Unequivocal delineation of clinicogenetic subgroups and development of a new model for improved outcome prediction in neuroblastoma

Multiple Genes with Potential Tumor Suppressive Activity Are Present on Chromosome 10q Loss in Neuroblastoma and Are Associated with Poor Prognosis

Neuroblastoma (NB) is a tumor affecting the peripheral sympathetic nervous system that substantially contributes to childhood cancer mortality. Despite recent advances in understanding the complexity of NB, the mechanisms determining its progression are still largely unknown. Some recurrent segmental chromosome aberrations (SCA) have been associated with poor survival. However, the prognostic role of most SCA has not yet been investigated. We examined a cohort of 260 NB primary tumors at disease onset for the loss of chromosome 10q, by array-comparative genomic hybridization (a-CGH) and Single Nucleotide Polymorphism (SNP) array and we found that 26 showed 10q loss, while the others 234 displayed different SCA. We observed a lower event-free survival for NB patients displaying 10q loss compared to patients with tumors carrying other SCA. Furthermore, analyzing the region of 10q loss, we identified a cluster of 75 deleted genes associated with poorer outcome. Low expression of six of these genes, above all CCSER2, was significantly correlated to worse survival using in silico data from 786 NB patients. These potential tumor suppressor genes can be partly responsible for the poor prognosis of NB patients with 10q loss.

Chromosome instability in neuroblastoma: A pathway to aggressive disease

For over 100-years, genomic instability has been investigated as a central player in the pathogenesis of human cancer. Conceptually, genomic instability includes an array of alterations from small deletions/insertions to whole chromosome alterations, referred to as chromosome instability. Chromosome instability has a paradoxical impact in cancer. In most instances, the introduction of chromosome instability has a negative impact on cellular fitness whereas in cancer it is usually associated with a worse prognosis. One exception is the case of neuroblastoma, the most common solid tumor outside of the brain in children. Neuroblastoma tumors have two distinct patterns of genome instability: whole-chromosome aneuploidy, which is associated with a better prognosis, or segmental chromosomal alterations, which is a potent negative prognostic factor. Through a computational screen, we found that low levels of the de- ubiquitinating enzyme USP24 have a highly significant negative impact on survival in neuroblastoma. At the molecular level, USP24 loss leads to destabilization of the microtubule assembly factor CRMP2 - producing mitotic errors and leading to chromosome missegregation and whole-chromosome aneuploidy. This apparent paradox may be reconciled through a model in which whole chromosome aneuploidy leads to the subsequent development of segmental chromosome alterations. Here we review the mechanisms behind chromosome instability and the evidence for the progressive development of segmental alterations from existing numerical aneuploidy in support of a multi-step model of neuroblastoma progression.

Chromosome 11q loss and MYCN amplification demonstrate synthetic lethality with checkpoint kinase 1 inhibition in neuroblastoma

Neuroblastoma is the most common extracranial solid tumor found in children and despite intense multi-modal therapeutic approaches, low overall survival rates of high-risk patients persist. Tumors with heterozygous loss of chromosome 11q and MYCN amplification are two genetically distinct subsets of neuroblastoma that are associated with poor patient outcome. Using an isogenic 11q deleted model system and high-throughput drug screening, we identify checkpoint kinase 1 (CHK1) as a potential therapeutic target for 11q deleted neuroblastoma. Further investigation reveals MYCN amplification as a possible additional biomarker for CHK1 inhibition, independent of 11q loss. Overall, our study highlights the potential power of studying chromosomal aberrations to guide preclinical development of novel drug targets and combinations. Additionally, our study builds on the growing evidence that DNA damage repair and replication stress response pathways offer therapeutic vulnerabilities for the treatment of neuroblastoma.

Targeting the DNA damage response in pediatric malignancies

INTRODUCTION

High levels of DNA damage and mutations in DNA damage response genes creates a high reliance on DNA damage repair in various tumors. This creates a vulnerability for new cancer therapies. Although there is extensive data for the use of these agents in adult tumors, the evaluation of these compounds in the pediatric population remains in the early stages.

AREAS COVERED

In this review, we discuss the role of the DNA damage response as a therapeutic vulnerability in pediatric malignancies, provide a summary of clinical data for the use of DNA damage response inhibitors in cancer, and review how these compounds can be extended to the pediatric population.

EXPERT OPINION

A number of pediatric cancers rely on robust DNA damage repair to maintain cell viability. This provides a therapeutic vulnerability in cancer cells resistant to other traditional therapies. Unfortunately, although clinical evaluation of inhibitors of various components of the DNA damage response has been done in adults, pediatric data remains limited. Further studies are needed to evaluate the efficacy of these compounds in the pediatric population.

Risk Factors Associated with Metastatic Site Failure in Patients with High-Risk Neuroblastoma

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We observed an increased hazard for failure at metastatic sites which remain persistently avid on MIBG following systemic therapy.

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-Limited response to induction therapy described by Curie and SIOPEN score selects patients at greater risk for poly-metastatic site failure.

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-The low proportion of metastatic sites treated with radiotherapy precluded definitive testing of its impact on the hazard for metastatic site failure.

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-Patients who are unable to undergo transplant, and/or have extensive disease at diagnosis (lung metastases) may be poor candidates for consolidative metastatic site directed radiotherapy given the high competing risk of failure at a new metastatic site.

Purpose

This retrospective study sought to identify predictors of metastatic site failure (MSF) at new and/or original (present at diagnosis) sites in high-risk neuroblastoma patients.

Methods and materials

Seventy-six high-risk neuroblastoma patients treated on four institutional prospective trials from 1997 to 2014 with induction chemotherapy, surgery, myeloablative chemotherapy, stem-cell rescue, and were eligible for consolidative primary and metastatic site (MS) radiotherapy were eligible for study inclusion. Computed-tomography and I­123 MIBG scans were used to assess disease response and Curie scores at diagnosis, post-induction, post-transplant, and treatment failure. Outcomes were described using the Kaplan–Meier estimator. Cox proportional hazards frailty (cphfR) and CPH regression (CPHr) were used to identify covariates predictive of MSF at a site identified either at diagnosis or later.

Results

MSF occurred in 42 patients (55%). Consolidative MS RT was applied to 30 MSs in 10 patients. Original-MSF occurred in 146 of 383 (38%) non­irradiated and 18 of 30 (60%) irradiated MSs (p = 0.018). Original- MSF occurred in post­induction MIBG-avid MSs in 68 of 81 (84%) non­irradiated and 12 of 14 (85%) radiated MSs (p = 0.867). The median overall and progression-free survival rates were 61 months (95% CI 42.6­Not Reached) and 24.1 months (95% CI 16.5­38.7), respectively. Multivariate CPHr identified inability to undergo transplant (HR 32.4 95%CI 9.3­96.8, p < 0.001) and/or maintenance chemotherapy (HR 5.2, 95%CI 1.7­16.2, p = 0.005), and the presence of lung metastases at diagnosis (HR 4.4 95%CI 1.7­11.1, p = 0.002) as predictors of new MSF. The new MSF-free survival rate at 3 years was 25% and 87% in patients with and without high-risk factors.

Conclusions

Incremental improvements in systemic therapy influence the patterns and type of metastatic site failure in neuroblastoma. Persistence of MIBG-avidity following induction chemotherapy and transplant at MSs increased the hazard for MSF.

From DNA Copy Number Gains and Tumor Dependencies to Novel Therapeutic Targets for High-Risk Neuroblastoma

Neuroblastoma is a pediatric tumor arising from the sympatho-adrenal lineage and a worldwide leading cause of childhood cancer-related deaths. About half of high-risk patients die from the disease while survivors suffer from multiple therapy-related side-effects. While neuroblastomas present with a low mutational burden, focal and large segmental DNA copy number aberrations are highly recurrent and associated with poor survival. It can be assumed that the affected chromosomal regions contain critical genes implicated in neuroblastoma biology and behavior. More specifically, evidence has emerged that several of these genes are implicated in tumor dependencies thus potentially providing novel therapeutic entry points. In this review, we briefly review the current status of recurrent DNA copy number aberrations in neuroblastoma and provide an overview of the genes affected by these genomic variants for which a direct role in neuroblastoma has been established. Several of these genes are implicated in networks that positively regulate MYCN expression or stability as well as cell cycle control and apoptosis. Finally, we summarize alternative approaches to identify and prioritize candidate copy-number driven dependency genes for neuroblastoma offering novel therapeutic opportunities.

