MYCN-non-amplified metastatic neuroblastoma with good prognosis and spontaneous regression: a molecular portrait of stage 4S

Identification and validation of a novel five-gene signature in high-risk MYCN-not-amplified neuroblastoma

OBJECTIVE

High-risk neuroblastoma patients often have poor outcomes despite multi-treatment options. The risk stratification of high-risk MYCN-not-amplified (HR-MYCN-NA) patients remains difficult. This study aims to identify a gene set signature that can help further stratify HR-MYCN-NA patients for a potential personalized therapeutic strategy.

METHODS

Three microarrays and one single-cell RNA sequence dataset were acquired and analyzed. Firstly, the prognostic-related genes (PRGs) in HR-MYCN-NA tumor cells were identified using TARGET-NB and GSE137804 datasets. Then, the prognostic model was established by LASSO-Cox regression, and verified in external cohort (GSE49710, GSE45547). Moreover, a time-dependent receiver operating characteristic curve (ROC) and area under the ROC (AUC) was used to assess survival prediction. A nomogram was established to predict the 1-, 3- and 5-year overall survival (OS) of HR-MYCN-NA patients.

RESULTS

In the training set, a five-PRGs signature, which include GAL, GFRA3, MARCKS, PSMD13, and ZNHIT3 genes, was identified and successfully stratified HR-MYCN-NA patients into ultra-high risk (UHR) and high-risk (HR) subtypes (HR = 4.29, P < 0.001). ROC curve analysis confirmed its predictive power (AUC = 0.74-0.82), suggesting a good predictive efficacy. Consistently, high-risk scores also predicted worse OS (HR = 2, P = 0.033) in the external validation dataset (AUC = 0.67-0.71). Moreover, the overall C-index of the nomogram was 0.75 (P < 0.001), which indicated good agreement between the observed and predicted survival rates. Further integrating the five PRGs signature with clinical factors, these 5 gene signature (HR = 4.45, P < 0.001) and tumor grade (HR = 4.15, P = 0.02) were found to be independent prognostic factors for HR-MYCN-NA patients.

CONCLUSION

The novel five PRGs signature could well predict the survival of HR-MYCN-NA patients, which may provide constructive information for these subsets.

Cytotoxic effect of Rotheca serrata on cancer cell lines MCF-7 and neuroblastoma SH-SY5Y

INTRODUCTION

Rotheca serrata (Lamiaceae), a highly medicinal plant is used as an antidote for snakebite and the plant possesses medicinal properties like hepatoprotective, antitussive, antioxidant, anticancer, neuro-protective, used in rheumatoid arthritis and is also a α-glucoside inhibitor. AIM OF THE STUDY: This work aimed to study the anticancerous effect of Rotheca serrata (root and leaf) on cancer cell lines MCF-7 (breast cancer cell line) and Neuroblastoma SH-SY5Y.

MATERIALS AND METHODS

This investigation was a preliminary one which supported the retrospective and safe use of plants as described in Ayurveda. Dulbecco's Modified Eagle Medium with High Glucose (DMEM-HG) for culturing MCF-7- Human Breast cancer cell line and Minimum essential Medium (MEM)+F12 medium for culturing SH-SY5Y- Homo sapiens bone marrow neuroblast were used. MTT assay measured the cell proliferation rate and conversely, when metabolic events lead to apoptosis or necrosis, the reduction in cell viability.

RESULTS

The results indicated that the Methanolic extract of Rotheca serrata (root and leaf) showed high anticancer activity. Different concentrations of plant extracts (25, 50, 100, 200, 400 µg/ml) were used to study the anticancerous activity, amongst which the significant results were obtained for 400 µg/ml concentration (both root & leaf). Effective anticancer activity against MCF - 7 breast cancer cells was shown in methanoilc extracts and were expressed as IC 50 values; in root (IC 50 value = 61.8259 ± 7.428 µg/ml) and in leaf (IC 50 value = 78.1497 ± 6.316 µg/ml). The MTT assay in case of neuroblastoma (SH-SY5Y) cell lines revealed that 400 µg/ml concentration of leaf methanolic extract showed effective inhibition of cancer cells with IC 50 value 37.8462 ± 2.957 µg/ml as compared to IC 50 value of root methanolic extract which was 57.0895 ± 2.351 µg/ml.

CONCLUSION

R. serrata possess anticancer activity against breast cancer cell line (MCF-7) and neuroblastoma (SH-SY 5Y) cell lines. This study may to design plant-based drugs without side effects. Dosage compensation for specific type of cancer needs to be monitored in patients with 1st stage.

Development and validation of a 21-gene prognostic signature in neuroblastoma

Survival outcomes for patients with neuroblastoma vary markedly and reliable prognostic markers and risk stratification tools are lacking. We sought to identify and validate a transcriptomic signature capable of predicting risk of mortality in patients with neuroblastoma. The TARGET NBL dataset (n = 243) was used to develop the model and two independent cohorts, E-MTAB-179 (n = 478) and GSE85047 (n = 240) were used as validation sets. EFS was the primary outcome and OS was the secondary outcome of interest for all analysis. We identified a 21-gene signature capable of stratifying neuroblastoma patients into high and low risk groups in the E-MTAB-179 (HR 5.87 [3.83-9.01], p < 0.0001, 5 year AUC 0.827) and GSE85047 (HR 3.74 [2.36-5.92], p < 0.0001, 5 year AUC 0.815) validation cohorts. Moreover, the signature remained independent of known clinicopathological variables, and remained prognostic within clinically important subgroups. Further, the signature was effectively incorporated into a risk model with clinicopathological variables to improve prognostic performance across validation cohorts (Pooled Validation HR 6.93 [4.89-9.83], p < 0.0001, 5 year AUC 0.839). Similar prognostic utility was also demonstrated with OS. The identified signature is a robust independent predictor of EFS and OS outcomes in neuroblastoma patients and can be combined with clinically utilized clinicopathological variables to improve prognostic performance.

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.

Comparison of Stage 4 and Stage 4s Neuroblastoma Identifies Autophagy-Related Gene and LncRNA Signatures Associated With Prognosis

Background: The spontaneous regression of neuroblastoma (NB) is most prevalent and well-documented in stage 4s NB patients. However, whether autophagy plays roles in the spontaneous regression of NB is unknown. Objective: This study aimed to identify autophagy-related genes (ARGs) and autophagy-related long non-coding RNAs (lncRNAs) differentially expressed in stage 4 and stage 4s NB and to build prognostic risk signatures on the basis of the ARGs and autophagy-related lncRNAs. Methods: One RNA-sequence (RNA-Seq) dataset (TARGET NBL, n = 153) was utilized as discovery cohort, and two microarray datasets (n = 498 and n = 223) were used as validation cohorts. Differentially expressed ARGs were identified by comparing stage 4s and stage 4 NB samples. An ARG signature risk score and an autophagy-related lncRNA signature risk score were constructed. The receiver operating characteristic (ROC) curve analyses were used to evaluate the survival prediction ability of the two signatures. Gene function annotation and Gene Set Enrichment Analysis (GSEA) were performed to clarify the autophagic biological processes enriched in different risk groups. Results: Nine ARGs were integrated into the ARG signature. Patients in the high-risk group of the ARG signature had significantly poorer overall survival (OS) than patients in the low-risk group. The ROC curves analyses revealed that the ARG signature performed very well in predicting OS [5-year area under the curve (AUC) = 0.81]. Seven autophagy-related lncRNAs were integrated into the autophagy-related lncRNA signature. Patients in the high-risk group of the lncRNA signature had significantly poorer OS than patients in the low-risk group. The ROC curve analyses also revealed that the lncRNA signature performed well in predicting OS (5-year AUC = 0.77). Both the ARG signature and lncRNA signature are independent with other clinical risk factors in the multivariate Cox regression survival analyses. GSEAs revealed that autophagy-related biological processes are enriched in low-risk groups. Conclusions: Autophagy-related genes and lncRNAs are differentially expressed between stage 4 and stage 4s NB. The ARG signature and autophagy-related lncRNA signature successfully stratified NB patients into two risk groups. Autophagy-related biological processes are highly enriched in low-risk NB groups.

