Neuroblastoma: biological insights into a clinical enigma

Discovery of non-substrate, environmentally sensitive turn-on fluorescent probes for imaging HDAC8 in tumor cells and tissue slices

Histone deacetylase 8 (HDAC8) is overexpressed in multiple cancers and lack of effective chemical probes which could detect and visualize HDAC8 in tumor cells and tissues remains unsolved. In this work, three novel turn-on HDAC8 fluorescent probes 17-19 derived from solvatochromic fluorophore 4-sulfamonyl-7-aminobenzoxadiazole (SBD) conjugating with a potent HDAC8 inhibitor PCI-34051 (IC₅₀ = 10 nM) as the recognition group were fabricated. The probes exhibited much stronger fluorescence when they transfer from hydrophilic environment (Φ < 8%) to hydrophobic environment (Φ > 46%). Compared with PCI-34051 (K_D = 9.16 × 10^-6 M), probes 17 (K_D = 5.37 × 10^-6 M), 18 (K_D = 3.57 × 10^-6 M) and 19 (K_D = 8.89 × 10^-6 M) possessed slightly better affinity for HDAC8. Probe 19 was selected for cell imaging and it showed significantly enhanced fluorescence only after binding into the cavity of HDAC8 in SH-SY5Y and MDA-MB-231 tumor cells. Co-localization results demonstrated that HDAC8 is expressed in cytoplasm and nucleus. Furthermore, probe 19 was successfully utilized to distinguish the expression level of HDAC8 in SH-SY5Y tumor and normal tissue slices.

DHODH is an independent prognostic marker and potent therapeutic target in neuroblastoma

Despite intensive therapy, children with high-risk neuroblastoma are at risk of treatment failure. We applied a multiomic system approach to evaluate metabolic vulnerabilities in human neuroblastoma. We combined metabolomics, CRISPR screening, and transcriptomic data across more than 700 solid tumor cell lines and identified dihydroorotate dehydrogenase (DHODH), a critical enzyme in pyrimidine synthesis, as a potential treatment target. Of note, DHODH inhibition is currently under clinical investigation in patients with hematologic malignancies. In neuroblastoma, DHODH expression was identified as an independent risk factor for aggressive disease, and high DHODH levels correlated to worse overall and event-free survival. A subset of tumors with the highest DHODH expression was associated with a dismal prognosis, with a 5-year survival of less than 10%. In xenograft and transgenic neuroblastoma mouse models treated with the DHODH inhibitor brequinar, tumor growth was dramatically reduced, and survival was extended. Furthermore, brequinar treatment was shown to reduce the expression of MYC targets in 3 neuroblastoma models in vivo. A combination of brequinar and temozolomide was curative in the majority of transgenic TH-MYCN neuroblastoma mice, indicating a highly active clinical combination therapy. Overall, DHODH inhibition combined with temozolomide has therapeutic potential in neuroblastoma, and we propose this combination for clinical testing.

Targeting RAS in neuroblastoma: Is it possible?

Neuroblastoma is a common solid tumor in children and a leading cause of cancer death in children. Neuroblastoma exhibits genetic, morphological, and clinical heterogeneity that limits the efficacy of current monotherapies. With further research on neuroblastoma, the pathogenesis of neuroblastoma is found to be complex, and more and more treatment therapies are needed. The importance of personalized therapy is growing. Currently, various molecular features, including RAS mutations, are being used as targets for the development of new therapies for patients with neuroblastoma. A recent study found that RAS mutations are frequently present in recurrent neuroblastoma. RAS mutations have been shown to activate the MAPK pathway and play an important role in neuroblastoma. Treating RAS mutated neuroblastoma is a difficult challenge, but many preclinical studies have yielded effective results. At the same time, many of the therapies used to treat RAS mutated tumors also have good reference values for treating RAS mutated neuroblastoma. The success of KRAS-G12C inhibitors has greatly stimulated confidence in the direct suppression of RAS. This review describes the biological role of RAS and the frequency of RAS mutations in neuroblastoma. This paper focuses on the strategies, preclinical, and clinical progress of targeting carcinogenic RAS in neuroblastoma, and proposes possible prospects and challenges in the future.

Expression and activation of nuclear hormone receptors result in neuronal differentiation and favorable prognosis in neuroblastoma

BACKGROUND

Neuroblastoma (NB), a childhood tumor derived from the sympathetic nervous system, presents with heterogeneous clinical behavior. While some tumors regress spontaneously without medical intervention, others are resistant to therapy, associated with an aggressive phenotype. MYCN-amplification, frequently occurring in high-risk NB, is correlated with an undifferentiated phenotype and poor prognosis. Differentiation induction has been proposed as a therapeutic approach for high-risk NB. We have previously shown that MYCN maintains an undifferentiated state via regulation of the miR-17 ~ 92 microRNA cluster, repressing the nuclear hormone receptors (NHRs) estrogen receptor alpha (ERα) and the glucocorticoid receptor (GR).

METHODS

Cell viability was determined by WST-1. Expression of differentiation markers was analyzed by Western blot, RT-qPCR, and immunofluorescence analysis. Metabolic phenotypes were studied using Agilent Extracellular Flux Analyzer, and accumulation of lipid droplets by Nile Red staining. Expression of angiogenesis, proliferation, and neuronal differentiation markers, and tumor sections were assessed by immunohistochemistry. Gene expression from NB patient as well as adrenal gland cohorts were analyzed using GraphPad Prism software (v.8) and GSEA (v4.0.3), while pseudo-time progression on post-natal adrenal gland cells from single-nuclei transcriptome data was computed using scVelo.

RESULTS

Here, we show that simultaneous activation of GR and ERα potentiated induction of neuronal differentiation, reduced NB cell viability in vitro, and decreased tumor burden in vivo. This was accompanied by a metabolic reprogramming manifested by changes in the glycolytic and mitochondrial functions and in lipid droplet accumulation. Activation of the retinoic acid receptor alpha (RARα) with all-trans retinoic acid (ATRA) further enhanced the differentiated phenotype as well as the metabolic switch. Single-cell nuclei transcriptome analysis of human adrenal glands indicated a sequential expression of ERα, GR, and RARα during development from progenitor to differentiated chromaffin cells. Further, in silico analysis revealed that patients with higher combined expression of GR, ERα, and RARα mRNA levels had elevated expression of neuronal differentiation markers and a favorable outcome.

CONCLUSION

Together, our findings suggest that combination therapy involving activation of several NHRs could be a promising pharmacological approach for differentiation treatment of NB patients.

The cytotoxic action of BCI is not dependent on its stated DUSP1 or DUSP6 targets in neuroblastoma cells

Neuroblastoma (NB) is a heterogeneous cancer of the sympathetic nervous system, which accounts for 7-10% of paediatric malignancies worldwide. Due to the lack of targetable molecular aberrations in NB, most treatment options remain relatively nonspecific. Here, we investigated the therapeutic potential of BCI, an inhibitor of DUSP1 and DUSP6, in cultured NB cells. BCI was cytotoxic in a range of NB cell lines and induced a short-lived activation of the AKT and stress-inducible MAP kinases, although ERK phosphorylation was unaffected. Furthermore, a phosphoproteomic screen identified significant upregulation of JNK signalling components and suppression in mTOR and R6K signalling. To assess the specificity of BCI, CRISPR-Cas9 was employed to introduce insertions and deletions in the DUSP1 and DUSP6 genes. Surprisingly, BCI remained fully cytotoxic in NB cells with complete loss of DUSP6 and partial depletion of DUSP1, suggesting that BCI exerts cytotoxicity in NB cells through a complex mechanism that is unrelated to these phosphatases. Overall, these data highlight the risk of using an inhibitor such as BCI as supposedly specific DUSP1/6, without understanding its full range of targets in cancer cells.

