Cell survival signaling in neuroblastoma

Revisiting Neuroblastoma: Nrf2, NF-κB and Phox2B as a Promising Network in Neuroblastoma

Neuroblastoma is the most common solid extracranial tumor during childhood; it displays extraordinary heterogeneous clinical courses, from spontaneous regression to poor outcome in high-risk patients due to aggressive growth, metastasizing, and treatment resistance. Therefore, the identification and detailed analysis of promising tumorigenic molecular mechanisms are inevitable. This review highlights the abnormal regulation of NF-κB, Nrf2, and Phox2B as well as their interactions among each other in neuroblastoma. NF-κB and Nrf2 play a key role in antioxidant responses, anti-inflammatory regulation and tumor chemoresistance. Recent studies revealed a regulation of NF-κB by means of the Nrf2/antioxidant response element (ARE) system. On the other hand, Phox2B contributes to the differentiation of immature sympathetic nervous system stem cells: this transcription factor regulates the expression of RET, thereby facilitating cell survival and proliferation. As observed in other tumors, we presume striking interactions between NF-κB, Nrf2, and Phox2B, which might constitute an important crosstalk triangle, whose decompensation may trigger a more aggressive phenotype. Consequently, these transcription factors could be a promising target for novel therapeutic approaches and hence, further investigation on their regulation in neuroblastoma shall be reinforced.

Neural crest cells development and neuroblastoma progression: Role of Wnt signaling

Neuroblastoma (NB) is one of the most common heterogeneous extracranial cancers in infancy that arises from neural crest (NC) cells of the sympathetic nervous system. The Wnt signaling pathway, both canonical and noncanonical pathway, is a highly conserved signaling pathway that regulates the development and differentiation of the NC cells during embryogenesis. Reports suggest that aberrant activation of Wnt ligands/receptors in Wnt signaling pathways promote progression and relapse of NB. Wnt signaling pathways regulate NC induction and migration in a similar manner; it regulates proliferation and metastasis of NB. Inhibiting the Wnt signaling pathway or its ligands/receptors induces apoptosis and abrogates proliferation and tumorigenicity in all major types of NB cells. Here, we comprehensively discuss the Wnt signaling pathway and its mechanisms in regulating the development of NC and NB pathogenesis. This review highlights the implications of aberrant Wnt signaling in the context of etiology, progression, and relapse of NB. We have also described emerging strategies for Wnt-based therapies against the progression of NB that will provide new insights into the development of Wnt-based therapeutic strategies for NB.

Effects of dedifferentiated fat cells on neurogenic differentiation and cell proliferation in neuroblastoma cells

PURPOSE

Mesenchymal stem cells (MSCs) can induce differentiation of neuroblastoma (NB) cells. Properties of dedifferentiated fat cells (DFATs) are similar to those of MSCs. Here, we investigated whether DFATs can induce NB cell differentiation and suppress cell proliferation.

METHODS

DFATs were obtained from mature adipocytes isolated from adipose tissue from a ceiling culture. NB cells were cultured in a medium with or without DFATs and, subsequently, cultured in a DFAT-conditioned medium (CM) with or without phosphatidylinositol 3-kinase (PI3K) inhibitor. The neurite lengths were measured, and mRNA expression levels of the neurofilament (NF) and tubulin beta III (TUBβ3) were assessed using quantitative real-time RT-PCR. Cell viability was assessed using the WST-1 assay.

RESULTS

NB cells cultured with DFATs caused elongation of the neurites and upregulated the expression of NF and Tubβ3. NB cells cultured in DFAT-CM demonstrated increased cell viability. NB cells cultured with DFAT-CM and PI3K inhibitors suppressed cell viability. NB cells cultured with DFAT-CM and PI3K inhibitor demonstrated increased neurite length and expression, and upregulation of Tubβ3.

CONCLUSION

The combined use of DFAT-CM and PI3K inhibitors suppresses the proliferation of NB cells and induces their differentiation. Thus, DFAT may offer new insights into therapeutic approaches in neuroblastoma.