Combined analysis of RNA-sequence and microarray data reveals effective metabolism-based prognostic signature for neuroblastoma

The relationship between metabolism reprogramming and neuroblastoma (NB) is largely unknown. In this study, one RNA‐sequence data set (n = 153) was used as discovery cohort and two microarray data sets (n = 498 and n = 223) were used as validation cohorts. Differentially expressed metabolic genes were identified by comparing stage 4s and stage 4 NBs. Twelve metabolic genes were selected by LASSO regression analysis and integrated into the prognostic signature. The metabolic gene signature successfully stratifies NB patients into two risk groups and performs well in predicting survival of NB patients. The prognostic value of the metabolic gene signature is also independent with other clinical risk factors. Nine metabolism‐related long non‐coding RNAs (lncRNAs) were also identified and integrated into the metabolism‐related lncRNA signature. The lncRNA signature also performs well in predicting survival of NB patients. These results suggest that the metabolic signatures have the potential to be used for risk stratification of NB. Gene set enrichment analysis (GSEA) reveals that multiple metabolic processes (including oxidative phosphorylation and tricarboxylic acid cycle, both of which are emerging targets for cancer therapy) are enriched in the high‐risk NB group, and no metabolic process is enriched in the low‐risk NB group. This result indicates that metabolism reprogramming is associated with the progression of NB and targeting certain metabolic pathways might be a promising therapy for NB.

Identification of prognostic long noncoding RNAs associated with spontaneous regression of neuroblastoma

Background

The association between long noncoding RNAs (lncRNAs) and spontaneous regression of neuroblastoma (NB) has rarely been investigated and remains unknown.

Objective

To identify prognostic lncRNAs involved in the spontaneous regression of NB.

Methods

Differential expression analyses were performed between those samples with an outcome of death in stage 4 NB group and those samples with an outcome of survival in stage 4S NB group in two independent public datasets, respectively. Univariate Cox proportional hazard regression survival analysis was performed in each of the entire cohort to identify those lncRNAs significantly associated with overall survival (OS). Those lncRNAs independently associated with OS were then identified by multivariate Cox survival analysis and used to construct an lncRNA risk score.

Results

A total of 20 differentially expressed and survival‐related lncRNAs were identified sharing between the two independent cohorts. The expression of each of these 20 lncRNAs was significantly correlated with the expression of NTRK1, which is a well‐known factor involved in NB spontaneous regression. Four lncRNAs (LNC00839, FIRRE, LOC283177, and LOC101928100) were identified to be significantly associated with survival independent with each other and a four‐lncRNA signature risk score was constructed. Patients with high lncRNA signature risk score had a significantly poorer OS and event‐free survival than those with low lncRNA signature risk score. The four‐lncRNA signature has a good performance in predicting survival independent with MYCN amplification (nonamplified vs amplified), age status (<18 months vs ≥18 months), risk status (low risk vs high risk), and International Neuroblastoma Staging System (INSS) stage (INSS 1/2/3/4S vs INSS 4).

Conclusions

We identified 20 survival‐related lncRNAs that might be associated with the spontaneous regression of NB and developed a four‐lncRNA signature risk score. The four‐lncRNA signature is an independent prognostic factor for survival of NB patients.

Discovery, characterization and potential roles of a novel NF-YAx splice variant in human neuroblastoma

BACKGROUND

Identification of novel cancer-associated splice variants is of potential diagnostic, prognostic and therapeutic importance. NF-Y transcription factor is comprised of NF-YA, NF-YB and NF-YC subunits, binds inverted CCAAT-boxes in ≈70% of gene promoters, regulates > 1000 cancer-associated genes and proteins involved in proliferation, staminality, differentiation, apoptosis, metabolism and is subject to component alternative splicing. RT-PCR evaluation of alternative NF-YA splicing in primary human neuroblastomas (NBs), led to discovery of a novel NF-YAx splice variant, also expressed during mouse embryo development and induced by doxorubicin in NB cells. Here, we report the discovery and characterisation of NF-YAx and discus its potential roles in NB.

METHODS

NF-YAx cDNA was RT-PCR-cloned from a stage 3 NB (provided by the Italian Association of Haematology and Paediatric Oncology, Genova, IT), sequenced and expressed as a protein using standard methods and compared to known fully-spliced NF-YAl and exon B-skipped NF-YAs isoforms in: EMSAs for capacity to form NF-Y complexes; by co-transfection, co-immunoprecipitation and Western blotting for capacity to bind Sp1; by IF for localisation; in AO/EtBr cell-death and colony formation assays for relative cytotoxicity, and by siRNA knockdown, use of inhibitors and Western blotting for potential mechanisms of action. Stable SH-SY5Y transfectants of all three NF-YA isoforms were also propagated and compared by RT-PCR and Western blotting for differences in cell-death and stem cell (SC)-associated gene expression, in cell-death assays for sensitivity to doxorubicin and in in vitro proliferation, substrate-independent growth and in vivo tumour xenograft assays for differences in growth and tumourigenic capacity.

RESULTS

NF-YAx was characterized as a novel variant with NF-YA exons B, D and partial F skipping, detected in 20% of NF-YA positive NBs, was the exclusive isoform in a stage 3 NB, expressed in mouse stage E11.5-14 embryos and induced by doxorubicin in SH-SY5Y NB cells. The NF-YAx protein exhibited nuclear localisation, competed with other isoforms in CCAAT box-binding NF-Y complexes but, in contrast to other isoforms, did not bind Sp1. NF-YAx expression in neural-related progenitor and NB cells repressed Bmi1 expression, induced KIF1Bβ expression and promoted KIF1Bβ-dependent necroptosis but in NB cells also selected tumourigenic, doxorubicin-resistant, CSC-like sub-populations, resistant to NF-YAx cytotoxicity.

CONCLUSIONS

The discovery of NF-YAx in NBs, its expression in mouse embryos and induction by doxorubicin in NB cells, unveils a novel NF-YA splice mechanism and variant, regulated by and involved in development, genotoxic-stress and NB. NF-YAx substitution of other isoforms in NF-Y complexes and loss of capacity to bind Sp1, characterises this novel isoform as a functional modifier of NF-Y and its promotion of KIF1Bβ-dependent neural-lineage progenitor and NB cell necroptosis, association with doxorubicin-induced necroptosis and expression in mouse embryos coinciding with KIF1Bβ-dependent sympathetic neuroblast-culling, confirm a cytotoxic function and potential role in suppressing NB initiation. On the other hand, the in vitro selection of CSC-like NB subpopulations resistant to NF-YAx cytotoxicity not only helps to explain high-level exclusive NF-YAx expression in a stage 3 NB but also supports a role for NF-YAx in disease progression and identifies a potential doxorubicin-inducible mechanism for post-therapeutic relapse.

Hijacking of Embryonic Programs by Neural Crest-Derived Neuroblastoma: From Physiological Migration to Metastatic Dissemination

In the developing organism, complex molecular programs orchestrate the generation of cells in adequate numbers, drive them to migrate along the correct pathways towards appropriate territories, eliminate superfluous cells, and induce terminal differentiation of survivors into the appropriate cell-types. Despite strict controls constraining developmental processes, malignancies can emerge in still immature organisms. This is the case of neuroblastoma (NB), a highly heterogeneous disease, predominantly affecting children before the age of 5 years. Highly metastatic forms represent half of the cases and are diagnosed when disseminated foci are detectable. NB arise from a transient population of embryonic cells, the neural crest (NC), and especially NC committed to the establishment of the sympatho-adrenal tissues. The NC is generated at the dorsal edge of the neural tube (NT) of the vertebrate embryo, under the action of NC specifier gene programs. NC cells (NCCs) undergo an epithelial to mesenchymal transition, and engage on a remarkable journey in the developing embryo, contributing to a plethora of cell-types and tissues. Various NCC sub-populations and derived lineages adopt specific migratory behaviors, moving individually as well as collectively, exploiting the different embryonic substrates they encounter along their path. Here we discuss how the specific features of NCC in development are re-iterated during NB metastatic behaviors.

