Recent insights into the biology of neuroblastoma

Novel targeted therapy for neuroblastoma: silencing the MXD3 gene using siRNA

BackgroundNeuroblastoma is the second most common extracranial cancer in children. Current therapies for neuroblastoma, which use a combination of chemotherapy drugs, have limitations for high-risk subtypes and can cause significant long-term adverse effects in young patients. Therefore, a new therapy is needed. In this study, we investigated the transcription factor MXD3 as a potential therapeutic target in neuroblastoma.MethodsMXD3 expression was analyzed in five neuroblastoma cell lines by immunocytochemistry and quantitative real-time reverse transcription PCR, and in 18 primary patient tumor samples by immunohistochemistry. We developed nanocomplexes using siRNA and superparamagnetic iron oxide nanoparticles to target MXD3 in neuroblastoma cell lines in vitro as a single-agent therapeutic and in combination with doxorubicin, vincristine, cisplatin, or maphosphamide-common drugs used in current neuroblastoma treatment.ResultsMXD3 was highly expressed in neuroblastoma cell lines and in patient tumors that had high-risk features. Neuroblastoma cells treated in vitro with the MXD3 siRNA nanocomplexes showed MXD3 protein knockdown and resulted in cell apoptosis. Furthermore, on combining MXD3 siRNA nanocomplexes with each of the four drugs, all showed additive efficacy.ConclusionThese results indicate that MXD3 is a potential new target and that the use of MXD3 siRNA nanocomplexes is a novel therapeutic approach for neuroblastoma.

Targeting of PHOX2B expression allows the identification of drugs effective in counteracting neuroblastoma cell growth

The pathogenic role of the PHOX2B gene in neuroblastoma is indicated by heterozygous mutations in neuroblastoma patients and by gene overexpression in both neuroblastoma cell lines and tumor samples.

PHOX2B encodes a transcription factor which is crucial for the correct development and differentiation of sympathetic neurons.

PHOX2B overexpression is considered a prognostic marker for neuroblastoma and it is also used by clinicians to monitor minimal residual disease. Furthermore, it has been observed that neuronal differentiation in neuroblastoma is dependent on down-regulation of PHOX2B expression, which confirms that PHOX2B expression may be considered a target in neuroblastoma.

Here, PHOX2B promoter or 3′ untranslated region were used as molecular targets in an in vitro high-throughput approach that led to the identification of molecules able to decrease PHOX2B expression at transcriptional and likely even at post-transcriptional levels. Further functional investigations carried out on PHOX2B mRNA levels and biological consequences, such as neuroblastoma cell apoptosis and growth, showed that chloroquine and mycophenolate mofetil are most promising agents for neuroblastoma therapy based on down-regulation of PHOX2B expression.

Finally, a strong correlation between the effect of drugs in terms of down-regulation of PHOX2B expression and of biological consequences in neuroblastoma cells confirms the role of PHOX2B as a potential molecular target in neuroblastoma.

Results of neuroblastoma treatment in Lithuania: a single centre experience

Background.

Neuroblastoma (NB) is the most common extracranial solid tumour in children. This is a very rare disease with heterogeneous biology varying from complete spontaneous regression to a highly aggressive tumour responsible for 15% of malignancy-related death in early childhood. Analyses of survival rates in Europe have shown a considerable difference between Northern/Western and Eastern European countries. Treatment results of NB in Lithuania have never been analyzed.

Aim.

To assess the survival rate of children with NB according to initial spread of the disease, age at diagnosis, the MYCN amplification, risk group, and treatment period.

Patients and methods.

A retrospective single-centre analysis of patients’ records was performed. Children diagnosed and treated for NB between 2000 and 2015 at the Centre of Paediatric Oncology and Haematology of the Children’s Hospital, Affiliate of Vilnius University Hospital Santaros Klinikos were included. The patients were divided into three groups according to the spread of the disease: group 1 – patients with local NB older than 12 years of age; group 2 – stage IV patients, also called the M stage; group 3 – infants with stages 4S and MS. The patients were stratified into three risk groups – low, intermediate and high risk. Estimates of five-year overall survival (OS_5y) were calculated using the Kaplan-Meier method comparing survival probability according to spread of the disease, age at diagnosis, the MYCN amplification, risk group and treatment period (2000–2007 vs 2008–2015).

