Functional polymorphisms of the TET1 gene increase the risk of neuroblastoma in Chinese children

Common genetic mutations are absent in neuroblastoma, one of the most common childhood tumours. As a demethylase of 5-methylcytosine (m5C) modification, TET1 plays an important role in tumourigenesis and differentiation. However, the association between TET1 gene polymorphisms and susceptibility to neuroblastoma has not been reported. Three TET1 gene polymorphisms (rs16925541 A > G, rs3998860 G > A and rs12781492 A > C) in 402 Chinese patients with neuroblastoma and 473 cancer-free controls were assessed using TaqMan. Multivariate logistic regression analysis was used to evaluate the association between TET1 gene polymorphisms and susceptibility to neuroblastoma. The GTEx database was used to analyse the impact of these polymorphisms on peripheral gene expression. The relationship between gene expression and prognosis was analysed using Kaplan–Meier analysis with the R2 platform. We found that both rs3998860 G > A and rs12781492 A > C were significantly associated with increased neuroblastoma risk. Stratified analysis further showed that rs3998860 G > A and rs12781492 A > C significantly increased neuroblastoma risk in certain subgroups. In the combined risk genotype model, 1–3 risk genotypes significantly increased risk of neuroblastoma compared with the 0 risk genotype. rs3998860 G > A and rs12781492 A > C were significantly associated with increased STOX1 mRNA expression in adrenal and whole blood, and high expression of STOX1 mRNA in adrenal and whole blood was significantly associated with worse prognosis. In summary, TET1 gene polymorphisms are significantly associated with increased neuroblastoma risk; further research is required for the potential mechanism and therapeutic prospects in neuroblastoma.     

The reaction of the neuroblastoma cells in the culture on the influence of tretionine and neurotoxine

Effect of the tretionine (retinoid) and aluminum chloride (neurotoxin) on the growth and differentiation of neuroblastoma cells in culture after their introduction into the medium separately and in combination was studied. The introduction of these substances creates a new information field in the medium, which becomes apparent by the reactions of neuroblastoma found on the populational and cellular levels of its organization. The presence of tretionine stimulates proliferation and induces differentiation of the cells into astrocytes. Aluminum chloride inhibits cell proliferation and enhances the process of their destruction in the monolayer. The variety of the reactions of neuroblastoma cells to the presence of these substances in the medium indicates the existence and functioning of a mechanism that selects from the information introduced only the portion which may contribute to adaptation of neuroblastoma cells to the changed culture conditions.     

Identification of a phosphoprotein specifically induced by the transforming DNA of rat neuroblastomas

DNAs from nitrosoethylurea-induced rat neuroblastomas transform NIH/3T3 mouse fibroblasts in a transfection assay. DNAs of such transformed cells can be used in a subsequent cycle of transfection to generate secondary foci that contain virtually no foreign genetic material besides the sequences carrying the rat neuroblastoma transforming function. These secondary neuroblastoma transfectants were injected into young mice and grew out into fibrosarcomas. Sera from these mice were examined for reactivity with any proteins which were induced specifically by the neuroblastoma transforming sequence. These sera precipitate a polypeptide of about 185,000 daltons from ³⁵S-methionine-labeled cell lysates of the rat neuroblastoma cells that served as DNA donors and in all transfection-derived primary and secondary foci. This protein is present in high levels in all neuroblastoma transfectant clones, but was not detectable in a variety of other transformed cells. Antisera were prepared from mice bearing tumors induced by transformed cells derived by transfection of DNAs from various tumor cell types unrelated to rat neuroblastoma. These antisera failed to immunoprecipitate the 185,000 dalton protein. These data indicate that the synthesis of the 185,000 dalton protein is specifically induced by the neuroblastoma transforming sequence. The protein may be encoded by the transforming sequence and may mediate transformation in this chemically induced tumor.     

Screening for neuroblastoma in the north of England.