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.

A Deep-Learning Model With the Attention Mechanism Could Rigorously Predict Survivals in Neuroblastoma

BACKGROUND

Neuroblastoma is one of the most devastating forms of childhood cancer. Despite large amounts of attempts in precise survival prediction in neuroblastoma, the prediction efficacy remains to be improved.

METHODS

Here, we applied a deep-learning (DL) model with the attention mechanism to predict survivals in neuroblastoma. We utilized 2 groups of features separated from 172 genes, to train 2 deep neural networks and combined them by the attention mechanism.

RESULTS

This classifier could accurately predict survivals, with areas under the curve of receiver operating characteristic (ROC) curves and time-dependent ROC reaching 0.968 and 0.974 in the training set respectively. The accuracy of the model was further confirmed in a validation cohort. Importantly, the two feature groups were mapped to two groups of patients, which were prognostic in Kaplan-Meier curves. Biological analyses showed that they exhibited diverse molecular backgrounds which could be linked to the prognosis of the patients.

CONCLUSIONS

In this study, we applied artificial intelligence methods to improve the accuracy of neuroblastoma survival prediction based on gene expression and provide explanations for better understanding of the molecular mechanisms underlying neuroblastoma.

Non-Coding RNAs Participate in the Pathogenesis of Neuroblastoma

Neuroblastoma is one of the utmost frequent neoplasms during the first year of life. This pediatric cancer is believed to be originated during the embryonic life from the neural crest cells. Previous studies have detected several types of chromosomal aberrations in this tumor. More recent studies have emphasized on expression profiling of neuroblastoma samples to identify the dysregulated genes in this type of cancer. Non-coding RNAs are among the mostly dysregulated genes in this type of cancer. Such dysregulation has been associated with a number of chromosomal aberrations that are frequently detected in neuroblastoma. In this study, we explain the role of non-coding transcripts in the malignant transformation in neuroblastoma and their role as biomarkers for this pediatric cancer.

ALK ligand ALKAL2 potentiates MYCN-driven neuroblastoma in the absence of ALK mutation

High‐risk neuroblastoma (NB) is responsible for a disproportionate number of childhood deaths due to cancer. One indicator of high‐risk NB is amplification of the neural MYC (MYCN) oncogene, which is currently therapeutically intractable. Identification of anaplastic lymphoma kinase (ALK) as an NB oncogene raised the possibility of using ALK tyrosine kinase inhibitors (TKIs) in treatment of patients with activating ALK mutations. 8–10% of primary NB patients are ALK‐positive, a figure that increases in the relapsed population. ALK is activated by the ALKAL2 ligand located on chromosome 2p, along with ALK and MYCN, in the “2p‐gain” region associated with NB. Dysregulation of ALK ligand in NB has not been addressed, although one of the first oncogenes described was v‐sis that shares > 90% homology with PDGF. Therefore, we tested whether ALKAL2 ligand could potentiate NB progression in the absence of ALK mutation. We show that ALKAL2 overexpression in mice drives ALK TKI‐sensitive NB in the absence of ALK mutation, suggesting that additional NB patients, such as those exhibiting 2p‐gain, may benefit from ALK TKI‐based therapeutic intervention.

Imbalance between genomic gain and loss identifies high-risk neuroblastoma patients with worse outcomes

Survival in high-risk neuroblastoma (HR-NB) patients remains poor despite multimodal treatment. We aimed to identify HR-NB patients with worse outcomes by analyzing the genomic instability derived from segmental chromosomal aberrations. We calculated 3 genomic instability indexes for primary tumor SNP array profiles from 127 HR-NB patients: (1) Copy number aberration burden (%gains_length+%losses_length), (2) copy number load (CNL) (%gains_length-%losses_length) and (3) net genomic load (NGL) (%gains_amount-%losses_amount). Tumors were classified according to positive or negative CNL and NGL genomic subtypes. The impact of the genomic instability indexes on overall survival (OS) was assessed with Cox regression. We identified 38% of HR-NB patients with poor 5-year OS. A negative CNL genomic background was related to poor prognosis in patients ≥18 months showing tumors with homogeneous MYCN amplification (9.5% survival probability, P < 0.05) and patients with non-MYCN amplified NB (18.8% survival probability related to >2.4% CNL, P < 0.01). A positive CNL genomic background was associated with worse outcome in patients with heterogeneous MYCN amplification (22.5% survival probability, P < 0.05). We conclude that characterizing a tumor genomic background according to predominance of genome gained or lost contributes toward improved outcome prediction and brings greater insight into the tumor biology of HR-NB patients.

The p140Cap adaptor protein as a molecular hub to block cancer aggressiveness

The p140Cap adaptor protein is a scaffold molecule encoded by the SRCIN1 gene, which is physiologically expressed in several epithelial tissues and in the neurons. However, p140Cap is also strongly expressed in a significant subset of cancers including breast cancer and neuroblastoma. Notably, cancer patients with high p140Cap expression in their primary tumors have a lower probability of developing a distant event and ERBB2-positive breast cancer sufferers show better survival. In neuroblastoma patients, SRCIN1 mRNA levels represent an independent risk factor, which is inversely correlated to disease aggressiveness. Consistent with clinical data, SRCIN1 gain or loss of function mouse models demonstrated that p140Cap may affect tumor growth and metastasis formation by controlling the signaling pathways involved in tumorigenesis and metastatic features. This study reviews data showing the relevance of SRCIN1/p140Cap in cancer patients, the impact of SRCIN1 status on p140Cap expression, the specific mechanisms through which p140Cap can limit cancer progression, the molecular functions regulated by p140Cap, along with the p140Cap interactome, to unveil its key role for patient stratification in clinics.

Gene Expression Signature of Acquired Chemoresistance in Neuroblastoma Cells

Drug resistance of childhood cancer neuroblastoma is a serious clinical problem. Patients with relapsed disease have a poor prognosis despite intense treatment. In the present study, we aimed to identify chemoresistance gene expression signatures in vincristine resistant neuroblastoma cells. We found that vincristine-resistant neuroblastoma cells formed larger clones and survived under reduced serum conditions as compared with non-resistant parental cells. To identify the possible mechanisms underlying vincristine resistance in neuroblastoma cells, we investigated the expression profiles of genes known to be involved in cancer drug resistance. This specific gene expression patterns could predict the behavior of a tumor in response to chemotherapy and for predicting the prognosis of high-risk neuroblastoma patients. Our signature could help chemoresistant neuroblastoma patients in avoiding useless and harmful chemotherapy cycles.

Neuroblastoma stage 4S: Tumor regression rate and risk factors of progressive disease

BACKGROUND

The clinical course of neuroblastoma stage 4S or MS is characterized by a high rate of spontaneous tumor regression and favorable outcome. However, the clinical course and rate of the regression are poorly understood.

METHODS

A retrospective cohort study was performed, including all patients with stage 4S neuroblastoma without MYCN amplification, from two Dutch centers between 1972 and 2012. We investigated the clinical characteristics, the biochemical activity reflected in urinary catecholamine excretion, and radiological imaging to describe the kinetics of tumor regression, therapy response and outcome.

RESULTS

The cohort of 31 patients reached a 10-year overall survival of 84% ± 7% (median follow-up 16 years; range, 3.3-39). During the regressive phase, liver size normalized in 91% of the patients and catecholamine excretion in 83%, both after a median of two months (liver size: range, 0-131; catecholamines: range, 0-158). The primary tumors completely regressed in 69% after 13 months (range, 6-73), and the liver architecture normalized in 52% after 15 months (range, 5-131). Antitumor treatment was given in 52% of the patients. Interestingly, regression rates were similar for treated and untreated patients. Four of seven patients < 4 weeks old died of rapid liver expansion and organ compression. Three patients progressed to stage 4, 3 to 13 months after diagnosis; all had persistently elevated catecholamines.