ERK Inhibitor Ulixertinib Inhibits High-Risk Neuroblastoma Growth In Vitro and In Vivo

Neuroblastoma (NB) is a pediatric tumor of the peripheral nervous system. Approximately 80% of relapsed NB show RAS-MAPK pathway mutations that activate ERK, resulting in the promotion of cell proliferation and drug resistance. Ulixertinib, a first-in-class ERK-specific inhibitor, has shown promising antitumor activity in phase 1 clinical trials for advanced solid tumors. Here, we show that ulixertinib significantly and dose-dependently inhibits cell proliferation and colony formation in different NB cell lines, including PDX cells. Transcriptomic analysis revealed that ulixertinib extensively inhibits different oncogenic and neuronal developmental pathways, including EGFR, VEGF, WNT, MAPK, NGF, and NTRK1. The proteomic analysis further revealed that ulixertinib inhibits the cell cycle and promotes apoptosis in NB cells. Additionally, ulixertinib treatment significantly sensitized NB cells to the conventional chemotherapeutic agent doxorubicin. Furthermore, ulixertinib potently inhibited NB tumor growth and prolonged the overall survival of the treated mice in two different NB mice models. Our preclinical study demonstrates that ulixertinib, either as a single agent or in combination with current therapies, is a novel and practical therapeutic approach for NB.

Kigelia africana inhibits proliferation and induces cell death in stage 4 Neuroblastoma cell lines

Neuroblastoma (NB) is one of the most common solid pediatric tumors and especially high-risk NBs still account for about 12-15% of cancer related deaths in children. Kigelia africana (KA) is a plant used in traditional African medicine which has already shown its anti-cancer potential in several in vitro and in vivo studies. The aim of this study is to evaluate the effect of KA fruit extract on stage 4 high-risk NB cells. Therefore, NB cell lines with and without MYCN amplification and non-neoplastic cells were treated with KA fruit extract at different concentrations. The effect of KA on cell viability and apoptosis rate were assessed by bioluminescence-/fluorescence-based assays. Several proteins involved in survival, tumor growth, inflammation and metastasis were detected via western blot and immunofluorescence. Secreted cytokines were detected via ELISA. Phytochemical composition of the extract was analyzed by liquid chromatography with tandem mass spectrometry (LC/MS/MS). Our group demonstrates a dose- and time-dependent selective cytotoxic effect of KA fruit extract on NB, especially in MYCN non-amplified tumor cells, by inhibiting cell proliferation and inducing cell death. Western blot and immunofluorescence results demonstrate a regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), disialoganglioside GD2 and epidermal growth factor receptor (EGFR) in KA-treated tumor cells. Our results evidence striking anti-cancer properties of KA fruit and pave the way for further surveys on the therapeutic properties and mechanisms of action in NB.

The significance of PAK4 in signaling and clinicopathology: A review

P21-activated protein kinases (PAKs) are thought to be at the center of tumor signaling pathways. As a representative member of the group II PAK family, P21-activated protein kinase 4 (PAK4) plays an important role in the development of tumors, with several biological functions such as participating in oncogenic transformation, promoting cell division, resisting aging and apoptosis, regulating cytoskeleton and adhesion, as well as suppressing antitumor immune responses. PAK4 is also crucial in biological processes, including the occurrence, proliferation, survival, migration, invasion, drug resistance, and immune escape of tumor cells. It is closely related to poor prognosis and tumor-related pathological indicators, which have significant clinical and pathological significance. Therefore, this article offers a review of the structure, activation, and biological functions of PAK4 and its clinical and pathological importance. This overview should be of assistance for future research on PAK4 and tumors and provide new ideas for tumor treatment and prognostic evaluation of patients.

RRS1 knockdown inhibits the proliferation of neuroblastoma cell via PI3K/Akt/NF-κB pathway

BACKGROUND

RRS1 plays an important role in regulating ribosome biogenesis. Recently, RRS1 has emerged as an oncoprotein involved in tumorigenicity of some cancers. However its role in neuroblastoma remains unknown.

METHODS

RRS1 expression was detected in pediatric neuroblastoma patients' tissues and cell lines. The effects of RRS1 knockdown on proliferation, apoptosis, and cell cycle were evaluated in neuroblastoma cell lines. RRS1-related survival pathway was analyzed by co-immunoprecipitation (Co-IP), mass spectrometry, reverse transcription-quantitative real-time PCR (RT-qPCR), and western blot. Protein-protein interaction (PPI) network was constructed using Cytoscape software and the STRING databases.

RESULTS

Increased RRS1 level was found in neuroblastoma cases (35.6%) and cell lines. High RRS1 expression levels were associated with poor prognosis. RRS1 knockdown inhibited cell proliferation, induced apoptosis, and caused cell cycle arrest in SK-N-AS and SH-SY5Y cells. Co-IP and mass spectrometry analysis showed that RRS1 affects PI3K/Akt and nuclear factor κB (NF-κB) pathways. RT-qPCR and western blot results revealed that RRS1 knockdown inhibited the PI3K/Akt/NF-κB pathway through dephosphorylation of key proteins. In PPI network, AKT, PI3K, and P65 connected RRS1 with differentially expressed proteins more closely.