Results.

Overall 60 children (31 girls and 29 boys) with NB were included. The median age at diagnosis was 1.87 years (ranged from 4 days to 15 years). Seventy-eight percent of cases were found to be differentiated or undifferentiated NB, 22% – ganglioneuroblastoma. The local form of the disease was predominant: 57% (34/60) of patients were allocated to the group 1, 37% (22/60) with initial metastatic disease were assigned to group 2, and infants with 4S or MS stage comprising 7% (4/60) allocated to group 3, respectively. The probability of OS_5y for the entire cohort was 71% with the median follow-up of 8.8 ± 4.8 years. The probability of OS_5y for local disease (group 1) was significantly higher compared to metastatic disease (group 2) (94% vs. 34%, p = 0.001, respectively) as well as for infants compared to children older than 12 months at the time of diagnosis (90% vs 60%, p = 0.009, respectively). The MYCN gene amplification had a negative influence on OS_5y, with 78% of MYCN-negative patients surviving in comparison to 40% of MYCN-positive patients who did not survive (p = 0.153). The high-risk patients had significantly worse OS_5y than children with intermediated or low risk (35% vs. 82% vs. 100%, respectively, p = 0.001). Comparison of OS_5y between two treatment periods in the entire patient population revealed a non-significant increase in survival from 66% in the 2000–2007 period to 82% in the 2008–2015 period (p = 0.291), mostly due to a dramatic improvement achieved for high-risk patients whose survival rate increased from 9% in the 2000–2007 period to 70% in the 2008–2015 period (p = 0.009).

Conclusions.

There was a slight predominance of low-risk patients, probably due to a higher number of infants. A better probability of OS_5y was confirmed in infants with local disease and in MYCN-negative patients. The OS_5y for children treated for NB at our institution over 16 years increased from 66% in the 2000–2007 period to 82% in the 2008–2015 period with the most significant improvement achieved for high risk patients. The current survival rate of children treated for NB at our institution is in line with the reported numbers in Northern and Western European countries.

Sphingosine-1-Phosphate Receptor-1 Promotes Environment-Mediated and Acquired Chemoresistance

Drug resistance is a major barrier for the development of effective and durable cancer therapies. Overcoming this challenge requires further defining the cellular and molecular mechanisms underlying drug resistance, both acquired and environment-mediated drug resistance (EMDR). Here, using neuroblastoma (NB), a childhood cancer with high incidence of recurrence due to resistance to chemotherapy, as a model we show that human bone marrow-mesenchymal stromal cells induce tumor expression of sphingosine-1-phosphate receptor-1 (S1PR1), leading to their resistance to chemotherapy. Targeting S1PR1 by shRNA markedly enhances etoposide-induced apoptosis in NB cells and abrogates EMDR, while overexpression of S1PR1 significantly protects NB cells from multidrug-induced apoptosis via activating JAK-STAT3 signaling. Elevated S1PR1 expression and STAT3 activation are also observed in human NB cells with acquired resistance to etoposide. We show in vitro and in human NB xenograft models that treatment with FTY720, an FDA-approved drug and antagonist of S1PR1, dramatically sensitizes drug-resistant cells to etoposide. In summary, we identify S1PR1 as a critical target for reducing both EMDR and acquired chemoresistance in NB. Mol Cancer Ther; 16(11); 2516-27. ©2017 AACR.

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.

Retinoic acid and TGF-β signalling cooperate to overcome MYCN-induced retinoid resistance

BACKGROUND

Retinoid therapy is widely employed in clinical oncology to differentiate malignant cells into their more benign counterparts. However, certain high-risk cohorts, such as patients with MYCN-amplified neuroblastoma, are innately resistant to retinoid therapy. Therefore, we employed a precision medicine approach to globally profile the retinoid signalling response and to determine how an excess of cellular MYCN antagonises these signalling events to prevent differentiation and confer resistance.