CONCLUSION

Patients < 4 weeks old with neuroblastoma stage 4S are at risk of fatal outcome caused by progression of liver metastases. In other patients, tumor regression is characterized by a rapid biochemical normalization that precedes radiological regression.

Identification of a minimal region of loss on chromosome 6q27 associated with poor survival of high-risk neuroblastoma patients

Patients with high-risk neuroblastoma (HR-NB) often initially respond to therapy, but afterward they become resistant and disease recurred. Unfortunately, it does not exist one or more specific chromosome defects associated with relapse or refractory NB. Recently, genomic evidence from primary tumors indicated that the distal region of chromosome 6q is loss in HR-NB patients with fatal outcome. We identified a minimal common region of loss of chromosome 6q27 spanning an area of 2.09 Mb by high-resolution DNA copy number data of a small cohort of HR-NB samples carrying 6q loss. This region of loss harbored five genes T, SFT2D1, RPS6KA2, FGFR1OP, and UNC93A. We found that low SFT2D1, RPS6KA2, and FGFR1OP gene expression predicted poor outcome in HR-NB patients using public R2 Platform. Further functional studies will be essential to confirm the presumed tumor suppressor gene(s) located within 6q27 region. These results suggest that SFT2D1, RPS6KA2, and FGFR1OP genes may be responsible for poor prognosis of HR-NB tumors with 6q27 loss, and their haploinsufficiency may be crucial in accelerating tumor progression.

Genomic Amplifications and Distal 6q Loss: Novel Markers for Poor Survival in High-risk Neuroblastoma Patients

Background

Neuroblastoma is characterized by substantial clinical heterogeneity. Despite intensive treatment, the survival rates of high-risk neuroblastoma patients are still disappointingly low. Somatic chromosomal copy number aberrations have been shown to be associated with patient outcome, particularly in low- and intermediate-risk neuroblastoma patients. To improve outcome prediction in high-risk neuroblastoma, we aimed to design a prognostic classification method based on copy number aberrations.

Methods

In an international collaboration, normalized high-resolution DNA copy number data (arrayCGH and SNP arrays) from 556 high-risk neuroblastomas obtained at diagnosis were collected from nine collaborative groups and segmented using the same method. We applied logistic and Cox proportional hazard regression to identify genomic aberrations associated with poor outcome.

Results

In this study, we identified two types of copy number aberrations that are associated with extremely poor outcome. Distal 6q losses were detected in 5.9% of patients and were associated with a 10-year survival probability of only 3.4% (95% confidence interval [CI] = 0.5% to 23.3%, two-sided P = .002). Amplifications of regions not encompassing the MYCN locus were detected in 18.1% of patients and were associated with a 10-year survival probability of only 5.8% (95% CI = 1.5% to 22.2%, two-sided P < .001).

Conclusions

Using a unique large copy number data set of high-risk neuroblastoma cases, we identified a small subset of high-risk neuroblastoma patients with extremely low survival probability that might be eligible for inclusion in clinical trials of new therapeutics. The amplicons may also nominate alternative treatments that target the amplified genes.

The SRCIN1/p140Cap adaptor protein negatively regulates the aggressiveness of neuroblastoma

Neuroblastoma is the most common extra-cranial pediatric solid tumor, responsible for 13–15% of pediatric cancer death. Its intrinsic heterogeneity makes it difficult to target for successful therapy. The adaptor protein p140Cap/SRCIN1 negatively regulates tumor cell features and limits breast cancer progression. This study wish to assess if p140Cap is a key biological determinant of neuroblastoma outcome. RNAseq profiles of a large cohort of neuroblastoma patients show that SRCIN1 mRNA levels are an independent risk factor inversely correlated to disease aggressiveness. In high-risk patients, CGH+SNP microarray analysis of primary neuroblastoma identifies SRCIN1 as frequently altered by hemizygous deletion, copy-neutral loss of heterozygosity, or disruption. Functional experiments show that p140Cap negatively regulates Src and STAT3 signaling, affects anchorage-independent growth and migration, in vivo tumor growth and spontaneous lung metastasis formation. p140Cap also increases sensitivity of neuroblastoma cells to doxorubicin and etoposide treatment, as well as to a combined treatment with chemotherapy drugs and Src inhibitors. Our functional findings point to a causal role of p140Cap in curbing the aggressiveness of neuroblastoma, due to its ability to impinge on specific molecular pathways, and to sensitize cells to therapeutic treatment. This study provides the first evidence that the SRCIN1/p140Cap adaptor protein is a key player in neuroblastoma as a new independent prognostic marker for patient outcome and treatment. Altogether, these data highlight the potential clinical impact of SRCIN1/p140Cap expression in neuroblastoma tumors, in terms of reducing cytotoxic effects of chemotherapy, one of the main issues for pediatric tumor treatment.

The Transcribed-Ultra Conserved Regions: Novel Non-Coding RNA Players in Neuroblastoma Progression

The Transcribed-Ultra Conserved Regions (T-UCRs) are a class of novel non-coding RNAs that arise from the dark matter of the genome. T-UCRs are highly conserved between mouse, rat, and human genomes, which might indicate a definitive role for these elements in health and disease. The growing body of evidence suggests that T-UCRs contribute to oncogenic pathways. Neuroblastoma is a type of childhood cancer that is challenging to treat. The role of non-coding RNAs in the pathogenesis of neuroblastoma, in particular for cancer development, progression, and therapy resistance, has been documented. Exosmic non-coding RNAs are also involved in shaping the biology of the tumor microenvironment in neuroblastoma. In recent years, the involvement of T-UCRs in a wide variety of pathways in neuroblastoma has been discovered. Here, we present an overview of the involvement of T-UCRs in various cellular pathways, such as DNA damage response, proliferation, chemotherapy response, MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian)) amplification, gene copy number, and immune response, as well as correlate it to patient survival in neuroblastoma.

Opportunities and challenges of circulating biomarkers in neuroblastoma

Molecular analysis of nucleic acid and protein biomarkers is becoming increasingly common in paediatric oncology for diagnosis, risk stratification and molecularly targeted therapeutics. However, many current and emerging biomarkers are based on analysis of tumour tissue, which is obtained through invasive surgical procedures and in some cases may not be accessible. Over the past decade, there has been growing interest in the utility of circulating biomarkers such as cell-free nucleic acids, circulating tumour cells and extracellular vesicles as a so-called liquid biopsy of cancer. Here, we review the potential of emerging circulating biomarkers in the management of neuroblastoma and highlight challenges to their implementation in the clinic.

Loss of whole chromosome X predicts prognosis of neuroblastoma patients with numerical genomic profile

BACKGROUND

Neuroblastoma (NB), a pediatric tumor of the sympathetic nervous system, is characterized by very frequent chromosomal aberrations at the onset of the disease. Identification of further risk factors for relapse, which could lead to increased survival and potentially reduced late effects among survivors, is still urgently needed. Segmental chromosome aberrations (SCA) are associated with poor prognosis, whereas numerical whole-chromosome aberrations (NCA) are found in patients with a good prognosis; however, a small percentage of the latter patients (10%-15%) subsequently relapse and/or die of disease.

PROCEDURE

DNA copy-number data from 174 NB patients with an NCA genomic profile were analyzed. Association between NCA and event-free survival (EFS) was investigated by the Kaplan-Meier estimator and prognostic decision tree (DT).

RESULTS

DT identified 65 patients with normal chromosome X and an excellent five-year EFS (100%) independently from the stage at diagnosis. The association between poor EFS and whole chromosome X alterations was confirmed after stratification into two groups of different expected prognosis and by internal validation via bootstrap analysis. Furthermore, the association was also observed in an independent cohort of NB patients extracted from the data set of the National Cancer Institute TARGET Project for Neuroblastoma, but sample size was small (n = 75) and statistical significance was not achieved.

CONCLUSIONS

Loss of whole chromosome X may represent a new prognostic marker for NB patients with an NCA genomic profile. If confirmed by further studies, this finding could indicate that such patients should be reclassified as intermediate risk and treated accordingly.