MYCN induces cell-specific tumorigenic growth in RB1-proficient human retinal organoid and chicken retina models of retinoblastoma

Retinoblastoma is a rare, intraocular paediatric cancer that originates in the neural retina and is most frequently caused by bi-allelic loss of RB1 gene function. Other oncogenic mutations, such as amplification and increased expression of the MYCN gene, have been found even with proficient RB1 function. In this study, we investigated whether MYCN over-expression can drive carcinogenesis independently of RB1 loss-of-function mutations. The aim was to elucidate the events that result in carcinogenesis and identify the cancer cell-of-origin. We used the chicken retina, a well-established model for studying retinal neurogenesis, and established human embryonic stem cell-derived retinal organoids as model systems. We over-expressed MYCN by electroporation of piggyBac genome-integrating expression vectors. We found that over-expression of MYCN induced tumorigenic growth with high frequency in RB1-proficient chicken retinas and human organoids. In both systems, the tumorigenic cells expressed markers for undifferentiated cone photoreceptor/horizontal cell progenitors. The over-expression resulted in metastatic retinoblastoma within 7–9 weeks in chicken. Cells expressing MYCN could be grown in vitro and, when orthotopically injected, formed tumours that infiltrated the sclera and optic nerve and expressed markers for cone progenitors. Investigation of the tumour cell phenotype determined that the potential for neoplastic growth was embryonic stage-dependent and featured a cell-specific resistance to apoptosis in the cone/horizontal cell lineage, but not in ganglion or amacrine cells. We conclude that MYCN over-expression is sufficient to drive tumorigenesis and that a cell-specific resistance to apoptosis in the cone/horizontal cell lineage mediates the cancer phenotype.

Mutations in ALK signaling pathways conferring resistance to ALK inhibitor treatment lead to collateral vulnerabilities in neuroblastoma cells

BACKGROUND

Development of resistance to targeted therapies has tempered initial optimism that precision oncology would improve poor outcomes for cancer patients. Resistance mechanisms, however, can also confer new resistance-specific vulnerabilities, termed collateral sensitivities. Here we investigated anaplastic lymphoma kinase (ALK) inhibitor resistance in neuroblastoma, a childhood cancer frequently affected by activating ALK alterations.

METHODS

Genome-wide forward genetic CRISPR-Cas9 based screens were performed to identify genes associated with ALK inhibitor resistance in neuroblastoma cell lines. Furthermore, the neuroblastoma cell line NBLW-R was rendered resistant by continuous exposure to ALK inhibitors. Genes identified to be associated with ALK inhibitor resistance were further investigated by generating suitable cell line models. In addition, tumor and liquid biopsy samples of four patients with ALK-mutated neuroblastomas before ALK inhibitor treatment and during tumor progression under treatment were genomically profiled.

RESULTS

Both genome-wide CRISPR-Cas9-based screens and preclinical spontaneous ALKi resistance models identified NF1 loss and activating NRASQ61K mutations to confer resistance to chemically diverse ALKi. Moreover, human neuroblastomas recurrently developed de novo loss of NF1 and activating RAS mutations after ALKi treatment, leading to therapy resistance. Pathway-specific perturbations confirmed that NF1 loss and activating RAS mutations lead to RAS-MAPK signaling even in the presence of ALKi. Intriguingly, NF1 loss rendered neuroblastoma cells hypersensitive to MEK inhibition.

CONCLUSIONS

Our results provide a clinically relevant mechanistic model of ALKi resistance in neuroblastoma and highlight new clinically actionable collateral sensitivities in resistant cells.

TP53 and TP53-associated genes are correlated with the prognosis of paediatric neuroblastoma

Background

TP53 is rarely mutated in paediatric neuroblastoma. The prognosis of TP53 and TP53-associated genes in paediatric neuroblastoma is unclear. The objectives of the study were to analyse datasets of 2477 paediatric neuroblastoma patients from eight independent cohorts to reveal the prognosis of TP53 and TP53-associated genes.

Results

High TP53 mRNA expression was associated with shortened event-free survival and overall survival in paediatric neuroblastoma. Moreover, a higher enrichment score of the TP53 signalling pathway was associated with worse clinical outcomes of paediatric neuroblastoma. Among the genes associated with TP53, CCNE1, CDK2 and CHEK2 were correlated with unfavourable clinical outcomes, while SESN1 was correlated with favourable clinical outcomes of paediatric neuroblastoma in the eight independent neuroblastoma cohorts. TP53, CCNE1, CDK2 and CHEK2 were overexpressed in neuroblastoma patients with MYCN amplification, while SESN1 was downregulated in neuroblastoma patients with MYCN amplification. CCNE1, SESN1, MYCN amplification and age at diagnosis were independent prognostic markers of neuroblastoma. CCNE1 was also highly expressed in paediatric neuroblastoma patients with an age at diagnosis ≥ 18 months, while SESN1 was downregulated in paediatric neuroblastoma patients with an age at diagnosis ≥ 18 months. Combinations of CCNE1 with age at diagnosis or combinations of SESN1 with age at diagnosis achieved superior prognostic effects in paediatric neuroblastoma. Finally, we constructed a nomogram risk model of paediatric neuroblastoma based on age and TP53, CCNE1, CDK2, CHEK2 and SESN1 expression. The nomogram model could predict the overall survival of paediatric neuroblastoma and MYCN nonamplified paediatric neuroblastoma with high specificity and sensitivity.

Conclusions

TP53 and TP53-associated genes CCNE1, CDK2, CHEK2 and SESN1 were significantly associated with the clinical outcomes of paediatric neuroblastoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01059-5.

TTF1 suppresses neuroblastoma growth and induces neuroblastoma differentiation by targeting TrkA and the miR-204/TrkB axis

Neuroblastoma (NB) is the most common extracranial malignant solid tumor in children. We found that TTF1, TrkA, and miR-204 were lowly expressed, whereas TrkB was highly expressed in undifferentiated NB tissues. Meanwhile, TTF1 expression correlated positively with TrkA and miR-204 expression but negatively with TrkB expression. The TTF1 promoter was hypermethylated in undifferentiated NB tissues and SK-N-BE cells, leading to TTF1 downregulation. We also identified miR-204, which directly targets TrkB, as a transcriptional target of TTF1. Functionally, TTF1 suppressed proliferation, migration, and invasion of NB cells, whereas induced cell cycle arrest, apoptosis, and autophagy of NB cells by regulating TrkA and the miR-204-TrkB axis. Furthermore, TTF1 suppressed tumor growth and promoted neurogenic differentiation in a NB xenograft mouse model. Our study demonstrates that TTF1 reduces tumor growth and induces neurogenic differentiation in NB by directly targeting TrkA and the miR-204/TrkB axis.

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TTF1, TrkA, and miR-204 were lowly expressed in undifferentiated NB tissues

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TTF1 promoter was hypermethylated in undifferentiated NB tissues and cells

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TTF1 suppressed proliferation of NB cells by regulating TrkA and the miR-204-TrkB axis

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TTF1 suppressed tumor growth and promoted neurogenic differentiation in vivo

Paediatric neuroblastoma presenting as an asymptomatic abdominal mass: a report on the importance of a complete clinical examination with a view to a timely diagnosis and therapeutic guidance in paediatric oncology

Neuroblastoma (NB) is the most common extracranial solid tumour in children after lymphoblastic leukaemias, brain tumours and lymphomas.We report a case of an NB in a previously healthy toddler. Though she had no abdominal complaints, on physical examination, she had a palpable mass identified over the right upper portion of the abdomen. Imaging studies demonstrated a heterogeneous tumour with an irregular capsule and visible calcifications.After initial diagnosis, the patient underwent chemotherapy and was subjected to a radical resection of the tumour 4 months later. One-year follow-up of the patient showed no recurrence.In children, oncological diseases are often asymptomatic or have non-specific symptoms, and in remote locations where specialised/paediatric services may not be available, the importance of medical training in paediatrics is highlighted, with emphasis on performing a complete clinical examination, namely abdominal palpation. The role of timely referral will be evident in such a situation.

Targeted Analysis of Cell-free Circulating Tumor DNA is Suitable for Early Relapse and Actionable Target Detection in Patients with Neuroblastoma

PURPOSE

Treating refractory or relapsed neuroblastoma remains challenging. Monitoring body fluids for tumor-derived molecular information indicating minimal residual disease supports more frequent diagnostic surveillance and may have the power to detect resistant subclones before they give rise to relapses. If actionable targets are identified from liquid biopsies, targeted treatment options can be considered earlier.