Stage 4 s neuroblastoma: features, management and outcome of 268 cases from the Italian Neuroblastoma Registry

BACKGROUND

Infants diagnosed with stage 4 s neuroblastoma commonly experience spontaneous disease regression, with few succumbing without response to therapy. We analyzed a large cohort of such infants enrolled in the Italian Neuroblastoma Registry to detect changes over time in presenting features, treatment and outcome.

METHODS

Of 3355 subjects aged 0-18 years with previously untreated neuroblastoma diagnosed between 1979 and 2013, a total of 280 infants (8.3%) had stage 4 s characteristics, 268 of whom were eligible for analyses. Three treatment eras were identified on the basis of based diagnostic and chemotherapy adopted. Group 1 patients received upfront chemotherapy; Group 2 and 3 patients underwent observation in the absence of life-threatening symptoms (LTS), except for Group 3 patients with amplified MYCN gene, who received more aggressive therapy.

RESULTS

The three groups were comparable, with few exceptions. Ten-year overall survival significantly increased from 76.9 to 89.7% and was worse for male gender, age 0-29 days and presence of selected LTS on diagnosis, elevated LDH, and abnormal biologic features. Infants who underwent primary resection ± chemotherapy did significantly better. On multivariate analysis, treatment eras and the association of hepatomegaly to dyspnea were independently associated with worse outcome.

CONCLUSIONS

Our data confirm that stage 4 s neuroblastoma is curable in nearly 90% of cases. Hepatomegaly associated to dyspnea was the most important independent risk factor. The cure rate could be further increased through timely identification of patients at risk who might benefit from surgical techniques, such as intra-arterial chemoembolization and/or liver transplantation, which must be carried out in institutions with specific expertise.

Identification of Potential Prognostic Genes for Neuroblastoma

Background and Objective: Neuroblastoma (NB), the most common pediatric solid tumor apart from brain tumor, is associated with dismal long-term survival. The aim of this study was to identify a gene signature to predict the prognosis of NB patients.

Materials and Methods: GSE49710 dataset from the Gene Expression Omnibus (GEO) database was downloaded and differentially expressed genes (DEGs) were analyzed using R package “limma” and SPSS software. The gene ontology (GO) and pathway enrichment analysis were established via DAVID database. Random forest (RF) and risk score model were used to pick out the gene signature in predicting the prognosis of NB patients. Simultaneously, the receiving operating characteristic (ROC) and Kaplan-Meier curve were plotted. GSE45480 and GSE16476 datasets were employed to validate the robustness of the gene signature.

Results: A total of 131 DEGs were identified, which were mainly enriched in cancer-related pathways. Four genes (ERCC6L, AHCY, STK33, and NCAN) were selected as a gene signature, which was included in the top six important features in RF model, to predict the prognosis in NB patients, its area under the curve (AUC) could reach 0.86, and Cox regression analysis revealed that the 4-gene signature was an independent prognostic factor of overall survival and event-free survival. As well as in GSE16476. Additionally, the robustness of discriminating different groups of the 4-gene signature was verified to have a commendable performance in GSE45480 and GSE49710.

Conclusion: The present study identified a gene-signature in predicting the prognosis in NB, which may provide novel prognostic markers, and some of the genes may be as treatment targets according to biological experiments in the future.

Defining Risk Factors for Chemotherapeutic Intervention in Infants With Stage 4S Neuroblastoma: A Report From Children's Oncology Group Study ANBL0531

PURPOSE

Infants with stage 4S neuroblastoma usually have favorable outcomes with observation or minimal chemotherapy. However, young infants with symptoms secondary to massive hepatomegaly or with unfavorable tumor biology are at high risk of death. Our aim was to improve outcomes for patients with symptomatic and/or unfavorable biology 4S neuroblastoma with a uniform treatment approach using a biology- and response-based algorithm.

PATIENTS AND METHODS

The subset of patients with 4S disease with MYCN-not amplified tumors with impaired or impending organ dysfunction, or with unfavorable histology and/or diploid DNA index, were eligible. Patients were assigned to receive two, four, or eight cycles of chemotherapy on the basis of histology, diploid DNA index, chromosome arm 1p or 11q loss of heterozygosity (LOH) status, and symptoms.

RESULTS

Forty-nine eligible patients were enrolled: 41 were symptomatic and 28 had unfavorable biology. Seventeen patients (symptomatic, favorable biology) were assigned two cycles, 21 patients (any unfavorable biologic feature without 1p or 11q LOH) were assigned four cycles, and 11 patients (unfavorable biology including 1p and/or 11q LOH [n = 7] or symptomatic with unknown biology [n = 4]), were assigned eight cycles. The 3-year overall survival was 81.4% ± 5.8%. Eight of nine deaths were in patients younger than 2 months of age at diagnosis (median, 9 days [range, 1 to 68 days]): five acute deaths were a result of hepatomegaly and associated toxicities; two were a result of late relapse in patients with unfavorable biology; and two were a result of treatment complications. No deaths occurred after protocol-mandated pre-emptive treatment of infants younger than 2 months with hepatomegaly, regardless of symptoms. A new scoring algorithm for emergent chemotherapy in patients with 4S disease was developed on the basis of this experience.

CONCLUSION

The outcome for 4S neuroblastoma can be improved with pre-emptive chemotherapy for evolving hepatomegaly or other baseline comorbidities in infants younger than 2 months of age.

Event-free survival of infants and toddlers enrolled in the HR-NBL-1/SIOPEN trial is associated with the level of neuroblastoma mRNAs at diagnosis

BACKGROUND

The purpose of this study was to evaluate whether levels of neuroblastoma mRNAs in bone marrow and peripheral blood from stage M infants (≤12 months of age at diagnosis, MYCN amplified) and toddlers (between 12 and 18 months, any MYCN status) predict event-free survival (EFS).

METHODS

Bone marrow aspirates and peripheral blood samples from 97 infants/toddlers enrolled in the European High-Risk Neuroblastoma trial were collected at diagnosis in PAXgene™ blood RNA tubes. Samples were analyzed by reverse transcription quantitative polymerase chain reaction according to standardized procedures.

RESULTS

Bone marrow tyrosine hydroxylase (TH) or paired-like homeobox 2b (PHOX2B) levels in the highest tertile were associated with worse EFS; hazard ratios, adjusted for age and MYCN status, were 1.5 and 1.8 respectively. Expression of both TH and PHOX2B in the highest tertile predicted worse outcome (p = 0.015), and identified 20 (23%) infants/toddlers with 5-year EFS of 20% (95%CI: 4%-44%). Prognostic significance was maintained after adjusting for over-fitting bias (p = 0.038), age and MYCN status. In peripheral blood, PHOX2B levels in the highest tertile predicted a two-fold increased risk of an event (p = 0.032), and identified 23 (34%) infants/toddlers with 5-year EFS of 29% (95%CI: 12%-48%). Time-dependent receiver operating characteristic analysis confirmed the prognostic value of combined TH and PHOX2B in bone marrow and of PHOX2B in peripheral blood during the first year of follow-up.

CONCLUSIONS

High levels of bone marrow TH and PHOX2B and of peripheral blood PHOX2B at diagnosis allow early identification of a group of high-risk infant and toddlers with neuroblastoma who may be candidates for alternative treatments. Integration with additional biomarkers, as well as validation in additional international trials is warranted.

