Histone lysine demethylase 4 family proteins maintain the transcriptional program and adrenergic cellular state of MYCN-amplified neuroblastoma.

Neuroblastoma with MYCN amplification (MNA) is a high-risk disease that has a poor survival rate. Neuroblastoma displays cellular heterogeneity, including more differentiated (adrenergic) and more primitive (mesenchymal) cellular states. Here, we demonstrate that MYCN oncoprotein promotes a cellular state switch in mesenchymal cells to an adrenergic state, accompanied by induction of histone lysine demethylase 4 family members (KDM4A-C) that act in concert to control the expression of MYCN and adrenergic core regulatory circulatory (CRC) transcription factors. Pharmacologic inhibition of KDM4 blocks expression of MYCN and the adrenergic CRC transcriptome with genome-wide induction of transcriptionally repressive H3K9me3, resulting in potent anticancer activity against neuroblastomas with MNA by inducing neuroblastic differentiation and apoptosis. Furthermore, a short-term KDM4 inhibition in combination with conventional, cytotoxic chemotherapy results in complete tumor responses of xenografts with MNA. Thus, KDM4 blockade may serve as a transformative strategy to target the adrenergic CRC dependencies in MNA neuroblastomas.

Integrative analysis with machine learning identifies diagnostic and prognostic signatures in neuroblastoma based on differentially DNA methylated enhancers between INSS stage 4 and 4S neuroblastoma.

INTRODUCTION: Accumulating evidence demonstrates that aberrant methylation of enhancers is crucial in gene expression profiles across several cancers. However, the latent effect of differently expressed enhancers between INSS stage 4S and 4 neuroblastoma (NB) remains elusive. METHODS: We utilized the transcriptome and methylation data of stage 4S and 4 NB patients to perform Enhancer Linking by Methylation/Expression Relationships (ELMER) analysis, discovering a differently expressed motif within 67 enhancers between stage 4S and 4 NB. Harnessing the 67 motif genes, we established the INSS stage related signature (ISRS) by amalgamating 12 and 10 distinct machine learning (ML) algorithms across 113 and 101 ML combinations to precisely diagnose stage 4 NB among all NB patients and to predict the prognosis of NB patients. Based on risk scores calculated by prognostic ISRS, patients were categorized into high and low-risk groups according to median risk score. We conducted comprehensive comparisons between two risk groups, in terms of clinical applications, immune microenvironment, somatic mutations, immunotherapy, chemotherapy and single-cell analysis. Ultimately, we empirically validated the differential expressions of two ISRS model genes, CAMTA2 and FOXD1, through immunochemistry staining. RESULTS: Through leave-one-out cross-validation, in both feature selection and model construction, we selected the random forest algorithm to diagnose stage 4 NB, and Enet algorithm to develop prognostic ISRS, due to their highest average C-index across five NB cohorts. After validations, the ISRS demonstrated a stable predictive capability, outperforming the previously published NB signatures and several clinic variables. We stratified NB patients into high and low-risk group based on median risk score, which showed the low-risk group with a superior survival outcome, an abundant immune infiltration, a decreased mutation landscape, and an enhanced sensitivity to immunotherapy. Single-cell analysis between two risk groups reveals biologically cellular variations underlying ISRS. Finally, we verified the significantly higher protein levels of CAMTA2 and FOXD1 in stage 4S NB, as well as their protective prognosis value in NB. CONCLUSION: Based on multi-omics data and ML algorithms, we successfully developed the ISRS to enable accurate diagnosis and prognostic stratification in NB, which shed light on molecular mechanisms of spontaneous regression and clinical utilization of ISRS.

Integrated machine learning-driven disulfidptosis profiling: CYFIP1 and EMILIN1 as therapeutic nodes in neuroblastoma.