METHODS

We applied RNA sequencing (RNA-seq) and interaction proteomics coupled with network-based systems level analysis to identify targetable vulnerabilities of MYCN-mediated retinoid resistance. We altered MYCN expression levels in a MYCN-inducible neuroblastoma cell line to facilitate or block retinoic acid (RA)-mediated neuronal differentiation. The relevance of differentially expressed genes and transcriptional regulators for neuroblastoma outcome were then confirmed using existing patient microarray datasets.

RESULTS

We determined the signalling networks through which RA mediates neuroblastoma differentiation and the inhibitory perturbations to these networks upon MYCN overexpression. We revealed opposing regulation of RA and MYCN on a number of differentiation-relevant genes, including LMO4, CYP26A1, ASCL1, RET, FZD7 and DKK1. Furthermore, we revealed a broad network of transcriptional regulators involved in regulating retinoid responsiveness, such as Neurotrophin, PI3K, Wnt and MAPK, and epigenetic signalling. Of these regulators, we functionally confirmed that MYCN-driven inhibition of transforming growth factor beta (TGF-β) signalling is a vulnerable node of the MYCN network and that multiple levels of cross-talk exist between MYCN and TGF-β. Co-targeting of the retinoic acid and TGF-β pathways, through RA and kartogenin (KGN; a TGF-β signalling activating small molecule) combination treatment, induced the loss of viability of MYCN-amplified retinoid-resistant neuroblastoma cells.

CONCLUSIONS

Our approach provides a powerful precision oncology tool for identifying the driving signalling networks for malignancies not primarily driven by somatic mutations, such as paediatric cancers. By applying global omics approaches to the signalling networks regulating neuroblastoma differentiation and stemness, we have determined the pathways involved in the MYCN-mediated retinoid resistance, with TGF-β signalling being a key regulator. These findings revealed a number of combination treatments likely to improve clinical response to retinoid therapy, including co-treatment with retinoids and KGN, which may prove valuable in the treatment of high-risk MYCN-amplified neuroblastoma.

Neuroblastoma: A Tough Nut to Crack

Neuroblastoma, an embryonal tumor arising from neural crest-derived progenitor cells, is the most common solid tumor in childhood, with more than 700 cases diagnosed per year in the United States. In the past several decades, significant advances have been made in the treatment of neuroblastoma. Treatment advances reflect improved understanding of the biology of neuroblastoma. Although amplification of MYCN was discovered in the early 1980s, our understanding of neuroblastoma oncogenesis has advanced in the last decade as a result of high-throughput genomic analysis, exome and whole-genome sequencing, genome-wide association studies, and synthetic lethal drug screens. Our refined understanding of neuroblastoma biology and genetics is reflected in improved prognostic stratification and appropriate tailoring of therapy in recent clinical trials. Moreover, for high-risk neuroblastoma, a disease that was uniformly fatal 3 decades ago, recent clinical trials incorporating autologous hematopoietic transplant and immunotherapy utilizing anti-GD2 antibody plus cytokines have shown improved event-free and overall survival. These advances have resulted in a growing population of long-term survivors of neuroblastoma. Examination of the late effects and second malignant neoplasms (SMNs) in both older generations of survivors and more recently treated survivors will inform both design of future trials and surveillance guidelines for long-term follow-up. As a consequence of advances in understanding of the biology of neuroblastoma, successful clinical trials, and refined understanding of the late effects and SMNs of survivors, the promise of precision medicine is becoming a reality for patients with neuroblastoma.

Epigenetic dysregulation in neuroblastoma: A tale of miRNAs and DNA methylation

In neuroblastoma, the epigenetic landscape is more profoundly altered in aggressive compared to lower grade tumors and the concomitant hypermethylation of many genes, defined as "methylator phenotype", has been associated with poor outcome. DNA methylation can interfere with gene expression acting at distance through the methylation or demethylation of the regulatory regions of miRNAs. The multiplicity of miRNA targets may result in the simultaneous alteration of many biological pathways like cell proliferation, apoptosis, migration and differentiation. We have analyzed the methylation status of a set of miRNAs in a panel of neuroblastoma cell lines and identified a subset of hypermethylated and down-regulated miRNAs (miRNA 34b-3p, miRNA 34b-5p, miRNA34c-5p, and miRNA 124-2-3p) involved in the regulation of cell cycle, apoptosis and in the control of MYCN expression. These miRNAs share, in part, some of the targets whose expression is inversely correlated to the methylation and expression of the corresponding miRNA. To simulate the effect of the demethylation of miRNAs, we transfected the corresponding miRNA-mimics in the same cell lines and observed the down-regulation of a set of their target genes as well as the partial block of the cell cycle and the activation of the apoptotic pathway. The epigenetic alterations of miRNAs described in the present study were found also in a subset of patients at high risk of progression. Our data disclosed a complex network of interactions between epigenetically altered miRNAs and target genes, that could interfere at multiple levels in the control of cell homeostasis.

