Allelic deletion at chromosome bands 11q14-23 is common in neuroblastoma

DNA Ligase 4 Contributes to Cell Proliferation against DNA-PK Inhibition in MYCN-Amplified Neuroblastoma IMR32 Cells

Identifying the vulnerability of altered DNA repair machinery that displays synthetic lethality with MYCN amplification is a therapeutic rationale in unfavourable neuroblastoma. However, none of the inhibitors for DNA repair proteins are established as standard therapy in neuroblastoma. Here, we investigated whether DNA-PK inhibitor (DNA-PKi) could inhibit the proliferation of spheroids derived from neuroblastomas of MYCN transgenic mice and MYCN-amplified neuroblastoma cell lines. DNA-PKi exhibited an inhibitory effect on the proliferation of MYCN-driven neuroblastoma spheroids, whereas variable sensitivity was observed in those cell lines. Among them, the accelerated proliferation of IMR32 cells was dependent on DNA ligase 4 (LIG4), which comprises the canonical non-homologous end-joining pathway of DNA repair. Notably, LIG4 was identified as one of the worst prognostic factors in patients with MYCN-amplified neuroblastomas. It may play complementary roles in DNA-PK deficiency, suggesting the therapeutic potential of LIG4 inhibition in combination with DNA-PKi for MYCN-amplified neuroblastomas to overcome resistance to multimodal therapy.

Difluoromethylornithine (DFMO) and Neuroblastoma: A Review

Neuroblastoma is a type of cancer that affects the sympathetic nervous system and is the most common extracranial solid tumor in children. Difluoromethylornithine (DFMO) is a drug that has shown promise as a treatment option for high-risk neuroblastoma. This review aims to provide an overview of the current research on the use of DFMO in neuroblastoma treatment. The review includes a discussion of the mechanisms of action of DFMO, as well as its potential for use in combination with other treatments such as chemotherapy and immunotherapy. The review also examines the current clinical trials involving DFMO in high-risk neuroblastoma patients and provides insights into the challenges and future directions for the use of DFMO in neuroblastoma treatment. Overall, the review highlights the potential of DFMO as a promising therapy for neuroblastoma and highlights the need for further research to fully understand its potential benefits and limitations.

Impact of 11q Loss of Heterozygosity Status on the Response of High-Risk Neuroblastoma With MYCN Amplification to Neoadjuvant Chemotherapy

PURPOSE

The aim of this study was to investigate whether 11q loss of heterozygosity (LOH) aberration would impact the response of the primary tumor to neoadjuvant chemotherapy or to the degree of surgical resection in neuroblastoma (NB) patients with MYCN amplification.

METHODS

The clinical data of 42 NB patients with MYCN amplification who were newly diagnosed and received treatments at our hospital from 2011 to 2020 were retrospectively analyzed. According to the results of the segmental chromosome aberration analysis, the patients enrolled were assigned to an 11qLOH positive group and an 11qLOH negative group.

RESULTS

There was no significant difference in the mean number of chemotherapy courses completed before surgery between the 11qLOH positive and 11qLOH negative groups (p = 0.242). Each of the 42 patients had metaiodobenzylguanidine (MIBG) scans both before and after neoadjuvant chemotherapy. The percentage of patients who had a clinical MIBG change in the 11qLOH positive group was lower than the percentage in the 11qLOH negative group (27.27 vs. 66.67%, p = 0.030). The 11qLOH negative group seemed to have a higher rate of surgical resection (≥90%); however, the difference between the two groups was not statistically significant (p = 0.088). Furthermore, the 11qLOH negative group did not show significantly superior event-free survival and overall survival rates compared with the 11qLOH positive group.

CONCLUSIONS

This study showed that patients with NB and MYCN amplification in combination with 11qLOH might be less likely to respond to neoadjuvant chemotherapy when compared with patients with NB and MYCN amplification without 11qLOH.

Chromosome Imbalances in Neuroblastoma-Recent Molecular Insight into Chromosome 1p-deletion, 2p-gain, and 11q-deletion Identifies New Friends and Foes for the Future

Simple Summary

Neuroblastoma is a pediatric cancer that arises in the sympathetic nervous system. High-risk neuroblastoma is clinically challenging and identification of novel therapies, particularly those that offer a reduction in morbidity for these patients, is a high priority. Combining genetic analyses with investigation of molecular mechanisms, while considering recent advances in our understanding of key developmental events, provides avenues for future treatment. Here we review and highlight several recently published articles that address novel molecular mechanisms arising from chromosome 1p, 2p, and 11q aberrations, which likely contribute to high-risk neuroblastoma, and discusses their potential impact on treatment options.

Abstract

Neuroblastoma is the most common extracranial solid pediatric tumor, with around 15% childhood cancer-related mortality. High-risk neuroblastomas exhibit a range of genetic, morphological, and clinical heterogeneities, which add complexity to diagnosis and treatment with existing modalities. Identification of novel therapies is a high priority in high-risk neuroblastoma, and the combination of genetic analysis with increased mechanistic understanding—including identification of key signaling and developmental events—provides optimism for the future. This focused review highlights several recent findings concerning chromosomes 1p, 2p, and 11q, which link genetic aberrations with aberrant molecular signaling output. These novel molecular insights contribute important knowledge towards more effective treatment strategies for neuroblastoma.

Copy number alteration analysis for neuroblastoma using droplet digital polymerase chain reaction

BACKGROUND

Neuroblastoma (NB) is a malignant tumor derived from the neural crest. MYCN amplification is a well-known adverse molecular prognostic factor for NB. Genome copy number alterations (CNAs) such as chromosome (Chr) 11q deletion, 1p deletion, and 17q gain are associated with a poor prognosis. Fluorescence in situ hybridization (FISH) and Southern blotting analysis are frequently used to detect MYCN amplification. Although comparative genomic hybridization (CGH) and single-nucleotide polymorphism (SNP) chip arrays can easily detect CNAs, these methods are impractical for clinical use due to their cost and run time. Consequently, genome copy number analysis using digital droplet PCR has become widely used to monitor CNAs.