Targeting anaplastic lymphoma kinase in neuroblastoma

Over the last decade, anaplastic lymphoma kinase (ALK), a receptor tyrosine kinase (RTK), has been identified as a fusion partner in a diverse variety of translocation events resulting in oncogenic signaling in many different cancer types. In tumors where the full‐length ALK RTK itself is mutated, such as neuroblastoma, the picture regarding the role of ALK as an oncogenic driver is less clear. Neuroblastoma is a complex and heterogeneous tumor that arises from the neural crest derived peripheral nervous system. Although high‐risk neuroblastoma is rare, it often relapses and becomes refractory to treatment. Thus, neuroblastoma accounts for 10–15% of all childhood cancer deaths. Since most cases are in children under the age of 2, understanding the role and regulation of ALK during neural crest development is an important goal in addressing neuroblastoma tumorigenesis. An impressive array of tyrosine kinase inhibitors (TKIs) that act to inhibit ALK have been FDA approved for use in ALK‐driven cancers. ALK TKIs bind differently within the ATP‐binding pocket of the ALK kinase domain and have been associated with different resistance mutations within ALK itself that arise in response to therapeutic use, particularly in ALK‐fusion positive non‐small cell lung cancer (NSCLC). This patient population has highlighted the importance of considering the relevant ALK TKI to be used for a given ALK mutant variant. In this review, we discuss ALK in neuroblastoma, as well as the use of ALK TKIs and other strategies to inhibit tumor growth. Current efforts combining novel approaches and increasing our understanding of the oncogenic role of ALK in neuroblastoma are aimed at improving the efficacy of ALK TKIs as precision medicine options in the clinic.

Meta-mining of copy number profiles of high-risk neuroblastoma tumors

Neuroblastoma, a pediatric tumor of the sympathetic nervous system, is predominantly driven by copy number aberrations, which predict survival outcome in global neuroblastoma cohorts and in low-risk cases. For high-risk patients there is still a need for better prognostic biomarkers. Via an international collaboration, we collected copy number profiles of 556 high-risk neuroblastomas generated on different array platforms. This manuscript describes the composition of the dataset, the methods used to process the data, including segmentation and aberration calling, and data validation. t-SNE analysis shows that samples cluster according to MYCN status, and shows a difference between array platforms. 97.3% of samples are characterized by the presence of segmental aberrations, in regions frequently affected in neuroblastoma. Focal aberrations affect genes known to be involved in neuroblastoma, such as ALK and LIN28B. To conclude, we compiled a unique large copy number dataset of high-risk neuroblastoma tumors, available via R2 and a Shiny web application. The availability of patient survival data allows to further investigate the prognostic value of copy number aberrations.

BAP1 induces cell death via interaction with 14-3-3 in neuroblastoma

BRCA1-associated protein 1 (BAP1) is a nuclear deubiquitinating enzyme that is associated with multiprotein complexes that regulate key cellular pathways, including cell cycle, cellular differentiation, cell death, and the DNA damage response. In this study, we found that the reduced expression of BAP1 pro6motes the survival of neuroblastoma cells, and restoring the levels of BAP1 in these cells facilitated a delay in S and G2/M phase of the cell cycle, as well as cell apoptosis. The mechanism that BAP1 induces cell death is mediated via an interaction with 14-3-3 protein. The association between BAP1 and 14-3-3 protein releases the apoptotic inducer protein Bax from 14-3-3 and promotes cell death through the intrinsic apoptosis pathway. Xenograft studies confirmed that the expression of BAP1 reduces tumor growth and progression in vivo by lowering the levels of pro-survival factors such as Bcl-2, which in turn diminish the survival potential of the tumor cells. Patient data analyses confirmed the finding that the high-BAP1 mRNA expression correlates with a better clinical outcome. In summary, our study uncovers a new mechanism for BAP1 in the regulation of cell apoptosis in neuroblastoma cells.

Development of a new outcome prediction model for Chinese patients with penile squamous cell carcinoma based on preoperative serum C-reactive protein, body mass index, and standard pathological risk factors: the TNCB score group system

Purpose

To determine the predictive value and feasibility of the new outcome prediction model for Chinese patients with penile squamous cell carcinoma.

Results

The 3-year disease-specific survival (DSS) was 92.3% in patients with < 8.70 mg/L CRP and 54.9% in those with elevated CRP (P < 0.001). The 3-year DSS was 86.5% in patients with a BMI < 22.6 Kg/m2 and 69.9% in those with a higher BMI (P = 0.025). In a multivariate analysis, pathological T stage (P < 0.001), pathological N stage (P = 0.002), BMI (P = 0.002), and CRP (P = 0.004) were independent predictors of DSS. A new scoring model was developed, consisting of BMI, CRP, and tumor T and N classification. In our study, we found that the addition of the above-mentioned parameters significantly increased the predictive accuracy of the system of the American Joint Committee on Cancer (AJCC) anatomic stage group. The accuracy of the new prediction category was verified.

Methods

A total of 172 Chinese patients with penile squamous cell cancer were analyzed retrospectively between November 2005 and November 2014. Statistical data analysis was conducted using the nonparametric method. Survival analysis was performed with the log-rank test and the Cox proportional hazard model. Based on regression estimates of significant parameters in multivariate analysis, a new BMI-, CRP- and pathologic factors-based scoring model was developed to predict disease-specific outcomes. The predictive accuracy of the model was evaluated using the internal and external validation.

Conclusion

The present study demonstrated that the TNCB score group system maybe a precise and easy to use tool for predicting outcomes in Chinese penile squamous cell carcinoma patients.

MiRNA Influences in Neuroblast Modulation: An Introspective Analysis

Neuroblastoma (NB) is the most common occurring solid paediatric cancer in children under the age of five years. Whether of familial or sporadic origin, chromosome abnormalities contribute to the development of NB and cause dysregulation of microRNAs (miRNAs). MiRNAs are small non-coding, single stranded RNAs that target messenger RNAs at the post-transcriptional levels by repressing translation within all facets of human physiology. Such gene 'silencing' activities by miRNAs allows the development of regulatory feedback loops affecting multiple functions within the cell, including the possible differentiation of neural stem cell (NSC) lineage selection. Neurogenesis includes stages of self-renewal and fate specification of NSCs, migration and maturation of young neurones, and functional integration of new neurones into the neural circuitry, all of which are regulated by miRNAs. The role of miRNAs and their interaction in cellular processes are recognised aspects of cancer genetics, and miRNAs are currently employed as biomarkers for prognosis and tumour characterisation in multiple cancer models. Consequently, thorough understanding of the mechanisms of how these miRNAs interplay at the transcriptomic level will definitely lead to the development of novel, bespoke and efficient therapeutic measures, with this review focusing on the influences of miRNAs on neuroblast modulations leading to neuroblastoma.

The mutational landscape of MYCN, Lin28b and ALKF1174L driven murine neuroblastoma mimics human disease

Genetically engineered mouse models have proven to be essential tools for unraveling fundamental aspects of cancer biology and for testing novel therapeutic strategies. To optimally serve these goals, it is essential that the mouse model faithfully recapitulates the human disease. Recently, novel mouse models for neuroblastoma have been developed. Here, we report on the further genomic characterization through exome sequencing and DNA copy number analysis of four of the currently available murine neuroblastoma model systems (ALK, Th-MYCN, Dbh-MYCN and Lin28b). The murine tumors revealed a low number of genomic alterations – in keeping with human neuroblastoma - and a positive correlation of the number of genetic lesions with the time to onset of tumor formation was observed. Gene copy number alterations are the hallmark of both murine and human disease and frequently affect syntenic genomic regions. Despite low mutational load, the genes mutated in murine disease were found to be enriched for genes mutated in human disease. Taken together, our study further supports the validity of the tested mouse models for mechanistic and preclinical studies of human neuroblastoma.