CONCLUSIONS

This study suggests RRS1 knockdown may inhibit neuroblastoma cell proliferation by the PI3K/Akt/NF-κB pathway. Therefore, RRS1 may be a potential target for neuroblastoma treatment.

IMPACT

RRS1 is involved in the progression of neuroblastoma. Knockdown of RRS1 contributes to inhibit the survival of neuroblastoma cells. RRS1 is associated with the PI3K/Akt/NF-κB signaling pathway in neuroblastoma cells. RRS1 may be a promising target for neuroblastoma therapy.

Electrochemical distinction of neuronal and neuroblastoma cells via the phosphorylation of the cellular extracellular membrane

In this contribution we establish a proof of concept method for monitoring, quantifying and differentiating the extracellular phosphorylation of Human SHSY5Y undifferentiated neuronal cells and neuroblastoma cells by three prominent ectokinases PKA, PKC and Src. Herein it is demonstrated that a combination of different experimental techniques, including fluroesence microscopy, quartz crystal microscopy (QCM) and electrochemistry, can be used to detect extracellular phosphorylation levels of neuronal and neuroblastoma cells. Phosphorylation profiles of the three ectokinases, PKA, PKC and Src, were investigated using fluorescence microscopy and the number of phosphorylation sites per kinase was estimated using QCM. Finally, the phosphorylation of the extracellular membrane was determined using electrochemistry. Our results clearly demonstrate that the extracellular phosphorylation of neuronal cells differs significantly in terms of its phosphorylation profile from diseased neuroblastoma cells and the strength of surface electrochemical techniques in the differentiation process. We reveal that using electrochemistry, the percent compositions of neuronal and neuroblastoma cells can also be identified.

Tideglusib attenuates growth of neuroblastoma cancer stem/progenitor cells in vitro and in vivo by specifically targeting GSK-3β

BACKGROUND

Neuroblastoma (NB) is the most frequently diagnosed extracranial solid tumor among the pediatric population. It is an embryonic tumor with high relapse rates pertaining to the presence of dormant slowly dividing cancer stem cells (CSC) within the tumor bulk that are responsible for therapy resistance. Therefore, there is a dire need to develop new therapeutic approaches that specifically target NB CSCs. Glycogen synthase kinase (GSK)-3β is a serine/threonine kinase that represents a common signaling node at the intersection of many pathways implicated in NB CSCs. GSK-3β sustains the survival and maintenance of CSCs and renders them insensitive to chemotherapeutic agents and radiation.

METHODS

In our study, we aimed at evaluating the potential anti-tumor effect of Tideglusib (TDG), an irreversible GSK-3β inhibitor drug, on three human NB cell lines, SK-N-SH, SH-SY5Y, and IMR-32.

RESULTS

Our results showed that TDG significantly reduced cell proliferation, viability, and migration of the NB cells, in a dose- and time-dependent manner, and also significantly hindered the neurospheres formation eradicating the self-renewal ability of highly resistant CSCs. Besides, TDG potently reduced CD133 cancer stem cell marker expression in both SH-SY5Y cells and G1 spheres. Lastly, TDG inhibited NB tumor growth and progression in vivo.

CONCLUSION

Collectively, we concluded that TDG could serve as an effective treatment capable of targeting the NB CSCs and hence overcoming therapy resistance. Yet, future studies are warranted to further investigate its potential role in NB and decipher the subcellular and molecular mechanisms underlying this role.

GO Nanosheets: Promising Nano Carrier for the S29, 1-(2-Chloro-2-(4-chlorophenyl-ethyl)-N-(4-fluorobenzyl)-1H-pyrazolo[3,4-d] pyrimidin-4-amine, Therapeutic Agent in Neuroblastoma