METHODS

In this study, we used digital droplet polymerase chain reaction to detect MYCN amplification and Chr 11q CNA, which was used for risk stratification according to the International Neuroblastoma Risk Group classification system. We compared the results with data from SNP chip arrays in seven NB cell lines and eight primary NB samples.

RESULTS

Digital droplet PCR assays successfully detected MYCN amplification and 11q CNA. The results were very consistent with those obtained by SNP chip assay.

CONCLUSIONS

Digital droplet PCR can be conducted more rapidly than FISH or Southern blotting. Accordingly, it should be useful for on-site clinical applications aimed at detecting CNAs in NB and performing risk stratification promptly after diagnosis.

Acceleration or Brakes: Which Is Rational for Cell Cycle-Targeting Neuroblastoma Therapy?

Unrestrained proliferation is a common feature of malignant neoplasms. Targeting the cell cycle is a therapeutic strategy to prevent unlimited cell division. Recently developed rationales for these selective inhibitors can be subdivided into two categories with antithetical functionality. One applies a “brake” to the cell cycle to halt cell proliferation, such as with inhibitors of cell cycle kinases. The other “accelerates” the cell cycle to initiate replication/mitotic catastrophe, such as with inhibitors of cell cycle checkpoint kinases. The fate of cell cycle progression or arrest is tightly regulated by the presence of tolerable or excessive DNA damage, respectively. This suggests that there is compatibility between inhibitors of DNA repair kinases, such as PARP inhibitors, and inhibitors of cell cycle checkpoint kinases. In the present review, we explore alterations to the cell cycle that are concomitant with altered DNA damage repair machinery in unfavorable neuroblastomas, with respect to their unique genomic and molecular features. We highlight the vulnerabilities of these alterations that are attributable to the features of each. Based on the assessment, we offer possible therapeutic approaches for personalized medicine, which are seemingly antithetical, but both are promising strategies for targeting the altered cell cycle in unfavorable neuroblastomas.

11q Deletion or ALK Activity Curbs DLG2 Expression to Maintain an Undifferentiated State in Neuroblastoma

High-risk neuroblastomas typically display an undifferentiated or poorly differentiated morphology. It is therefore vital to understand molecular mechanisms that block the differentiation process. We identify an important role for oncogenic ALK-ERK1/2-SP1 signaling in the maintenance of undifferentiated neural crest-derived progenitors through the repression of DLG2, a candidate tumor suppressor gene in neuroblastoma. DLG2 is expressed in the murine "bridge signature" that represents the transcriptional transition state when neural crest cells or Schwann cell precursors differentiate to chromaffin cells of the adrenal gland. We show that the restoration of DLG2 expression spontaneously drives neuroblastoma cell differentiation, highlighting the importance of DLG2 in this process. These findings are supported by genetic analyses of high-risk 11q deletion neuroblastomas, which identified genetic lesions in the DLG2 gene. Our data also suggest that further exploration of other bridge genes may help elucidate the mechanisms underlying the differentiation of NC-derived progenitors and their contribution to neuroblastomas.

Tailoring Therapy for Children With Neuroblastoma on the Basis of Risk Group Classification: Past, Present, and Future

For children with neuroblastoma, the likelihood of cure varies widely according to age at diagnosis, disease stage, and tumor biology. Treatments are tailored for children with this clinically heterogeneous malignancy on the basis of a combination of markers that are predictive of risk of relapse and death. Sequential risk-based, cooperative-group clinical trials conducted during the past 4 decades have led to improved outcome for children with neuroblastoma. Increasingly accurate risk classification and refinements in treatment stratification strategies have been achieved with the more recent discovery of robust genomic and molecular biomarkers. In this review, we discuss the history of neuroblastoma risk classification in North America and Europe and highlight efforts by the International Neuroblastoma Risk Group (INRG) Task Force to develop a consensus approach for pretreatment stratification using seven risk criteria including an image-based staging system-the INRG Staging System. We also update readers on the current Children's Oncology Group risk classifier and outline plans for the development of a revised 2021 Children's Oncology Group classifier that will incorporate INRG Staging System criteria to facilitate harmonization of risk-based frontline treatment strategies conducted around the globe. In addition, we discuss new approaches to establish increasingly robust, future risk classification algorithms that will further refine treatment stratification using machine learning tools and expanded data from electronic health records and the INRG Data Commons.

Low DLG2 gene expression, a link between 11q-deleted and MYCN-amplified neuroblastoma, causes forced cell cycle progression, and predicts poor patient survival

Background

Neuroblastoma (NB) is a childhood neural crest tumor. There are two groups of aggressive NBs, one with MYCN amplification, and another with 11q chromosomal deletion; these chromosomal aberrations are generally mutually exclusive. The DLG2 gene resides in the 11q-deleted region, thus makes it an interesting NB candidate tumor suppressor gene.

Methods

We evaluated the association of DLG2 gene expression in NB with patient outcomes, stage and MYCN status, using online microarray data combining independent NB patient data sets. Functional studies were also conducted using NB cell models and the fruit fly.