Novel Mechanisms of ALK Activation Revealed by Analysis of the Y1278S Neuroblastoma Mutation

Numerous mutations have been observed in the Anaplastic Lymphoma Kinase (ALK) receptor tyrosine kinase (RTK) in both germline and sporadic neuroblastoma. Here, we have investigated the Y1278S mutation, observed in four patient cases, and its potential importance in the activation of the full length ALK receptor. Y1278S is located in the 1278-YRASYY-1283 motif of the ALK activation loop, which has previously been reported to be important in the activation of the ALK kinase domain. In this study, we have characterized activation loop mutations within the context of the full length ALK employing cell culture and Drosophila melanogaster model systems. Our results show that the Y1278S mutant observed in patients with neuroblastoma harbors gain-of-function activity. Secondly, we show that the suggested interaction between Y1278 and other amino acids might be of less importance in the activation process of the ALK kinase than previously proposed. Thirdly, of the three individual tyrosines in the 1278-YRASYY-1283 activation loop, we find that Y1283 is the critical tyrosine in the activation process. Taken together, our observations employing different model systems reveal new mechanistic insights on how the full length ALK receptor is activated and highlight differences with earlier described activation mechanisms observed in the NPM-ALK fusion protein, supporting a mechanism of activation more in line with those observed for the Insulin Receptor (InR).

11q deletion in neuroblastoma: a review of biological and clinical implications

Deletion of the long arm of chromosome 11 (11q deletion) is one of the most frequent events that occur during the development of aggressive neuroblastoma. Clinically, 11q deletion is associated with higher disease stage and decreased survival probability. During the last 25 years, extensive efforts have been invested to identify the precise frequency of 11q aberrations in neuroblastoma, the recurrently involved genes, and to understand the molecular mechanisms of 11q deletion, but definitive answers are still unclear. In this review, it is our intent to compile and review the evidence acquired to date on 11q deletion in neuroblastoma.

MYCN overexpression is associated with unbalanced copy number gain, altered nuclear location, and overexpression of chromosome arm 17q genes in neuroblastoma tumors and cell lines

MYCN amplification and MYCN overexpression are poor prognostic factors in neuroblastoma. Tumors with unbalanced chromosome arm 17q gain are often associated with MYCN amplification; however, the relationship between chromosome 17 copy number status and MYCN expression is not known. We investigated the relationship between MYCN expression and chromosome 17 copy number, nuclear location, and gene expression. By performing dual-colored fluorescence in situ hybridization on 16 primary neuroblastomas, we found that those with unbalanced gain of 17q have high MYCN expression, those with no gain have medium expression, and those with numerical gain have low expression (P < 0.0001). We also found that the nuclear location of 17q correlates with chromosome 17 copy number status: copies in tumors with unbalanced gain and no gain of chromosome 17 occupy a more central location than those in tumors with balanced gain (P < 0.0001). We show that a more central nuclear location of 17q coincides with increased expression of genes found within this chromosome arm. To further understand the association between MYCN expression and chromosome 17, we overexpressed MYCN in two low-expressing MYCN cell lines, SHEP and GIMEN. We found that both cell lines had an unbalanced gain of chromosome 17q, a more central nuclear location of the region and increased expression of the 17q genes. Therefore, this study indicates, for the first time, a functional relationship between MYCN overexpression and the gain of 17q in neuroblastoma.

Neuroblastoma after childhood: prognostic relevance of segmental chromosome aberrations, ATRX protein status, and immune cell infiltration

Neuroblastoma (NB) is a common malignancy in children but rarely occurs during adolescence or adulthood. This subgroup is characterized by an indolent disease course, almost uniformly fatal, yet little is known about the biologic characteristics. The aim of this study was to identify differential features regarding DNA copy number alterations, α-thalassemia/mental retardation syndrome X-linked (ATRX) protein expression, and the presence of tumor-associated inflammatory cells. Thirty-one NB patients older than 10 years who were included in the Spanish NB Registry were considered for the current study; seven young and middle-aged adult patients (range 18-60 years) formed part of the cohort. We performed single nucleotide polymorphism arrays, immunohistochemistry for immune markers (CD4, CD8, CD20, CD11b, CD11c, and CD68), and ATRX protein expression. Assorted genetic profiles were found with a predominant presence of a segmental chromosome aberration (SCA) profile. Preadolescent and adolescent NB tumors showed a higher number of SCA, including 17q gain and 11q deletion. There was also a marked infiltration of immune cells, mainly high and heterogeneous, in young and middle-aged adult tumors. ATRX negative expression was present in the tumors. The characteristics of preadolescent, adolescent, young adult, and middle-aged adult NB tumors are different, not only from childhood NB tumors but also from each other. Similar examinations of a larger number of such tumor tissues from cooperative groups should lead to a better older age–dependent tumor pattern and to innovative, individual risk-adapted therapeutic approaches for these patients.

The neuroblastoma and ganglion components of nodular ganglioneuroblastoma are genetically similar: evidence against separate clonal origins

Nodular ganglioneuroblastoma is characterized by a macroscopic nodule of neuroblastoma within a ganglioneuromatous component. These two components have been considered to originate from separate clones, with the neuroblastoma clone accounting for the clinical behavior of nodular ganglioneuroblastoma. In order to investigate the clonal origin of the cellular components (neuroblasts, ganglion cells, and Schwann cells) of nodular ganglioneuroblastoma, paraffin-embedded tumor samples from eight cases were analyzed by single nucleotide polymorphism array and in situ hybridization. DNA was extracted separately from neuroblastomatous and ganglioneuromatous areas. By in situ hybridization, MYCN gain (4-10 gene copies/nucleus) was detected in 7/8 neuroblastoma samples. In ganglioneuromatous regions, gains were also detected in ganglion cells but not in Schwann cells. Single-nucleotide polymorphism array studies identified chromosome losses (11q and 14q) and gains (12, 13q, 17q and 18q) in the neuroblastoma component, whereas the ganglioneuromatous component showed fewer or no genetic alterations. There were no unique copy number changes distinguishing nodular ganglioneuroblastoma from other subtypes of neuroblastoma. By in situ hybridization, ganglion cells but not Schwann cells showed the same alterations detected in neuroblasts. Thus, neuroblasts and ganglion cells in nodular ganglioneuroblastoma are genetically related and may arise from the same clone. In contrast, the Schwann cells have a different origin and may be derived from a non-neoplastic neural crest precursor. Our results suggest that the clinical behavior of nodular ganglioneuroblastoma cannot be explained by the presence of separate clones with distinct genetic signatures.

Alternative NHEJ Pathway Components Are Therapeutic Targets in High-Risk Neuroblastoma

In neuroblastoma, MYCN genomic amplification and segmental chromosomal alterations including 1p or 11q loss of heterozygocity and/or 17q gain are associated with progression and poor clinical outcome. Segmental alterations are the strongest predictor of relapse and result from unbalanced translocations attributable to erroneous repair of chromosomal breaks. Although sequence analysis of affected genomic regions suggests that these errors arise by nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB), abnormalities in NHEJ have not been implicated in neuroblastoma pathogenesis. On this basis, the hypothesis that an error-prone mechanism of NHEJ is critical for neuroblastoma cell survival was tested. Plasmid-based DSB repair assays demonstrated efficient NHEJ activity in human neuroblastoma cells with repair products that were error-prone relative to nontransformed cells. Neuroblastoma cells derived from tumorigenic neuroblastic phenotypes had differential DNA repair protein expression patterns compared with nontumorigenic cells. Tumorigenic neuroblastoma cells were deficient in DNA ligase IV (Lig4) and Artemis (DCLRE1C), mediators of canonical NHEJ. Conversely, enzymes required for an error-prone alternative NHEJ pathway (alt-NHEJ), DNA Ligase IIIα (Lig3), DNA Ligase I (Lig1), and PARP1 protein were upregulated. Inhibition of Lig3 and Lig1 led to DSB accumulation and cell death, linking alt-NHEJ to cell survival in neuroblastoma. Neuroblastoma cells demonstrated sensitivity to PARP1 inhibition (PARPi) that paralleled PARP1 expression. In a dataset of human neuroblastoma patient tumors, overexpression of genes encoding alt-NHEJ proteins associated with poor survival.

IMPLICATIONS

These findings provide an insight into DNA repair fidelity in neuroblastoma and identify components of the alt-NHEJ pathway as promising therapeutic targets.

