhances T cell and NK cell immunogenicity by inducing a tumor-cell lineage switch

BACKGROUND

Immunotherapy in high-risk neuroblastoma (HR-NBL) does not live up to its full potential due to inadequate (adaptive) immune engagement caused by the extensive immunomodulatory capacity of HR-NBL. We aimed to tackle one of the most notable immunomodulatory processes in neuroblastoma (NBL), absence of major histocompatibility complex class I (MHC-I) surface expression, a process greatly limiting cytotoxic T cell engagement. We and others have previously shown that MHC-I expression can be induced by cytokine-driven immune modulation. Here, we aimed to identify tolerable pharmacological repurposing strategies to upregulate MHC-I expression and therewith enhance T cell immunogenicity in NBL.

METHODS

Drug repurposing libraries were screened to identify compounds enhancing MHC-I surface expression in NBL cells using high-throughput flow cytometry analyses optimized for adherent cells. The effect of positive hits was confirmed in a panel of NBL cell lines and patient-derived organoids. Compound-treated NBL cell lines and organoids were cocultured with preferentially expressed antigen of melanoma (PRAME)-reactive tumor-specific T cells and healthy-donor natural killer (NK) cells to determine the in vitro effect on T cell and NK cell cytotoxicity. Additional immunomodulatory effects of histone deacetylase inhibitors (HDACi) were identified by transcriptome and translatome analysis of treated organoids.

RESULTS

Drug library screening revealed MHC-I upregulation by inhibitor of apoptosis inhibitor (IAPi)- and HDACi drug classes. The effect of IAPi was limited due to repression of nuclear factor kappa B (NFκB) pathway activity in NBL, while the MHC-I-modulating effect of HDACi was widely translatable to a panel of NBL cell lines and patient-derived organoids. Pretreatment of NBL cells with the HDACi entinostat enhanced the cytotoxic capacity of tumor-specific T cells against NBL in vitro, which coincided with increased expression of additional players regulating T cell cytotoxicity (eg, TAP1/2 and immunoproteasome subunits). Moreover, MICA and MICB, important in NK cell cytotoxicity, were also increased by entinostat exposure. Intriguingly, this increase in immunogenicity was accompanied by a shift toward a more mesenchymal NBL cell lineage.

CONCLUSIONS

This study indicates the potential of combining (immuno)therapy with HDACi to enhance both T cell-driven and NKcell-driven immune responses in patients with HR-NBL.

Linking neural crest development to neuroblastoma pathology

Although rare, childhood (paediatric) cancers are a major cause of death in young children. Unlike many adult cancers, paediatric cancers, such as neuroblastoma (NB), are developmental diseases that rarely show genetic predispositions. NB is the most common extracranial solid tumour in children, accounting for ∼15% of paediatric cancer deaths. This heterogeneous cancer arises from undifferentiated neural crest-derived progenitor cells. As neural crest cells are multipotent and migratory, they are often considered the embryonic paradigm of cancer stem cells. However, very little is known about the events that trigger tumour initiation and progression. Here, we discuss recent insights into sympathoadrenal lineage specification, as well as genetic factors associated with NB. With this in mind, we consider the molecular underpinnings of NB in the context of developmental trajectories of the neural crest lineage. This allows us to compare distinct subtypes of the disease and gene-function interactions during sensitive phases of neural crest development.

The PRC2 molecule EED is a target of epigenetic therapy for neuroblastoma

Epigenetic modifications by polycomb repressive complex (PRC) molecules appear to play a role in the tumorigenesis and aggressiveness of neuroblastoma (NB). Embryonic ectoderm development (EED) is a member of the PRC2 complex that binds to the H3K27me3 mark deposited by EZH2 via propagation on adjacent nucleosomes. We herein investigated the molecular roles of EED in MYCN-amplified NB cells using EED-knockdown (KD) shRNAs, EED-knockout sgRNAs, and the EED small molecule inhibitor EED226. The suppression of EED markedly inhibited NB cell proliferation and flat and soft agar colony formation. A transcriptome analysis using microarrays of EED-KD NB cells indicated the de-repression of cell cycle-regulated and differentiation-related genes. The results of a GSEA analysis suggested that inhibitory cell cycle-regulated gene sets were markedly up-regulated. Furthermore, an epigenetic treatment with the EED inhibitor EED226 and the HDAC inhibitors valproic acid/SAHA effectively suppressed NB cell proliferation and colony formation. This combined epigenetic treatment up-regulated cell cycle-regulated and differentiation-related genes. The ChIP sequencing analysis of histone codes and PRC molecules suggested an epigenetic background for the de-repression of down-regulated genes in MYCN-amplified/PRC2 up-regulated NB.