Results

Using the array data we concluded that higher DLG2 expression was positively correlated to patient survival. We could also see that expression of DLG2 was inversely correlated with MYCN status and tumor stage. Cell proliferation was lowered in both 11q-normal and 11q-deleted NB cells after DLG2 over expression, and increased in 11q-normal NB cells after DLG2 silencing. Higher level of DLG2 increased the percentage of cells in the G2/M phase and decreased the percentage of cells in the G1 phase. We detected increased protein levels of Cyclin A and Cyclin B in fruit fly models either over expressing dMyc or with RNAi-silenced dmDLG, indicating that both events resulted in enhanced cell cycling. Induced MYCN expression in NB cells lowered DLG2 gene expression, which was confirmed in the fly; when dMyc was over expressed, the dmDLG protein level was lowered, indicating a link between Myc over expression and low dmDLG level.

Conclusion

We conclude that low DLG2 expression level forces cell cycle progression, and that it predicts poor NB patient survival. The low DLG2 expression level could be caused by either MYCN-amplification or 11q-deletion.

Graphical abstract

Targeting the DNA Damage Response for the Treatment of High Risk Neuroblastoma

Despite intensive multimodal therapy, the survival rate for high risk neuroblastoma (HR-NB) remains <50%. Most cases initially respond to treatment but almost half will subsequently relapse with aggressive treatment resistant disease. Novel treatments exploiting the molecular pathology of NB and/or overcoming resistance to current genotoxic therapies are needed before survival rates can significantly improve. DNA damage response (DDR) defects are frequently observed in HR-NB including allelic deletion and loss of function mutations in key DDR genes, oncogene induced replication stress and cell cycle checkpoint dysfunction. Exploiting defects in the DDR has been a successful treatment strategy in some adult cancers. Here we review the genetic features of HR-NB which lead to DDR defects and the emerging molecular targeting agents to exploit them.

Chromosome band 11q23 deletion predicts poor prognosis in bone marrow metastatic neuroblastoma patients without MYCN amplification

Background

Interphase fluorescence in situ hybridization (FISH) of bone marrow cells has been confirmed to be a direct and valid method to assess the v-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog (MYCN) amplification in patients with bone marrow metastatic neuroblastoma. MYCN amplification alone, however, is insufficient for pretreatment risk stratification. Chromosome band 11q23 deletion has recently been included in the risk stratification of neuroblastoma. In the present study, we aimed to evaluate the biological characteristics and prognostic impact of 11q23 deletion and MYCN amplification in patients with bone marrow metastatic neuroblastoma.

Methods

We analyzed the MYCN and 11q23 statuses of 101 patients with bone marrow metastatic neuroblastoma using interphase FISH of bone marrow cells. We specifically compared the biological characteristics and prognostic impact of both aberrations.

Results

MYCN amplification and 11q23 deletion were seen in 12 (11.9%) and 40 (39.6%) patients. The two markers were mutually exclusive. MYCN amplification occurred mainly in patients with high lactate dehydrogenase (LDH) and high neuron-specific enolase (NSE) levels (both P < 0.001), and MYCN-amplified patients had more events (tumor relapse, progression, or death) than MYCN-normal patients (P = 0.004). 11q23 deletion was associated only with age (P = 0.001). Patients with MYCN amplification had poorer outcomes than those with normal MYCN (3-year event-free survival [EFS] rate: 8.3 ± 8.0% vs. 43.8 ± 8.5%, P < 0.001; 3-year overall survival [OS] rate: 10.4 ± 9.7% vs. 63.5% ± 5.7%, P < 0.001). 11q23 deletion reflected a poor prognosis only for patients with normal MYCN (3-year EFS rate: 34.3 ± 9.5% vs. 53.4 ± 10.3%, P = 0.037; 3-year OS rate: 42.9 ± 10.4% vs. 75.9 ± 6.1%, P = 0.048). Those with both MYCN amplification and 11q23 deletion had the worst outcome (P < 0.001).

Conclusions

Chromosome band 11q23 deletion predicts poor prognosis only in bone marrow metastatic neuroblastoma patients without MYCN amplification. Combined assessment of the two markers was much superior to single-marker assessment in recognizing the patients at a high risk of disease progression.

Non-High-Risk Neuroblastoma: Classification and Achievements in Therapy

Neuroblastoma, a tumor of the sympathetic nervous system, is the most common extra-cranial neoplasm of childhood. Variables with prognostic significance in patients with neuroblastoma, including age at diagnosis, disease stage, tumor histology, MYCN gene amplification, tumor cell ploidy, and the presence of segmental chromosomal aberrations are utilized to classify patients based on risk of disease recurrence. Patients with non-high-risk neuroblastoma, low- and intermediate-risk categories, represent nearly half of all newly diagnosed cases. This group has an excellent event-free and overall survival with current therapy. Over time, the objective in treatment of non-high-risk neuroblastoma has been reduction of therapy intensity to minimize short- and long-term adverse events all the while maintaining excellent outcomes.

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.

Multiple mechanisms disrupt the let-7 microRNA family in neuroblastoma

Poor prognosis in neuroblastoma is associated with genetic amplification of MYCN. MYCN is itself a target of let-7, a tumour suppressor family of microRNAs implicated in numerous cancers. LIN28B, an inhibitor of let-7 biogenesis, is overexpressed in neuroblastoma and has been reported to regulate MYCN. Here we show, however, that LIN28B is dispensable in MYCN-amplified neuroblastoma cell lines, despite de-repression of let-7. We further demonstrate that MYCN messenger RNA levels in amplified disease are exceptionally high and sufficient to sponge let-7, which reconciles the dispensability of LIN28B. We found that genetic loss of let-7 is common in neuroblastoma, inversely associated with MYCN amplification, and independently associated with poor outcomes, providing a rationale for chromosomal loss patterns in neuroblastoma. We propose that let-7 disruption by LIN28B, MYCN sponging, or genetic loss is a unifying mechanism of neuroblastoma development with broad implications for cancer pathogenesis.