BACKGROUND: Neuroblastoma (NB), a prevalent pediatric solid tumor, presents formidable challenges due to its high malignancy and intricate pathogenesis. The role of disulfidptosis, a novel form of programmed cell death, remains poorly understood in the context of NB. METHODS: Gaussian mixture model (GMM)-identified disulfidptosis-related molecular subtypes in NB, differential gene analysis, survival analysis, and gene set variation analysis were conducted subsequently. Weighted gene co-expression network analysis (WGCNA) selected modular genes most relevant to the disulfidptosis core pathways. Integration of machine learning approaches revealed the combination of the Least absolute shrinkage and selection operator (LASSO) and Random Survival Forest (RSF) provided optimal dimensionality reduction of the modular genes. The resulting model was validated, and a nomogram assessed disulfidptosis characteristics in NB. Core genes were filtered and subjected to tumor phenotype and disulfidptosis-related experiments. RESULTS: GMM clustering revealed three distinct subtypes with diverse prognoses, showing significant variations in glucose metabolism, cytoskeletal structure, and tumor-related pathways. WGCNA highlighted the red module of genes highly correlated with disulfide isomerase activity, cytoskeleton formation, and glucose metabolism. The LASSO and RSF combination yielded the most accurate and stable prognostic model, with a significantly worse prognosis for high-scoring patients. Cytological experiments targeting core genes (CYFIP1, EMILIN1) revealed decreased cell proliferation, migration, invasion abilities, and evident cytoskeletal deformation upon core gene knockdown. CONCLUSIONS: This study showcases the utility of disulfidptosis-related gene scores for predicting prognosis and molecular subtypes of NB. The identified core genes, CYFIP1 and EMILIN1, hold promise as potential therapeutic targets and diagnostic markers for NB.

Downregulation of miR-337-3p in hypoxia/reoxygenation neuroblastoma cells increases KCTD11 expression.

Neurodegeneration is linked to the progressive loss of neural function and is associated with several diseases. Hypoxia is a hallmark in many of these diseases, and several therapies have been developed to treat this disease, including gene expression therapies that should be tightly controlled to avoid side effects. Cells experiencing hypoxia undergo a series of physiological responses that are induced by the activation of various transcription factors. Modulation of microRNA (miRNA) expression to alter transcriptional regulation has been demonstrated to be beneficial in treating multiple diseases, and in this study, we therefore explored potential miRNA candidates that could influence hypoxia-induced nerve cell death. Our data suggest that in mouse neuroblasts Neuro-2a cells with hypoxia/reoxygenation (H/R), miR-337-3p is downregulated to increase the expression of Potassium channel tetramerization domain containing 11 (KCTD11) and subsequently promote apoptosis. Here, we demonstrate for the first time that KCTD11 plays a role in the cellular response to hypoxia, and we also provide a possible regulatory mechanism by identifying the axis of miR-337-3p/KCTD11 as a promising candidate modulator of nerve cell survival after H/R exposure.

Targeted Modification of Epigenetic Marks Using CRISPR/dCas9-SunTag-Based Modular Epigenetic Toolkit.

The epigenome, consisting of chemical modifications to DNA and histone proteins, can alter gene expression. Clustered regularly interspaced short palindromic repeats/dead CRISPR-associated protein 9 (CRISPR/dCas9) systems enable precise target gene-specific gene modulation by attaching different "effector" domains to the dCas9 protein to activate or repress specific genes. CRISPR/dCas9-SunTag is an improved system version, allowing more efficient and precise gene activation or repression by recruiting multiple copies of the protein of interest. A CRISPR/dCas9-SunTag-based modular epigenetic toolkit was developed, enabling gene-specific epigenetic architecture modulation. This protocol generated a stable SH-SY5Y cell line expressing the CRISPR/dCas9-SunTag-JARID1A system to study H3K4Me3-mediated promoter regulation at a 200-400 bp of fine resolution. The procedure involved designing sgRNAs, subcloning dCas9-5XGCN4 into pLvx-DsRed, validating epigenetic mark changes with ChIP, and validating gene expression changes with RT-qPCR. This epigenetic toolkit is valuable for researchers to understand the relationship between gene-specific epigenetic modifications and gene expression.

De novo missense variants in exon 9 of SEPHS1 cause a neurodevelopmental condition with developmental delay, poor growth, hypotonia, and dysmorphic features.