Aldehyde dehydrogenase activity plays a Key role in the aggressive phenotype of neuroblastoma

BACKGROUND

The successful targeting of neuroblastoma (NB) by associating tumor-initiating cells (TICs) is a major challenge in the development of new therapeutic strategies. The subfamily of aldehyde dehydrogenases 1 (ALDH1) isoenzymes, which comprises ALDH1A1, ALDH1A2, and ALDH1A3, is involved in the synthesis of retinoic acid, and has been identified as functional stem cell markers in diverse cancers. By combining serial neurosphere passages with gene expression profiling, we have previously identified ALDH1A2 and ALDH1A3 as potential NB TICs markers in patient-derived xenograft tumors. In this study, we explored the involvement of ALDH1 isoenzymes and the related ALDH activity in NB aggressive properties.

METHODS

ALDH activity and ALDH1A1/A2/A3 expression levels were measured using the ALDEFLUOR™ kit, and by real-time PCR, respectively. ALDH activity was inhibited using the specific ALDH inhibitor diethylaminobenzaldehyde (DEAB), and ALDH1A3 gene knock-out was generated through the CRISPR/Cas9 technology.

RESULTS

We first confirmed the enrichment of ALDH1A2 and ALDH1A3 mRNA expression in NB cell lines and patient-derived xenograft tumors during neurosphere passages. We found that high ALDH1A1 expression was associated with less aggressive NB tumors and cell lines, and correlated with favorable prognostic factors. In contrast, we observed that ALDH1A3 was more widely expressed in NB cell lines and was associated with poor survival and high-risk prognostic factors. We also identified an important ALDH activity in various NB cell lines and patient-derived xenograft tumors. Specific inhibition of ALDH activity with diethylaminobenzaldehyde (DEAB) resulted in a strong reduction of NB cell clonogenicity, and TIC self-renewal potential, and partially enhanced NB cells sensitivity to 4-hydroxycyclophosphamide. Finally, the specific knock-out of ALDH1A3 via CRISPR/Cas9 gene editing reduced NB cell clonogenicity, and mediated a cell type-dependent inhibition of TIC self-renewal properties.

CONCLUSIONS

Together our data uncover the participation of ALDH enzymatic activity in the aggressive properties and 4-hydroxycyclophosphamide resistance of NB, and show that the specific ALDH1A3 isoenzyme increases the aggressive capacities of a subset of NB cells.

New therapeutic strategies in neuroblastoma: combined targeting of a novel tyrosine kinase inhibitor and liposomal siRNAs against ALK

Many different aberrations in the Anaplastic Lymphoma Kinase (ALK) were found to be oncogenic drivers in several cancers including neuroblastoma (NB), therefore ALK is now considered a critical player in NB oncogenesis and a promising therapeutic target. The ALK-inhibitor crizotinib has a limited activity against the various ALK mutations identified in NB patients.

We tested: the activity of the novel ALK-inhibitor X-396 administered alone or in combination with Targeted Liposomes carrying ALK-siRNAs (TL[ALK-siRNA]) that are active irrespective of ALK gene mutational status; the pharmacokinetic profiles and the biodistribution of X-396; the efficacy of X-396 versus crizotinib treatment in NB xenografts; whether the combination of X-396 with the TL[ALK-siRNA] could promote long-term survival in NB mouse models.

X-396 revealed good bioavailability, moderate half-life, high mean plasma and tumor concentrations. X-396 was more effective than crizotinib in inhibiting in vitro cell proliferation of NB cells and in reducing tumor volume in subcutaneous NB models in a dose-dependent manner.