OBJECTIVE--To determine the feasibility of establishing a system of screening for neuroblastoma. DESIGN--Prospective study of mass screening in four clearly defined geographical areas. SETTING--Four health districts of the Northern region of England. SUBJECTS--20,829 babies aged 6 months, 92% of target population. INTERVENTIONS--Collection of urine on filter paper for analysis of content of homovanillic and vanillylmandelic acid in relation to urinary creatinine concentrations. MAIN OUTCOME MEASURES--Derivation of reference range. Identification of babies with homovanillic or vanillylmandelic acid > 3 SD above the mean (positive cases). Investigation of positive cases for evidence of neuroblastoma. RESULTS--The upper limit of normal (3 SD above the mean) for vanillylmandelic acid was 15 mumol/mmol creatinine and for homovanillic acid 24 mumol/mmol creatinine. Of the 20,829 babies screened, 2537 (12.2%) required a second sample to be taken because the first sample was inadequate. Of these, 527 (2.5%) provided a liquid urine specimen and 10 (0.04%) had positive results for neuroblastoma. Two of them had neuroblastoma (true positives) and eight did not (false positives). A further three children from the cohort were subsequently found to have neuroblastoma; they had raised homovanillic acid or vanillylmandelic acid values, or both, but screened negative at 6 months. CONCLUSIONS--Screening for neuroblastoma is possible in the health care system of the United Kingdom. Evaluation of the efficacy of screening in reducing the mortality from neuroblastoma requires a controlled trial.     

Preclinical Evaluation of Engineered Oncolytic Herpes Simplex Virus for the Treatment of Neuroblastoma

Despite intensive research efforts and therapeutic advances over the last few decades, the pediatric neural crest tumor, neuroblastoma, continues to be responsible for over 15% of pediatric cancer deaths. Novel therapeutic options are needed for this tumor. Recently, investigators have shown that mice with syngeneic murine gliomas treated with an engineered, neuroattenuated oncolytic herpes simplex virus-1 (oHSV), M002, had a significant increase in survival. M002 has deletions in both copies of the γ₁34.5 gene, enabling replication in tumor cells but precluding infection of normal neural cells. We hypothesized that M002 would also be effective in the neural crest tumor, neuroblastoma. We showed that M002 infected, replicated, and decreased survival in neuroblastoma cell lines. In addition, we showed that in murine xenografts, treatment with M002 significantly decreased tumor growth, and that this effect was augmented with the addition of ionizing radiation. Importantly, survival could be increased by subsequent doses of radiation without re-dosing of the virus. Finally, these studies showed that the primary entry protein for oHSV, CD111 was expressed by numerous neuroblastoma cell lines and was also present in human neuroblastoma specimens. We concluded that M002 effectively targeted neuroblastoma and that this oHSV may have potential for use in children with unresponsive or relapsed neuroblastoma.     

Reverse Engineering the Neuroblastoma Regulatory Network Uncovers MAX as One of the Master Regulators of Tumor Progression

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

Interferon-gamma upregulates the susceptibility of human neuroblastoma cells to interleukin-2-activated natural killer cells

The influence of interferon-gamma on the susceptibility of neuroblastoma cells in cell-mediated killing was investigated. Neuroblastoma cells were only weakly susceptible targets for peripheral mononuclear cells. However, enrichment of natural killer (NK) cells or activation of NK cells with interleukin-2 resulted in a considerable increase of neuroblastoma cell lysis. Pretreatment of neuroblastoma targets with interferon-gamma additionally increased the susceptibility to enriched NK cells as well as to interleukin-2-activated NK cells. The conjugate formation between enriched NK cells and the neuroblastoma targets was not affected by the pretreatment of the targets with interferon-gamma. Concomitantly, treatment of the neuroblastoma targets with interferon-gamma resulted in a strong induction of otherwise poorly expressed major histocompatibility complex (MHC) class I antigen expression. These results suggest that the increased expression of MHC class I antigens on target cells is not always correlated with decreased sensitivity for NK cells but can also be followed by an increased susceptibility for NK cells.     

miR-329 suppresses the growth and motility of neuroblastoma by targeting KDM1A

MicroRNAs (miRNAs) act as key regulators of multiple cancers. miR-329 functions as a tumor suppressor in some malignancies. However, its role in neuroblastoma remains poorly understood. We found that miR-329 was decreased in metastatic tumor tissues compared with matched primary tumor tissues. Forced overexpression of miR-329 substantially suppressed cell proliferation, colony formation, migration, and invasion of neuroblastoma cells. Lysine-specific demethylase 1 (KDM1A) was found to be a target of miR-329. Furthermore, down-regulation of KDM1A by shRNA performed similar effects with overexpression of miR-329. Overexpression of KDM1A partially reversed the tumor suppressive effects of miR-329 in neuroblastoma cells. Collectively, miR-329 may suppress neuroblastoma cell growth and motility partially by targeting KDM1A.     