Graphene oxide (GO) derivatives are reported as a valid alternative to conventional carriers of therapeutic agents, because they have a large surface area, an excellent electrical and thermal conductivity and a great capacity for selective binding of drugs and therapeutics, due to the functionalization of their surfaces, edges and sides. In this work GO nanosheets, synthesized by electrochemical exfoliation of graphite (patent N 102015000023739, Tor Vergata University), were investigated as possible carriers of an anticancer drug, the S29, an inhibitor of a cytoplasmic tyrosine kinase (c-SRC) on a neuroblastoma cell line (SK N BE 2 cells). Neuroblastoma is a heterogenous tumor whose characteristics range from spontaneous regression to aggressive phenotypes that are due to different mutations that often occur in SRC family kinases. Inhibitors of tyrosine kinases are currently investigated for their anti-tumoral effects on aggressive neuroblastomas, but their uptake in cells and pharmacokinetics needs to be improved. In this work S29 was stably conjugated with highly water-dispersible GO nanoparticles. S29/GO complex formation was induced by 1h sonication and its stability was analyzed by chromatography coupled with spectrophotometry and mass spectrometry. The synthesized composite (GO-S29) was delivered into SK N BE 2 cells and its effects on cell viability, production of reactive oxygen species (ROS) and migration were studied. The results show that the compound GO-S29 exerts anti-tumoral effects on the neuroblastoma cell line, higher than both GO and S29 do alone and that GO has an additive effect on S29.

Expression pattern of EEF1A2 in brain tumors: Histological analysis and functional role as a promoter of EMT

AIMS

Glioblastomas are highly aggressive brain tumors with a very poor survival rate. EEF1A2, the proto-oncogenic isoform of the EEF1A translation factor family, has been found to be overexpressed and promoting tumorigenesis in multiple cancers. Interestingly, recent studies reported reduced expression of this protein in brain tumors, drawing our attention to find the functional role and mechanism of this protein in brain tumor progression.

MAIN METHODS

Using representative cell line as models, the role of EEF1A2 in cell proliferation, migration and invasion were assessed using MTS assay, scratch wound-healing assay, transwell migration and invasion assay, respectively. Activation of key signaling pathways was assessed using western blots and real-time PCR. Finally, using immunohistochemistry we checked the protein levels of EEF1A2 in CNS tumors.

KEY FINDINGS

EEF1A2 was found to increase the proliferative, migratory and invasive properties of cell lines of both glial and neuronal origin. PI3K activation directly correlated with EEF1A2 levels. Protein levels of key EMT markers viz. Twist, Snail, and Slug were increased upon ectopic EEF1A2 expression. Furthermore, EEF1A2 was found to affect the expression levels of key inflammatory cytokines, growth factors and matrix metalloproteases. IHC analysis showed that EEF1A2 is upregulated in tumor tissues compared to normal tissue.

SIGNIFICANCE

EEF1A2 acts as an oncogene in both neuronal and glial cells and triggers an EMT program via PI3K pathway. However, it shows enhanced expression in neuronal cells of the brain than the glial cells, which could explain the previously reported anomaly.

Licochalcone A Inhibits BDNF and TrkB Gene Expression and Hypoxic Growth of Human Tumor Cell Lines

Hypoxic cellular proliferation is a common feature of tumor cells and is associated with tumor progression. Therefore, the inhibition of hypoxic cellular proliferation is expected to regulate malignancy processes. Licochalcone A (LicA) is known to show inhibitory effects on cell growth in normoxia, but it is unclear whether LicA exerts similar effects in hypoxia. Here, we studied the inhibitory activity of LicA in the hypoxic cellular proliferation of tumor cells and its molecular mechanism using human cell lines derived from various tumors including neuroblastoma and colorectal cancer. LicA inhibited cell growth at a 50% inhibitory concentration between 7.0 and 31.1 µM in hypoxia. LicA significantly suppressed hypoxic induction of tropomyosin receptor kinase B (TrkB) gene expression at the transcription level. LicA also downregulated mRNA levels of the TrkB high-affinity ligand brain-derived neurotrophic factor, but not neurotrophin-4, another TrkB ligand, or glyceraldehyde-3-phosphate dehydrogenase, indicating that the inhibitory activity of LicA is selective. Since both LicA-treatment and TrkB-knockdown decreased activation of protein kinase B in hypoxia, LicA exerts its inhibitory effect against hypoxic cell growth through inhibition of the TrkB-AKT axis. These results suggest that LicA has therapeutic potential for malignant tumors including neuroblastoma and colorectal cancer.