EXPERIMENTAL DESIGN

Droplet digital PCR assays assessing MYCN and ALK copy numbers and allelic frequencies of ALK p.F1174L and ALK p.R1275Q mutations were applied to longitudinally collected liquid biopsies and matched tumor tissue samples from 31 patients with high-risk neuroblastoma. Total cell-free DNA (cfDNA) levels and marker detection were compared with data from routine clinical diagnostics.

RESULTS

Total cfDNA concentrations in blood plasma from patients with high-risk neuroblastoma were higher than in healthy controls and consistently correlated with neuron-specific enolase levels and lactate dehydrogenase activity but not with 123I-meta-iodobenzylguanidine scores at relapse diagnosis. Targeted cfDNA diagnostics proved superior for early relapse detection to all current diagnostics in 2 patients. Marker analysis in cfDNA indicated intratumor heterogeneity for cell clones harboring MYCN amplifications and druggable ALK alterations that were not detectable in matched tumor tissue samples in 17 patients from our cohort. Proof of concept is provided for molecular target detection in cerebrospinal fluid from patients with isolated central nervous system relapses.

CONCLUSIONS

Tumor-specific alterations can be identified and monitored during disease course in liquid biopsies from pediatric patients with high-risk neuroblastoma. This approach to cfDNA surveillance warrants further prospective validation and exploitation for diagnostic purposes and to guide therapeutic decisions.

Identification and Validation of Inflammatory Response-Related Gene Signatures to Predict the Prognosis of Neuroblastoma

Background. Neuroblastoma (NB) is the third most common malignant tumor in children. The inflammation is believed to be closely related to NB patients’ prognosis. However, there is no comprehensive research to study the role of inflammatory response-related gene (IRRG) in NB patients. Methods. We downloaded the gene expression profiles of NB patients from GEO and TARGET database, and the expression of 200 IRRGs was extracted. Then, we performed differentially analysis between INSS stage 4 and INSS stage 4S NB patients. The univariate and multivariate Cox regression analyses were performed to screen out the overall survival- (OS-) and event-free survival- (EFS-) related IRRGs in GSE49710, and two signatures were constructed; both signatures were evaluated by Kaplan-Meier (K-M) survival curve and receiver operating characteristic (ROC) curve. Finally, the TARGET cohort was used to validate IRRG signatures, and the independence of the prognostic IRRG signatures was evaluated by integrating clinical information. Results. We screened out 10 OS-related IRRGs and 11 EFS-related IRRGs. Then, we identified that OS- and EFS-related IRRG signatures and found that the OS and EFS of NB patients in the low-risk group were significantly superior than those in the high-risk group (both $P$ value < 0.0001). The AUC values of 3-, 5-, and 7-year OS are 0.910, 0.933, and 0.921, respectively, and 3-, 5-, and 7-year EFS are 0.840, 0.835, and 0.837, respectively. In addition, we found that both IRRG signatures can be used as independent prognostic indicators for patients with NB. Both IRRG signatures still have good predictive ability in validation cohort. Conclusions. We constructed and validated two prognostic gene signatures based on IRRGs. Our study helped us to better understand the role of inflammation in NB and provided new insights for the prognosis assessment and treatment strategy for NB patients.

Identification of a Vitamin-D Receptor Antagonist, MeTC7, which Inhibits the Growth of Xenograft and Transgenic Tumors In Vivo

Vitamin-D receptor (VDR) mRNA is overexpressed in neuroblastoma and carcinomas of lung, pancreas, and ovaries and predicts poor prognoses. VDR antagonists may be able to inhibit tumors that overexpress VDR. However, the current antagonists are arduous to synthesize and are only partial antagonists, limiting their use. Here, we show that the VDR antagonist MeTC7 (5), which can be synthesized from 7-dehydrocholesterol (6) in two steps, inhibits VDR selectively, suppresses the viability of cancer cell-lines, and reduces the growth of the spontaneous transgenic TH-MYCN neuroblastoma and xenografts in vivo. The VDR selectivity of 5 against RXRα and PPAR-γ was confirmed, and docking studies using VDR-LBD indicated that 5 induces major changes in the binding motifs, which potentially result in VDR antagonistic effects. These data highlight the therapeutic benefits of targeting VDR for the treatment of malignancies and demonstrate the creation of selective VDR antagonists that are easy to synthesize.

Whole-tumour apparent diffusion coefficient (ADC) histogram analysis to identify MYCN-amplification in neuroblastomas: preliminary results

OBJECTIVES

To determine the role of apparent diffusion coefficient (ADC) histogram analysis in the identification of MYCN-amplification status in neuroblastomas.

METHODS

We retrospectively evaluated imaging records from 62 patients with neuroblastomas (median age: 15 months (interquartile range (IQR): 7-24 months); 38 females) who underwent magnetic resonance imaging at our institution before the initiation of any therapy or biopsy. Fourteen patients had MYCN-amplified (MYCNA) neuroblastoma. Histogram parameters of ADC maps from the entire tumour was obtained from the baseline images and the normalised images. The Mann-Whitney U test was used to compare the absolute and normalised histogram parameters amongst neuroblastomas with and without MYCN-amplification. Receiver operating characteristic (ROC) curves and area under the curves (AUC) were generated for the statistically significant histogram parameters. Cut-offs obtained from the ROC curves were evaluated on an external validation set (n-15, MYCNA-6, F-7, age 24 months (10-60)). A logistic regression model was trained to predict MYCNA by combining statistically significant histogram parameters and was evaluated on the validation set.

RESULTS

MYCN-amplified neuroblastomas had statistically significant higher maximum ADC and lower minimum ADC than non-amplified neuroblastomas. They also demonstrated higher entropy, variance, energy, and lower uniformity than non-amplified neoplasms (p > 0.05). Energy, entropy, and maximum ADC had AUC of 0.85, 0.79, and 0.82, respectively.

CONCLUSIONS

Whole tumour ADC histogram analysis of neuroblastomas can differentiate between tumours with and without MYCN-amplification. These parameters can help identify areas for targeted biopsies or can be used to predict subtypes of these high-risk tumours before biopsy results are available.

KEY POINTS

• MYCN-amplification significantly affects treatment decisions in neuroblastomas. • MYCN-amplified neuroblastomas had significantly different ADC histogram metrics as compared to tumours without amplification. • ADC histogram metrics can be used to predict MYCN-amplification status based on imaging.

The role of ncRNAs in neuroblastoma: mechanisms, biomarkers and therapeutic targets

Neuroblastoma (NB) is a malignant tumor in young children that originates from the neural crest of the sympathetic nervous system. Generally, NB occurs in the adrenal glands, but it can also affect the nerve tissues of the neck, chest, abdomen, and pelvis. Understanding the pathophysiology of NB and developing novel therapeutic approaches are critical. Noncoding RNAs (ncRNAs) are associated with crucial aspects of pathology, metastasis and drug resistance in NB. Here, we summarized the pretranscriptional, transcriptional and posttranscriptional regulatory mechanisms of ncRNAs involved in NB, especially focusing on regulatory pathways. Furthermore, ncRNAs with the potential to serve as biomarkers for risk stratification, drug resistance and therapeutic targets are also discussed, highlighting the clinical application of ncRNAs in NB.

circ0125803 facilitates tumor progression by sponging miR-197-5p and upregulating E2F1 in neuroblastoma

BACKGROUND

Circular RNAs (circRNAs) are one type of RNAs with many different functions. circRNAs are very crucial in human malignancy progression. However, few studies have investigated the function and exact mechanism of circRNAs in neuroblastoma. In the current study, we investigated the biological function of circ0125803 in the proliferation and metastasis of neuroblastoma.

METHODS

A high-throughput circRNA microarray sequencing was conducted to screen differentially expressed circRNAs and in neuroblastoma. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression level of circRNA and miRNA. RNA immunoprecipitation and dual luciferase reporter experiments were both conducted to investigate the molecular interaction mechanism of circ0125803 in neuroblastoma.