Immunohistochemical evidence for a plasma membrane localization of dopamine-beta-hydroxylase in the mouse neuroblastoma

Dopamine-beta-hydroxylase (D beta H), a glycoprotein enzyme which converts dopamine into noradrenaline, was purified from C1300 mouse neuroblastoma and used to raise antibodies in rabbits. Using an indirect immunofluorescence technique the cellular localization of D beta H in C1300 mouse neuroblastoma was compared with that of the superior cervical ganglion. C1300 neuroblastoma D beta H was found to be predominantly localized in the plasma membrane, in contrast to its intracellular localization in the superior cervical ganglion of A/J mice. At least part of the enzyme was found to be associated with the external side of the plasma membrane.     

Cellular characteristics of neuroblastoma cells: regulation by the ELR--CXC chemokine CXCL10 and expression of a CXCR3-like receptor

Bone marrow stroma cells secrete the chemokine CXCL12 that may support bone marrow metastasis formation by neuroblastoma cells. The present study demonstrates that bone marrow stroma cell lines also secrete CXCL10, a chemokine that was shown in the past to have anti-malignancy functions. A receptor recognized by antibodies against CXCR3 was shown to be expressed by six neuroblastoma cell lines. Further detailed analysis was performed on the NUB6 and SK-NMC neuroblastoma cells, showing that CXCL10 induced potent Erk phosphorylation in a G(alpha)i-dependent manner. The role of a CXCR3-like receptor in Erk phosphorylation was substantiated by the ability of CXCL11, another potent CXCR3 ligand, to induce Erk phosphorylation in the NUB6 and SK-NMC cells. Further characterization of CXCL10 activities indicated that CXCL10 partly inhibited the growth of the NUB6 and SK-NMC cells. Both NUB6 and SK-NMC cells did not migrate to CXCL10, although their migratory machinery was intact, as evidenced by their migration to bone marrow constituents. Altogether, these results suggest that CXCL10 interacts with a CXCR3-like receptor in neuroblastoma cell lines, raising the possibility that following the homing of the tumor cells to the bone marrow (through a CXCL10-independent mechanism), CXCL10 may partly inhibit neuroblastoma cell growth at this site.     

Electrophoretic patterns of glucose metabolizing enzymes and acid phosphatase in mouse and human neuroblastoma cells

The electrophoretic patterns of glucose metabolizing enzymes and acid phosphatase in mouse and human neuroblastoma cells were investigated. Mouse neuroblastoma cells had one band of lactate dehydrogenase (LDH) and two bands of acid phosphatase, whereas human neuroblastoma cells had five bands of LDH and one band of acid phosphatase. Glucose-6-phosphate dehydrogenase (G-6-PD) and 6-phosphogluconate dehydrogenase (6-PGD) were expressed as a single band in both mouse and human neuroblastoma cells. The electrophoretic pattern of LDH was similar in mouse neuroblastoma cells grown in culture or in vivo. The electrophoretic band of G-6-PD in mouse neuroblastoma cells grown in vivo appeared to be less dense than that observed in cells grown in culture; however, the reverse was true for 6-PGD. Among all enzymes examined, only the electrophoretic pattern of G-6-PD in cAMP-induced “differentiated” mouse neuroblastoma was different in comparison to control cells.     