Spontaneous regression of neuroblastoma

Neuroblastomas are characterized by heterogeneous clinical behavior, from spontaneous regression or differentiation into a benign ganglioneuroma, to relentless progression despite aggressive, multimodality therapy. Indeed, neuroblastoma is unique among human cancers in terms of its propensity to undergo spontaneous regression. The strongest evidence for this comes from the mass screening studies conducted in Japan, North America and Europe and it is most evident in infants with stage 4S disease. This propensity is associated with a pattern of genomic change characterized by whole chromosome gains rather than segmental chromosome changes but the mechanism(s) underlying spontaneous regression are currently a matter of speculation. There is evidence to support several possible mechanisms of spontaneous regression in neuroblastomas: (1) neurotrophin deprivation, (2) loss of telomerase activity, (3) humoral or cellular immunity and (4) alterations in epigenetic regulation and possibly other mechanisms. It is likely that a better understanding of the mechanisms of spontaneous regression will help to identify targeted therapeutic approaches for these tumors. The most easily targeted mechanism is the delayed activation of developmentally programmed cell death regulated by the tropomyosin receptor kinase A (TrkA) pathway. Pan-Trk inhibitors are currently in clinical trials and so Trk inhibition might be used as the first line of therapy in infants with biologically favorable tumors that require treatment. Alternative approaches consist of breaking immune tolerance to tumor antigens but approaches to telomere shortening or epigenetic regulation are not easily druggable. The different mechanisms of spontaneous neuroblastoma regression are reviewed here, along with possible therapeutic approaches.

Origin and initiation mechanisms of neuroblastoma

Neuroblastoma is an embryonal malignancy that affects normal development of the adrenal medulla and paravertebral sympathetic ganglia in early childhood. Extensive studies have revealed the molecular characteristics of human neuroblastomas, including abnormalities at genome, epigenome and transcriptome levels. However, neuroblastoma initiation mechanisms and even its origin are long-standing mysteries. In this review article, we summarize the current knowledge about normal development of putative neuroblastoma sources, namely sympathoadrenal lineage of neural crest cells and Schwann cell precursors that were recently identified as the source of adrenal chromaffin cells. A plausible origin of enigmatic stage 4S neuroblastoma is also discussed. With regard to the initiation mechanisms, we review genetic abnormalities in neuroblastomas and their possible association to initiation mechanisms. We also summarize evidences of neuroblastoma initiation observed in genetically engineered animal models, in which epigenetic alterations were involved, including transcriptomic upregulation by N-Myc and downregulation by polycomb repressive complex 2. Finally, several in vitro experimental methods are proposed that hopefully will accelerate our comprehension of neuroblastoma initiation. Thus, this review summarizes the state-of-the-art knowledge about the mechanisms of neuroblastoma initiation, which is critical for developing new strategies to cure children with neuroblastoma.

Toxicological and efficacy assessment of post-transition metal (Indium) phthalocyanine for photodynamic therapy in neuroblastoma

Metallo-phthalocyanines due to their photophysical characteristics as high yield of triplet state and long lifetimes, appear to be good candidates for photodynamic therapy (PDT). Complexes with diamagnetic metals such as Zn2+, Al3+ Ga3+ and In3+meet such requirements and are recognized as potential PDT agents. Clinically, Photofrin® PDT in neuroblastoma therapy proved in pediatric subjects diagnosed with progressive/recurrent malignant brain tumors increased progression free survival and overall survival outcome. Our study focuses on the dark toxicity testing of a Chloro-Indium-phthalocyanine photosensitizer (In-Pc) upon SH-SY5Y neuroblastoma cell line and its experimental in vitro PDT. Upon testing, In-Pc has shown a relatively high singlet oxygen quantum yield within the cells subjected to PDT (0.553), and 50 μg/mL IC50. Classical toxicological and efficacy assessment were completed with dynamic cellular impedance measurement methodology. Using this technology we have shown that long time incubation of neuroblastoma cell lines in In-Pc (over 5 days) does not significantly hinder cell proliferation when concentration are ≤ 10 μg/mL. When irradiating neuroblastoma cells loaded with non-toxic concentration of In-Pc, 50% of cells entered apoptosis. Transmission electron microscopy has confirmed apoptotic characteristics of cells. Investigating the proliferative capacity of the in vitro treated cells we have shown that cells that "escape" the irradiation protocol, present a reduced proliferative capacity. In conclusion, In-Pc represents another photosensitizer that can display sound PDT properties enhancing neuroblastoma therapy armentarium.

An improved method for bivariate meta-analysis when within-study correlations are unknown

Multivariate meta-analysis, which jointly analyzes multiple and possibly correlated outcomes in a single analysis, is becoming increasingly popular in recent years. An attractive feature of the multivariate meta-analysis is its ability to account for the dependence between multiple estimates from the same study. However, standard inference procedures for multivariate meta-analysis require the knowledge of within-study correlations, which are usually unavailable. This limits standard inference approaches in practice. Riley et al proposed a working model and an overall synthesis correlation parameter to account for the marginal correlation between outcomes, where the only data needed are those required for a separate univariate random-effects meta-analysis. As within-study correlations are not required, the Riley method is applicable to a wide variety of evidence synthesis situations. However, the standard variance estimator of the Riley method is not entirely correct under many important settings. As a consequence, the coverage of a function of pooled estimates may not reach the nominal level even when the number of studies in the multivariate meta-analysis is large. In this paper, we improve the Riley method by proposing a robust variance estimator, which is asymptotically correct even when the model is misspecified (ie, when the likelihood function is incorrect). Simulation studies of a bivariate meta-analysis, in a variety of settings, show a function of pooled estimates has improved performance when using the proposed robust variance estimator. In terms of individual pooled estimates themselves, the standard variance estimator and robust variance estimator give similar results to the original method, with appropriate coverage. The proposed robust variance estimator performs well when the number of studies is relatively large. Therefore, we recommend the use of the robust method for meta-analyses with a relatively large number of studies (eg, m≥50). When the sample size is relatively small, we recommend the use of the robust method under the working independence assumption. We illustrate the proposed method through 2 meta-analyses.

Downregulation of bone morphogenetic protein receptor 2 promotes the development of neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor of childhood. In this study, we examined the expression of bone morphogenetic protein receptor 2 (BMPR2) in primary NB and adjacent non-tumor samples (adrenal gland). BMPR2 expression was significantly downregulated in NB tissues, particularly in high-grade NB, and was inversely related to the expression of the NB differentiation markers ferritin and enolase. The significance of the downregulation was further explored in cultured NB cells. While enforced expression of BMPR2 decreased cell proliferation and colony-forming activity, shRNA-mediated knockdown of BMPR2 led to increased cell growth and clonogenicity. In mice, NB cells harboring BMPR2 shRNA showed significantly increased tumorigenicity compared with control cells. We also performed a retrospective analysis of NB patients and identified a significant positive correlation between tumor BMPR2 expression and overall survival. These findings suggest that BMPR2 may play an important role in the development of NB.

The role of stem cells in benign tumors

As stem cells contribute to the development and homeostasis of normal adult tissues, malfunction of stem cells in self-renewal and differentiation has been associated with tumorigenesis. A growing number of evidences indicating that tumor initiating cells play a crucial role, not only in malignancies, but also in generation and development of benign tumors. Here we offer an overview of the identification and functional characterization of benign tumor initiating cells in several tissues and organs, which typically show capacities of uncontrolled self-renewal to fuel the tumor growth and abnormal differentiation to give rise to tumor heterogeneity. They may originate from alteration of normal stem cells, which confer the benign tumor initiating cells with different repertoire of "stemness". The plastic functions of benign tumor initiating cells are determined by niche regulation mediated via several signaling and epigenetic cues. Therefore, targeting stem cell function represents an important strategy for understanding the biology and management of benign tumors.

An 18 gene expression-based score classifier predicts the clinical outcome in stage 4 neuroblastoma

Background

The prognosis of children with metastatic stage 4 neuroblastoma (NB) has remained poor in the past decade.

Patients and methods

Using microarray analyses of 342 primary tumors, we here developed and validated an easy to use gene expression-based risk score including 18 genes, which can robustly predict the outcome of stage 4 patients.

Results

This classifier was a significant predictor of overall survival in two independent validation cohorts [cohort 1 (n = 214): P = 6.3 × 10⁻⁵; cohort 2 (n = 27): P = 3.1 × 10⁻²]. The prognostic value of the risk score was validated by multivariate analysis including the established markers age and MYCN status (P = 0.027). In the pooled validation cohorts (n = 241), integration of the risk score with the age and/or MYCN status identified subgroups with significantly differing overall survival (ranging from 35 to 100 %).