RESULTS

We identified hsa_circ_0125803 (circ0125803) as an extremely upregulated circRNA in neuroblastoma samples. Knockdown of circ0125803 significantly decreased the growth rate and invasion rate in neuroblastoma. Our data demonstrated upregulation of circ0125803 promotes the neuroblastoma progression by blocking miR-197-5p and upregulating E2F1 expression.

CONCLUSION

This study uncovered the biological function of the circ0125803-miR-197-5p-E2F1 axis in neuroblastoma metastasis and growth.

Filamin A increases aggressiveness of human neuroblastomas

Background

The actin-binding protein filamin A (FLNA) regulates oncogenic signal transduction important for tumor growth, but the role of FLNA in the progression of neuroblastoma (NB) has not been explored.

Methods

We analyzed FLNA mRNA expression in the R2 NB-database and FLNA protein expression in human NB tumors. We then silenced FLNA expression in human SKNBE2 and IMR32 NB cells by lentiviral vector encoding shRNA FLNA and assayed the cells for proliferation, migration, colony, spheroid formation, and apoptosis. SKNBE2 xenografts expressing or lacking FLNA in BALB/c nude mice were analyzed by both routine histopathology and immunohistochemistry.

Results

We observed shorter patient survival with higher expression of FLNA mRNA than patients with lower FLNA mRNA expression, and high-risk NB tumors expressed higher FLNA levels. SKNBE2 cells expressing higher FLNA levels proliferated more than IMR32 cells expressing lower FLNA levels. NB cell lines transfected with siRNA FLNA proliferated and migrated less, expressed lower levels of phosphorylated AKT and ERK1/2, formed smaller colonies and spheroids, as well as increased apoptosis. After inoculation of SKNBE2 cells infected with lentivirus expressing shRNA FLNA, size of NB tumors and number of proliferating cells were decreased. Furthermore, we identified STAT3 as an interacting partner of FLNA. Silencing FLNA mRNA reduced levels of phosphorylated STAT3 and MYCN, and induced expression NF-κB, cleaved caspase 3, and p53.

Conclusion

Inhibition of FLNA impaired NB cell signaling and function and reduced NB tumor size in vivo, suggesting that drugs targeting either FLNA or its interaction with STAT3 may be useful in the treatment of NB.

PCLAF promotes neuroblastoma G1/S cell cycle progression via the E2F1/PTTG1 axis

PCLAF (PCNA clamp-associated factor), also known as PAF15/ KIAA0101, is overexpressed in most human cancers and is a predominant regulator of tumor progression. However, its biological function in neuroblastoma remains unclear. PCLAF is extremely overexpressed in neuroblastoma and is associated with poor prognosis. Through the analysis of various data sets, we found that the high expression of PCLAF is positively correlated with increased stage and high risk of neuroblastoma. Most importantly, knocking down PCLAF could restrict the proliferation of neuroblastoma cells in vitro and in vitro. By analyzing RNA-seq data, we found that the enrichment of cell cycle-related pathway genes was most significant among the differentially expressed downregulated genes after reducing the expression of PCLAF. In addition, PCLAF accelerated the G1/S transition of the neuroblastoma cell cycle by activating the E2F1/PTTG1 signaling pathway. In this study, we reveal the mechanism by which PCLAF facilitates cell cycle progression and recommend that the PCLAF/E2F1/PTTG1 axis is a therapeutic target in neuroblastoma.

C1GALT1 expression predicts a favorable prognosis and suppresses malignant phenotypes via TrkA signaling in neuroblastoma

Neuroblastoma (NB) is a childhood tumor derived from the sympathoadrenal lineage of the neural crest progenitor cells. Core 1 β1,3-galactosyltransferase (C1GALT1) controls the crucial step of GalNAc-type O-glycosylation, and its altered expression affects cancer behaviors. However, the role of C1GALT1 in NB tumors remains unclear. Our data showed that C1GALT1 expression was significantly associated with differentiated tumor histology, correlated with TrkA expression, and predicted good prognosis independently in NB. Downregulation of C1GALT1 promotes malignant behaviors of NB cells in vitro and in vivo. Mechanistic investigation showed that knockdown of C1GALT1 in NB cells increased TrkA pulled down through Vicia villosa agglutinin beads, indicating the modulation of O-glycans on TrkA by C1GALT1, and silencing C1GALT1 suppressed the TrkA expression on the NB cell surface. Overexpression of C1GALT1 increased the protein levels of TrkA and promoted the differentiation of NB cells, whereas knockdown of TrkA inhibited C1GALT1-induced neuronal differentiation. Moreover, the inhibitory effects of migration and invasion in C1GALT1-overexpressing NB cells were blocked by TrkA downregulation. C1GALT1 knockdown enhanced AKT phosphorylation but attenuated ERK phosphorylation, and these properties were consistent in C1GALT1-overexpressing NB cells with TrkA knockdown. Taken together, our data provided the first evidence for the existence of GalNAc-type O-glycans on TrkA and altered O-glycan structures by C1GALT1 can regulate TrkA signaling in NB cells. This study sheds light on the novel prognostic role of C1GALT1 in NB and provides new information of C1GALT1 and TrkA on the pathogenesis of NB.

Single-cell landscape analysis reveals distinct regression trajectories and novel prognostic biomarkers in primary neuroblastoma

Neuroblastoma (NB), which is the most common pediatric extracranial solid tumor, varies widely in its clinical presentation and outcome. NB has a unique ability to spontaneously differentiate and regress, suggesting a potential direction for therapeutic intervention. However, the underlying mechanisms of regression remain largely unknown, and more reliable prognostic biomarkers are needed for predicting trajectories for NB. We performed scRNA-seq analysis on 17 NB clinical samples and three peritumoral adrenal tissues. Primary NB displayed varied cell constitution, even among tumors of the same pathological subtype. Copy number variation patterns suggested that neuroendocrine cells represent the malignant cell type. Based on the differential expression of sets of related marker genes, a subgroup of neuroendocrine cells was identified and projected to differentiate into a subcluster of benign fibroblasts with highly expressed CCL2 and ZFP36, supporting a progressive pathway of spontaneous NB regression. We also identified prognostic markers (STMN2, TUBA1A, PAGE5, and ETV1) by evaluating intra-tumoral heterogeneity. Lastly, we determined that ITGB1 in M2-like macrophages was associated with favorable prognosis and may serve as a potential diagnostic marker and therapeutic target. In conclusion, our findings reveal novel mechanisms underlying regression and potential prognostic markers and therapeutic targets of NB.

TWIST1 expression is associated with high-risk neuroblastoma and promotes primary and metastatic tumor growth

The embryonic transcription factors TWIST1/2 are frequently overexpressed in cancer, acting as multifunctional oncogenes. Here we investigate their role in neuroblastoma (NB), a heterogeneous childhood malignancy ranging from spontaneous regression to dismal outcomes despite multimodal therapy. We first reveal the association of TWIST1 expression with poor survival and metastasis in primary NB, while TWIST2 correlates with good prognosis. Secondly, suppression of TWIST1 by CRISPR/Cas9 results in a reduction of tumor growth and metastasis colonization in immunocompromised mice. Moreover, TWIST1 knockout tumors display a less aggressive cellular morphology and a reduced disruption of the extracellular matrix (ECM) reticulin network. Additionally, we identify a TWIST1-mediated transcriptional program associated with dismal outcome in NB and involved in the control of pathways mainly linked to the signaling, migration, adhesion, the organization of the ECM, and the tumor cells versus tumor stroma crosstalk. Taken together, our findings confirm TWIST1 as promising therapeutic target in NB.

Prognostic Value of Interim 18F-DOPA and 18F-FDG PET/CT Findings in Stage 3-4 Pediatric Neuroblastoma

PURPOSE

This retrospective study aimed to determine the prognostic value of imaging parameters derived from midtherapy 18F-fluorodihydroxyphenylalanine (18F-DOPA) and 18F-FDG PET in pediatric patients with stage 3-4 neuroblastoma.