In orthotopic NB xenografts, X-396 significantly increased life span independently of the ALK mutation status. In combination studies, all effects were significantly improved in the mice treated with TL[ALK-siRNA] and X-396 compared to mice receiving the single agents.

Our findings provide a rational basis to design innovative molecular-based treatment combinations for clinical application in ALK-driven NB tumors.

Induced differentiation inhibits sphere formation in neuroblastoma

Neuroblastoma arises from the neural crest, the precursor cells of the sympathoadrenal axis, and differentiation status is a key prognostic factor used for clinical risk group stratification and treatment strategies. Neuroblastoma tumor-initiating cells have been successfully isolated from patient tumor samples and bone marrow using sphere culture, which is well established to promote growth of neural crest stem cells. However, accurate quantification of sphere-forming frequency of commonly used neuroblastoma cell lines has not been reported. Here, we show that MYCN-amplified neuroblastoma cell lines form spheres more frequently than non-MYCN-amplified cell lines. We also show that sphere formation is directly sensitive to cellular differentiation status. 13-cis-retinoic acid is a clinically used differentiating agent that induces a neuronal phenotype in neuroblastoma cells. Induced differentiation nearly completely blocked sphere formation. Furthermore, sphere formation was specifically FGF-responsive and did not respond to increasing doses of EGF. Taken together, these data suggest that sphere formation is an accurate method of quantifying the stemness phenotype in neuroblastoma.

Next-generation sequencing reveals germline mutations in an infant with synchronous occurrence of nephro- and neuroblastoma

Although neuro- and nephroblastoma are common solid tumors in children, the simultaneous occurrence is very rare and is often associated with syndromes. Here, we present a unique case of synchronous occurrence of neuro- and nephroblastoma in an infant with no signs of congenital anomalies or a syndrome. We performed genetic testing for possible candidate genes as underlying mutation using the next-generation sequencing (NGS) approach to target 94 genes and 284 single-nucleotide polymorphisms (SNPs) involved in cancer. We uncovered a novel heterozygous germline missense mutation p.F58L (c.172T→C) in the anaplastic lymphoma kinase (ALK) gene and one novel heterozygous rearrangement Q418Hfs(*)11 (c.1254_1264delins TTACTTAGTACAAGAACTG) in the Fanconi anemia gene FANCD2 leading to a truncated protein. Besides, several SNPs associated with the occurrence of neuroblastoma and/or nephroblastoma or multiple primary tumors were identified. The next-generation sequencing approach might in the future be useful not only in understanding tumor etiology but also in recognizing new genetic markers and targets for future personalized therapy.

Understanding genistein in cancer: The "good" and the "bad" effects: A review

Nowadays, diet and specific dietary supplements are seen as potential adjuvants to prevent different chronic diseases, including cancer, or to ameliorate pharmacological therapies. Soybean is one of the most important food components in Asian diet. A plethora of evidence supports the in vitro and in vivo anticancer effects of genistein, a soybean isoflavone. Major tumors affected by genistein here reviewed are breast, prostate, colon, liver, ovarian, bladder, gastric, brain cancers, neuroblastoma and chronic lymphocytic leukemia. However, it is not always clear if and when genistein is beneficial against tumors (the "good" effects), or the opposite, when the same molecule exerts adverse effects (the "bad" effects), favouring cancer cell proliferation. This review will critically evaluate this concept in the light of the different molecular mechanisms of genistein which occur when the molecule is administered at low doses (chemopreventive effects), or at high doses (pharmacological effects).