The kinase ALK stimulates the kinase ERK5 to promote the expression of the oncogene MYCN in neuroblastoma

Anaplastic lymphoma kinase (ALK) is an important molecular target in neuroblastoma. Although tyrosine kinase inhibitors abrogating ALK activity are currently in clinical use for the treatment of ALK-positive (ALK(+)) disease, monotherapy with ALK tyrosine kinase inhibitors may not be an adequate solution for ALK(+) neuroblastoma patients. Increased expression of the gene encoding the transcription factor MYCN is common in neuroblastomas and correlates with poor prognosis. We found that the kinase ERK5 [also known as big mitogen-activated protein kinase (MAPK) 1 (BMK1)] is activated by ALK through a pathway mediated by phosphoinositide 3-kinase (PI3K), AKT, MAPK kinase kinase 3 (MEKK3), and MAPK kinase 5 (MEK5). ALK-induced transcription of MYCN and stimulation of cell proliferation required ERK5. Pharmacological or RNA interference-mediated inhibition of ERK5 suppressed the proliferation of neuroblastoma cells in culture and enhanced the antitumor efficacy of the ALK inhibitor crizotinib in both cells and xenograft models. Together, our results indicate that ERK5 mediates ALK-induced transcription of MYCN and proliferation of neuroblastoma, suggesting that targeting both ERK5 and ALK may be beneficial in neuroblastoma patients.

Modulation of chemotherapeutic drug resistance in neuroblastoma SK-N-AS cells by the neural apoptosis inhibitory protein and miR-520f

The acquisition of multidrug resistance is a major impediment to the successful treatment of neuroblastoma, a clinically heterogeneous cancer accounting for ∼15% of all pediatric cancer deaths. The MYCN transcription factor, whose gene is amplified in ∼30% of high-risk neuroblastoma cases, influences drug resistance by regulating a cadre of genes, including those involved with drug efflux, however, other high-risk subtypes of neuroblastoma lacking MYCN amplification, such as those with chromosome 11q deletions, also acquire multidrug resistance. To elucidate additional mechanisms involved with drug resistance in non-MYCN amplified tumour cells, an SK-N-AS subline (SK-N-AsCis24) that is significantly resistant to cisplatin and cross resistant to etoposide was developed through a pulse-selection process. High resolution aCGH analysis of SK-N-AsCis24 revealed a focal gain on chromosome 5 containing the coding sequence for the neural apoptosis inhibitory protein (NAIP). Significant overexpression of NAIP mRNA and protein was documented, while experimental modulation of NAIP levels in both SK-N-AsCis24 and in parental SK-N-AS cells confirmed that NAIP was responsible for the drug resistant phenotype by apoptosis inhibition. Furthermore, a decrease in the NAIP targeting microRNA, miR-520f, was also demonstrated to be partially responsible for increased NAIP levels in SK-N-AsCis24. Interestingly, miR-520f levels were determined to be significantly lower in postchemotherapy treatment tumours relative to matched prechemotherapy samples, consistent with a role for this miRNA in the acquisition of drug resistance in vivo, potentially through decreased NAIP targeting. Our findings provide biological novel insight into neuroblastoma drug-resistance and have implications for future therapeutic research.

A Cre-conditional MYCN-driven neuroblastoma mouse model as an improved tool for preclinical studies

Neuroblastoma, a childhood cancer that originates from neural crest-derived cells, is the most common deadly solid tumor of infancy. Amplification of the MYCN oncogene, which occurs in approximately 20–25% of human neuroblastomas, is the most prominent genetic marker of high-stage disease. The availability of valid preclinical in vivo models is a prerequisite to develop novel targeted therapies. We here report on the generation of transgenic mice with Cre-conditional induction of MYCN in dopamine β-hydroxylase-expressing cells, termed LSL-MYCN;Dbh-iCre. These mice develop neuroblastic tumors with an incidence of >75%, regardless of strain background. Molecular profiling of tumors revealed upregulation of the MYCN-dependent miR-17–92 cluster as well as expression of neuroblastoma marker genes, including tyrosine hydroxylase and the neural cell adhesion molecule 1. Gene set enrichment analyses demonstrated significant correlation with MYC-associated expression patterns. Array comparative genome hybridization showed that chromosomal aberrations in LSL-MYCN;Dbh-iCre tumors were syntenic to those observed in human neuroblastomas. Treatment of a cell line established from a tumor derived from a LSL-MYCN;Dbh-iCre mouse with JQ1 or MLN8237 reduced cell viability and demonstrated oncogene addiction to MYCN. Here we report establishment of the first Cre-conditional human MYCN-driven mouse model for neuroblastoma that closely recapitulates the human disease with respect to tumor localization, histology, marker expression and genomic make up. This mouse model is a valuable tool for further functional studies and to assess the effect of targeted therapies.

Recent insights into the biology of neuroblastoma

Neuroblastoma (NB) is an embryonal tumor of the sympathetic nervous system which accounts for 8-10% of pediatric cancers. It is characterized by a broad spectrum of clinical behaviors from spontaneous regression to fatal outcome despite aggressive therapies. Considerable progress has been made recently in the germline and somatic genetic characterization of patients and tumors. Indeed, predisposition genes that account for a significant proportion of familial and syndromic cases have been identified and genome-wide association studies have retrieved a number of susceptibility loci. In addition, genome-wide sequencing, copy-number and expression studies have been conducted on tumors and have detected important gene modifications, profiles and signatures that have strong implications for the therapeutic stratification of patients. The identification of major players in NB oncogenesis, including MYCN, ALK, PHOX2B and LIN28B, has enabled the development of new animal models. Our review focuses on these recent advances, on the insights they provide on the mechanisms involved in NB development and their applications for the clinical management of patients.

Ultra-High Density SNParray in Neuroblastoma Molecular Diagnostics

Neuroblastoma serves as a paradigm for applying tumor genomic data for determining patient prognosis and thus for treatment allocation. MYCN status, i.e., amplified vs. non-amplified, was one of the very first biomarkers in oncology to discriminate aggressive from less aggressive or even favorable clinical courses of neuroblastoma. However, MYCN amplification is by far not the only genetic change associated with unfavorable clinical courses. So called “segmental chromosomal aberrations,” (SCAs) i.e., gains or losses of chromosomal fragments, can also indicate tumor aggressiveness. The clinical use of these genomic aberrations has, however, been hampered for many years by methodical and interpretational problems. Only after reaching worldwide consensus on markers, methodology, and data interpretation, information on SCAs has recently been implemented in clinical studies. Now, a number of collaborative studies within COG, GPOH, and SIOPEN use genomic information to stratify therapy for patients with localized and metastatic disease. Recently, new types of DNA based aberrations influencing the clinical behavior of neuroblastomas have been described. Deletions or mutations of genes like ATRX and a phenomenon referred to as “chromothripsis” are all assumed to correlate with an unfavorable clinical behavior. However, these genomic aberrations need to be scrutinized in larger studies applying the most appropriate techniques. Single nucleotide polymorphism arrays have proven successful in deciphering genomic aberrations of cancer cells; these techniques, however, are usually not applied in the daily routine. Here, we present an ultra-high density (UHD) SNParray technique which is, because of its high specificity and sensitivity and the combined copy number and allele information, highly appropriate for the genomic diagnosis of neuroblastoma and other malignancies.

Clinical characteristics and outcome of patients with neuroblastoma presenting genomic amplification of loci other than MYCN

Background

Somatically acquired genomic alterations with MYCN amplification (MNA) are key features of neuroblastoma (NB), the most common extra-cranial malignant tumour of childhood. Little is known about the frequency, clinical characteristics and outcome of NBs harbouring genomic amplification(s) distinct from MYCN.

Methods

Genomic profiles of 1100 NBs from French centres studied by array-CGH were re-examined specifically to identify regional amplifications. Patients were included if amplifications distinct from the MYCN locus were seen. A subset of NBs treated at Institut Curie and harbouring MNA as determined by array-CGH without other amplification was also studied. Clinical and histology data were retrospectively collected.