METHODS

We enrolled 32 stage 3-4 pediatric neuroblastoma patients who underwent 18F-DOPA and 18F-FDG PET/CT scans before and after 3 chemotherapy cycles. We measured metabolic and volumetric parameters and applied a metabolic burden scoring system to evaluate the primary tumor extent and soft tissue metastases and that of bone/bone marrow involvement. The associations between these parameters and clinical outcomes were investigated.

RESULTS

Over a median follow-up period of 47 months (range, 3-137 months), 16 patients experienced disease progression, and 13 died. After adjustment for clinical factors, multivariate Cox proportional hazard models showed that interim tumor FDG/FDOPA SUVmax (hazard ratio [HR], 5.94; 95% confidence interval [CI], 1.10-34.98) and interim FDOPA whole-body metabolic burden scores (WBMB) (HR, 7.30; 95% CI, 1.50-35.50) were significant prognostic factors for overall survival (OS). Only interim FDOPA WBMB scores (HR, 7.05; 95% CI, 1.02-48.7) were predictive of progression-free survival. Based on median cutoff values, prognosis (OS and progression-free survival) was significantly associated with an interim FDOPA WBMB score ≥21.92 (all P < 0.05) and interim tumor FDG/FDOPA (SUVmax) score ≥0.57 with poor OS (P < 0.05).

CONCLUSIONS

Our results indicate that midtreatment FDG and FDOPA PET/CT could serve as prognostic markers in stage 3-4 neuroblastoma patients.

Recurrent driver mutations in benign tumors

The understanding of the molecular pathogenesis of benign tumors may bring essential information to clarify the process of tumorigenesis, and ultimately improve the understanding of events such as malignant transformation. The definition of benign neoplasia is not always straightforward and herein the issues surrounding this concept are discussed. Benign neoplasms share all cancer hallmarks with malignancies, except for metastatic potential. Recently, next-generation sequencing has provided unprecedented opportunities to unravel the genetic basis of benign neoplasms and, so far, we have learned that benign neoplasms are indeed characterized by the presence of genetic mutations, including genes rearrangements. Driver mutations in advanced cancer are those that confer growth advantage, and which have been positively selected during cancer evolution. Herein, some discussion will be brought about this concept in the context of cancer prevention, involving precursor lesions and benign neoplasms. When considering early detection and cancer prevention, a driver mutation should not only be advantageous (i.e., confer survival advantage), but predisposing (i.e., promoting a cancer phenotype). By including the benign counterparts of malignant neoplasms in tumor biology studies, it is possible to evaluate the risk posed by a given mutation and to differentiate advantageous from predisposing mutations, further refining the concept of driver mutations. Therefore, the study of benign neoplasms should be encouraged because it provides valuable information on tumorigenesis central for understanding the progression from initiation to malignant transformation.

Adoptive Cellular Therapy for Pediatric Solid Tumors: Beyond Chimeric Antigen Receptor-T Cell Therapy

ABSTRACT

Children and adolescents with high-risk (metastatic and relapsed) solid tumors have poor outcomes despite intensive multimodal therapy, and there is a pressing need for novel therapeutic strategies. Adoptive cellular therapy (ACT) has demonstrated activity in multiple adult cancer types, and opportunity exists to expand the use of this therapy in children. Employment of immunotherapy in the pediatric population has realized only modest overall clinical trial results, with success thus far restricted mainly to antibody-based therapies and chimeric antigen receptor T-cell therapies for lymphoid malignancy. As we improve our understanding of the orchestrated cellular and molecular mechanisms involved in ACT, this will provide biologic insight and improved ACT strategies for pediatric malignancies. This review focuses on ACT strategies outside of chimeric antigen receptor T-cell therapy, including completed and ongoing clinical trials, and highlights promising preclinical data in tumor-infiltrating lymphocytes that enhance the clinical efficacy of ACT for high-risk pediatric solid tumors.

Deciphering the Role of MicroRNAs in Neuroblastoma

Neuroblastoma (NB) is a type of peripheral sympathetic nervous system cancer that most commonly affects children. It is caused by the improper differentiation of primitive neural crest cells during embryonic development. Although NB occurs for 8% of paediatric cancers, it accounts for 15% of cancer-related deaths. Despite a considerable increase in cytotoxic chemo- and radiotherapy, patients in advanced stages remain virtually incurable. Therefore, there is a desperate necessity for new treatment strategies to be investigated. Accumulating evidence suggested that microRNAs (miRNAs) are a class of non-coding RNAs with 19–25 nucleotides lengths and play a central role in the development of NB carcinogenesis. Fascinatingly, miRNA inhibitors have an antisense property that can inhibit miRNA function and suppress the activity of mature miRNA. However, many studies have addressed miRNA inhibition in the treatment of NB, but their molecular mechanisms and signalling pathways are yet to be analysed. In this study, we impart the current state of knowledge about the role of miRNA inhibition in the aetiology of NB.

Retrospective Analysis of INRG Clinical and Genomic Factors for 605 Neuroblastomas in Japan: A Report from the Japan Children’s Cancer Group Neuroblastoma Committee (JCCG-JNBSG)

Neuroblastomas (NBs) exhibit broad and divergent clinical behaviors and tumor risk classification at diagnosis is crucial for the selection of an appropriate therapeutic strategy for each patient. The present study aimed to validate the clinical relevance of International Neuroblastoma Risk Group (INRG) prognostic and genomic markers in a Japanese NB cohort using a retrospective analysis. Follow-up data based on 30 common INRG queries in 605 NB cases diagnosed in Japan between 1990 and 2014 were collected and the genome signature of each tumor sample was integrated. As previously indicated, age, tumor stage, MYCN, DNA ploidy, the adrenals as the primary tumor site, serum ferritin and lactate dehydrogenase (LDH) levels, segmental chromosome aberrations, and the number of chromosome breakpoints (BP) correlated with lower survival rates, while the thorax as the primary tumor site and numerical chromosome aberrations correlated with a favorable prognosis. In the patient group with stage 4, MYCN non-amplified tumors (n = 225), one of the challenging subsets for risk stratification, age ≥ 18 months, LDH ≥ 1400 U/L, and BP ≥ 7 correlated with lower overall and event-free survival rates (p < 0.05). The genome subgroup GG-P2s (partial chromosome gain/loss type with 1p/11q losses and 17q gain, n = 30) was strongly associated with a lower overall survival rate (5-year survival rate: 34%, p < 0.05). Therefore, the combination of the tumor genomic pattern (GG-P2s and BP ≥ 7) with age at diagnosis and LDH will be a promising predictor for MYCN-non-amplified high-risk NBs in patient subsets, in accordance with previous findings from the INRG project.

Bioprinted Cancer Model of Neuroblastoma in a Renal Microenvironment as an Efficiently Applicable Drug Testing Platform

Development of new anticancer drugs with currently available animal models is hampered by the fact that human cancer cells are embedded in an animal-derived environment. Neuroblastoma is the most common extracranial solid malignancy of childhood. Major obstacles include managing chemotherapy-resistant relapses and resistance to induction therapy, leading to early death in very-high-risk patients. Here, we present a three-dimensional (3D) model for neuroblastoma composed of IMR-32 cells with amplified genes of the myelocytomatosis viral related oncogene&nbsp;MYCN and the anaplastic lymphoma kinase (ALK) in a renal environment of exclusively human origin, made of human embryonic kidney 293 cells and primary human kidney fibroblasts. The model was produced with two pneumatic extrusion printheads using a commercially available bioprinter. Two drugs were exemplarily tested in this model: While the histone deacetylase inhibitor panobinostat selectively killed the cancer cells by apoptosis induction but did not affect renal cells in the therapeutically effective concentration range, the peptidyl nucleoside antibiotic blasticidin induced cell death in both cell types. Importantly, differences in sensitivity between two-dimensional (2D) and 3D cultures were cell-type specific, making the therapeutic window broader in the bioprinted model and demonstrating the value of studying anticancer drugs in human 3D models. Altogether, this cancer model allows testing cytotoxicity and tumor selectivity of new anticancer drugs, and the open scaffold design enables the free exchange of tumor and microenvironment by any cell type.