Coexistence of neuroblastoma and ganglioneuroma in a girl with a hemizygous deletion of chromosome 11q14.1-23.3

Constitutional 11q interstitial deletion syndrome presents with congenital anomalies including microcephaly with craniostenosis, minor dysmorphic features, vitreoretinopathy, and renal anomalies. This syndrome is occasionally associated with neuroblastoma (NB) as a life-threatening complication, which is important for clinical care. Although the corresponding locus to NB has been predicted to exist in 11q22-23 by previous deletion studies related to NB, the causative haploinsufficient genes have not yet been identified. We herein reported for the first time the simultaneous coexistence of adrenal NB and abdominal prevertebral ganglioneuroma in a 6-year-old girl with a constitutional hemizygous 11q14.1-23.3 deletion. Of the 11 haploinsufficient genes predicted with an in silico database, we focused on NCAM1 and CADM1 as the genes accountable for NB and ganglioneuroma. The deletion range, especially the 11q22.3 involvement, needs to be determined in 11q deletion cases in order to predict susceptibility to peripheral nerve tumors involving NB and ganglioneuroma.

Ataxia-telangiectasia mutated (ATM) silencing promotes neuroblastoma progression through a MYCN independent mechanism

Neuroblastoma, a childhood cancer with highly heterogeneous biology and clinical behavior, is characterized by genomic aberrations including amplification of MYCN. Hemizygous deletion of chromosome 11q is a well-established, independent marker of poor prognosis. While 11q22-q23 is the most frequently deleted region, the neuroblastoma tumor suppressor in this region remains to be identified. Chromosome bands 11q22-q23 contain ATM, a cell cycle checkpoint kinase and tumor suppressor playing a pivotal role in the DNA damage response. Here, we report that haploinsufficiency of ATM in neuroblastoma correlates with lower ATM expression, event-free survival, and overall survival. ATM loss occurs in high stage neuroblastoma without MYCN amplification. In SK-N-SH, CLB-Ga and GI-ME-N human neuroblastoma cells, stable ATM silencing promotes neuroblastoma progression in soft agar assays, and in subcutaneous xenografts in nude mice. This effect is dependent on the extent of ATM silencing and does not appear to involve MYCN. Our findings identify ATM as a potential haploinsufficient neuroblastoma tumor suppressor, whose inactivation mirrors the increased aggressiveness associated with 11q deletion in neuroblastoma.

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.

Detection of MYCN amplification using blood plasma: noninvasive therapy evaluation and prediction of prognosis in neuroblastoma

PURPOSE

Amplification of neuroblastoma derived (avian)v-myc myelocytomatosis viral related oncogene (MYCN) is an important risk-stratified indicator in neuroblastoma. To evaluate the feasibility of noninvasive measurement of MYCN amplification, we analyzed MYCN amplification in stored blood plasma samples.

METHODS

We used quantitative real-time PCR to determine MYCN copy numbers in plasma-derived DNA of 10 healthy volunteers and 50 neuroblastoma cases. The copy number was calculated as the ratio of copies of MYCN to those of a reference gene. Plasma samples obtained after surgery or neoadjuvant therapy were also analyzed in five cases and four cases, respectively.

RESULTS

In 34 neuroblastoma cases, MYCN was nonamplified in both tumor tissue and blood plasma. In 16 neuroblastoma cases, MYCN was amplified in both tumor tissue and blood plasma; 13 of the 16 cases showed poor outcomes. MYCN amplification was undetectable in blood plasma shortly after surgery or neoadjuvant therapy. The correlation coefficient between MYCN copy numbers in tumor tissue and in blood plasma was approximately 0.9.

CONCLUSION

We can detect MYCN amplification of tumor tissue noninvasively and quantitatively by measuring the MYCN copy number in blood plasma. Determination of MYCN copy number in plasma may be useful when evaluating surgery and neoadjuvant chemotherapy.

The role of genetic and epigenetic alterations in neuroblastoma disease pathogenesis

Neuroblastoma is a highly heterogeneous tumor accounting for 15 % of all pediatric cancer deaths. Clinical behavior ranges from the spontaneous regression of localized, asymptomatic tumors, as well as metastasized tumors in infants, to rapid progression and resistance to therapy. Genomic amplification of the MYCN oncogene has been used to predict outcome in neuroblastoma for over 30 years, however, recent methodological advances including miRNA and mRNA profiling, comparative genomic hybridization (array-CGH), and whole-genome sequencing have enabled the detailed analysis of the neuroblastoma genome, leading to the identification of new prognostic markers and better patient stratification. In this review, we will describe the main genetic factors responsible for these diverse clinical phenotypes in neuroblastoma, the chronology of their discovery, and the impact on patient prognosis.

The transcription factor CREBZF is a novel positive regulator of p53

CREBZF is a member of the mammalian ATF/CREB family of transcription factors. Here, we describe a novel functional interaction between CREBZF and the tumor suppressor p53. CREBZF was identified in a yeast two-hybrid screen using HEY1, recently characterized as an indirect p53 activator, as bait. CREBZF interacts in vitro with both HEY1 and p53, and CREBZF expression stabilizes and activates p53. Moreover, CREBZF cooperates synergistically with HEY1 to enhance p53 transcriptional activity. On the other hand, partial depletion of endogenous CREBZF diminishes p53 protein levels and inhibits HEY1-mediated activation of p53. CREBZF-positive effects on p53 signaling may reflect, at least in part, an observed induction of posttranslational modifications in p53 known to prevent its degradation. CREBZF expression protects HCT116 cells from UV radiation-induced cell death. In addition, CREBZF expression confers sensitivity to 5-fluorouracil, a p53-activating chemotherapeutic drug. Our study suggests that CREBZF may participate in the modulation of p53 tumor suppressor function.