Low UBE4B expression increases sensitivity of chemoresistant neuroblastoma cells to EGFR and STAT5 inhibition

Neuroblastoma is the most common malignancy in infants. Overexpression of the epidermal growth factor receptor (EGFR) in neuroblastoma tumors underlies resistance to chemotherapeutics. UBE4B, an E3/E4 ubiquitin ligase involved in EGFR degradation, is located on chromosome 1p36, a region in which loss of heterozygosity is observed in approximately one-third of neuroblastoma tumors and is correlated with poor prognosis. In chemoresistant neuroblastoma cells, depletion of UBE4B yielded significantly reduced cell proliferation and migration, and enhanced apoptosis in response to EGFR inhibitor, Cetuximab. We have previously shown that UBE4B levels are inversely correlated with EGFR levels in neuroblastoma tumors. We searched for additional targets of UBE4B that mediate cellular alterations associated with tumorogenesis in chemoresistant neuroblastoma cells depleted of UBE4B using reverse phase protein arrays. The expression of STAT5a, an effector protein downstream of EGFR, doubled in the absence of UBE4B, and verified by quantitative immunoblotting. Chemoresistant neuroblastoma cells were treated with SH-4-54, a STAT5 inhibitor, and observed insignificant effects on cell proliferation, migration, and apoptosis. However, SH-4-54 significantly enhanced the anti-proliferative and anti-migratory effects of Cetuximab in naïve SK-N-AS neuroblastoma cells. Interestingly, in UBE4B depleted SK-N-AS cells, SH-4-54 significantly potentiated the effect of Cetuximab rendering cells increasingly sensitive an otherwise minimally effective Cetuximab concentration. Thus, neuroblastoma cells with low UBE4B levels were significantly more sensitive to combined EGFR and STAT5 inhibition than parental cells. These findings may have potential therapeutic implications for patients with 1p36 chromosome LOH and low tumor UBE4B expression.

IGF1R facilitates epithelial-mesenchymal transition and cancer stem cell properties in neuroblastoma via the STAT3/AKT axis

Background

Neuroblastoma (NB) displays the most heterogeneity in clinical manifestation. The insulin-like growth factor 1 receptor (IGF1R) has long been recognized for its role in tumourigenesis and growth. The IGF/IGF1R pathway is important in maintaining cell survival. It is reported that IGF1R participates in the occurrence of NB, but the mechanism is still unclear.

Methods

Human NB cell lines IMR-32 and SH-SY5Y were recruited in this study. IGF1R was knocked down by transfection with short hairpin RNA. Signal transducer and activator of transcription 3 (STAT3) expression was inhibited by Cryptotanshinone treatment. Cell proliferation, migration, and invasion were determined by MTT assay, wound healing assay, and cell invasion assay, respectively. The cancer stem cell properties were characterized by tumour sphere formation assay and colony formation assay. The mRNA and protein expression levels of related proteins were detected by RT-PCR and Western blot, respectively.

Results

The knockdown of IGF1R inhibits NB cell tumourigenesis and the epithelial-mesenchymal transition (EMT) of NB cells. Additionally, IGF1R was found to stimulate cancer stem cell-like properties in NPC cells. The knockdown of IGF1R significantly reduced the phosphorylation of AKT, and STAT3, indicating that the activation of the AKT and STAT3 pathways was inhibited by IGF1R knockdown. Furthermore, IGF1R was demonstrated to stimulate cancer stem cell-like properties in NB cells via the regulation of the STAT3/AKT axis.

Conclusion

IGF1R promotes cancer stem cell properties to facilitate EMT in neuroblastoma via the STAT3/AKT axis.

Dual-Specificity Phosphatases in Neuroblastoma Cell Growth and Differentiation

Dual-specificity phosphatases (DUSPs) are important regulators of neuronal cell growth and differentiation by targeting proteins essential to neuronal survival in signaling pathways, among which the MAP kinases (MAPKs) stand out. DUSPs include the MAPK phosphatases (MKPs), a family of enzymes that directly dephosphorylate MAPKs, as well as the small-size atypical DUSPs, a group of low molecular-weight enzymes which display more heterogeneous substrate specificity. Neuroblastoma (NB) is a malignancy intimately associated with the course of neuronal and neuroendocrine cell differentiation, and constitutes the source of more common extracranial solid pediatric tumors. Here, we review the current knowledge on the involvement of MKPs and small-size atypical DUSPs in NB cell growth and differentiation, and discuss the potential of DUSPs as predictive biomarkers and therapeutic targets in human NB.

Retinoic acid-induced survival effects in SH-SY5Y neuroblastoma cells

Neuroblastoma is a malignant childhood cancer arising from the embryonic sympathoadrenal lineage of the neural crest. Retinoic acid (RA) is included in the multimodal therapy of patients with high-risk neuroblastoma to eliminate minimal residual disease. However, the formation of RA-resistant cells substantially lowers 5-year overall survival rates. To examine mechanisms that lead to treatment failure, we chose human SH-SY5Y cells, which are known to tolerate incubation with RA by activating the survival kinases Akt and extracellular signal-regulated kinase 1/2. Characterization of downstream pathways showed that both kinases increased the phosphorylation of the ubiquitin ligase mouse double minute homolog 2 (Mdm2) and thereby enhanced p53 degradation. When p53 signaling was sustained by blocking complex formation with Mdm2 or enhancing c-Jun N-terminal kinase (JNK) activation, cell viability was significantly reduced. In addition, Akt-mediated phosphorylation of the cell-cycle regulator p21 stimulated complex formation with caspase-3, which also contributed to cell protection. Thus, treatment with RA augmented survival signaling and attenuated basal apoptotic pathways in SH-SY5Y cells, which increased cell viability.