MYCN directly targets NeuroD1 to promote cellular proliferation in neuroblastoma

NeuroD1 is a neuronal differentiation factor that contains a basic helix-loop-helix (bHLH) motif. Recently, NeuroD1 was found to be associated with tumorigenesis in neuroblastoma (NB), and is known to promote cell proliferation and migration in these cells. Here, we found that MYCN regulates the expression of NeuroD1 in NB cells, and that the downregulation of MYCN using short hairpin RNAs (shRNA) results in the inhibition of cellular proliferation in NB cells. Moreover, the phenotype induced by MYCN shRNA was rescued by the exogenous expression of NeuroD1. Chromatin immunoprecipitation (ChIP) assay showed that MYCN directly binds to the E-box element in the NeuroD1 promoter region. In addition, our evaluation of two clinical databases showed that there was a positive correlation between the expression of MYCN and NeuroD1 in NB patients, which supports our in vitro data. In conclusion, this study demonstrates that MYCN-regulated NeuroD1 expression is one of the important mechanisms underlying enhanced cellular proliferation induced by the increase of MYCN expression in NB, and our results provide an important therapeutic target for NB in the future.

Neuroblastoma Among Omani Children: Clinical characteristics and survival outcome from a dedicated centre

Objectives

A limited number of publications from the Middle East have focused on neuroblastoma, a common childhood malignancy. This study describes the clinical characteristics and survival outcome of Omani children with neuroblastoma treated at the National Oncology Centre, Oman, between 2010 and 2017.

Methods

From January 2010 to December 2017, data on Omani children aged less than 13 years with neuroblastoma were retrospectively collected. Survival data were statistically correlated with known prognostic factors, including age, stage of disease, MYCN profile and presence of metastasis.

Results

A total of 56 Omani children were included. in this study. The male to female ratio was 1:1. The mean age at presentation was one year and 10 months. The two most common presenting complaints were body masses (48.2%) and constitutional symptoms (33.9%). Approximately, 54.5% were high risk, 35.7% were intermediate risk and 9.8% were low risk. High-risk neuroblastoma was mainly found in children older than one year (76.6%), with low risk mainly observed in children less than one year of age (80%). The overall survival of all groups combined was 74% (P <0.05); the event-free survival (EFS) was 67% (P <0.05). The overall survival rates over five years for the high-risk, intermediate-risk and low risk groups were 60%, 88% and 100%, respectively, and the EFS was 51%, 79% and 100%, respectively.

Conclusion

Omani children with neuroblastoma mainly presented with masses or constitutional symptoms and had an advanced disease at presentation which was associated with inferior survival. The survival outcomes were reasonably similar to published international data.

PPM1D Is a Therapeutic Target in Childhood Neural Tumors

Simple Summary

Medulloblastoma and neuroblastoma are childhood tumors of the central nervous system or the peripheral nervous system, respectively. These are the most common and deadly tumors of childhood. A common genetic feature of medulloblastoma and neuroblastoma is frequent segmental gain or amplification of chromosome 17q. Located on chromosome 17q23.2 is PPM1D which encodes WIP1, a phosphatase that acts as a regulator of p53 and DNA repair. Overexpression of WIP1 correlates with poor patient prognosis. We investigated the effects of genetic or pharmacologic inhibition of WIP1 activity and found that medulloblastoma and neuroblastoma cells were strongly dependent on WIP1 expression for survival. We also tested a number of small molecule inhibitors of WIP1 and show that SL-176 was the most effective compound suppressing the growth of medulloblastoma and neuroblastoma in vitro and in vivo.

Abstract

Childhood medulloblastoma and high-risk neuroblastoma frequently present with segmental gain of chromosome 17q corresponding to aggressive tumors and poor patient prognosis. Located within the 17q-gained chromosomal segments is PPM1D at chromosome 17q23.2. PPM1D encodes a serine/threonine phosphatase, WIP1, that is a negative regulator of p53 activity as well as key proteins involved in cell cycle control, DNA repair and apoptosis. Here, we show that the level of PPM1D expression correlates with chromosome 17q gain in medulloblastoma and neuroblastoma cells, and both medulloblastoma and neuroblastoma cells are highly dependent on PPM1D expression for survival. Comparison of different inhibitors of WIP1 showed that SL-176 was the most potent compound inhibiting medulloblastoma and neuroblastoma growth and had similar or more potent effects on cell survival than the MDM2 inhibitor Nutlin-3 or the p53 activator RITA. SL-176 monotherapy significantly suppressed the growth of established medulloblastoma and neuroblastoma xenografts in nude mice. These results suggest that the development of clinically applicable compounds inhibiting the activity of WIP1 is of importance since PPM1D activating mutations, genetic gain or amplifications and/or overexpression of WIP1 are frequently detected in several different cancers.

Combined Detection of Copy Number Variations of MYCN and ALK using Droplet Digital Polymerase Chain Reaction to Identify High-Risk Patients with Neuroblastoma

OBJECTIVE

The current study sought to explore the significance of copy number variations (CNVs) of MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived [avian]) and ALK (anaplastic lymphoma kinase) genes individually as well as their combined impact on clinical outcome and overall survival of patients with neuroblastoma (NB).

METHODS

A total 71 individuals including healthy controls (n = 11), circulating DNA (n = 11), and primary tumors (n = 49) were evaluated to detect CNVs of MYCN and ALK genes using droplet digital polymerase chain reaction. Data were correlated with univariate and multivariate survival analysis.

RESULTS

CNVs of MYCN and ALK were detected in 27% and 18.2% from circulating DNA samples. A statistically significant difference in CNVs was noted between healthy controls and circulating DNA samples for MYCN (P = 0.001) and ALK (P = 0.004) genes. Further, we noted >70% concordance in CNVs of MYCN (P = 0.030) and ALK (P = 0.040) from primary tumors and concordant plasma samples of patients with NB. Multivariate survival analysis for disease-free survival (P = 0.031) and overall survival (P = 0.011) showed that CNVs of both genes emerged at step 1 and thus remained as significant markers for predicting early recurrence and shorter survival, respectively, for patients with NB.

CONCLUSIONS

Our study showed that the analysis of circulating DNA by droplet digital polymerase chain reaction is a helpful technique to identify high-risk patients for aggressive therapy at an early stage of disease. We also concluded that codetection of MYCN and ALK is a more powerful tool for identifying high-risk patients with NB. Thus, this study showed a novel coordinately significant prognostic role of MYCN and ALK CNVs.

NTRK1/TrkA Activation Overrides the G2/M-Checkpoint upon Irradiation

High expression of the receptor tyrosine kinase TrkA/NTRK1 is associated with a favorable outcome in several solid tumors of childhood including neuroblastoma. During development, TrkA/NTRK1 governs migration and differentiation of neuronal precursor cells, while it is associated with mitotic dysfunction and altered DNA damage response, among others, in neuroblastoma. Here, we used human neuroblastoma cell lines with inducible TrkA/NTRK1 expression to mechanistically explore the role of TrkA/NTRK1 signaling in checkpoint activation after DNA damage induced by ionizing radiation (IR). TrkA/NTRK1 activated cells showed increased short-term cell viability upon IR compared to vector control cells. This was accompanied by a deficient G₂/M-checkpoint at both low (1 Gy) and high doses (4 Gy) of IR. In a tightly controlled setting, we confirmed that this effect was strictly dependent on activation of TrkA/NTRK1 by its ligand, nerve growth factor (NGF). TrkA/NTRK1-expressing cells displayed impaired ATM and CHK1 phosphorylation, resulting in stabilization of CDC25B. In line with these findings, ATM or ATR inhibition recapitulated the effects of TrkA/NTRK1 activation on the IR-induced G₂/M-checkpoint. In conclusion, we here provide first evidence for a previously unrecognized function of NTRK signaling in checkpoint regulation and the response to IR.

Deep analysis of neuroblastoma core regulatory circuitries using online databases and integrated bioinformatics shows their pan-cancer roles as prognostic predictors

AIM

Neuroblastoma is a heterogeneous childhood cancer derived from the neural crest. The dual cell identities of neuroblastoma include Mesenchymal (MES) and Adrenergic (ADRN). These identities are conferred by a small set of tightly-regulated transcription factors (TFs) binding super enhancers, collectively forming core regulatory circuitries (CRCs). The purpose of this study was to gain a deep understanding of the role of MES and ADRN TFs in neuroblastoma and other cancers as potential indicators of disease prognosis, progression, and relapse.