Upregulation of p75NTR by Histone Deacetylase Inhibitors Sensitizes Human Neuroblastoma Cells to Targeted Immunotoxin-Induced Apoptosis

Histone deacetylase (HDAC) inhibitors are novel chemotherapy agents with potential utility in the treatment of neuroblastoma, the most frequent solid tumor of childhood. Previous studies have shown that the exposure of human neuroblastoma cells to some HDAC inhibitors enhanced the expression of the common neurotrophin receptor p75NTR. In the present study we investigated whether the upregulation of p75NTR could be exploited to render neuroblastoma cells susceptible to the cytotoxic action of an anti-p75NTR antibody conjugated to the toxin saporin-S6 (p75IgG-Sap). We found that two well-characterized HDAC inhibitors, valproic acid (VPA) and entinostat, were able to induce a strong expression of p75NTR in different human neuroblastoma cell lines but not in other cells, with entinostat, displaying a greater efficacy than VPA. Cell pretreatment with entinostat enhanced p75NTR internalization and intracellular saporin-S6 delivery following p75IgG-Sap exposure. The addition of p75IgG-Sap had no effect on vehicle-pretreated cells but potentiated the apoptotic cell death that was induced by entinostat. In three-dimensional neuroblastoma cell cultures, the subsequent treatment with p75IgG-Sap enhanced the inhibition of spheroid growth and the impairment of cell viability that was produced by entinostat. In athymic mice bearing neuroblastoma xenografts, chronic treatment with entinostat increased the expression of p75NTR in tumors but not in liver, kidney, heart, and cerebellum. The administration of p75IgG-Sap induced apoptosis only in tumors of mice that were pretreated with entinostat. These findings define a novel experimental strategy to selectively eliminate neuroblastoma cells based on the sequential treatment with entinostat and a toxin-conjugated anti-p75NTR antibody.

A New Player in Neuroblastoma: YAP and Its Role in the Neuroblastoma Microenvironment

Neuroblastoma is the most common extra-cranial pediatric solid tumor that accounts for more than 15% of childhood cancer-related deaths. High risk neuroblastomas that recur during or after intense multimodal therapy have a <5% chance at a second sustained remission or cure. The solid tumor microenvironment (TME) has been increasingly recognized to play a critical role in cancer progression and resistance to therapy, including in neuroblastoma. The Yes-Associated Protein (YAP) in the Hippo pathway can regulate cancer proliferation, tumor initiation, and therapy response in many cancer types and as such, its role in the TME has gained interest. In this review, we focus on YAP and its role in neuroblastoma and further describe its demonstrated and potential effects on the neuroblastoma TME. We also discuss the therapeutic strategies for inhibiting YAP in neuroblastoma.

Reactivation of silenced α-N-catenin induces retinoic acid sensitivity in neuroblastoma cells

BACKGROUND

High-risk neuroblastoma remains the most difficult pediatric solid tumor to treat and is associated with chemotherapy and radiation resistance that may be secondary to epigenetic modifications. We have previously found that α-N-catenin, a cell-adhesion protein encoded by the gene CTNNA2, plays a tumor suppressor role in neuroblastoma by inhibiting the NF-κB signaling pathway. A subset of neuroblastoma tumors that lack α-N-catenin are resistant to all-trans retinoic acid. However, the mechanism of CTNNA2 silencing in neuroblastoma remains unknown. Herein, we sought to determine the mechanism of α-N-catenin silencing in neuroblastoma.