Selenophosphate synthetase (SEPHS) plays an essential role in selenium metabolism. Two mammalian SEPHS paralogues, SEPHS1 and SEPHS2, share high sequence identity and structural homology with SEPHS. Here, we report nine individuals from eight families with developmental delay, growth and feeding problems, hypotonia, and dysmorphic features, all with heterozygous missense variants in SEPHS1. Eight of these individuals had a recurrent variant at amino acid position 371 of SEPHS1 (p.Arg371Trp, p.Arg371Gln, and p.Arg371Gly); seven of these variants were known to be de novo. Structural modeling and biochemical assays were used to understand the effect of these variants on SEPHS1 function. We found that a variant at residue Trp352 results in local structural changes of the C-terminal region of SEPHS1 that decrease the overall thermal stability of the enzyme. In contrast, variants of a solvent-exposed residue Arg371 do not impact enzyme stability and folding but could modulate direct protein-protein interactions of SEPSH1 with cellular factors in promoting cell proliferation and development. In neuronal SH-SY5Y cells, we assessed the impact of SEPHS1 variants on cell proliferation and ROS production and investigated the mRNA expression levels of genes encoding stress-related selenoproteins. Our findings provided evidence that the identified SEPHS1 variants enhance cell proliferation by modulating ROS homeostasis. Our study supports the hypothesis that SEPHS1 plays a critical role during human development and provides a basis for further investigation into the molecular mechanisms employed by SEPHS1. Furthermore, our data suggest that variants in SEPHS1 are associated with a neurodevelopmental disorder.

Tiam1 regulates proliferation, invasion, and differentiation in neuroblastoma through the Tiam1/Rac1 signaling pathway.

Neuroblastoma is the most common extracranial solid tumor in children. The purpose of the present study is to detect the prognostic role and potential therapeutic efficacy of the T lymphoma invasion and metastasis 1 (Tiam1) in neuroblastoma. The overexpression of Tiam1 protein is frequently observed in neuroblastoma. Tiam1 expression is closely associated with adverse prognosis of neuroblastoma and risk group classification. Knockdown of TIAM1 by lentivirus expressing short hairpin RNA against TIAM1 (sh-TIAM1) inhibited the proliferation, invasion and cell-cycle progression, and promoted apoptosis of the neuroblastoma cell lines SH-SY5Y and SK-N-AS. Additionally, downregulation of the differentiation-related protein expression and decreased Rac1 expression was observed in the sh-TIAM1-transfected SH-SY5Y cells. In vivo, nude mice bearing TIAM1 knockdown SH-SY5Y cells showed improved overall survival and tumor growth suppression. The results demonstrate that inhibition of Tiam1 expression is a potential strategy for targeted therapy in neuroblastoma.

Molecular-guided therapy for the treatment of patients with relapsed and refractory childhood cancers: a Beat Childhood Cancer Research Consortium trial.

BACKGROUND: Children with relapsed central nervous system (CNS tumors), neuroblastoma, sarcomas, and other rare solid tumors face poor outcomes. This prospective clinical trial examined the feasibility of combining genomic and transcriptomic profiling of tumor samples with a molecular tumor board (MTB) approach to make real­time treatment decisions for children with relapsed/refractory solid tumors. METHODS: Subjects were divided into three strata: stratum 1-relapsed/refractory neuroblastoma; stratum 2-relapsed/refractory CNS tumors; and stratum 3-relapsed/refractory rare solid tumors. Tumor samples were sent for tumor/normal whole-exome (WES) and tumor whole-transcriptome (WTS) sequencing, and the genomic data were used in a multi-institutional MTB to make real­time treatment decisions. The MTB recommended plan allowed for a combination of up to 4 agents. Feasibility was measured by time to completion of genomic sequencing, MTB review and initiation of treatment. Response was assessed after every two cycles using Response Evaluation Criteria in Solid Tumors (RECIST). Patient clinical benefit was calculated by the sum of the CR, PR, SD, and NED subjects divided by the sum of complete response (CR), partial response (PR), stable disease (SD), no evidence of disease (NED), and progressive disease (PD) subjects. Grade 3 and higher related and unexpected adverse events (AEs) were tabulated for safety evaluation. RESULTS: A total of 186 eligible patients were enrolled with 144 evaluable for safety and 124 evaluable for response. The average number of days from biopsy to initiation of the MTB-recommended combination therapy was 38 days. Patient benefit was exhibited in 65% of all subjects, 67% of neuroblastoma subjects, 73% of CNS tumor subjects, and 60% of rare tumor subjects. There was little associated toxicity above that expected for the MGT drugs used during this trial, suggestive of the safety of utilizing this method of selecting combination targeted therapy. CONCLUSIONS: This trial demonstrated the feasibility, safety, and efficacy of a comprehensive sequencing model to guide personalized therapy for patients with any relapsed/refractory solid malignancy. Personalized therapy was well tolerated, and the clinical benefit rate of 65% in these heavily pretreated populations suggests that this treatment strategy could be an effective option for relapsed and refractory pediatric cancers. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02162732. Prospectively registered on June 11, 2014.