METHODS

To that end, we first investigated the expression and mutational profile of MES and ADRN TFs in neuroblastoma. Moreover, we established their correlation with neuroblastoma risk groups and overall survival while establishing their extended networks with long non-coding RNAs (lncRNAs). Furthermore, we analysed the pan-cancer expression and mutational profile of these TFs and their correlation with patient survival and finally their network connectivity, using a panel of bioinformatic tools including GEPIA2, human pathology atlas, TIMER2, Omicsnet, and Cytoscape.

RESULTS

We show the association of multiple MES and ADRN TFs with neuroblastoma risk groups and overall survival and find significantly higher expression of various MES and ADRN TFs compared to normal tissues and their association with overall survival and disease-free survival in multiple cancers. Moreover, we report the strong correlation of the expression of these TFs with the infiltration of stromal and immune cells in the tumour microenvironment and with stemness and metastasis-related genes. Furthermore, we reveal extended pan-cancer networks comprising these TFs that influence the tumour microenvironment and metastasis and may be useful indicators of cancer prognosis and patient survival.

CONCLUSION

Our meta-analysis shows the significance of MES and ADRN TFs as indicators of patient prognosis and the putative utility of these TFs as potential novel biomarkers.

ATR inhibition enables complete tumour regression in ALK-driven NB mouse models

High-risk neuroblastoma (NB) often involves MYCN amplification as well as mutations in ALK. Currently, high-risk NB presents significant clinical challenges, and additional therapeutic options are needed. Oncogenes like MYCN and ALK result in increased replication stress in cancer cells, offering therapeutically exploitable options. We have pursued phosphoproteomic analyses highlighting ATR activity in ALK-driven NB cells, identifying the BAY1895344 ATR inhibitor as a potent inhibitor of NB cell growth and proliferation. Using RNA-Seq, proteomics and phosphoproteomics we characterize NB cell and tumour responses to ATR inhibition, identifying key components of the DNA damage response as ATR targets in NB cells. ATR inhibition also produces robust responses in mouse models. Remarkably, a 2-week combined ATR/ALK inhibition protocol leads to complete tumor regression in two independent genetically modified mouse NB models. These results suggest that NB patients, particularly in high-risk groups with oncogene-induced replication stress, may benefit from ATR inhibition as therapeutic intervention.

Effective therapeutic options are still needed in neuroblastoma treatment. Here, the authors, through a comprehensive proteomics analysis, identify ATR as a potential therapeutic target of neuroblastoma and demonstrate the efficacy of the ATR inhibitor BAY1895344 in combination with the ALK tyrosine kinase inhibitor lorlatinib.

p53-Mediated Radiosensitization of 177Lu-DOTATATE in Neuroblastoma Tumor Spheroids

p53 is involved in DNA damage response and is an exciting target for radiosensitization in cancer. Targeted radionuclide therapy against somatostatin receptors with ¹⁷⁷Lu-DOTATATE is currently being explored as a treatment for neuroblastoma. The aim of this study was to investigate the novel p53-stabilizing peptide VIP116 in neuroblastoma, both as monotherapy and together with ¹⁷⁷Lu-DOTATATE. Five neuroblastoma cell lines, including two patient-derived xenograft (PDX) lines, were characterized in monolayer cultures. Four out of five were positive for ¹⁷⁷Lu-DOTATATE uptake. IC₅₀ values after VIP116 treatments correlated with p53 status, ranging between 2.8–238.2 μM. IMR-32 and PDX lines LU-NB-1 and LU-NB-2 were then cultured as multicellular tumor spheroids and treated with ¹⁷⁷Lu-DOTATATE and/or VIP116. Spheroid growth was inhibited in all spheroid models for all treatment modalities. The most pronounced effects were observed for combination treatments, mediating synergistic effects in the IMR-32 model. VIP116 and combination treatment increased p53 levels with subsequent induction of p21, Bax and cleaved caspase 3. Combination treatment resulted in a 14-fold and 1.6-fold induction of MDM2 in LU-NB-2 and IMR-32 spheroids, respectively. This, together with differential MYCN signaling, may explain the varying degree of synergy. In conclusion, VIP116 inhibited neuroblastoma cell growth, potentiated ¹⁷⁷Lu-DOTATATE treatment and could, therefore, be a feasible treatment option for neuroblastoma.

A Focus on Regulatory Networks Linking MicroRNAs, Transcription Factors and Target Genes in Neuroblastoma

Neuroblastoma (NB) is a tumor of the peripheral sympathetic nervous system that substantially contributes to childhood cancer mortality. NB originates from neural crest cells (NCCs) undergoing a defective sympathetic neuronal differentiation and although the starting events leading to the development of NB remain to be fully elucidated, the master role of genetic alterations in key oncogenes has been ascertained: (1) amplification and/or over-expression of MYCN, which is strongly associated with tumor progression and invasion; (2) activating mutations, amplification and/or over-expression of ALK, which is involved in tumor initiation, angiogenesis and invasion; (3) amplification and/or over-expression of LIN28B, promoting proliferation and suppression of neuroblast differentiation; (4) mutations and/or over-expression of PHOX2B, which is involved in the regulation of NB differentiation, stemness maintenance, migration and metastasis. Moreover, altered microRNA (miRNA) expression takes part in generating pathogenetic networks, in which the regulatory loops among transcription factors, miRNAs and target genes lead to complex and aberrant oncogene expression that underlies the development of a tumor. In this review, we have focused on the circuitry linking the oncogenic transcription factors MYCN and PHOX2B with their transcriptional targets ALK and LIN28B and the tumor suppressor microRNAs let-7, miR-34 and miR-204, which should act as down-regulators of their expression. We have also looked at the physiologic role of these genetic and epigenetic determinants in NC development, as well as in terminal differentiation, with their pathogenic dysregulation leading to NB oncogenesis.

Biomimetic matrix for the study of neuroblastoma cells: A promising combination of stiffness and retinoic acid

Neuroblastoma is the third most common pediatric cancer composed of malignant immature cells that are usually treated pharmacologically by all trans-retinoic acid (ATRA) but sometimes, they can spontaneously differentiate into benign forms. In that context, biomimetic cell culture models are warranted tools as they can recapitulate many of the biochemical and biophysical cues of normal or pathological microenvironments. Inspired by that challenge, we developed a neuroblastoma culture system based on biomimetic LbL films of physiological biochemical composition and mechanical properties. For that, we used chondroitin sulfate A (CSA) and poly-L-lysine (PLL) that were assembled and mechanically tuned by crosslinking with genipin (GnP), a natural biocompatible crosslinker, in a relevant range of stiffness (30-160 kPa). We then assessed the adhesion, survival, motility, and differentiation of LAN-1 neuroblastoma cells. Remarkably, increasing the stiffness of the LbL films induced neuritogenesis that was strengthened by the combination with ATRA. These results highlight the crucial role of the mechanical cues of the neuroblastoma microenvironment since it can dramatically modulate the effect of pharmacologic drugs. In conclusion, our biomimetic platform offers a promising tool to help fundamental understanding and pharmacological screening of neuroblastoma differentiation and may assist the design of translational biomaterials to support neuronal regeneration. STATEMENT OF SIGNIFICANCE: Neuroblastoma is one of the most common pediatric tumor commonly treated by the administration of all-trans-retinoic acid (ATRA). Unfortunately, advanced neuroblastoma often develop ATRA resistance. Accordingly, in the field of pharmacological investigations on neuroblastoma, there is a tremendous need of physiologically relevant cell culture systems that can mimic normal or pathological extracellular matrices. In that context, we developed a promising matrix-like cell culture model that provides new insights on the crucial role of mechanical properties of the microenvironment upon the success of ATRA treatment on the neuroblastoma maturation. We were able to control adhesion, survival, motility, and differentiation of neuroblastoma cells. More broadly, we believe that our system will help the design of in vitro pharmacological screening strategy.