PHOX2A and PHOX2B are differentially regulated during retinoic acid-driven differentiation of SK-N-BE(2)C neuroblastoma cell line

PHOX2B and its paralogue gene PHOX2A are two homeodomain proteins in the network regulating the development of autonomic ganglia that have been associated with the pathogenesis of neuroblastoma (NB), because of their over-expression in different NB cell lines and tumour samples. We used the SK-N-BE(2)C cell line to show that all-trans retinoic acid (ATRA), a drug that is widely used to inhibit growth and induce differentiation in NBs, regulates both PHOX2A and PHOX2B expression, albeit by means of different mechanisms: it up-regulates PHOX2A and down-regulates PHOX2B. Both mechanisms act at transcriptional level, but prolonged ATRA treatment selectively degrades the PHOX2A protein, whereas the corresponding mRNA remains up-regulated. Further, we show that PHOX2A is capable of modulating PHOX2B expression, but this mechanism is not involved in the PHOX2B down-regulation induced by retinoic acid. Our findings demonstrate that PHOX2A expression is finely controlled during retinoic acid differentiation and this, together with PHOX2B down-regulation, reinforces the idea that they may be useful biomarkers for NB staging, prognosis and treatment decision making.

Genetic discoveries and treatment advances in neuroblastoma

PURPOSE OF REVIEW

Major advances in our understanding of the genetic basis of neuroblastoma, and the role somatic alterations play in driving tumor growth, have led to improvements in risk-stratified therapy and have provided the rationale for targeted therapies. In this review, we highlight current risk-based treatment approaches and discuss the opportunities and challenges of translating recent genomic discoveries into the clinic.

RECENT FINDINGS

Significant progress in the treatment of neuroblastoma has been realized using risk-based treatment strategies. Outcome has improved for all patients, including those classified as high-risk, although survival remains poor for this cohort. Integration of whole-genome DNA copy number and comprehensive molecular profiles into neuroblastoma classification systems will allow more precise prognostication and refined treatment assignment. Promising treatments that include targeted systemic radiotherapy, pathway-targeted small molecules, and therapy targeted at cell surface molecules are being evaluated in clinical trials, and recent genomic discoveries in relapsed tumor samples have led to the identification of new actionable mutations.

SUMMARY

The integration of refined treatment stratification based on whole-genome profiles with therapeutics that target the molecular drivers of malignant behavior in neuroblastoma has the potential to dramatically improve survival, with decreased toxicity.

Oncologic Phenotype of Peripheral Neuroblastic Tumors Associated With PHOX2B Non-Polyalanine Repeat Expansion Mutations

BACKGROUND

Germline non-polyalanine repeat expansion mutations in PHOX2B (PHOX2B NPARM) predispose to peripheral neuroblastic tumors (PNT), frequently in association with other neurocristopathies: Hirschsprung disease (HSCR) or congenital central hypoventilation syndrome (CCHS). Although PHOX2B polyalanine repeat expansions predispose to a low incidence of benign PNTs, the oncologic phenotype associated with PHOX2B NPARM is still not known in detail.

METHODS

We analyzed prognostic factors, treatment toxicity, and outcome of patients with PNT and PHOX2B NPARM.

RESULTS

Thirteen patients were identified, six of whom also had CCHS and/or HSCR, one also had late-onset hypoventilation with hypothalamic dysfunction (LO-CHS/HD), and six had no other neurocristopathy. Four tumours were "poorly differentiated," and nine were differentiated, including five ganglioneuromas, three ganglioneuroblastomas, and one differentiating neuroblastoma, hence illustrating that PHOX2B NPARM are predominantly associated with differentiating tumors. Nevertheless, three patients had stage 4 and one patient had stage 3 disease. Segmental chromosomal alterations, correlating with poor prognosis, were found in all the six tumors analyzed by array-comparative genomic hybridization. One patient died of tumor progression, one is on palliative care, one died of hypoventilation, and 10 patients are still alive, with median follow-up of 5 years.

CONCLUSIONS

Based on histological phenotype, our series suggests that heterozygous PHOX2B NPARM do not fully preclude ganglion cell differentiation in tumors. However, this tumor predisposition syndrome may also be associated with poorly differentiated tumors with unfavorable genomic profiles and clinically aggressive behaviors. The intrafamilial variability and the unpredictable tumor prognosis should be considered in genetic counseling.