Molecular characterization of the pediatric preclinical testing panel

PURPOSE

Identifying novel therapeutic agents for the treatment of childhood cancers requires preclinical models that recapitulate the molecular characteristics of their respective clinical histotypes.

EXPERIMENTAL DESIGN AND RESULTS

Here, we have applied Affymetrix HG-U133Plus2 profiling to an expanded panel of models in the Pediatric Preclinical Testing Program. Profiling led to exclusion of two tumor lines that were of mouse origin and five osteosarcoma lines that did not cluster with human or xenograft osteosarcoma samples. We compared expression profiles of the remaining 87 models with profiles from 112 clinical samples representing the same histologies and show that model tumors cluster with the appropriate clinical histotype, once "immunosurveillance" genes (contributed by infiltrating immune cells in clinical samples) are eliminated from the analysis. Analysis of copy number alterations using the Affymetrix 100K single nucleotide polymorphism GeneChip showed that the models have similar copy number alterations to their clinical counterparts. Several consistent copy number changes not reported previously were found (e.g., gain at 22q11.21 that was observed in 5 of 7 glioblastoma samples, loss at 16q22.3 that was observed in 5 of 9 Ewing's sarcoma and 4 of 12 rhabdomyosarcoma models, and amplification of 21q22.3 that was observed in 5 of 7 osteosarcoma models). We then asked whether changes in copy number were reflected by coordinate changes in gene expression. We identified 493 copy number-altered genes that are nonrandom and appear to identify histotype-specific programs of genetic alterations.

CONCLUSIONS

These data indicate that the preclinical models accurately recapitulate expression profiles and genetic alterations common to childhood cancer, supporting their value in drug development.

CADM1 is a strong neuroblastoma candidate gene that maps within a 3.72 Mb critical region of loss on 11q23

Background

Recurrent loss of part of the long arm of chromosome 11 is a well established hallmark of a subtype of aggressive neuroblastomas. Despite intensive mapping efforts to localize the culprit 11q tumour suppressor gene, this search has been unsuccessful thus far as no sufficiently small critical region could be delineated for selection of candidate genes.

Methods

To refine the critical region of 11q loss, the chromosome 11 status of 100 primary neuroblastoma tumours and 29 cell lines was analyzed using a BAC array containing a chromosome 11 tiling path. For the genes mapping within our refined region of loss, meta-analysis on published neuroblastoma mRNA gene expression datasets was performed for candidate gene selection. The DNA methylation status of the resulting candidate gene was determined using re-expression experiments by treatment of neuroblastoma cells with the demethylating agent 5-aza-2'-deoxycytidine and bisulphite sequencing.

Results

Two small critical regions of loss within 11q23 at chromosomal band 11q23.1-q23.2 (1.79 Mb) and 11q23.2-q23.3 (3.72 Mb) were identified. In a first step towards further selection of candidate neuroblastoma tumour suppressor genes, we performed a meta-analysis on published expression profiles of 692 neuroblastoma tumours. Integration of the resulting candidate gene list with expression data of neuroblastoma progenitor cells pinpointed CADM1 as a compelling candidate gene. Meta-analysis indicated that CADM1 expression has prognostic significance and differential expression for the gene was noted in unfavourable neuroblastoma versus normal neuroblasts. Methylation analysis provided no evidence for a two-hit mechanism in 11q deleted cell lines.

Conclusion

Our study puts CADM1 forward as a strong candidate neuroblastoma suppressor gene. Further functional studies are warranted to elucidate the role of CADM1 in neuroblastoma development and to investigate the possibility of CADM1 haploinsufficiency in neuroblastoma.

Loss in chromosome 11q identifies tumors with increased risk for metastatic relapses in localized and 4S neuroblastoma

PURPOSE

To improve risk prediction in neuroblastoma and to specify the type of a possible relapse, alterations in the long arm of chromosome 11 were analyzed.

EXPERIMENTAL DESIGN

A representative cohort of 611 neuroblastomas was investigated for deletion events in distal chromosome 11q using interphase fluorescence in situ hybridization.

RESULTS

Alterations in 11q were found in 159 of 611 tumors in the whole cohort (26%) and were associated with stage 4 disease (P < 0.001) and age at diagnosis of >2.5 years (P < 0.001). Event-free survival and overall survival were significantly poorer for patients with 11q loss in the whole cohort (event-free survival and overall survival, P < 0.001) and in different subsets: neuroblastoma without MYCN amplification (MNA) (event-free survival and overall survival, P < 0.001), with MNA (event-free survival, P = 0.03; overall survival, P = 0.02), and MYCN-nonamplified stage 1, 2, 3, and 4S tumors with and without del 1p (event-free survival and overall survival, P < 0.001). In stage 4, the 11q status did not discriminate outcome. By multivariate analysis, the 11q status proved prognostic for event-free survival in the whole cohort (P = 0.008; hazard ratio, 1.573) and in the subgroup of stages 1, 2, 3, and 4S without MNA (P < 0.001; hazard ratio, 3.534). Moreover, 11q alterations were strongly correlated with the occurrence of metastatic relapses (P < 0.001).

CONCLUSION

In addition to the current risk stratification, the status of 11q enables the identification of patients with an increased risk for relapses in general and metastatic relapses in particular.

Implications of MYCN amplification in patients with stage 4 neuroblastoma who undergo intensive chemotherapy

BACKGROUND/PURPOSE

This study aims to clarify the implications of MYCN amplification in patients with high-risk neuroblastomas treated with 2 different regimens of induction chemotherapy established by the Japan Study Group for Advanced Neuroblastoma.