MYCN in Neuroblastoma: "Old Wine into New Wineskins"

MYCN Proto-Oncogene, BHLH Transcription Factor (MYCN) has been one of the most studied genes in neuroblastoma. It is known for its oncogenetic mechanisms, as well as its role in the prognosis of the disease and it is considered one of the prominent targets for neuroblastoma therapy. In the present work, we attempted to review the literature, on the relation between MYCN and neuroblastoma from all possible mechanistic sites. We have searched the literature for the role of MYCN in neuroblastoma based on the following topics: the references of MYCN in the literature, the gene's anatomy, along with its transcripts, the protein's anatomy, the epigenetic mechanisms regulating MYCN expression and function, as well as MYCN amplification. MYCN plays a significant role in neuroblastoma biology. Its functions and properties range from the forming of G-quadraplexes, to the interaction with miRNAs, as well as the regulation of gene methylation and histone acetylation and deacetylation. Although MYCN is one of the most primary genes studied in neuroblastoma, there is still a lot to be learned. Our knowledge on the exact mechanisms of MYCN amplification, etiology and potential interventions is still limited. The knowledge on the molecular mechanisms of MYCN in neuroblastoma, could have potential prognostic and therapeutic advantages.

EHMT2/G9a as an Epigenetic Target in Pediatric and Adult Brain Tumors

Epigenetic mechanisms, including post-translational modifications of DNA and histones that influence chromatin structure, regulate gene expression during normal development and are also involved in carcinogenesis and cancer progression. The histone methyltransferase G9a (euchromatic histone lysine methyltransferase 2, EHMT2), which mostly mediates mono- and dimethylation by histone H3 lysine 9 (H3K9), influences gene expression involved in embryonic development and tissue differentiation. Overexpression of G9a has been observed in several cancer types, and different classes of G9a inhibitors have been developed as potential anticancer agents. Here, we review the emerging evidence suggesting the involvement of changes in G9a activity in brain tumors, namely glioblastoma (GBM), the main type of primary malignant brain cancer in adults, and medulloblastoma (MB), the most common type of malignant brain cancer in children. We also discuss the role of G9a in neuroblastoma (NB) and the drug development of G9a inhibitors.

CAR T cell therapy in solid tumors; with an extensive focus on obstacles and strategies to overcome the challenges

The application of the CAR T cell therapy in hematologic malignancies holds prosperous results that intensified the unprecedented enthusiasm to employ this fascinating strategy in other types of human malignancies. Although the researchers invested a great deal of effort to exploit the utmost efficacy of these cells in the context of solid tumors, few articles reviewed obstacles and opportunities. The current review aims to provide comprehensive literature of recent advances of CAR T cell therapy in a wide range of solid tumors; and also, to discuss the original data obtained from international research laboratories on this topic. Despite promising results, several radical obstacles are on the way of this approach. This review discusses the most important drawbacks and also responds to questions on how the intrinsic features of solid tumors in addition to the tumor microenvironment-related challenges and the immune-relating adverse effects can curb satisfactory outcomes of CAR T cells. The last section allocates a special focus on innovative and contemporary policies which have already been adopted to surmount these challenges. Finally, we comment on the future research aspects in which the efficacy, as well as the safety of CAR T cell therapy, might be improved.

Neuroblastoma-Telomere maintenance, deregulated signaling transduction and beyond

The childhood malignancy neuroblastoma belongs to the group of embryonal tumors and originates from progenitor cells of the sympathoadrenal lineage. Treatment options for children with high-risk and relapsed disease are still very limited. In recent years, an ever-growing molecular diversity was identified using (epi)-genetic profiling of neuroblastoma tumors, indicating that molecularly targeted therapies could be a promising therapeutic option. In this review article, we summarize the various molecular subtypes and genetic events associated with neuroblastoma and describe recent advances in targeted therapies. We lay a strong emphasis on the importance of telomere maintenance mechanisms for understanding tumor progression and risk classification of neuroblastoma.

Combination of a synthetic retinoid and a DNA demethylating agent induced differentiation of neuroblastoma through retinoic acid signal reprogramming

BACKGROUND

The CpG island methylator phenotype of neuroblastoma (NBL) is strongly associated with poor prognosis and can be targeted by 5-aza-2'-deoxycytidine (5-aza-dC). Differentiation therapy is a standard maintenance therapy for high-risk NBLs. However, the in vivo effect of tamibarotene, a synthetic retinoic acid, and the efficacy of its combination with 5-aza-dC have not been studied. Here, we conducted a preclinical study to assess the in vivo tamibarotene effect and the combination.

METHODS

Treatment effects were analysed by in vitro cell growth and differentiation state and by in vivo xenograft suppression. Demethylated genes were analysed by DNA methylation microarrays and geneset enrichment.

RESULTS

Tamibarotene monotherapy induced neural extension and upregulation of differentiation markers of NBL cells in vitro, and tumour regression without severe side effects in vivo. 5-Aza-dC monotherapy suppressed tumour growth both in vitro and in vivo, and induced demethylation of genes related to nervous system development and function. Pre-treatment with 5-aza-dC in vitro enhanced upregulation of differentiation markers and genes involved in retinoic acid signaling. Pre-treatment with 5-aza-dC in vivo significantly suppressed tumour growth and reduced the variation in tumour sizes.

CONCLUSIONS

Epigenetic drug-based differentiation therapy using 5-aza-dC and TBT is a promising strategy for refractory NBLs.

Analysis of Asymmetric Cell Division Using Human Neuroblastoma Cell Lines as a Model System

Neuroblastoma is one of the most common childhood solid tumors and develops from neural stem cells that normally comprise the embryonic structure termed the neural crest. Human neuroblastoma cell lines have special properties as they exhibit cell growth and are induced to become mature neurons by drugs such as retinoid. Therefore, we examined asymmetric cell division (ACD) using human neuroblastoma cells as an ACD model, and confirmed that ACD in human cancer cells is evolutionally conserved. Furthermore, we demonstrated that MYCN is involved in cell division fate. We introduce the brief history of ACD study using neuroblastoma cell lines and discuss why human neuroblastoma cells are an ideal model system for clarifying the mechanism of ACD.

Establishment and Validation of a Prognostic Immune Signature in Neuroblastoma

BACKGROUND

Neuroblastoma (NBL) is the most common extracranial solid tumor in childhood, and patients with high-risk neuroblastoma had a relatively poor prognosis despite multimodal treatment. To improve immunotherapy efficacy in neuroblastoma, systematic profiling of the immune landscape in neuroblastoma is an urgent need.

METHODS

RNA-seq and according clinical information of neuroblastoma were downloaded from the TARGET database and GEO database (GSE62564). With an immune-related-gene set obtained from the ImmPort database, Immune-related Prognostic Gene Pairs for Neuroblastoma (IPGPN) for overall survival (OS) were established with the TARGET-NBL cohort and then verified with the GEO-NBL cohort. Immune cell infiltration analysis was subsequently performed. The integrated model was established with IPGPN and clinicopathological parameters. Immune cell infiltration was analyzed with the XCELL algorithm. Functional enrichment analysis was performed with clusterProfiler package in R.

RESULTS

Immune-related Prognostic Gene Pairs for Neuroblastoma was successfully established with seven immune-related gene pairs (IGPs) involving 13 unique genes in the training cohort. In the training cohort, IPGPN successfully stratified neuroblastoma patients into a high and low immune-risk groups with different OS (HR=3.92, P = 2 × 10^-8) and event-free survival (HR=3.66, P=2 × 10^-8). ROC curve analysis confirmed its predictive power. Consistently, high IPGPN also predicted worse OS (HR=1.84, P = .002) and EFS in validation cohort (HR=1.38, P = .06) Moreover, higher activated dendritic cells, M1 macrophage, Th1 CD4⁺, and Th2 CD4⁺ T cell enrichment were evident in low immune-risk group. Further integrating IPGPN with age and stage demonstrated improved predictive performance than IPGPN alone.

CONCLUSION

Herein, we presented an immune landscape with IPGPN for prognosis prediction in neuroblastoma, which complements the present understanding of the immune signature in neuroblastoma.