MYCN gene expression is required for the onset of the differentiation programme in neuroblastoma cells

Neuroblastoma is an embryonic tumour of the sympathetic nervous system and is one of the most common cancers in childhood. A high differentiation stage has been associated with a favourable outcome; however, the mechanisms governing neuroblastoma cell differentiation are not completely understood. The MYCN gene is considered the hallmark of neuroblastoma. Even though it has been reported that MYCN has a role during embryonic development, it is needed its decrease so that differentiation can be completed. We aimed to better define the role of MYCN in the differentiation processes, particularly during the early stages. Considering the ability of MYCN to regulate non-coding RNAs, our hypothesis was that N-Myc protein might be necessary to activate differentiation (mimicking embryonic development events) by regulating miRNAs critical for this process. We show that MYCN expression increased in embryonic cortical neural precursor cells at an early stage after differentiation induction. To investigate our hypothesis, we used human neuroblastoma cell lines. In LAN-5 neuroblastoma cells, MYCN was upregulated after 2 days of differentiation induction before its expected downregulation. Positive modulation of various differentiation markers was associated with the increased MYCN expression. Similarly, MYCN silencing inhibited such differentiation, leading to negative modulation of various differentiation markers. Furthermore, MYCN gene overexpression in the poorly differentiating neuroblastoma cell line SK-N-AS restored the ability of such cells to differentiate. We identified three key miRNAs, which could regulate the onset of differentiation programme in the neuroblastoma cells in which we modulated MYCN. Interestingly, these effects were accompanied by changes in the apoptotic compartment evaluated both as expression of apoptosis-related genes and as fraction of apoptotic cells. Therefore, our idea is that MYCN is necessary during the activation of neuroblastoma differentiation to induce apoptosis in cells that are not committed to differentiate.     

Rapamycin induces the anti-apoptotic protein survivin in neuroblastoma

Neuroblastoma is the most common solid tumor of infancy, accounting for 15% of all cancer cell deaths in children. Expression of the anti-apoptotic protein survivin in these tumors correlates with poor prognostic features and resistance to therapy. The mammalian target of rapamycin (mTOR) protein is being explored as a potential therapeutic target in patients with this disease. The objective of this study was to test the hypothesis that rapamycin regulates survivin expression and function in neuroblastoma cells. To explore this hypothesis, we treated two different neuroblastoma lines (NB7, NB8) and a well-characterized control lung cancer cell line, A549, with varying doses of rapamycin (0.1-10μM) for serial time points (2-48 hours). RNA and protein expression levels were then evaluated by quantitative RT-PCR and western blotting, respectively. Cell proliferation and apoptosis were assayed by WST-1 and Annexin V. The results showed a rapamycin-dependent increase in survivin mRNA and protein levels in the neuroblastoma cell lines in a dose- and time-dependent fashion, while a decrease in these levels was observed in control cells. Rapamycin inhibited cell proliferation in both A549 and neuroblastoma cells however neuroblastoma cells had less apoptosis than A549 cells (9% vs. 20%). In summary, our results indicate that rapamycin induces expression of the anti-apoptotic protein survivin in neuroblastoma cells which may protect these cells from programmed cell death. Induction of survivin by rapamycin could therefore be a potential mechanism of neuroblastoma tumor cell resistance and rapamycin may not be an effective therapeutic agent for these tumors.     

Protein kinase C beta1 is implicated in the regulation of neuroblastoma cell growth and proliferation.

To investigate a putative involvement of protein kinase C (PKC) isoforms in supporting neuroblastoma cell proliferation, SK-N-BE(2) neuroblastoma cells were transfected with expression vectors coding for the C2 and V5 regions from different PKC isoforms. These structures have been suggested to inhibit the activity of their corresponding PKC isoform. The PKC fragments were fused to enhanced green fluorescent protein to facilitate the detection of transfected cells. Expression of the C2 domain from a classical PKC isoform (PKCalpha), but not of C2 domains from novel PKCdelta or PKCepsilon, suppressed the number of neuroblastoma cells positive for cyclin A and bromodeoxyuridine incorporation. This indicates a role for a classical isoform in regulating proliferation of these cells. Among the V5 fragments from PKCalpha, PKCbetaI, and PKCbetaII, the PKCbetaI V5 had the most suppressive effect on proliferation markers, and this fragment also displaced PKCbetaI from the nucleus. Furthermore, a PKCbeta-specific inhibitor, LY379196, suppressed the phorbol ester- and serum-supported growth of neuroblastoma cells. There was a marked enhancement by LY379196 of the growth-suppressive and/or cytotoxic effects of paclitaxel and vincristine. These results indicate that PKCbetaI has a positive effect on the growth and proliferation of neuroblastoma cells and demonstrate that inhibition of PKCbeta may be used to enhance the effect of microtubule-interacting anticancer agents on neuroblastoma cells.     