Photo-Magnetic Irradiation-Mediated Multimodal Therapy of Neuroblastoma Cells Using a Cluster of Multifunctional Nanostructures

The use of high intensity chemo-radiotherapies has demonstrated only modest improvement in the treatment of high-risk neuroblastomas. Moreover, undesirable drug specific and radiation therapy-incurred side effects enhance the risk of developing into a second cancer at a later stage. In this study, a safer and alternative multimodal therapeutic strategy involving simultaneous optical and oscillating (AC, Alternating Current) magnetic field stimulation of a multifunctional nanocarrier system has successfully been implemented to guide neuroblastoma cell destruction. This novel technique permitted the use of low-intensity photo-magnetic irradiation and reduced the required nanoparticle dose level. The combination of released cisplatin from the nanodrug reservoirs and photo-magnetic coupled hyperthermia mediated cytotoxicity led to the complete ablation of the B35 neuroblastoma cells in culture. Our study suggests that smart nanostructure-based photo-magnetic hybrid irradiation is a viable approach to remotely guide neuroblastoma cell destruction, which may be adopted in clinical management post modification to treat aggressive cancers.

Synthetic high-density lipoprotein nanoconjugate targets neuroblastoma stem cells, blocking migration and self-renewal

BACKGROUND

Pathways critical for neuroblastoma cancer stem cell function are targeted by 4,19,27-triacetyl withalongolide A (WGA-TA). Because neuroblastoma cells and their cancer stem cells highly overexpress the scavenger receptor class B type 1 receptor that binds to synthetic high-density lipoprotein, we hypothesized that a novel mimetic synthetic high-density lipoprotein nanoparticle would be an ideal carrier for the delivery of 4,19,27-triacetyl withalongolide to neuroblastoma and neuroblastoma cancer stem cells.

METHODS

Expression of scavenger receptor class B type 1 in validated human neuroblastoma cells was evaluated by quantitative polymerase chain reaction (qPCR) and Western blot. In vitro cellular uptake of synthetic high-density lipoprotein nanoparticles was observed with a fluorescence microscope. In vivo biodistribution of synthetic high-density lipoprotein nanoparticles was investigated with IVIS imaging. Self-renewal and migration/invasion were assessed by sphere formation and Boyden chamber assays, respectively. Viability was analyzed by CellTiter-Glo assay. Cancer stem cell markers were evaluated by flow cytometry.

RESULTS

qPCR and Western blot analysis revealed a higher level of scavenger receptor class B type 1 expression and drug uptake in N-myc amplified neuroblastoma cells. In vitro uptake of synthetic high-density lipoprotein was almost completely blocked by excess synthetic high-density lipoprotein. The synthetic high-density lipoprotein nanoparticles mainly accumulated in the tumor and liver, but not in other organs. Synthetic HDL-4,19,27-triacetyl withalongolide showed a 1,000-fold higher potency than the carrier (synthetic high-density lipoprotein) alone (P < .01) to kill neuroblastoma cells. Additionally, a dose-dependent decrease in sphere formation, invasion, migration, and cancer stem cell markers was observed after treatment of neuroblastoma cells with synthetic high-density lipoprotein-4,19,27-triacetyl withalongolide A.

CONCLUSION

Synthetic high-density lipoprotein is a promising platform to improve the delivery of anticancer drug 4,19,27-triacetyl withalongolide A to neuroblastomas and neuroblastoma cancer stem cells through SR-B1 targeting in vitro and in vivo.