METHODS

Two human neuroblastoma cell lines, SK-N-AS and BE(2)-C, were stably transfected with a plasmid expressing CTNNA2. Both cell lines were treated with the histone deacetylase inhibitor Trichostatin A alone and in combination with retinoic acid. Cell survival and colony formation were measured. Cellular differentiation and expression of cell survival signaling pathways were analyzed. Immunoblotting and reverse transcription quantitative polymerase chain reaction were used to examine protein and messenger RNA expression.

RESULTS

Retinoic acid treatment induced cellular differentiation and inhibited cellular proliferation in BE(2)-C cells but did not induce differentiation in SK-N-AS cells. Re-expression of α-N-catenin enhanced the sensitivity to retinoic acid-induced cell growth arrest and downregulated key cell survival pathways in both cell lines. Trichostatin A treatment induced CTNNA2 expression in SK-N-AS cells, and combination treatment with Trichostatin A induced retinoic acid sensitivity in retinoic acid-resistant cells.

CONCLUSION

Re-expression of α-N-catenin in retinoic acid-resistant cells induced sensitivity to retinoic acid treatment and is controlled epigenetically via histone deacetylase. α-N-catenin is a potential biomarker for retinoic acid sensitivity and combination treatment with Trichostatin A and retinoic acid may improve survival among children with high-risk, retinoic acid-resistant neuroblastoma.

Personalized Medicine for Neuroblastoma: Moving from Static Genotypes to Dynamic Simulations of Drug Response

High-risk neuroblastoma is an aggressive childhood cancer that is characterized by high rates of chemoresistance and frequent metastatic relapse. A number of studies have characterized the genetic and epigenetic landscape of neuroblastoma, but due to a generally low mutational burden and paucity of actionable mutations, there are few options for applying a comprehensive personalized medicine approach through the use of targeted therapies. Therefore, the use of multi-agent chemotherapy remains the current standard of care for neuroblastoma, which also conceptually limits the opportunities for developing an effective and widely applicable personalized medicine approach for this disease. However, in this review we outline potential approaches for tailoring the use of chemotherapy agents to the specific molecular characteristics of individual tumours by performing patient-specific simulations of drug-induced apoptotic signalling. By incorporating multiple layers of information about tumour-specific aberrations, including expression as well as mutation data, these models have the potential to rationalize the selection of chemotherapeutics contained within multi-agent treatment regimens and ensure the optimum response is achieved for each individual patient.

Development and Validation of a Prediction Model of Overall Survival in High-Risk Neuroblastoma Using Mechanistic Modeling of Metastasis

Prognosis of high-risk neuroblastoma (HRNB) remains poor despite multimodal therapies. Better prediction of survival could help to refine patient stratification and better tailor treatments. We established a mechanistic model of metastasis in HRNB relying on two processes: growth and dissemination relying on two patient-specific parameters: the dissemination rate μ and the minimal visible lesion size S_vis. This model was calibrated using diagnosis values of primary tumor size, lactate dehydrogenase circulating levels, and the meta-iodobenzylguanidine International Society for Paediatric Oncology European (SIOPEN) score from nuclear imaging, using data from 49 metastatic patients. It was able to describe the data of total tumor mass (lactate dehydrogenase, R² > 0.99) and number of visible metastases (SIOPEN, R² = 0.96). A prediction model of overall survival (OS) was then developed using Cox regression. Clinical variables alone were not able to generate a model with sufficient OS prognosis ability (P = .507). The parameter μ was found to be independent of the clinical variables and positively associated with OS (P = .0739 in multivariable analysis). Critically, addition of this computational biomarker significantly improved prediction of OS with a concordance index increasing from 0.675 (95% CI, 0.663 to 0.688) to 0.733 (95% CI, 0.722 to 0.744, P < .0001), resulting in significant OS prognosis ability (P = .0422).