Conclusion

Together, the 18-gene risk score classifier can identify patients with stage 4 NB with favorable outcome and may therefore improve risk assessment and treatment stratification of NB patients with disseminated disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0896-7) contains supplementary material, which is available to authorized users.

MYCN controls an alternative RNA splicing program in high-risk metastatic neuroblastoma

The molecular mechanisms underlying the aggressive behavior of MYCN driven neuroblastoma (NBL) is under intense investigation; however, little is known about the impact of this family of transcription factors on the splicing program. Here we used high-throughput RNA sequencing to systematically study the expression of RNA isoforms in stage 4 MYCN-amplified NBL, an aggressive subtype of metastatic NBL. We show that MYCN-amplified NBL tumors display a distinct gene splicing pattern affecting multiple cancer hallmark functions. Six splicing factors displayed unique differential expression patterns in MYCN-amplified tumors and cell lines, and the binding motifs for some of these splicing factors are significantly enriched in differentially-spliced genes. Direct binding of MYCN to promoter regions of the splicing factors PTBP1 and HNRNPA1 detected by ChIP-seq demonstrates that MYCN controls the splicing pattern by direct regulation of the expression of these key splicing factors. Furthermore, high expression of PTBP1 and HNRNPA1 was significantly associated with poor overall survival of stage4 NBL patients (p ≤ 0.05). Knocking down PTBP1, HNRNPA1 and their downstream target PKM2, an isoform of pro-tumor-growth, result in repressed growth of NBL cells. Therefore, our study reveals a novel role of MYCN in controlling global splicing program through regulation of splicing factors in addition to its well-known role in the transcription program. These findings suggest a therapeutically potential to target the key splicing factors or gene isoforms in high-risk NBL with MYCN-amplification.

Image-defined risk factor assessment of neurogenic tumors after neoadjuvant chemotherapy is useful for predicting intra-operative risk factors and the completeness of resection

BACKGROUND

Patients with neuroblastoma are now stratified at diagnosis according to the presence and number of image-defined risk factors (IDRFs). We examined the added value of IDRF assessment after neoadjuvant chemotherapy for predicting surgical resection.

MATERIAL AND METHODS

From 2009-2012, 39 out of 91 patients operated on in our institution for neuroblastic tumors received neoadjuvant chemotherapy based on ongoing SIOPEN protocols or treatment guidelines. IDRFs were assessed both at diagnosis and preoperatively on CT and/or MRI.

RESULTS

Median age at diagnosis was 30 months [range 2-191]. The tumor locations were adrenal (n = 20), paravertebral (n = 13) and perivascular (n = 6). INRGSS stages were L2 (n = 13), M (n = 25) and Ms (n = 1). Eleven tumors (28%) were MYCN-amplified. Chemotherapy reduced the number of IDRFs in 54% of patients overall (21/39): 61.5% (16/26) of M and Ms patients, and 38.5% (5/13) of non metastatic patients (P < 0.001). The number of IDRFs lost after chemotherapy was proportional to the degree of tumor shrinkage (P = 0.002), independent of the primary tumor location (P = 0.73), although the number was higher in patients with left versus right adrenal locations (P = 0.004). Patients with neuroblastoma on post-surgical histology lost more IDRFs (median: 1[0-9]) than patients with ganglioneuroblastoma (median: 0[0-4]) (P < 0.001). The completeness of resection was related only to the number of preoperative IDRFs (P = 0.028).

CONCLUSION

IDRF assessment after neoadjuvant chemotherapy is useful for predicting completeness of resection of neurogenic tumors. A larger international study is needed to confirm these results and to explore a possible correlation between preoperative IDRF status and survival.

Individual patient risk stratification of high-risk neuroblastomas using a two-gene score suited for clinical use

Several gene expression-based prognostic signatures have been described in neuroblastoma, but none have successfully been applied in the clinic. Here we have developed a clinically applicable prognostic gene signature, both with regards to number of genes and analysis platform. Importantly, it does not require comparison between patients and is applicable amongst high-risk patients. The signature is based on a two-gene score (R-score) with prognostic power in high-stage tumours (stage 4 and/or MYCN-amplified diagnosed after 18 months of age). QPCR-based and array-based analyses of matched cDNAs confirmed cross platform (array-qPCR) transferability. We also defined a fixed cut-off value identifying prognostically differing subsets of high-risk patients on an individual patient basis. This gene expression signature independently contributes to the current neuroblastoma classification system, and if prospectively validated could provide further stratification of high-risk patients, and potential upfront identification of a group of patients that are in need of new/additional treatment regimens.

Mechanisms of neuroblastoma regression

Recent genomic and biological studies of neuroblastoma have shed light on the dramatic heterogeneity in the clinical behaviour of this disease, which spans from spontaneous regression or differentiation in some patients, to relentless disease progression in others, despite intensive multimodality therapy. This evidence also suggests several possible mechanisms to explain the phenomena of spontaneous regression in neuroblastomas, including neurotrophin deprivation, humoral or cellular immunity, loss of telomerase activity and alterations in epigenetic regulation. A better understanding of the mechanisms of spontaneous regression might help to identify optimal therapeutic approaches for patients with these tumours. Currently, the most druggable mechanism is the delayed activation of developmentally programmed cell death regulated by the tropomyosin receptor kinase A pathway. Indeed, targeted therapy aimed at inhibiting neurotrophin receptors might be used in lieu of conventional chemotherapy or radiation in infants with biologically favourable tumours that require treatment. Alternative approaches consist of breaking immune tolerance to tumour antigens or activating neurotrophin receptor pathways to induce neuronal differentiation. These approaches are likely to be most effective against biologically favourable tumours, but they might also provide insights into treatment of biologically unfavourable tumours. We describe the different mechanisms of spontaneous neuroblastoma regression and the consequent therapeutic approaches.

TAZ promotes epithelial to mesenchymal transition via the upregulation of connective tissue growth factor expression in neuroblastoma cells

Neuroblastoma (NB) is a neuroendocrine cancer that occurs most commonly in infants and young children. The Hippo signaling pathway regulates cell proliferation and apoptosis, and its primary downstream effectors are TAZ and yes‑associated protein 1 (YAP). The effect of TAZ on the metastatic progression of neuroblastoma and the underlying mechanisms involved remain elusive. In the current study, it was determined by western blot analysis that the migratory and invasive properties of SK‑N‑BE(2) human neuroblastoma cells are associated with high expression levels of TAZ. Repressed expression of TAZ in SK‑N‑BE(2) cells was shown to result in a reduction in aggressiveness of the cell line, by Transwell migration and invasion assay. In contrast, overexpression of TAZ in SK‑N‑SH human neuroblastoma cells was shown by Transwell migration and invasion assays, and western blot analysis, to result in epithelial‑mesenchymal transition (EMT) and increased invasiveness. Mechanistically, the overexpression of TAZ was demonstrated to upregulate the expression levels of connective tissue growth factor (CTGF), by western blot analysis and chromatin immunoprecipitation assay, while the knockdown of TAZ downregulated it. Furthermore, TAZ was shown by luciferase assay to induce CTGF expression by modulating the activation of the TGF‑β/Smad3 signaling pathway. In conclusion, the present study is, to the best of our knowledge, the first to demonstrate that the overexpression of TAZ induces EMT, increasing the invasive abilities of neuroblastoma cells. This suggests that TAZ may serve as a potential target in the development of novel therapies for the treatment of neuroblastoma.

Anti-tumor activity of safranal against neuroblastoma cells

Objective:

Safranal (2,6,6-trimethyl-1,3-cyclohexadiene-1-carboxaldehyde, C10H14O) is an active ingredient in the saffron, which is used in traditional medicine, and also, the biological activity of saffron in anti-cancer is in development. It has been reported to have anti-oxidant effects, but its anti-tumor effects remain uncertain. The aim of this study was to evaluate effects of safranal on anti-tumor on neuroblastoma cells.