Assessment of citalopram and escitalopram on neuroblastoma cell lines. Cell toxicity and gene modulation

Selective serotonin reuptake inhibitors (SSRI) are common antidepressants which cytotoxicity has been assessed in cancers notably colorectal carcinomas and glioma cell lines. We assessed and compared the cytotoxicity of 2 SSRI, citalopram and escitalopram, on neuroblastoma cell lines. The study was performed on 2 non-MYCN amplified cell lines (rat B104 and human SH-SY5Y) and 2 human MYCN amplified cell lines (IMR32 and Kelly). Citalopram and escitalopram showed concentration-dependent cytotoxicity on all cell lines. Citalopram was more cytotoxic than escitalopram. IMR32 was the most sensitive cell line. The absence of toxicity on human primary Schwann cells demonstrated the safety of both molecules for myelin. The mechanisms of cytotoxicity were explored using gene-expression profiles and quantitative real-time PCR (qPCR). Citalopram modulated 1 502 genes and escitalopram 1 164 genes with a fold change ≥ 2. 1 021 genes were modulated by both citalopram and escitalopram; 481 genes were regulated only by citalopram while 143 genes were regulated only by escitalopram. Citalopram modulated 69 pathways (KEGG) and escitalopram 42. Ten pathways were differently modulated by citalopram and escitalopram. Citalopram drastically decreased the expression of MYBL2, BIRC5 and BARD1 poor prognosis factors of neuroblastoma with fold-changes of -107 (p<2.26 10⁻⁷), -24.1 (p<5.6 10⁻⁹) and -17.7 (p<1.2 10⁻⁷). CCNE1, AURKA, IGF2, MYCN and ERBB2 were more moderately down-regulated by both molecules. Glioma markers E2F1, DAPK1 and CCND1 were down-regulated. Citalopram displayed more powerful action with broader and distinct spectrum of action than escitalopram.

Surface marker profiling of SH-SY5Y cells enables small molecule screens identifying BMP4 as a modulator of neuroblastoma differentiation

Neuroblastoma is the most common extra-cranial solid tumor in children. Its broad spectrum of clinical outcomes reflects the underlying inherent cellular heterogeneity. As current treatments often do not lead to tumor eradication, there is a need to better define therapy-resistant neuroblastoma and to identify new modulatory molecules. To this end, we performed the first comprehensive flow cytometric characterization of surface molecule expression in neuroblastoma cell lines. Exploiting an established clustering algorithm (SPADE) for unbiased visualization of cellular subsets, we conducted a multiwell screen for small molecule modulators of neuroblastoma phenotype. In addition to SH-SY5Y cells, the SH-EP, BE(2)-M17 and Kelly lines were included in follow-up analysis as in vitro models of neuroblastoma. A combinatorial detection of glycoprotein epitopes (CD15, CD24, CD44, CD57, TrkA) and the chemokine receptor CXCR4 (CD184) enabled the quantitative identification of SPADE-defined clusters differentially responding to small molecules. Exposure to bone morphogenetic protein (BMP)-4 was found to enhance a TrkA^high/CD15⁻/CD184⁻ neuroblastoma cellular subset, accompanied by a reduction in doublecortin-positive neuroblasts and of NMYC protein expression in SH-SY5Y cells. Beyond yielding novel marker candidates for studying neuroblastoma pathology, our approach may provide tools for improved pharmacological screens towards developing novel avenues of neuroblastoma diagnosis and treatment.

The novel thiosemicarbazone, di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), inhibits neuroblastoma growth in vitro and in vivo via multiple mechanisms

Background

Neuroblastoma is a relatively common and highly belligerent childhood tumor with poor prognosis by current therapeutic approaches. A novel anti-cancer agent of the di-2-pyridylketone thiosemicarbazone series, namely di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), demonstrates promising anti-tumor activity. Recently, a second-generation analogue, namely di-2-pyridylketone 4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), has entered multi-center clinical trials for the treatment of advanced and resistant tumors. The current aim was to examine if these novel agents were effective against aggressive neuroblastoma in vitro and in vivo and to assess their mechanism of action.

Methods

Neuroblastoma cancer cells as well as immortalized normal cells were used to assess the efficacy and selectivity of DpC in vitro. An orthotopic SK-N-LP/Luciferase xenograft model was used in nude mice to assess the efficacy of DpC in vivo. Apoptosis in tumors was confirmed by Annexin V/PI flow cytometry and H&E staining.

Results

DpC demonstrated more potent cytotoxicity than Dp44mT against neuroblastoma cells in a dose- and time-dependent manner. DpC significantly increased levels of phosphorylated JNK, neuroglobin, cytoglobin, and cleaved caspase 3 and 9, while decreasing IkBα levels in vitro. The contribution of JNK, NF-ĸB, and caspase signaling/activity to the anti-tumor activity of DpC was verified by selective inhibitors of these pathways. After 3 weeks of treatment, tumor growth in mice was significantly (p < 0.05) reduced by DpC (4 mg/kg/day) given intravenously and the agent was well tolerated. Xenograft tissues showed significantly higher expression of neuroglobin, cytoglobin, caspase 3, and tumor necrosis factor-α (TNFα) levels and a slight decrease in interleukin-10 (IL-10).