Association of RASSF1A, DCR2, and CASP8 Methylation with Survival in Neuroblastoma: A Pooled Analysis Using Reconstructed Individual Patient Data

Neuroblastoma (NB) is a heterogeneous tumor affecting children. It shows a wide spectrum of clinical outcomes; therefore, development of risk stratification is critical to provide optimum treatment. Since epigenetic alterations such as DNA methylation have emerged as an important feature of both development and progression in NB, in this study, we aimed to quantify the effect of methylation of three distinct genes (RASSF1A, DCR2, and CASP8) on overall survival in NB patients. We performed a systematic review using PubMed, Embase, and Cochrane libraries. Individual patient data was retrieved from extracted Kaplan–Meier curves. Data from studies was then merged, and analysis was done on the full data set. Seven studies met the inclusion criteria. Methylation of the three genes had worse overall survival than the unmethylated arms. Five-year survival for the methylated arm of RASSF1A, DCR2, and CASP8 was 63.19% (95% CI 56.55-70.60), 57.78% (95% CI 47.63-70.08), and 56.39% (95% CI 49.53-64.19), respectively, while for the unmethylated arm, it was 93.10% (95% CI 87.40–99.1), 84.84% (95% CI 80.04-89.92), and 83.68% (95% CI 80.28-87.22), respectively. In conclusion, our results indicate that in NB patients, RASSF1A, DCR2, and CASP8 methylation is associated with poor prognosis. Large prospective studies will be necessary to confirm definitive correlation between methylation of these genes and survival taking into account all other known risk factors. (PROSPERO registration number CRD42017082264).

Molecular targeting therapies for neuroblastoma: Progress and challenges

There is an urgent need to identify novel therapies for childhood cancers. Neuroblastoma is the most common pediatric solid tumor, and accounts for ~15% of childhood cancer‐related mortality. Neuroblastomas exhibit genetic, morphological and clinical heterogeneity, which limits the efficacy of existing treatment modalities. Gaining detailed knowledge of the molecular signatures and genetic variations involved in the pathogenesis of neuroblastoma is necessary to develop safer and more effective treatments for this devastating disease. Recent studies with advanced high‐throughput “omics” techniques have revealed numerous genetic/genomic alterations and dysfunctional pathways that drive the onset, growth, progression, and resistance of neuroblastoma to therapy. A variety of molecular signatures are being evaluated to better understand the disease, with many of them being used as targets to develop new treatments for neuroblastoma patients. In this review, we have summarized the contemporary understanding of the molecular pathways and genetic aberrations, such as those in MYCN, BIRC5, PHOX2B, and LIN28B, involved in the pathogenesis of neuroblastoma, and provide a comprehensive overview of the molecular targeted therapies under preclinical and clinical investigations, particularly those targeting ALK signaling, MDM2, PI3K/Akt/mTOR and RAS‐MAPK pathways, as well as epigenetic regulators. We also give insights on the use of combination therapies involving novel agents that target various pathways. Further, we discuss the future directions that would help identify novel targets and therapeutics and improve the currently available therapies, enhancing the treatment outcomes and survival of patients with neuroblastoma.

Histone Deacetylases and Histone Deacetylase Inhibitors in Neuroblastoma

Histone deacetylases (HDACs) are enzymes that play a key role in regulating gene expression by remodeling chromatin structure. An imbalance of histone acetylation caused by deregulated HDAC expression and activity is known to promote tumor progression in a number of tumor types, including neuroblastoma, the most common solid tumor in children. Consequently, the inhibition of HDACs has emerged as a potential strategy to reverse these aberrant epigenetic changes, and several classes of HDAC inhibitors (HDACi) have been shown to inhibit tumor proliferation, or induce differentiation, apoptosis and cell cycle arrest in neuroblastoma. Further, the combined use of HDACi with other chemotherapy agents, or radiotherapy, has shown promising pre-clinical results and various HDACi have progressed to different stages in clinical trials. Despite this, the effects of HDACi are multifaceted and more work needs to be done to unravel their specific mechanisms of actions. In this review, we discuss the functional role of HDACs in neuroblastoma and the potential of HDACi to be optimized for development and use in the clinic for treatment of patients with neuroblastoma.