Results

In total, 56 patients were included and categorised into 3 groups. Group 1 (n = 8) presented regional amplification(s) without MNA. Locus 12q13-14 was a recurrent amplified region (4/8 cases). This group was heterogeneous in terms of INSS stages, primary localisations and histology, with atypical clinical features. Group 2 (n = 26) had MNA as well as other regional amplifications. These patients shared clinical features of those of a group of NBs MYCN amplified (Group 3, n = 22). Overall survival for group 1 was better than that of groups 2 and 3 (5 year OS: 87.5%±11% vs 34.9%±7%, log-rank p<0.05).

Conclusion

NBs harbouring regional amplification(s) without MNA are rare and seem to show atypical features in clinical presentation and genomic profile. Further high resolution genetic explorations are justified in this heterogeneous group, especially when considering these alterations as predictive markers for targeted therapy.

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.

Chromosome 17/17q gain and unaltered profiles in high resolution array-CGH are prognostically informative in neuroblastoma

The prognostic relevance of chromosome 17 gain in neuroblastoma is still discussed. This investigation specifies the frequency, type, size, and transcriptional relevance in a large patient cohort. Primary tumor material of 202 patients was analyzed using high-resolution oligonucleotide array-based comparative genomic hybridization (aCGH) and correlated with clinical and survival data. A subset (n = 145) was correlated for differentially expressed genes (DEG) by microarray analysis. Chromosome 17 aCGH analysis showed numerical gain in 94/202 patients (47%), partial gain in 93/202 patients (46%), and no gain in 15/202 patients (7%). The frequency of partial gain was higher in stage 4 neuroblastoma (stage 1 15%; stage 2 12%; stage 3 16%; stage 4S 7%; and stage 4 50%). Overall survival (OS) was superior in patients with numerical gain compared with patients with partial gain or no gain (5-y-OS: 0.95 ± 0.02 vs. 0.63 ± 0.05 vs. 0.60 ± 0.13; P < 0.001). Gene expression analysis demonstrated 95/130 DEGs between tumors with numerical or partial chromosome/no gain. Only one DEG (CCKBR) was detected comparing tumors with partial gain and those with no gain. In patients with partial gain, the distribution of breakpoints did not correlate with stage and 11q status, but with MYCN amplification and 1p status. The "best" breakpoints in cases with partial 17q gain were at 42.5 Mb for event-free and 26.6 Mb for OS. Numerical gain of chromosome 17 is associated with a better prognosis than partial and no gain. The group of tumors with partial gain was similar to the group without gain with respect to stage distribution, outcome, and gene expression profile.

Neuroblastoma in older children, adolescents and young adults: a report from the International Neuroblastoma Risk Group project

BACKGROUND

Neuroblastoma in older children and adolescents has a distinctive, indolent phenotype, but little is known about the clinical and biological characteristics that distinguish this rare subgroup. Our goal was to determine if an optimal age cut-off exists that defines indolent disease and if accepted prognostic factors and treatment approaches are applicable to older children.

PROCEDURE

Using data from the International Neuroblastoma Risk Group, among patients ≥18 months old (n = 4,027), monthly age cut-offs were tested to determine the effect of age on survival. The prognostic effect of baseline characteristics and autologous hematopoietic cell transplant (AHCT) for advanced disease was assessed within two age cohorts; ≥5 to <10 years (n = 730) and ≥10 years (n = 200).

RESULTS

Older age was prognostic of poor survival, with outcome gradually worsening with increasing age at diagnosis, without statistical evidence for an optimal age cut-off beyond 18 months. Among patients ≥5 years, factors significantly prognostic of lower event-free survival (EFS) and overall survival (OS) in multivariable analyses were INSS stage 4, MYCN amplification and unfavorable INPC histology classification. Among stage 4 patients, AHCT provided a significant EFS and OS benefit. Following relapse, patients in both older cohorts had prolonged OS compared to those ≥18 months to <5 years (P < 0.0001).

CONCLUSIONS

Despite indolent disease and infrequent MYCN amplification, older children with advanced disease have poor survival, without evidence for a specific age cut-off. Our data suggest that AHCT may provide a survival benefit in older children with advanced disease. Novel therapeutic approaches are required to more effectively treat these patients.

Mechanistic insight into ALK receptor tyrosine kinase in human cancer biology

The burgeoning field of anaplastic lymphoma kinase (ALK) in cancer encompasses many cancer types, from very rare cancers to the more prevalent non-small-cell lung cancer (NSCLC). The common activation of ALK has led to the use of the ALK tyrosine kinase inhibitor (TKI) crizotinib in a range of patient populations and to the rapid development of second-generation drugs targeting ALK. In this Review, we discuss our current understanding of ALK function in human cancer and the implications for tumour treatment.

New insights into the genetics of neuroblastoma

Neuroblastoma is a genetically and clinically heterogeneous tumor of childhood, arising from precursor cells of the sympathetic nervous system. It is still a challenging cancer for pediatric oncology, as some tumors will spontaneously regress, while others will become refractory to all forms of therapy. The clinical course of this disease is greatly influenced by both patient age and the genetic abnormalities that occur within the tumors. MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian)) amplification and loss of chromosome 11q heterozygosity have been known to be indicative of poor prognosis. In this article, we review how mutations and structural alterations in specific genes contribute to inheritable predisposition to neuroblastoma and/or to aggressive disease pathogenesis, as well as implications for diagnosis and therapy. These genes include PHOX2B (paired-like homeobox 2b), ALK (anaplastic lymphoma receptor tyrosine kinase), and ATRX (alpha thalassemia/mental retardation syndrome X-linked).

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.

Downregulation of Axl in non-MYCN amplified neuroblastoma cell lines reduces migration

Neuroblastomas (NBL) are common pediatric solid tumors with a variable clinical course. At diagnosis half of all neuroblastoma patients presents with metastatic disease. The mechanisms of metastasis are largely unknown. Gene expression profiles (HU133plus2.0 arrays, Affymetrix) of 17 NBL and 5 peripheral neuro-ectodermal cell lines were used to identify a subgroup of non-MYCN amplified (non-NMA) NBL cell lines with a distinct gene expression profile and characterized by high expression of AXL. Axl is a tyrosine kinase receptor which plays a role in the metastatic process of several types of cancer. We hypothesized that Axl contributes to the metastasizing potential of non-NMA NBL and tested if AXL silencing diminishes malignant properties of high Axl expressing cell lines. AXL was silenced in two non-NMA NBL cell lines by using a lentiviral shRNA construct that was able to transduce these cell lines with more than 90% infection efficiency. Axl mRNA and protein level were efficiently knocked-down resulting in a decrease of migration of Axl positive cell lines GI-M-EN and SH-EP-2, and decreased invasion of GI-M-EN. Morphologically, Axl knockdown induced more rounded cells with a loss of contact. Intracellularly, we observed induction of stress fibers (immunofluorescence F-actin). These changes in cytoskeleton were associated with decreased migration, but were not accompanied by changes in genes involved in epithelial to mesenchymal transition such as CDH2, VIM or MMP9. No effects were observed for cell proliferation, apoptosis or downstream pathways. In conclusion, AXL is identified as a possible mediator of NBL metastasis.

Age dependence of tumor genetics in unfavorable neuroblastoma: arrayCGH profiles of 34 consecutive cases, using a Swedish 25-year neuroblastoma cohort for validation

Background

Aggressive neuroblastoma remains a significant cause of childhood cancer death despite current intensive multimodal treatment protocols. The purpose of the present work was to characterize the genetic and clinical diversity of such tumors by high resolution arrayCGH profiling.

Methods

Based on a 32K BAC whole-genome tiling path array and using 50-250K Affymetrix SNP array platforms for verification, DNA copy number profiles were generated for 34 consecutive high-risk or lethal outcome neuroblastomas. In addition, age and MYCN amplification (MNA) status were retrieved for 112 unfavorable neuroblastomas of the Swedish Childhood Cancer Registry, representing a 25-year neuroblastoma cohort of Sweden, here used for validation of the findings. Statistical tests used were: Fisher’s exact test, Bayes moderated t-test, independent samples t-test, and correlation analysis.