Materials and Methods:

Neuroblastoma cells were cultured and exposed to safranal (0, 10, 15, 20, 50 μg/ml). Cell proliferation was examined using the 3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Apoptotic cells, cell cycle distribution, and sub-G1 fraction were analyzed using flow cytometric analysis after propidium iodide staining.

Results:

Safranal inhibited the growth of malignant cells in a dose-and time-dependent manner. The IC (50) values against the neuroblastoma cell line were determined as 11.1 and 23.3 μg/ml after 24 and 48 h, respectively. Safranal induced a sub-G1 peak in the flow cytometry histogram of treated cells compared to control cells indicating that apoptotic cell death is involved in safranal toxicity.

Conclusions:

Our pre-clinical study demonstrated a neuroblastoma cell line to be highly sensitive to safranal-mediated growth inhibition and apoptotic cell death. Although the molecular mechanisms of safranal action are not yet clearly understood, it appears to have potential as a therapeutic agent.

Expression of two parental imprinted miRNAs improves the risk stratification of neuroblastoma patients

Age at diagnosis, stage, and MYCN amplification are the cornerstones of the risk-stratification score of neuroblastoma that enables defining patients at low- and high risk. Refinement of this stratification is needed to optimize standard treatment and to plan future clinical trials. We investigated whether two parental imprinted miRNAs (miR-487b and miR-516a-5p) may lead to a risk score with a better discrimination. Expression levels of maternal miR-487b and paternal miR-516a-5p were determined using quantitative RT-PCR both for 231 neuroblastoma tumors (derivation set) and 101 independent neuroblastoma tumors (validation set). Survival outcomes were overall survival (OS) and disease-free survival (DFS). Multivariable Cox models were developed from derivation set and their performance evaluated using Akaike's information criterion (AIC) (goodness-of-fit) and time-dependent area under curves (discrimination). The selected model was validated using internal and external validation. The prognostic model including current prognostic factors plus miR-487b, miR-516a-5p, and interaction between two miRNAs was selected. Performance of this model was better in terms of both predictive ability (smallest AIC) and discrimination power (AUC close to 0.70). This model identifies three risk groups: high (3), intermediate (2), and low (1). Hazard ratios (HR) across risk groups were HR_2/1 = 6.3 (2.7–14.6), HR_3/1 = 14.8 (7.2–30.2) for OS and HR_2/1 = 2.8 (1.5–5.4), HR_3/1 = 7.2 (3.9–13.4) for DFS. The rank between these three risk groups was maintained and validated when performing internal and external validation. Expression of maternal miR-487b and paternal miR-516a-5p improves the risk stratification. This better discrimination at diagnosis is of clinical utility both for current and future treatments of neuroblastoma patients.

Reverse engineering the neuroblastoma regulatory network uncovers MAX as one of the master regulators of tumor progression

Neuroblastoma is the most common extracranial tumor and a major cause of infant cancer mortality worldwide. Despite its importance, little is known about its molecular mechanisms. A striking feature of this tumor is its clinical heterogeneity. Possible outcomes range from aggressive invasion to other tissues, causing patient death, to spontaneous disease regression or differentiation into benign ganglioneuromas. Several efforts have been made in order to find tumor progression markers. In this work, we have reconstructed the neuroblastoma regulatory network using an information-theoretic approach in order to find genes involved in tumor progression and that could be used as outcome predictors or as therapeutic targets. We have queried the reconstructed neuroblastoma regulatory network using an aggressive neuroblastoma metastasis gene signature in order to find its master regulators (MRs). MRs expression profiles were then investigated in other neuroblastoma datasets so as to detect possible clinical significance. Our analysis pointed MAX as one of the MRs of neuroblastoma progression. We have found that higher MAX expression correlated with favorable patient outcomes. We have also found that MAX expression and protein levels were increased during neuroblastoma SH-SY5Y cells differentiation. We propose that MAX is involved in neuroblastoma progression, possibly increasing cell differentiation by means of regulating the availability of MYC:MAX heterodimers. This mechanism is consistent with the results found in our SH-SY5Y differentiation protocol, suggesting that MAX has a more central role in these cells differentiation than previously reported. Overexpression of MAX has been identified as anti-tumorigenic in other works, but, to our knowledge, this is the first time that the link between the expression of this gene and malignancy was verified under physiological conditions.

Apoptotic Effects of Melandryum firmum Root Extracts in Human SH-SY5Y Neuroblastoma Cells

Melandryum firmum is a biennial plant that has been used in traditional medicine for treatment of bacterial and fungal infection. Here, we investigated molecular mechanisms underlying apoptotic effects of Melandryum firmum root extract (MFRE) in neuroblastoma cells, since the effect of this natural compound on cancer cells has not been fully clarified. The root extract of M. firmum reduced cell proliferation, as revealed by cell viability assay. However, MFRE-treated cells exhibited morphological changes including cell rounding, neurite retraction and membrane blebbing. These alterations of cellular shape suggest this morphological change might be due to the apoptosis which shows fragmented DNA. In addition, MFRE up-regulated the pro-apoptotic protein Bax and down-regulated the anti-apoptotic protein Bcl-2 and Mcl-1, which also finally activated cleaved caspase-3 in a dose-dependent manner, as determined by western blot analyses. Together, these findings demonstrate that apoptotic and cytotoxic effects of MFRE on SH-SY5Y cells are mediated by intrinsic mitochondria-mediated caspase pathway and that this natural extract might be effective as an anticancer agent for neuroblastoma malignancies.

Seasonal variations of date of diagnosis and birth for neuroblastoma patients in Italy

BACKGROUND

Analysis of seasonal variation of diagnosis or birth of childhood cancers may provide useful insight about possible aetiological risk factors, such as infectious agents and environmental exposures, but studies on neuroblastoma are lacking.

PROCEDURE

Two thousand seven hundred fifty-six cases of neuroblastoma, diagnosed between 1980 and 2010, registered in the Italian Neuroblastoma Registry, were included in the study. Subgroup analyses were carried out by age, gender and stage at diagnosis. Seasonal trend was assessed by a harmonic function in a Poisson regression model, adjusted for the number of live births.

RESULTS

No trend in the date of diagnosis was found either in the entire cohort or in the various sub-groups. Similarly, a seasonal trend of birth was not observed in the whole cohort. Conversely, in the subgroup of infants with stage 4S, a significant peak of July births was found (23.6% increment from the average, p=0.042). The summer peak was confirmed after stratifying 4S patients by gender and period of diagnosis.

CONCLUSIONS

A major effect of risk factors related to seasonality does not appear to affect the risk of developing neuroblastoma. However, the time pattern of birth observed by stage at diagnosis is consistent with the hypothesis that Stage 4S is a distinct disease with probably a different aetiology, as indicated by investigations on its metastatic pattern and its peculiar gene expression. An aetiological role of seasonally related factors, e.g., favouring the survival of defective neural crest stem cells, remains speculative and need confirmation by independent studies.

Neuroblastoma: developmental biology, cancer genomics and immunotherapy

Neuroblastoma is a solid tumour that arises from the developing sympathetic nervous system. Over the past decade, our understanding of this disease has advanced tremendously. The future challenge is to apply the knowledge gained to developing risk-based therapies and, ultimately, improving outcome. In this Review we discuss the key discoveries in the developmental biology, molecular genetics and immunology of neuroblastoma, as well as new translational tools for bringing these promising scientific advances into the clinic.