Anti-GD2 antibody and Vorinostat immunocombination therapy is highly effective in an aggressive orthotopic neuroblastoma model

Neuroblastoma is a childhood malignancy and in the majority of patients, the primary tumor arises in one of the adrenal glands. Neuroblastoma cells highly express the disialoganglioside GD2, which is the primary target for the development of neuroblastoma immunotherapy. Anti-GD2 mAbs have shown clinical efficacy and are integrated into standard treatment for high-risk neuroblastoma patients. We previously reported synergy between the HDAC inhibitor Vorinostat and anti-GD2 mAbs in a heterotopic, subcutaneous growing neuroblastoma model. Additionally, we have previously developed an orthotopic intra-adrenal neuroblastoma model showing more aggressive tumor growth. Here, we report that anti-GD2 mAb and Vorinostat immunocombination therapy is even more effective in suppressing neuroblastoma growth in the aggressive orthotopic model, resulting in increased animal survival. Intra-adrenal tumors from mice treated with Vorinostat were highly infiltrated with myeloid cells, including macrophages, displaying increased MHCII and Fc-receptor expression. Collectively, these data provide a strong rationale for clinical testing of anti-GD2 mAbs with concomitant Vorinostat in neuroblastoma patients.

Advances and Promises of Epigenetics for Forest Trees

The importance of tree genetic variability in the ability of forests to respond and adapt to environmental changes is crucial in forest management and conservation. Along with genetics, recent advances have highlighted “epigenetics” as an emerging and promising field of research for the understanding of tree phenotypic plasticity and adaptive responses. In this paper, we review recent advances in this emerging field and their potential applications for tree researchers and breeders, as well as for forest managers. First, we present the basics of epigenetics in plants before discussing its potential for trees. We then propose a bibliometric and overview of the literature on epigenetics in trees, including recent advances on tree priming. Lastly, we outline the promises of epigenetics for forest research and management, along with current gaps and future challenges. Research in epigenetics could use highly diverse paths to help forests adapt to global change by eliciting different innovative silvicultural approaches for natural- and artificial-based forest management.

5-aza-2'-Deoxycytidine Induces a RIG-I-Related Innate Immune Response by Modulating Mitochondria Stress in Neuroblastoma

Background: Neuroblastoma (NB) is one of the most common malignant solid tumors to occur in children, characterized by a wide range of genetic and epigenetic aberrations. We studied whether modifications of the latter with a 5-aza-2′-deoxycytidine (decitabine, Dac) DNA methyltransferase inhibitor can provide a therapeutic advantage in NB. Methods: NB cells with or without MYCN amplification were treated with Dac. We used flow cytometry to measure cell apoptosis and death and mitochondrial reactive oxygen species (mtROS), microarray to analyze gene expression profile and bisulfite pyrosequencing to determine the methylation level of the DDX58/RIG-I promoter. Western blot was used to detect markers related to innate immune response and apoptotic signaling, while immunofluorescent imaging was used to determine dsRNA. We generated mtDNA depleted ρ⁰ cells using long-term exposure to low-dose ethidium bromide. Results: Dac preferentially induced a RIG-I-predominant innate immune response and cell apoptosis in SK-N-AS NB cells, significantly reduced the methylation level of the DDX58/RIG-I promoter and increased dsRNA accumulation in the cytosol. Dac down regulated mitochondrial genes related to redox homeostasis, but augmented mtROS production. ρ⁰ cells demonstrated a blunted response in innate immune response and apoptotic cell death, as well as greatly diminished dsRNA. The response of NB cells to CDDP and poly(I:C) was potentiated by Dac in association with increased mtROS, which was blunted in ρ⁰ cells. Conclusions: This study indicates that Dac effectively induces a RIG-I-related innate immune response and apoptotic signaling primarily in SK-N-AS NB cells by hypomethylating DDX58/RIG-I promoter, elevated mtROS and increased dsRNA. Dac can potentiate the cytotoxic effects of CDDP and poly(I:C) in NB cells.

Nomogram for predicting overall survival in children with neuroblastoma based on SEER database

Purpose

This study was performed to establish and validate a nomogram for predicting the overall survival in children with neuroblastoma.