Results

MNA or segmental 11q loss (11q-) was found in 28/34 tumors. With two exceptions, these aberrations were mutually exclusive. Children with MNA tumors were diagnosed at significantly younger ages than those with 11q- tumors (mean: 27.4 vs. 69.5 months; p=0.008; n=14/12), and MNA tumors had significantly fewer segmental chromosomal aberrations (mean: 5.5 vs. 12.0; p<0.001). Furthermore, in the 11q- tumor group a positive correlation was seen between the number of segmental aberrations and the age at diagnosis (Pearson Correlation 0.606; p=0.037). Among nonMNA/non11q- tumors (n=6), one tumor displayed amplicons on 11q and 12q and three others bore evidence of progression from low-risk tumors due to retrospective evidence of disease six years before diagnosis, or due to tumor profiles with high proportions of numerical chromosomal aberrations. An early age at diagnosis of MNA neuroblastomas was verified by registry data, with an average of 29.2 months for 43 cases that were not included in the present study.

Conclusion

MNA and segmental 11q loss define two major genetic variants of unfavorable neuroblastoma with apparent differences in their pace of tumor evolution and in genomic integrity. Other possible, but less common, routes in the development of aggressive tumors are progression of low-risk infant-type lesions, and gene amplifications other than MYCN. Knowledge on such nosological diversity of aggressive neuroblastoma might influence future strategies for therapy.

Focal DNA copy number changes in neuroblastoma target MYCN regulated genes

Neuroblastoma is an embryonic tumor arising from immature sympathetic nervous system cells. Recurrent genomic alterations include MYCN and ALK amplification as well as recurrent patterns of gains and losses of whole or large partial chromosome segments. A recent whole genome sequencing effort yielded no frequently recurring mutations in genes other than those affecting ALK. However, the study further stresses the importance of DNA copy number alterations in this disease, in particular for genes implicated in neuritogenesis. Here we provide additional evidence for the importance of focal DNA copy number gains and losses, which are predominantly observed in MYCN amplified tumors. A focal 5 kb gain encompassing the MYCN regulated miR-17∼92 cluster as sole gene was detected in a neuroblastoma cell line and further analyses of the array CGH data set demonstrated enrichment for other MYCN target genes in focal gains and amplifications. Next we applied an integrated genomics analysis to prioritize MYCN down regulated genes mediated by MYCN driven miRNAs within regions of focal heterozygous or homozygous deletion. We identified RGS5, a negative regulator of G-protein signaling implicated in vascular normalization, invasion and metastasis, targeted by a focal homozygous deletion, as a new MYCN target gene, down regulated through MYCN activated miRNAs. In addition, we expand the miR-17∼92 regulatory network controlling TGFß signaling in neuroblastoma with the ring finger protein 11 encoding gene RNF11, which was previously shown to be targeted by the miR-17∼92 member miR-19b. Taken together, our data indicate that focal DNA copy number imbalances in neuroblastoma (1) target genes that are implicated in MYCN signaling, possibly selected to reinforce MYCN oncogene addiction and (2) serve as a resource for identifying new molecular targets for treatment.

Krüppel-like factor 4 (KLF4) suppresses neuroblastoma cell growth and determines non-tumorigenic lineage differentiation

Neuroblastoma (NB) is an embryonal tumor and possesses a unique propensity to exhibit either a spontaneous regression or an unrestrained growth. However, the underlying mechanism for this paradoxical clinical outcome remains largely unclear. Quantitative RT-PCR analysis on 102 primary NB tumors revealed that lower Krüppel-like factor 4 (KLF4) expression is frequently found in the unfavorable NB (Mann-Whitney test, P=0.027). In particular with the high-risk factors such as age of patient >1 year, MYCN amplification and low TRKA expression, the decreased expression of KLF4 was significantly associated with an unfavorable NB outcome. Despite knockdown of KLF4 alone is not sufficient to increase tumorigenicity of NB cells in vivo, stable expression of KLF4 short hairpin RNA in Be(2)-C cells significantly promoted growth of NB cells and inhibited cell differentiation toward fibromuscular lineage. In concordant with these observations, overexpression of KLF4 in SH-SY-5Y cells profoundly suppressed cell proliferation by direct upregulation of cell-cycle inhibitor protein p21(WAF1/CIP1), and knocking down p21(WAF1/CIP1) could partially rescue the suppressive effect of KLF4. Importantly, KLF4 overexpressing cells have lost their neuroblastic phenotypes, they were epithelial-like, strongly substrate-adherent, expressing smooth muscle marker and became non-tumorigenic, suggesting that KLF4 expression is crucial for lineage determination of NB cells, probably, favoring spontaneous tumor regression. Subsequent global gene expression profiling further revealed that transforming growth factor beta (TGFβ) and cell-cycle pathways are highly dysregulated upon KLF4 overexpression, and myogenic modulators, MEF2A and MYOD1 were found significantly upregulated. Taken together, we have demonstrated that KLF4 contributes to the favorable disease outcome by directly mediating the growth and lineage determination of NB cells.

Genome-wide promoter methylation analysis in neuroblastoma identifies prognostic methylation biomarkers

Background

Accurate outcome prediction in neuroblastoma, which is necessary to enable the optimal choice of risk-related therapy, remains a challenge. To improve neuroblastoma patient stratification, this study aimed to identify prognostic tumor DNA methylation biomarkers.

Results

To identify genes silenced by promoter methylation, we first applied two independent genome-wide methylation screening methodologies to eight neuroblastoma cell lines. Specifically, we used re-expression profiling upon 5-aza-2'-deoxycytidine (DAC) treatment and massively parallel sequencing after capturing with a methyl-CpG-binding domain (MBD-seq). Putative methylation markers were selected from DAC-upregulated genes through a literature search and an upfront methylation-specific PCR on 20 primary neuroblastoma tumors, as well as through MBD- seq in combination with publicly available neuroblastoma tumor gene expression data. This yielded 43 candidate biomarkers that were subsequently tested by high-throughput methylation-specific PCR on an independent cohort of 89 primary neuroblastoma tumors that had been selected for risk classification and survival. Based on this analysis, methylation of KRT19, FAS, PRPH, CNR1, QPCT, HIST1H3C, ACSS3 and GRB10 was found to be associated with at least one of the classical risk factors, namely age, stage or MYCN status. Importantly, HIST1H3C and GNAS methylation was associated with overall and/or event-free survival.

Conclusions

This study combines two genome-wide methylation discovery methodologies and is the most extensive validation study in neuroblastoma performed thus far. We identified several novel prognostic DNA methylation markers and provide a basis for the development of a DNA methylation-based prognostic classifier in neuroblastoma.

Segmental chromosomal alterations have prognostic impact in neuroblastoma: a report from the INRG project

Background:

In the INRG dataset, the hypothesis that any segmental chromosomal alteration might be of prognostic impact in neuroblastoma without MYCN amplification (MNA) was tested.

Methods:

The presence of any segmental chromosomal alteration (chromosome 1p deletion, 11q deletion and/or chromosome 17q gain) defined a segmental genomic profile. Only tumours with a confirmed unaltered status for all three chromosome arms were considered as having no segmental chromosomal alterations.

Results:

Among the 8800 patients in the INRG database, a genomic type could be attributed for 505 patients without MNA: 397 cases had a segmental genomic type, whereas 108 cases had an absence of any segmental alteration. A segmental genomic type was more frequent in patients >18 months and in stage 4 disease (P<0.0001). In univariate analysis, 11q deletion, 17q gain and a segmental genomic type were associated with a poorer event-free survival (EFS) (P<0.0001, P=0.0002 and P<0.0001, respectively). In multivariate analysis modelling EFS, the parameters age, stage and a segmental genomic type were retained in the model, whereas the individual genetic markers were not (P<0.0001 and RR=2.56; P=0.0002 and RR=1.8; P=0.01 and RR=1.7, respectively).

Conclusion:

A segmental genomic profile, rather than the single genetic markers, adds prognostic information to the clinical markers age and stage in neuroblastoma patients without MNA, underlining the importance of pangenomic studies.