Antibiotic drug tigecycline reduces neuroblastoma cells proliferation by inhibiting Akt activation in vitro and in vivo

As the first member of glycylcycline bacteriostatic agents, tigecycline is approved as a novel expanded-spectrum antibiotic, which is clinically available. However, accumulating evidence indicated that tigecycline was provided with the potential application in cancer therapy. In this paper, tigecycline was shown to exert an anti-proliferative effect on neuroblastoma cell lines. Furthermore, it was found that tigecycline induced G1-phase cell cycle arrest instead of apoptosis by means of Akt pathway inhibition. In neuroblastoma cell lines, the Akt activator insulin-like growth factor-1 (hereafter referred to as IGF-1) reversed tigecycline-induced cell cycle arrest. Besides, tigecycline inhibited colony formation and suppressed neuroblastoma cells xenograft formation and growth. After tigecycline treatment in vivo, the Akt pathway inhibition was confirmed as well. Collectively, our data provided strong evidences that tigecycline inhibited neuroblastoma cells growth and proliferation through the Akt pathway inhibition in vitro and in vivo. In addition, these results were supported by previous studies concerning the application of tigecycline in human tumors treatment, suggesting that tigecycline might act as a potential candidate agent for neuroblastoma treatment.

Directly targeting transcriptional dysregulation in cancer

Drugs that target intracellular signalling pathways have markedly improved progression-free survival of patients with cancers who were previously regarded as untreatable. However, the rapid emergence of therapeutic resistance, as a result of bypass signalling or downstream mutation within kinase-mediated signalling cascades, has curtailed the benefit gained from these therapies. Such resistance mechanisms are facilitated by the linearity and redundancy of kinase signalling pathways. We argue that, in each cancer, the dysregulation of key transcriptional regulators not only defines the cancer phenotype but is essential for its development and maintenance. Furthermore, we propose that, as therapeutic targets, these transcriptional regulators are less prone to bypass by alternative mutational events or clonal heterogeneity, and therefore we must rekindle our efforts to directly target transcriptional regulation across a broad range of cancers.

Nifurtimox reduces N-Myc expression and aerobic glycolysis in neuroblastoma

Neuroblastoma is one of the most common solid tumors in childhood and usually accompanied with poor prognosis and rapid tumor progression when diagnosed with amplification of the proto-oncogene N-Myc. The amplification of N-Myc has major influence on the maintenance of aerobic glycolysis, also known as the Warburg effect. This specific switch in the conversion of pyruvate to lactate instead of the conversion of pyruvate to acetyl-coenzyme A even in the presence of oxygen has important benefits for the tumor, e.g. increased production of enzymes and enzyme substrates that are involved in tumor progression, angiogenesis and inhibition of apoptosis. The antiprotozoal drug nifurtimox, which is generally used for the treatment of infections with the parasitic protozoan Trypanosoma cruzi, has been reported to have cytotoxic properties in the therapy of neuroblastoma. However, its action of mechanism has not been described in detail yet. The presented in vitro study on the neuroblastoma cell lines LA-N-1, IMR-32, LS and SK-N-SH shows an increased production of oxidative stress, a reduced lactate dehydrogenase enzyme activity and reduced lactate production after nifurtimox treatment. Furthermore, nifurtimox leads to reduced mRNA and protein levels of the proto-oncogene protein N-Myc. Thus, the current work gives new insights into the effect of nifurtimox on tumor metabolism revealing a shifted glucose metabolism from production of lactate to oxidative phosphorylation and a reduced expression of the major molecular prognostic factor in neuroblastoma N-Myc, presenting nifurtimox as a possible adjuvant therapeutic agent against (high risk) neuroblastoma.

miR-204 mediates post-transcriptional down-regulation of PHOX2B gene expression in neuroblastoma cells

Neuroblastoma (NB) is a rare childhood cancer of the peripheral sympathetic nervous system and accounts for approximately 10% of all pediatric tumors. Heterozygous PHOX2B mutations have been found in association with NB development in familial, sporadic and syndromic cases. In addition, the PHOX2B gene is widely over-expressed both in tumor samples and NB cell lines. Post-transcriptional gene regulation is known to be involved in mRNA stability and, in NB, microRNAs (miRNAs) seem to be responsible for altered expression of genes driving differentiation, apoptosis, and migration. To assess the possible impact of post-transcriptional regulation in NB cell lines, we have focused on the PHOX2B mRNA stability by both in silico analysis and functional studies on its 3'untranslated region (3'UTR). PHOX2B gene expression has resulted under post-transcriptional control, as suggested by: i) instability of PHOX2B mRNA, demonstrated by short mRNA half-life levels in both IMR32 and LAN-1 cell lines, ii) role of the PHOX2B-3'UTR, confirmed by the activity of proper reporter constructs, and iii) miRNA-204, shown to enhance the PHOX2B 3'UTR mediated down-regulation of the reporter construct activity. Finally, miRNA-204 has resulted to decrease the stability of the PHOX2B mRNA at different extents in the presence of different SNP rs1063611 alleles. Therefore, post-transcriptional down-regulation of the PHOX2B gene takes place in NB cell lines and miRNA-204 participates in such a 3'UTR mediated control.