Methods

The latest clinical data of neuroblastoma in Surveillance, Epidemiology, and End Results (SEER) database was extracted from 2000 to 2016. The cases included were randomly divided into training and validation cohorts. The survival curves were drawn with a Kaplan-Meier estimator to investigate the influences of certain single factors on overall survival. Also, least absolute shrinkage and selection operator regression was applied to further select the prognostic variables for neuroblastoma. Additionally, receiver operating characteristic (ROC) curves and calibration curves were used to evaluate the accuracy of the nomogram.

Results

In total, 1,262 patients were collected and 8 independent prognostic factors were achieved, including patients' age, sex, race, tumor grade, radiotherapy, chemotherapy, tumor site, and tumor size. Then we constructed a nomogram by using the data of the training cohort with 886 cases. Subsequently, the nomogram was validated internally and externally with 886 and 376 cases, respectively. The internal validation revealed that the area under the curves (AUC) of ROC curves of 1-, 3-, and 5-year overall survival were 0.69, 0.78, and 0.81, respectively. Accordingly, the external validation also showed that the AUC of 1-, 3-, and 5-year overall survival were all ≥0.69. Both methods of validation demonstrated that the predictive calibration curves were consistent with standard curves.

Conclusion

The nomogram possess the potential to be a new tool in predicting the survival rate of neuroblastoma patients.

Curcumin effect on cancer cells' multidrug resistance: An update

Chemotherapy is one of the main methods for cancer treatment. However, despite many advances in the design of anticancer drugs, their efficiency is limited due to their high toxicity and resistance of cells to chemotherapeutic drugs. In order to improve the cancer therapy, it is essential to use the compounds that can overcome drug resistance and increase treatment efficiency. Researchers have studied the effects of natural compounds for the controlling various drug resistance mechanisms. Curcumin is a natural phenolic compound which shows potent anticancer activities in different tumors, alone or as an adjuvant with other antitumor drugs to prevent or inhibit the survival and cancer progression by various mechanisms. The role of curcumin in overcoming drug resistance was followed by reviewing different applications of curcumin in cancer therapy. Afterward, the clinical impacts of curcumin, role of curcumin in decreasing drug resistance in different cancer cells and its mechanisms were discussed. It has been demonstrated that curcumin regulates signaling pathways in cancer cells, reduces the expression of proteins related to drug resistance, and increases the performance of antitumor drugs at various levels. Curcumin reverses multidrug resistance mechanisms and increases sensitivity of resistance cells to chemotherapy. This review mainly focuses on different mechanisms of drug resistance and curcumin as a nontoxic natural substance to eliminate the effects of drug resistance through modulation and controlling cell resistance pathways and eventually suggests curcumin as a potent chemosensitizer in cancers.

Interplay between epigenetic abnormalities and deregulated expression of microRNAs in cancer

Epigenetic abnormalities and aberrant expression of non-coding RNAs are two emerging features of cancer cells, both of which are responsible for deregulated gene expression. In this review, we describe the interplay between the two. Specific themes include epigenetic silencing of tumor suppressor miRNAs, epigenetic activation of oncogenic miRNAs, epigenetic aberrations caused by miRNAs, and naturally occurring compounds which modulate miRNA expression through epigenetic mechanisms.

Novel Therapies for Relapsed and Refractory Neuroblastoma

While recent increases in our understanding of the biology of neuroblastoma have allowed for more precise risk stratification and improved outcomes for many patients, children with high-risk neuroblastoma continue to suffer from frequent disease relapse, and despite recent advances in our understanding of neuroblastoma pathogenesis, the outcomes for children with relapsed neuroblastoma remain poor. These children with relapsed neuroblastoma, therefore, continue to need novel treatment strategies based on a better understanding of neuroblastoma biology to improve outcomes. The discovery of new tumor targets and the development of novel antibody- and cell-mediated immunotherapy agents have led to a large number of clinical trials for children with relapsed neuroblastoma, and additional clinical trials using molecular and genetic tumor profiling to target tumor-specific aberrations are ongoing. Combinations of these new therapeutic modalities with current treatment regimens will likely be needed to improve the outcomes of children with relapsed and refractory neuroblastoma.