METHODS

Between 1985 and 2003 in Japan, 392 patients with stage 4 neuroblastomas who were older than 12 months were treated with 2 regimens of induction chemotherapy (the combination of cyclophosphamide [CTX], cisplatin [CDDP], pirarubicin, and vincristine or etoposide). Regimen 91A3 or 98A3 (A3) (CTX 2400 mg/m2, CDDP 125 mg/m2) was a higher dose combination of CTX and CDDP than regimen 85A1 or 91A1 (A1) (CTX 1200 mg/m2, CDDP 90 mg/m2). The 392 cases were classified into 3 groups (A, 1 copy; B, 2-9 copies; C, more than 10 copies) based on the MYCN amplification status by a Southern blot analysis.

RESULTS

The 5-year overall survival rate (5-YS) was 41.1% for all 392 cases. Regarding the MYCN amplification status, the 5-YS was 46.6% for A group (n = 227), 22.7% for B group (n = 26), and 36.0% for C group (n = 139). A fluorescence in situ hybridization analysis showed the presence of the cells with more than 10 copies in cases with 2 to 9 copies based on the Southern blot findings. Of the 227 patients in a group, the 5-YS was 46.7% for the 70 cases treated by A3 and 47.0% for 154 cases treated by A1 (nonsignificant). The 5-YS of the 210 patients with stem cell transplantation (SCT) (51.%) was significantly better than that of the 127 patients without SCT (41.1%) (P < .05).

CONCLUSIONS

Regarding the MYCN amplification status, the tumor aggressiveness might thus be different between 2 and 9 copies and a single copy of MYCN. In neuroblastomas with 2 and 9 copies of MYCN based on a Southern blot analysis, the MYCN amplification status should be analyzed using the fluorescence in situ hybridization method. Induction chemotherapy followed by SCT according to the Japan Study Group for Advanced Neuroblastoma protocol improved the outcome of neuroblastomas with MYCN amplification; however, obtaining a further improvement in the long-term survival of stage 4 neuroblastomas may therefore require the development of an even more effective treatment modality.

Human fetal neuroblast and neuroblastoma transcriptome analysis confirms neuroblast origin and highlights neuroblastoma candidate genes

Transcriptome profiling of neuroblasts and neuroblastoma tumor cells provides strong support for a neuroblast origin of neuroblastoma and highlights new candidate neuroblastoma genes

Background

Neuroblastoma tumor cells are assumed to originate from primitive neuroblasts giving rise to the sympathetic nervous system. Because these precursor cells are not detectable in postnatal life, their transcription profile has remained inaccessible for comparative data mining strategies in neuroblastoma. This study provides the first genome-wide mRNA expression profile of these human fetal sympathetic neuroblasts. To this purpose, small islets of normal neuroblasts were isolated by laser microdissection from human fetal adrenal glands.

Results

Expression of catecholamine metabolism genes, and neuronal and neuroendocrine markers in the neuroblasts indicated that the proper cells were microdissected. The similarities in expression profile between normal neuroblasts and malignant neuroblastomas provided strong evidence for the neuroblast origin hypothesis of neuroblastoma. Next, supervised feature selection was used to identify the genes that are differentially expressed in normal neuroblasts versus neuroblastoma tumors. This approach efficiently sifted out genes previously reported in neuroblastoma expression profiling studies; most importantly, it also highlighted a series of genes and pathways previously not mentioned in neuroblastoma biology but that were assumed to be involved in neuroblastoma pathogenesis.

Conclusion

This unique dataset adds power to ongoing and future gene expression studies in neuroblastoma and will facilitate the identification of molecular targets for novel therapies. In addition, this neuroblast transcriptome resource could prove useful for the further study of human sympathoadrenal biogenesis.

Multilocus loss of heterozygosity allelotypes identify a genetic pathway associated with progression from low to high stage disease in neuroblastoma

Neuroblastoma is a heterogeneous tumour with a variety of clinical phenotypes, ranging from a localised tumour with excellent outcome (stage 1) to a metastatic, usually fatal malignancy (stage 4). In order to investigate the genetic relationship between these tumour subtypes, a loss of heterozygosity (LOH) analysis was carried out. Composite LOH allelotypes incorporating data from 96 loci on 5 chromosomes (1p, 3p, 4p, 11q, 14q), were constructed for 62 neuroblastomas. Neuroblastomas with similar allelotypes were clustered into groups and allelotype patterns correlated with clinical features. Three distinct genetic subgroups of neuroblastoma were observed. The largest group (50% of tumours) was characterised by specific allelotype patterns indicative of a stepwise accumulation of genetic alterations (11q LOH-->1p, 4p, and/or 14q LOH-->3p LOH), associated with progression from low to high stage disease. These tumours are distinct from MYCN amplified neuroblastomas which have a more rapid and aggressive disease course, and also a proportion of low stage tumours, often ganglioneuromas or ganglioneuroblastomas, with restricted growth potential.

Risk estimation in localized unresectable single copy MYCN neuroblastoma by the status of chromosomes 1p and 11q

In localized neuroblastoma, the identification of patients requiring intensive treatment is still difficult. We retrospectively analyzed data of 280 single copy MYCN stage 2 and 3 neuroblastoma patients with gross residual tumor after initial surgery. The 3-year-event free survival of the total group was 83+/-2%, and 3-year-overall survival was 92+/-2%. Patients < or=1.5 years had a better outcome than older children. Deletions/imbalances of chromosome 1p were found in 9/90 patients and were associated with a higher event rate but not with a higher death rate. Aberrations of chromosome 11q in 14/91 patients were correlated with a higher event and death rate. Multivariate analysis identified 1p aberrations as important for event free survival and 11q aberrations for overall survival.