Neuroblastoma, body mass index, and survival: a retrospective analysis

Extremes of body mass index (BMI) at diagnosis of childhood cancers have been associated with poorer prognosis. The aims of this retrospective review were to examine the growth and BMI status of children diagnosed with neuroblastoma (NB) and determine if BMI status at diagnosis affected survival. Between 1985 and 2005, 154 children were diagnosed with NB at Sydney Children's Hospitals Network (Westmead), Australia, of which 129 had both length/height and weight recorded in the medical records at diagnosis. BMI was calculated and children were classified as underweight (BMI <15th percentile), normal weight, and overweight (BMI >85th percentile). Disease stage was classified according to the International NB Staging System. At diagnosis, 24.0% of the children were classified as underweight and 11.6% were overweight. Six months after diagnosis all children except those with stage 4s disease had a decrease in BMI z-score; difference in estimated marginal mean -0.73, P < .001. After 12 months an increase in BMI z-score was observed and by 2 years BMI z-score was significantly higher than BMI z-score at baseline; difference in estimated marginal mean 0.81, P = .007. At the last follow-up (median 5.6 years [range 3-7] after diagnosis) the proportion of children who were classified as underweight decreased to 8.7% and the proportion of children who were classified as overweight increased to 27.5%. The overall survival rate was 61.2%; however, BMI status did not predict survival. In multivariable Cox regression modeling, stage at diagnosis was the only predictor of survival; children diagnosed with stage 4 were less likely to survive (hazard ratio [HR] [95%CI]: 7.02 [1.7-29.0], P = .007). Almost a quarter of children with NB were underweight at diagnosis. However, we did not demonstrate a prognostic association between BMI status and survival. The high proportion of children who were classified as overweight at follow-up indicates a need for nutritional interventions to prevent potential late effects.

Morphine protects SH-SY5Y human neuroblastoma cells against Dickkopf1-induced apoptosis

Morphine is used to relieve pain in patients with cancer in terminal phases. Dickkopf‑1 (DKK1), a secreted protein, is a negative regulator of the Wnt/β‑catenin signaling pathway. Morphine and DKK1 are associated with tumorigenesis. However, to the best of our knowledge, there is no study evaluating the effects of these two factors simultaneously. In the present study, the effects of morphine and DKK1 on neuroblastoma cells in vivo and in vitro were evaluated. To establish the in vitro effects of DKK1 and morphine, human neuroblastoma SH‑SY5Y cells were transfected with a DKK1‑expressing plasmid and cell migration, apoptosis, migration and invasion were evaluated prior to and following morphine treatment. The results indicated that DKK1 induced apoptosis and inhibited the mobility of neuroblastoma cells and that morphine attenuated these DKK1‑induced effects. To evaluate the effects of DKK1 and morphine in vivo, a mouse model of neuroblastoma was established, where mice bearing tumors of native SH-SY5Y cells were injected with DKK1. Tumor size, spatial memory and survival rate were investigated in untreated, DKK1‑treated and DKK1+morphine‑treated mice. Water maze and T‑maze tests were performed, which revealed that DKK1‑treated mice exhibited a better memory than DKK1 + morphine‑treated mice. The expression of DKK1 in established xenografted tumors was associated with decreased tumor size and an increased survival rate, whereas morphine reversed these effects. Furthermore, it was confirmed that morphine and DKK1 take effect, at least in part, via the Wnt/β‑catenin signaling pathway. The results of the present study indicate that morphine may protect neuroblastoma cells and thus, it may be used in neuroblastoma patients.