From the identification of actionable molecular targets to the generation of faithful neuroblastoma patient-derived preclinical models.

BACKGROUND: Neuroblastoma (NB) represents the most frequent and aggressive form of extracranial solid tumor of infants. Although the overall survival of patients with NB has improved in the last years, more than 50% of high-risk patients still undergo a relapse. Thus, in the era of precision/personalized medicine, the need for high-risk NB patient-specific therapies is urgent. METHODS: Within the PeRsonalizEd Medicine (PREME) program, patient-derived NB tumors and bone marrow (BM)-infiltrating NB cells, derived from either iliac crests or tumor bone lesions, underwent to histological and to flow cytometry immunophenotyping, respectively. BM samples containing a NB cells infiltration from 1 to 50 percent, underwent to a subsequent NB cells enrichment using immune-magnetic manipulation. Then, NB samples were used for the identification of actionable targets and for the generation of 3D/tumor-spheres and Patient-Derived Xenografts (PDX) and Cell PDX (CPDX) preclinical models. RESULTS: Eighty-four percent of NB-patients showed potentially therapeutically targetable somatic alterations (including point mutations, copy number variations and mRNA over-expression). Sixty-six percent of samples showed alterations, graded as "very high priority", that are validated to be directly targetable by an approved drug or an investigational agent. A molecular targeted therapy was applied for four patients, while a genetic counseling was suggested to two patients having one pathogenic germline variant in known cancer predisposition genes. Out of eleven samples implanted in mice, five gave rise to (C)PDX, all preserved in a local PDX Bio-bank. Interestingly, comparing all molecular alterations and histological and immunophenotypic features among the original patient's tumors and PDX/CPDX up to second generation, a high grade of similarity was observed. Notably, also 3D models conserved immunophenotypic features and molecular alterations of the original tumors. CONCLUSIONS: PREME confirms the possibility of identifying targetable genomic alterations in NB, indeed, a molecular targeted therapy was applied to four NB patients. PREME paves the way to the creation of clinically relevant repositories of faithful patient-derived (C)PDX and 3D models, on which testing precision, NB standard-of-care and experimental medicines.

Envision the future of precision medicine in pediatric cancer.

Exploring the diversity within the tumor microenvironment (TME) can offer crucial insights to steer cancer therapy toward precision medicine. In this issue of Cancer Cell, Wienke et al. undertake a comprehensive single-cell analysis of neuroblastoma, unveiling its immune landscape and identifying NECTIN2-TIGIT as a promising target for immunotherapy.

SAMHD1 dysfunction induces IL-34 expression via NF-κB p65 in neuronal SH-SY5Y cells.

Dysfunctional mutations in SAMHD1 cause Aicardi-Goutières Syndrome, an autoinflammatory encephalopathy with elevated interferon-α levels in the cerebrospinal fluid. Whether loss of function mutations in SAMHD1 trigger the expression of other cytokines apart from type I interferons in Aicardi-Goutières Syndrome is largely unclear. This study aimed to explore whether SAMHD1 dysfunction regulated the expression of IL-34, a key cytokine controlling the development and maintenance of microglia, in SH-SY5Y neural cells. We found that downregulation of SAMHD1 in SH-SY5Y cells resulted in the upregulation of IL-34 expression. The protein and mRNA levels of NF-κB p65, the transactivating subunit of a transcription factor NF-κB, were also upregulated in SAMHD1-knockdown SH-SY5Y cells. It was further found SAMHD1 knockdown in SH-SY5Y cells induced an upregulation of IL-34 expression through the canonical NF-κB-dependent pathway in which NF-κB p65, IKKα/ß and the NF-κB inhibitor IκBα were phosphorylated. Moreover, knockdown of SAMHD1 in SH-SY5Y cells led to the translocation of NF-κB p65 into the nucleus and promoted NF-κB transcriptional activity. In conclusion, we found SAMHD1 dysfunction induced IL-34 expression via NF-κB p65 in neuronal SH-SY5Y cells. This finding could lay the foundation for exploring the role of IL-34-targeting microglia in the pathogenesis of Aicardi-Goutières Syndrome.