The two human homologues of yeast UFD2 ubiquitination factor, UBE4A and UBE4B, are located in common neuroblastoma deletion regions and are subject to mutations in tumours

Chromosomes 11q and 1p are commonly deleted in advanced-stage neuroblastomas and are therefore assumed to contain tumour suppressor genes involved in the development of this cancer. The two UFD2 yeast gene human homologues, UBE4A and UBE4B, involved in the ubiquitin/proteasome pathway, are located in 11q and 1p, respectively. UBE4B has previously been analysed for mutations and one mutation in the splice donor site of exon 9, c.1439 + 1G > C, was found in a neuroblastoma tumour with fatal outcome. We speculated that the homologue UBE4A might be involved in an alternative tumourigenesis pathway. The coding exons of UBE4A were therefore sequenced. One putative missense mutation (1028T > C, leading to I343T, residing in exon 8) was found in neuroblastoma tumour 20R8; this finding was confirmed by sequencing in both directions. The change, isoleucine (non-polar) to threonine (polar), was situated in a highly conserved amino acid region. In addition, two novel variants were also found in intronic sequences of UBE4A. It might be speculated that the proteins generated from UBE4B and UBE4A are involved in protecting the cell from environmental stress and that inactivation of either of them could contribute to malignancy.

Chromosome 1p and 11q deletions and outcome in neuroblastoma

BACKGROUND

Neuroblastoma is a childhood cancer with considerable morbidity and mortality. Tumor-derived biomarkers may improve risk stratification.

METHODS

We screened 915 samples of neuroblastoma for loss of heterozygosity (LOH) at chromosome bands 1p36 and 11q23. Additional analyses identified a subgroup of cases of 11q23 LOH with unbalanced 11q LOH (unb11q LOH; defined as loss of 11q with retention of 11p). The associations of LOH with relapse and survival were determined.

RESULTS

LOH at 1p36 was identified in 209 of 898 tumors (23 percent) and LOH at 11q23 in 307 of 913 (34 percent). Unb11q LOH was found in 151 of 307 tumors with 11q23 LOH (17 percent of the total cohort). There was a strong association of 1p36 LOH, 11q23 LOH, and unb11q LOH with most high-risk disease features (P<0.001). LOH at 1p36 was associated with amplification of the MYCN oncogene (P<0.001), but 11q23 LOH and unb11q LOH were not (P<0.001 and P=0.002, respectively). Cases with unb11q LOH were associated with three-year event-free and overall survival rates (+/-SE) of 50+/-5 percent and 66+/-5 percent, respectively, as compared with 74+/-2 percent and 83+/-2 percent among cases without unb11q LOH (P<0.001 for both comparisons). In a multivariate model, unb11q LOH was independently associated with decreased event-free survival (P=0.009) in the entire cohort, and both 1p36 LOH and unb11q LOH were independently associated with decreased progression-free survival in the subgroup of patients with features of low-risk and intermediate-risk disease (P=0.002 and P=0.02, respectively).

CONCLUSIONS

Unb11q LOH and 1p36 LOH are independently associated with a worse outcome in patients with neuroblastoma.

No evidence for involvement of SDHD in neuroblastoma pathogenesis

BACKGROUND

Deletions in the long arm of chromosome 11 are observed in a subgroup of advanced stage neuroblastomas with poor outcome. The deleted region harbours the tumour suppressor gene SDHD that is frequently mutated in paraganglioma and pheochromocytoma, which are, like neuroblastoma, tumours originating from the neural crest. In this study, we sought for evidence for involvement of SDHD in neuroblastoma.

METHODS

SDHD was investigated on the genome, transcriptome and proteome level using mutation screening, methylation specific PCR, real-time quantitative PCR based homozygous deletion screening and mRNA expression profiling, immunoblotting, functional protein analysis and ultrastructural imaging of the mitochondria.

RESULTS

Analysis at the genomic level of 67 tumour samples and 37 cell lines revealed at least 2 bona-fide mutations in cell lines without allelic loss at 11q23: a 4bp-deletion causing skip of exon 3 resulting in a premature stop codon in cell line N206, and a Y93C mutation in cell line NMB located in a region affected by germline SDHD mutations causing hereditary paraganglioma. No evidence for hypermethylation of the SDHD promotor region was observed, nor could we detect homozygous deletions. Interestingly, SDHD mRNA expression was significantly reduced in SDHD mutated cell lines and cell lines with 11q allelic loss as compared to both cell lines without 11q allelic loss and normal foetal neuroblast cells. However, protein analyses and assessment of mitochondrial morphology presently do not provide clues as to the possible effect of reduced SDHD expression on the neuroblastoma tumour phenotype.

CONCLUSIONS

Our study provides no indications for 2-hit involvement of SDHD in the pathogenesis of neuroblastoma. Also, although a haplo-insufficient mechanism for SDHD involvement in advanced stage neuroblastoma could be considered, the present data do not provide consistent evidence for this hypothesis.

Neuroblastoma: evolving therapies for a disease with many faces

Neuroblastoma is the most common extra-cranial solid tumor in children and has a heterogeneous clinical presentation and course. Clinical and biologic features of this disease have been used to develop risk-based therapy. Patients with low-risk disease can be treated with surgery alone. Patients with intermediate-risk features have an excellent prognosis after treatment with surgery and a relatively short course of standard dose chemotherapy. Unfortunately, most children with neuroblastoma present with advanced disease. More than 60% of patients with high-risk features will succumb to their disease despite intensive therapy including a myeloablative consolidation. Research efforts to understand the biologic basis of neuroblastoma and to identify new, more effective therapies are essential to improve the outcome for these children.