Cytotoxic effect of gambogic acid on SH-SY5Y neuroblastoma cells is mediated by intrinsic caspase-dependent signaling pathway

Gambogic acid (GA) is the dry resin of Garcinia hanburyi (Guttiferae) with potent anti-tumor activity, various bioactivities, including detoxification, homeostasis, anti-inflammatory, and parasiticide, whereas the effect of this natural compound on cancer cells has not been clearly clarified. Here, we examined cellular cytotoxicity by cell viability assay and DNA fragmentation by DNA-ladder assay. Activation of different protein expressions were detected by western blot analyses. We first demonstrated that GA reduces the human SH-SY5Y neuroblastoma cell viability with IC50 of 1.28 μM at 6 h which has less toxicity in fibroblast cells. However, lower concentration GA significantly downregulated the expression of anti-apoptotic protein including Bcl-2, Bcl-xL, and Mcl-1, which also dramatically activated cleaved caspase-9 and -3 in a dose- and time-dependent manner. Consequently, GA-induced cytotoxicity was not mediated by the Fas/FasL and PI3 K/AKT/GSK-3β signaling pathway. In addition, GA-induced cells showed damage morphology which had become cell rounding, neurite retraction, membrane blebbing and shrunken in a dose- and time-dependent manner that clearly indicates this morphological change might be due to the process of apoptosis which shows fragmented DNA. Therefore, the findings presented in this study demonstrate that apoptotic effects of GA on SH-SY5Y cells are mediated by intrinsic mitochondrion-dependent caspase pathway which suggests this natural compound might be effective as an anti-cancer agent for neuroblastoma malignancies.

GALNT9 gene expression is a prognostic marker in neuroblastoma patients

BACKGROUND

The enzymes encoded by the GALNT [UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase (GALNAC-T)] gene family catalyze the first step of O-glycosylation. Little is known about the link between expression of the genes encoding GALNAC-T enzymes and tumor progression in neuroblastoma, a pediatric cancer that can be classified as either low or high risk. We assessed the expression of genes in the GALNT family in a large cohort of neuroblastoma patients and characterized members of this family that might be used as new prognostic markers.

METHODS

Reverse-transcription PCR analysis of 14 GALNT genes with a panel of neuroblastoma cell lines identified the GALNT9 gene as playing a potential role in disease progression. We used the log-rank test and the multivariable Cox proportional hazards model with a cohort of 122 neuroblastoma patients to analyze the relationship between GALNT9 expression and overall survival or disease-free survival.

RESULTS

In the high-risk neuroblastoma experimental model IGR-N-91, GALNT9 expression was present in neuroblasts derived from primary tumors but not in neuroblasts from metastatic bone marrow. Moreover, GALNT9 in neuroblastoma cell lines was expressed in substrate adherent (S)-type cell lines but not in neuronal (N)-type lines. In the tumor cohort, GALNT9 expression was associated with high overall survival, independent of the standard risk-stratification covariates. GALNT9 expression was significantly associated with disease-free survival for patients currently classified as at low risk (P < 0.0007).

CONCLUSIONS

GALNT9 expression correlates with both improved overall survival in low- and high-risk groups and an improved clinical outcome (overall and disease-free survival) in low-risk patients. Thus, the GALNT9 expression may be a prognostic marker for personalized therapy.

Antiproliferative and cytotoxic effects of resveratrol in mitochondria-mediated apoptosis in rat b103 neuroblastoma cells

Resveratrol, a natural compound, has been shown to possess anti-cancer, anti-aging, anti-inflammatory, anti-microbial, and neuroprotective activities. In this study, we examined the antiproliferative and cytotoxicity properties of resveratrol in Rat B103 neuroblastoma cells; although it's molecular mechanisms for the biological effects are not fully defined. Here, we examined the cellular cytotoxicity of resveratrol by cell viability assay, antiproliferation by BrdU assay, DNA fragmentation by DNA ladder assay, activation of caspases and Bcl-2 family proteins were detected by western blot analyses. The results of our investigation suggest that resveratrol increased cellular cytotoxicity of Rat B103 neuroblastoma cells in a dose-and time-dependent manner with IC₅₀ of 17.86 µM at 48 h. On the other hand, incubation of neuroblastoma cells with resveratrol resulted in S-phase cell cycle arrests which dose-dependently and significantly reduced BrdU positive cells through the downregulation of cyclin D1 protein. In addition, resveratrol dose-dependently and significantly downregulated the expression of anti-apoptotic protein includes Bcl-2, Bcl-xL and Mcl-1 and also activates cleavage caspase-9 and-3 via the downregulation of procaspase-9 and -3 in a dose-dependent manner which indicates that involvement of intrinsic mitochondria-mediated apoptotic pathway. In conclusion, resveratrol increases cellular cytotoxicity and inhibits the proliferation of B103 neuroblastoma cells by inducing mitochondria-mediated intrinsic caspase dependent pathway which suggests this natural compound could be used as therapeutic purposes for neuroblastoma malignancies.

Tyrosine phosphatase inhibitors combined with retinoic acid can enhance differentiation of neuroblastoma cells and trigger ERK- and AKT-dependent, p53-independent senescence

Retinoic acid (RA)-induced differentiation therapy is partially successful in neuroblastoma treatment. We found that a novel combination of vanadium-based PTP inhibitors with RA induced extensive differentiation in neuroblastoma cells. In contrast to RA alone, this led to either permanent differentiation or senescence after 14days of combined treatment followed by chemical removal. Senescence was dependent in part on synergistic AKT and ERK activation. p21 was also strongly induced, but in contrast to oncogene-induced senescence, p53 was not activated. Vanadium-based inhibitors thus serve strongly to enhance RA's ability to drive differentiation and a novel form of senescence in neuroblastoma cells.

Design of a multi-signature ensemble classifier predicting neuroblastoma patients' outcome

Background

Neuroblastoma is the most common pediatric solid tumor of the sympathetic nervous system. Development of improved predictive tools for patients stratification is a crucial requirement for neuroblastoma therapy. Several studies utilized gene expression-based signatures to stratify neuroblastoma patients and demonstrated a clear advantage of adding genomic analysis to risk assessment. There is little overlapping among signatures and merging their prognostic potential would be advantageous. Here, we describe a new strategy to merge published neuroblastoma related gene signatures into a single, highly accurate, Multi-Signature Ensemble (MuSE)-classifier of neuroblastoma (NB) patients outcome.

Methods

Gene expression profiles of 182 neuroblastoma tumors, subdivided into three independent datasets, were used in the various phases of development and validation of neuroblastoma NB-MuSE-classifier. Thirty three signatures were evaluated for patients' outcome prediction using 22 classification algorithms each and generating 726 classifiers and prediction results. The best-performing algorithm for each signature was selected, validated on an independent dataset and the 20 signatures performing with an accuracy > = 80% were retained.

Results

We combined the 20 predictions associated to the corresponding signatures through the selection of the best performing algorithm into a single outcome predictor. The best performance was obtained by the Decision Table algorithm that produced the NB-MuSE-classifier characterized by an external validation accuracy of 94%. Kaplan-Meier curves and log-rank test demonstrated that patients with good and poor outcome prediction by the NB-MuSE-classifier have a significantly different survival (p < 0.0001). Survival curves constructed on subgroups of patients divided on the bases of known prognostic marker suggested an excellent stratification of localized and stage 4s tumors but more data are needed to prove this point.

Conclusions

The NB-MuSE-classifier is based on an ensemble approach that merges twenty heterogeneous, neuroblastoma-related gene signatures to blend their discriminating power, rather than numeric values, into a single, highly accurate patients' outcome predictor. The novelty of our approach derives from the way to integrate the gene expression signatures, by optimally associating them with a single paradigm ultimately integrated into a single classifier. This model can be exported to other types of cancer and to diseases for which dedicated databases exist.

Age-dependent accumulation of genomic aberrations and deregulation of cell cycle and telomerase genes in metastatic neuroblastoma

About 50% of children with neuroblastoma (NB) show a metastatic disease and have a poor prognosis. However, disease progression is greatly variable and depends on patients' age and MYCN oncogene amplification. To investigate the role of patients' age in tumor aggressiveness, we performed array-CGH and gene expression profiles of three groups (G) of metastatic NBs: G1, stage 4S patients and MYCN single copy (MYCN-) tumors; G2, stage 4 patients, ≤ 18 months of age, MYCN- tumors and favorable outcome and G3, Stage 4 patients, ≥ 19 months with unfavorable outcome. G1 was characterized by numerical aberrations prevalently; on the contrary, all G3 tumors had structural rearrangements, whereas G2 showed an intermediate pattern. The average of numerical alterations decreased significantly from G1 to G2 to G3 (p < 0.01). Contrarily, the number of structural aberrations increased from G1 to G2 to G3 (p < 2.35 E-05). Noteworthy, G3/MYCN- NBs were characterized by several complex intrachromosome rearrangements. Expression analysis of the three groups showed significant differences in genes of Rho and Ras signaling pathways, development and adhesion, cell cycle regulation and telomerase activity. Accumulation of structural alterations increased with patients' age and was associated with a more aggressive disease. Abnormal expression of genes involved in cell cycle and telomerase in G3 may be responsible for the genomic instability in this cohort of patients. The higher DNA instability observed in G3/MYCN- NBs than in MYCN-amplified G3 may also explain why patients ≥ 19 months have a poor outcome independently by MYCN status.