Gene expression profiling in response to the histone deacetylase inhibitor BL1521 in neuroblastoma

Neuroblastoma is a childhood tumor with a poor survival in advanced stage disease despite intensive chemotherapeutic regimes. The new histone deacetylase (HDAC) inhibitor BL1521 has shown promising results in neuroblastoma. Inhibition of HDAC resulted in a decrease in proliferation and metabolic activity, induction of apoptosis and differentiation of neuroblastoma cells. In order to elucidate the mechanism mediating the effects of BL1521 on neuroblastoma cells, we investigated the gene expression profile of an MYCN single copy (SKNAS) and an MYCN amplified (IMR32) neuroblastoma cell line after treatment with BL1521 using the Affymetrix oligonucleotide array U133A. An altered expression of 255 genes was observed in both neuroblastoma cell lines. The majority of these genes were involved in gene expression, cellular metabolism, and cell signaling. We observed changes in the expression of vital genes belonging to the cell cycle (cyclin D1 and CDK4) and apoptosis (BNIP3, BID, and BCL2) pathway in response to BL1521. The expression of 37 genes was altered by both BL1521 and Trichostatin A, which could indicate a common gene set regulated by different HDAC inhibitors. BL1521 treatment changed the expression of a number of MYCN-associated genes. Several genes in the Wnt and the Delta/Notch pathways were changed in response to BL1521 treatment, suggesting that BL1521 is able to induce the differentiation of neuroblastoma cells into a more mature phenotype.     

Studies on the organization and localization of actin and myosin in neurons

The organization of actin in mouse neuroblastoma and chicken dorsal root ganglion (DRG) nerve cells was investigated by means of a variety of electron microscope techniques. Microspikes of neuroblastoma cells contained bundles of 7- to 8-nm actin filaments which originated in the interior of the neurite. In the presence of high concentrations of Mg++ ion, filaments in these bundles became highly ordered to form paracrystals. Actin filaments, but not bundles, were observed in growth cones of DRG cells. Actin was localized in the cell body, neurites, and microspikes of both DRG and neuroblastoma nerve cells by fluorescein-labeled S1. Myosin was localized primarily in the neurites of chick DRG nerve cells with fluorescein-labeled anti-brain myosin antibody. This antibody also stained stress fibers in fibroblasts and myoblasts but did not stain muscle myofibrils.     

Metabolic consequences of drug-induced inhibition of the pentose phosphate pathway in neuroblastoma and glioma cells.

6-Aminonicotinamide leads to a considerable accumulation of 6-phosphogluconate, which is 3 times higher in C-6 glial cells than it is in C-1300 neuroblastoma cells. Dephosphorylation of the accumulated 6-phosphogluconate causes a rise of intracellular gluconate, which can be released from the cells. The higher dephosphorylating capacity of neuroblastoma cells leads to an intracellular gluconate content which is 4 times that found in C-6 glial cells. Although 6-phosphogluconate is a potent competitive inhibitor of glucose phosphate isomerase, no reduction of glycolytic flux and ATP content in stationary phase neuroblastoma cells was found in contrast to observations in C-6 glial cells. Morphological changes are only found in C-6 glial cells during the experimental period.     

D-Glucose Transport in Cultured Cells of Neural Origin: The Membrane as Possible Control Point of Glucose Utilization

Abstract: The function of plasma membrane as control point of glucose metabolism has been studied in confluent monolayer of C1300 neuroblastoma (N2A) and glioma (C6) cells. In neuroblastoma, steady state intracellular glucose concentration reached the extracellular levels, while intracellular contents in C6 glioma cells remained very low. In C6 glial cells the amount of glycogen as source of energy was much higher than that found in C1300 neuroblastoma cells. Influx rates of D-glucose in C6 glioma cells were only half those found in neuroblastoma cells. During the influx period (0-40 s) the transport of glucose in these cells did not exceed the phosphorylation rate, whereas a steady, time-dependent increase in glucose content was observed in neuroblastoma cells. While glucose uptake in neuroblastoma cells seems to be regulated at the level of phosphorylating enzymes, the control point in C6 glioma is believed to be membrane transport.