Clinical trial inclusion in patients with relapsed/refractory neuroblastoma following the European Precision Cancer Medicine trial MAPPYACTS.

INTRODUCTION: Despite poor survival for patients with relapsed or refractory neuroblastoma, only 10-16% of patients are reported to be included in early phase trials. This study aimed to explore the impact of molecular profiling within the prospective precision cancer medicine trial MAPPYACTS (NCT02613962) on subsequent early phase trial recruitment and treatment by matched targeted therapies in this population. METHODS AND MATERIALS: Clinical data from all French patients with relapsed/refractory neuroblastoma enrolled in MAPPYACTS were analyzed for subsequent matched/non-matched targeted treatment based on clinical tumor board (CMTB) recommendations. RESULTS: From 93 patients with neuroblastoma included in French centers, 78 (84%) underwent whole exome and RNA sequencing and were discussed in the CMTB. Higher rate of successful sequencing analysis was observed in patients with relapsed disease compared to those with refractory disease (p = 0.0002). Among the 50 patients that presented with a new disease relapse/progression after the CMTB recommendations, 35 patients (70%) had at least one actionable alteration identified on the tumor at the time of relapse. Eighteen patients (36%) were included in an early phase clinical trial, 11 of these with a matched agent, 7 with a non-matched treatment; 13 patients were included in the AcSé ESMART trial. Five patients (10%) received a matched targeted therapy outside a clinical trial. CONCLUSION: Patients with neuroblastoma in the European MAPPYACTS trial were more likely to be included in early phase trials compared to previous reports. Early deep sequencing at first treatment failure, comprehensive therapeutic discussions in molecular tumor boards and innovative trials like AcSé -ESMART improve access to innovative therapies for patients with relapsed/refractory neuroblastoma. CLINICAL TRIAL REGISTRATION: NCT02613962.

Single-cell analyses of metastatic bone marrow in human neuroblastoma reveals microenvironmental remodeling and metastatic signature.

Neuroblastoma is an aggressive pediatric cancer with a high rate of metastasis to the BM. Despite intensive treatments including high-dose chemotherapy, the overall survival rate for children with metastatic neuroblastoma remains dismal. Understanding the cellular and molecular mechanisms of the metastatic tumor microenvironment is crucial for developing new therapies and improving clinical outcomes. Here, we used single-cell RNA-Seq to characterize immune and tumor cell alterations in neuroblastoma BM metastases by comparative analysis with patients without metastases. Our results reveal remodeling of the immune cell populations and reprogramming of gene expression profiles in the metastatic niche. In particular, within the BM metastatic niche, we observed the enrichment of immune cells, including tumor-associated neutrophils, macrophages, and exhausted T cells, as well as an increased number of Tregs and a decreased number of B cells. Furthermore, we highlighted cell communication between tumor cells and immune cell populations, and we identified prognostic markers in malignant cells that are associated with worse clinical outcomes in 3 independent neuroblastoma cohorts. Our results provide insight into the cellular, compositional, and transcriptional shifts underlying neuroblastoma BM metastases that contribute to the development of new therapeutic strategies.

Approval of DFMO for high-risk neuroblastoma patients demonstrates a step of success to target MYC pathway.

The "undruggable" MYC oncoproteins are deregulated in 70% human cancers. The approval of DFMO, an irreversible inhibitor of ornithine oxidase (ODC1) that is a direct transcriptional target of MYC, demonstrates that patients can benefit from targeting MYC activity via an indirect approach. However, the mechanism of action of DFMO needs further studies to understand how it works in post-immunotherapy neuroblastomas. Efforts to develop a more potent and safer drug to block MYC function will continue despite challenges.

Development of a Simple and Reproducible Cell-derived Orthotopic Xenograft Murine Model for Neuroblastoma.