Pediatric neuroblastomas: genetic and epigenetic 'danse macabre'

Neuroblastomas are the most frequently occurring solid tumors in children under 5 years. Spontaneous regression is more common in neuroblastomas than in any other tumor type, especially in young patients under 12 months. Unfortunately, the full clinical spectrum of neuroblastomas also includes very aggressive tumors, unresponsive to multi-modality treatment and accounting for most of the pediatric cancer mortalities under 5 years of age. It is generally emphasized that more than one biological entity of neuroblastoma exists. Structural genetic defects such as amplification of MYCN, gain of chromosome 17q and LOH of 1p and several other chromosomal regions have proven to be valuable as prognostic factors and will be discussed in relation to their clinical relevance. Recent research is starting to uncover important molecular pathways involved in the pathogenesis of neuroblastomas. The aim of this review is to discuss several important aspects of the biology of the neuroblast, such as the role of overexpressed oncogenes like MYCN and cyclin D1, the mechanisms leading to decreased apoptosis, like overexpression of BCL-2, survivin, NM23, epigenetic silencing of caspase 8 and the role of tumor suppressor genes, like p53, p73 and RASSF1A. In addition, the role of specific proteins overexpressed in neuroblastomas, such as the neurotrophin receptors TrkA, B and C in relation to spontaneous regression and anti-angiogenesis will be discussed. Finally, we will try to relate these pathways to the embryonal origin of neuroblastomas and discuss possible new avenues in the therapeutic approach of future neuroblastoma patients.

Advances in the diagnosis and treatment of neuroblastoma

Neuroblastoma, a childhood neoplasm arising from neural crest cells, is characterized by a diversity of clinical behavior ranging from spontaneous remission to rapid tumor progression and death. To a large extent, outcome can be predicted by the stage of disease and the age at diagnosis. However, the molecular events responsible for the variability in response to treatment and the rate of tumor growth remain largely unknown. Over the past decade, transformation-linked genetic changes have been identified in neuroblastoma tumors that have contributed to the understanding of tumor predisposition, metastasis, treatment responsiveness, and prognosis. The Children's Oncology Group recently developed a Neuroblastoma Risk Stratification System that is currently in use for treatment stratification purposes, based on clinical and biologic factors that are strongly predictive of outcome. This review discusses the current risk-based treatment approaches for children with neuroblastoma and recent advances in biologic therapy.

FISH analyses for alterations in chromosomes 1, 2, 3, and 11 define high-risk groups in neuroblastoma

BACKGROUND

The prognostic chromosomal markers 1p loss and MYCN amplification (MNA) are only present in a subgroup of approximately 30% of neuroblastomas. To further characterize high and low risk subsets we investigated alterations in chromosome arms 3p and 11q, additional changes in 1p and MYCN as well as the somy-status of chromosome 1 in the same sample.

PROCEDURE

Fluorescence in situ hybridization (FISH) was used as an alternative technique to PCR/LOH- or comparative genomic hybridization (CGH) analyses. Alterations in chromosomes 3p and 11q were investigated in 182 unselected tumors, 1p loss and MNA in 174 and 179 of these, respectively. The somy-status of chromosome 1 was determined in 165 tumors as it highly correlates with the tumor ploidy.

RESULTS

Alterations in the four chromosomal regions were found in the following frequencies: 3p26: 19%, 11q23: 29%, 1p36: 29%, MNA: 19%. Fifty-two percent of all cases displayed structural aberrations in at least one chromosomal region, 83% in stage 4 and 30% in stages 1-3, 4s. All aberrations were thus correlated with stage 4 disease but were also present in a substantial subset of localized and 4s tumors. Trisomy of chromosome 1 was found in 38% of the tumors, disomy or tetrasomy in 62%. Patients with alterations in any of the four chromosomes and di/tetrasomy 1 showed a significantly increased age at diagnosis. Loss in 1p and MNA were closely associated with each other, as well as 3p and 11q aberrations but not the groups 1p/MNA versus 3p/11q. Only a small portion of trisomic tumors showed aberrations in at least one of the four chromosomal regions (14%) in contrast to the majority of the di/tetrasomic cases (74%). As already known the MYCN status discriminated between good and poor outcome in localized and metastatic stage 4 tumors. In addition alterations in 1p or 11q, deletion in 3p and di/tetrasomy 1 were associated with an unfavorable prognosis in MYCN single copy tumors of stages 1-3, 4s. Multivariate analysis revealed 11q alterations and MNA as the most important chromosomal prognostic factors in all stages.

CONCLUSION

FISH analyses for chromosomal alterations in 3p and 11q as well as in 1p and MYCN allows to define different groups with an increased risk for disease progression.

Genetic parameters of neuroblastomas

Neuroblastoma is a malignant childhood tumor of migrating neuroectodermal cells derived from the neural crest and destined for the adrenal medulla and the sympathetic nervous system. The biological behavior of neuroblastomas is extremely variable and in some respects unique. Neuroblastomas tend to regress spontaneously in a portion of infants or to differentiate into a benign ganglioneuroma in some older patients. Unfortunately, in the majority of patients neuroblastoma is metastatic at the time of diagnosis, and it usually undergoes rapid progression with a fatal outcome. The mechanisms leading to this diverse clinical behavior of neuroblastomas are largely unclear. From the analysis of tumors at the cytogenetic and molecular level non-random genetic changes have been identified, including ploidy changes, amplification of the oncogene MYCN, deletions of chromosome 1p, gains of chromosome arm 17q, and deletions of 11q as well as of other genomic regions that allow tumors to be classified into subsets with distinct biological features and clinical behavior. MYCN status is widely accepted for therapy stratification. Additional genetic parameters are currently under investigation to refine risk assessment, but so far the molecular monitoring tools for prediction of therapy response and disease outcome are still incomplete. This should lead to more risk-adapted therapies according to the clinical-genetic parameters by which individual tumors are characterized. This review aims at discussing the role of genomic changes in neuroblastomas of diverse biological and clinical types.