Expression of miR-487b and miR-410 encoded by 14q32.31 locus is a prognostic marker in neuroblastoma

BACKGROUND

Combination of age at diagnosis, stage and MYCN amplification stratifies neuroblastoma into low-risk and high-risk. We aimed to establish whether a microRNA (miRNA) signature could be associated with prognosis in both groups.

METHODS

Microarray expression profiling of human miRNAs and quantitative reverse-transcriptase PCR of selected miRNAs were performed on a preliminary cohort of 13 patients. Results were validated on an independent cohort of 214 patients. The relationship between miRNA expression and the overall or disease-free survival was analysed on the total cohort of 227 patients using the log-rank test and the multivariable Cox proportional hazard model.

RESULTS

A total of 15 of 17 miRNAs that discriminated high-risk from low-risk neuroblastoma belonged to the imprinted human 14q32.31 miRNA cluster and two, miR-487b and miR-410, were significantly downregulated in the high-risk group. Multivariable analyses showed miR-487b expression as associated with overall survival and disease-free survival in the whole cohort, independently of clinical covariates. Moreover, miR-487b and miR-410 expression was significantly associated with disease-free survival of the non-MYCN-amplified favourable neuroblastoma: localised (stage 1, 2 and 3) and stage 4 of infant <18 months.

CONCLUSION

Expression of miR-487b and miR-410 shows predictive value beyond the classical high-/low-risk stratification and is a biomarker of relapse in favourable neuroblastoma.

Laparostomy closure in stage 4S neuroblastoma

Laparostomy in children is a rare procedure, and there is little in the literature as to the best method for closure in children with an open abdomen. We describe 2 cases with stage 4S neuroblastoma that required emergency decompressive laparostomy. Both cases highlight advantages and disadvantages with known techniques for achieving skin and fascia closure. We believe this to be the first report of a combination of extracellular matrix mesh and vacuum therapy for successful fascial and skin closure in stage 4S neuroblastoma.

p21Waf1 expression is regulated by nuclear intermediate filament vimentin in neuroblastoma

Background

Human neuroblastoma (NB) cell lines may present with either one of the so-called S-and N-subtypes. We have previously reported a strong correlation between protein expression levels of vimentin, an S-subtype marker, and the p21^Waf1 cyclin-dependent kinase inhibitor. We here investigated whether this correlation extend to the mRNA level in NB cell lines as well as in patients' tumors. We also further explored the relationship between expression of vimentin and p21, by asking whether vimentin could regulate p21 expression.

Methods

Vimentin and p21 mRNA levels in NB cell lines as well as in patients' tumors (n = 77) were quantified using Q-PCR. Q-PCR data obtained from tumors of high risk NB patients (n = 40) were analyzed in relation with the overall survival using the Log-rank Kaplan-Meier estimation. siRNA-mediated depletion or overexpression of vimentin in highly or low expressing vimentin cell lines, respectively, followed by protein expression and promoter activation assays were used to assess the role of vimentin in modulating p21 expression.

Results

We extend the significant correlation between vimentin and p21 expression to the mRNA level in NB cell lines as well as in patients' tumors. Overall survival analysis from Q-PCR data obtained from tumors of high risk patients suggests that lower levels of p21 expression could be associated with a poorer outcome. Our data additionally indicate that the correlation observed between p21 and vimentin expression levels results from p21 transcriptional activity being regulated by vimentin. Indeed, downregulating vimentin resulted in a significant decrease in p21 mRNA and protein expression as well as in p21 promoter activity. Conversely, overexpressing vimentin triggered an increase in p21 promoter activity in cells with a nuclear expression of vimentin.

Conclusion

Our results suggest that p21 mRNA tumor expression level could represent a refined prognostic factor for high risk NB patients. Our data also show that vimentin regulates p21 transcription; this is the first demonstration of a gene regulating function for this type III-intermediate filament.

Homeobox transcription factor Prox1 in sympathetic ganglia of vertebrate embryos: correlation with human stage 4s neuroblastoma

Previously, we observed expression of the homeobox transcription factor Prox1 in neuroectodermal embryonic tissues. Besides essential functions during embryonic development, Prox1 has been implicated in both progression and suppression of malignancies. Here, we show that Prox1 is expressed in embryonic sympathetic trunk ganglia of avian and murine embryos. Prox1 protein is localized in the nucleus of neurofilament-positive sympathetic neurons. Sympathetic progenitors represent the cell of origin of neuroblastoma (NB), the most frequent solid extracranial malignancy of children. NB may progress to life-threatening stage 4, or regress spontaneously in the special stage 4s. By qRT-PCR, we show that Prox1 is expressed at low levels in 24 human NB cell lines compared with human lymphatic endothelial cells (LECs), whereas equal immunostaining of nuclei can be seen in embryonic LECs and sympathetic neurons. In NB stages 1, 2, 3, and 4, we observed almost equal expression levels, but significantly higher amounts in stage 4s NB. By immunohistochemistry, we found variable amounts of Prox1 protein in nuclei of NB cells, showing intra and interindividual differences. Because stage 4s NB are susceptible to postnatal apoptosis, we assume that high Prox1 levels are critical for their behavior.

Prognostic impact of gene expression-based classification for neuroblastoma

PURPOSE

To evaluate the impact of a predefined gene expression-based classifier for clinical risk estimation and cytotoxic treatment decision making in neuroblastoma patients.

PATIENTS AND METHODS

Gene expression profiles of 440 internationally collected neuroblastoma specimens were investigated by microarray analysis, 125 of which were examined prospectively. Patients were classified as either favorable or unfavorable by a 144-gene prediction analysis for microarrays (PAM) classifier established previously on a separate set of 77 patients. PAM classification results were compared with those of current prognostic markers and risk estimation strategies.

RESULTS

The PAM classifier reliably distinguished patients with contrasting clinical courses (favorable [n = 249] and unfavorable [n = 191]; 5-year event free survival [EFS] 0.84 +/- 0.03 v 0.38 +/- 0.04; 5-year overall survival [OS] 0.98 +/- 0.01 v 0.56 +/- 0.05, respectively; both P < .001). Moreover, patients with divergent outcome were robustly discriminated in both German and international cohorts and in prospectively analyzed samples (P <or= .001 for both EFS and OS for each). In subgroups with clinical low-, intermediate-, and high-risk of death from disease, the PAM predictor significantly separated patients with divergent outcome (low-risk 5-year OS: 1.0 v 0.75 +/- 0.10, P < .001; intermediate-risk: 1.0 v 0.82 +/- 0.08, P = .042; and high-risk: 0.81 +/- 0.08 v 0.43 +/- 0.05, P = .001). In multivariate Cox regression models based on both EFS and OS, PAM was a significant independent prognostic marker (EFS: hazard ratio [HR], 3.375; 95% CI, 2.075 to 5.492; P < .001; OS: HR, 11.119, 95% CI, 2.487 to 49.701; P < .001). The highest potential clinical impact of the classifier was observed in patients currently considered as non-high-risk (n = 289; 5-year EFS: 0.87 +/- 0.02 v 0.44 +/- 0.07; 5-year OS: 1.0 v 0.80 +/- 0.06; both P < .001).

CONCLUSION

Gene expression-based classification using the 144-gene PAM predictor can contribute to improved treatment stratification of neuroblastoma patients.