BACKGROUND/AIM: Neuroblastoma is a common childhood cancer with poor survival for children with high-risk disease, and ongoing research to improve outcomes is needed. Patient-derived xenografts (PDX) and genetically engineered mouse models (GEMM) are reliable models for oncologic research; however, they are resource-intensive, expensive, and require significant expertise to develop and maintain. We developed an orthotopic xenograft murine model of neuroblastoma that utilizes cryopreserved banks of human neuroblastoma cell lines, requires minimal equipment, and is easily reproducible. MATERIALS AND METHODS: The neuroblastoma cell line NB1643 was obtained from the Children's Oncology Group (COG) Childhood Cancer Repository. Nod-SCID-gamma (NSG) mice underwent orthotopic injection of 2x106 NB1643 cells suspended in 10 µl of collagen hydrogel directly into the adrenal gland via an open retroperitoneal surgical approach. Mice were monitored by ultrasound and in vivo imaging system (IVIS) until the tumor reached the volume of the ipsilateral kidney. Tumor identity was confirmed by necropsy and histologic analysis. RESULTS: A total of 55 mice underwent surgery. Eight died due to anesthetic or surgical complications. 39/47 (78%) survivors grew primary adrenal tumors. Average anesthesia time was 30 min. Ultrasound and IVIS successfully characterized tumor growth in all mice. Average time to target tumor size was 5 weeks (range=3-9). Gross pathologic and histologic analysis confirmed adrenal tumors consistent with neuroblastoma in all mice with adrenal masses. CONCLUSION: A cell-derived orthotopic xenograft murine model can be successfully used to create an in vivo model of neuroblastoma. This model can be utilized in environments where PDX or GEMM models are not feasible.

HNRNPA2B1 and HNRNPR stabilize ASCL1 in an m6A-dependent manner to promote neuroblastoma progression.

HNRNPA2B1 and HNRNPR stabilize ASCL1 mRNA in neuroblastoma, but whether their regulatory effects depend on m6A modification and whether their function involves ASCL1 remain unknown. This study investigated the m6A-dependent binding of HNRNPA2B1 and HNRNPR to ASCL1 and subsequent regulation, as well as the expression, clinical significance, and function of HNRNPA2B1 and HNRNPR in neuroblastoma. We revealed that METTL14 mediated ASCL1 m6A modification to stabilize ASCL1. HNRNPA2B1 and HNRNPR significantly enriched ASCL1 mRNA by binding to the 5' and 3' untranslated regions, respectively, and METTL14 knockdown reduced this enrichment. Mutations in m6A sites in the untranslated regions of ASCL1 mRNA considerably decreased probe capacity to engage HNRNPA2B1 and HNRNPR. HNRNPR interacts with IGF2BP1, and knocking down either impaired binding to ASCL1 mRNA. HNRNPA2B1 and HNRNPR knockdown suppressed neuroblastoma cell growth and invasion, while ASCL1 overexpression restored these effects. The high HNRNPA2B1 and HNRNPR expression in neuroblastoma correlated with ASCL1 expression. Thus, HNRNPA2B1 and HNRNPR bind and stabilize ASCL1 mRNA in an m6A-dependent manner to promote neuroblastoma progression. This study not only discovered a new mechanism underlying the high ASCL1 expression in neuroblastoma but also identified the HNRNPA2B1/HNRNPR/ASCL1 axis as a promising target for inhibiting neuroblastoma progression.

MTHFD1 regulates the NADPH redox homeostasis in MYCN-amplified neuroblastoma.

MYCN amplification is an independent poor prognostic factor in patients with high-risk neuroblastoma (NB). Further exploring the molecular regulatory mechanisms in MYCN-amplified NB will help to develop novel therapy targets. In this study, methylenetetrahydrofolate dehydrogenase 1 (MTHFD1) was identified as the differentially expressed gene (DEG) highly expressed in MYCN-amplified NB, and it showed a positive correlation with MYCN and was associated with a poor prognosis of NB patients. Knockdown of MTHFD1 inhibited proliferation and migration, and induced apoptosis of NB cells in vitro. Mouse model experiments validated the tumorigenic effect of MTHFD1 in NB in vivo. In terms of the mechanism, ChIP-qPCR and dual-luciferase reporter assays demonstrated that MTHFD1 was directly activated by MYCN at the transcriptional level. As an important enzyme in the folic acid metabolism pathway, MTHFD1 maintained the NADPH redox homeostasis in MYCN-amplified NB. Knockdown of MTHFD1 reduced cellular NADPH/NADP+ and GSH/GSSG ratios, increased cellular reactive oxygen species (ROS) and triggered the apoptosis of NB cells. Moreover, genetic knockdown of MTHFD1 or application of the anti-folic acid metabolism drug methotrexate (MTX) potentiated the anti-tumor effect of JQ1 both in vitro and in vivo. Taken together, MTHFD1 as an oncogene is a potential therapeutic target for MYCN-amplified NB. The combination of MTX with JQ1 is of important clinical translational significance for the treatment of patients with MYCN-amplified NB.

The causal relationship between gut microbiota and neuroblastoma: a bidirectional Mendelian randomization analysis and meta-analysis.

Neuroblastoma (NB) is a type of neuroectodermal tumor that originates from primitive sympathetic ganglion cells. Although many risk factors contributing to the occurrence of NB have been reported in recent years, the role of the gut microbiota in its development remains unclear. A bidirectional Mendelian randomization (MR) analysis was conducted to elucidate the causal relationship between the gut microbiota and NB. In the MR analysis, we employed the inverse-variance weighted (IVW) method as the primary criterion for assessing causality, while also utilizing three additional approaches, including MR-Egger, weighted median model, and weighted mode, for comprehensive evaluation. For gut microbiota that were causally associated with NB, a reverse MR was also used to assess the stability of this causal relationship. Finally, we also used external cohorts for validation and performed a meta-analysis of the results. The IVW results indicated a causal relationship between six gut microbiota and NB. Among the six gut microbiota, genus Lachnospiraceae [IVW odds ratio (OR): 2.66, 95% confidence interval (CI): 1.09-6.51, P value: 0.03] exhibited a detrimental effect against NB. On the other hand, the class Actinobacteria (IVW OR: 0.24, 95% CI: 0.07-0.77, P value: 0.02), the family Bifidobacteriaceae (IVW OR: 0.40, 95% CI: 0.17-0.96, P value: 0.04), the genus Desulfovibrio (IVW OR: 0.50, 95% CI: 0.25-0.97, P value: 0.04), the genus Bifidobacterium (IVW OR: 0.39, 95% CI: 0.16-0.92, P value: 0.03), and the genus Howardella (IVW OR: 0.55, 95% CI: 0.31-0.97, P value: 0.04) displayed a protective effect on NB. A reverse MR analysis did not reveal a causality between NB and the six gut microbiota. Meta-analysis showed that genus Bifidobacterium (meta OR: 0.41, 95% CI: 0.22-0.75, P < 0.01) and genus Lachnospiraceae (meta OR: 2.20, 95% CI: 1.01-4.79, P < 0.05) were still significant. IMPORTANCE: Bidirectional Mendelian randomization was used to explore the causality between gut microbiota and neuroblastoma (NB). The results showed that there is a causal relationship between the six gut microbiota and NB, of which two gut microbiota were further confirmed in the meta-analysis. This may provide a new perspective on the prevention and treatment of NB.

METTL3 drives telomere targeting of TERRA lncRNA through m6A-dependent R-loop formation: a therapeutic target for ALT-positive neuroblastoma.

Telomerase-negative tumors maintain telomere length by alternative lengthening of telomeres (ALT), but the underlying mechanism behind ALT remains poorly understood. A proportion of aggressive neuroblastoma (NB), particularly relapsed tumors, are positive for ALT (ALT+), suggesting that a better dissection of the ALT mechanism could lead to novel therapeutic opportunities. TERRA, a long non-coding RNA (lncRNA) derived from telomere ends, localizes to telomeres in a R-loop-dependent manner and plays a crucial role in telomere maintenance. Here we present evidence that RNA modification at the N6 position of internal adenosine (m6A) in TERRA by the methyltransferase METTL3 is essential for telomere maintenance in ALT+ cells, and the loss of TERRA m6A/METTL3 results in telomere damage. We observed that m6A modification is abundant in R-loop enriched TERRA, and the m6A-mediated recruitment of hnRNPA2B1 to TERRA is critical for R-loop formation. Our findings suggest that m6A drives telomere targeting of TERRA via R-loops, and this m6A-mediated R-loop formation could be a widespread mechanism employed by other chromatin-interacting lncRNAs. Furthermore, treatment of ALT+ NB cells with a METTL3 inhibitor resulted in compromised telomere targeting of TERRA and accumulation of DNA damage at telomeres, indicating that METTL3 inhibition may represent a therapeutic approach for ALT+ NB.