Conclusions

DpC was found to be highly potent against neuroblastoma, demonstrating its potential as a novel therapeutic for this disease. The ability of DpC to increase TNFα in tumors could also promote the endogenous immune response to mediate enhanced cancer cell apoptosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0330-x) contains supplementary material, which is available to authorized users.

MicroRNA miR-93-5p regulates expression of IL-8 and VEGF in neuroblastoma SK-N-AS cells

The role of the microRNA miR-93-5p on the secretome profile and the expression levels of vascular endothelial growth factor (VEGF) and interleukin-8 (IL-8) was investigated in the neuroblastoma SK-N-AS cell line by Bio-Plex analysis and RT-qPCR. The results indicate that VEGF and IL-8 are the major miR-93-5p molecular targets. This conclusion was based on in vitro transfection with pre-miR-93-5p and anti-miR-93-5p; these treatments inversely modulated both VEGF and IL-8 gene expression and protein release in the neuroblastoma SK-N-AS cell line. Computational analysis showed the presence of miR-93-5p consensus sequences in the 3'UTR region of both VEGF and IL-8 mRNAs, predicting possible interaction with miR-93-5p and confirming a potential regulatory role of this microRNA.

Different inhibition of Gβγ-stimulated class IB phosphoinositide 3-kinase (PI3K) variants by a monoclonal antibody. Specific function of p101 as a Gβγ-dependent regulator of PI3Kγ enzymatic activity

Class IB phosphoinositide 3-kinases γ (PI3Kγ) are second-messenger-generating enzymes downstream of signalling cascades triggered by G-protein-coupled receptors (GPCRs). PI3Kγ variants have one catalytic p110γ subunit that can form two different heterodimers by binding to one of a pair of non-catalytic subunits, p87 or p101. Growing experimental data argue for a different regulation of p87-p110γ and p101-p110γ allowing integration into distinct signalling pathways. Pharmacological tools enabling distinct modulation of the two variants are missing. The ability of an anti-p110γ monoclonal antibody [mAb(A)p110γ] to block PI3Kγ enzymatic activity attracted us to characterize this tool in detail using purified proteins. In order to get insight into the antibody-p110γ interface, hydrogen-deuterium exchange coupled to MS (HDX-MS) measurements were performed demonstrating binding of the monoclonal antibody to the C2 domain in p110γ, which was accompanied by conformational changes in the helical domain harbouring the Gβγ-binding site. We then studied the modulation of phospholipid vesicles association of PI3Kγ by the antibody. p87-p110γ showed a significantly reduced Gβγ-mediated phospholipid recruitment as compared with p101-p110γ. Concomitantly, in the presence of mAb(A)p110γ, Gβγ did not bind to p87-p110γ. These data correlated with the ability of the antibody to block Gβγ-stimulated lipid kinase activity of p87-p110γ 30-fold more potently than p101-p110γ. Our data argue for differential regulatory functions of the non-catalytic subunits and a specific Gβγ-dependent regulation of p101 in PI3Kγ activation. In this scenario, we consider the antibody as a valuable tool to dissect the distinct roles of the two PI3Kγ variants downstream of GPCRs.

Safety of bevacizumab in patients younger than 4 years of age

PURPOSE

Limited data exist regarding the safety and efficacy of bevacizumab in pediatric patients under the age of 4 years. Here, we report a large cohort of pediatric patients under 4 years of age treated with bevacizumab.

METHODS

The primary objective was to document adverse events with a possible relationship to bevacizumab. Patients (n = 16) were identified through retrospective chart review and harbored a variety of conditions (44% central nervous system (CNS) tumors, 31% vascular anomalies, 13% neuroblastoma, 12% other).

RESULTS

The median age was 34.3 months (range 4.9-47.3), including five patients <2 years of age. Patients received bevacizumab for a median duration of 6.2 months, alone or with chemotherapy, and a median dose of 9.25 mg/kg (range 7.0-11.8). Partial responses were seen in 19% of patients, and clinical improvements were seen in 69%. Adverse events known to be associated with bevacizumab occurred in 37%. Outcomes observed in this population resemble those reported for bevacizumab in older pediatric patients. The overall pattern and frequency of adverse events observed was similar to those seen in reports of older pediatric patients with a variety of conditions. The highest level of efficacy observed was seen among patients with vascular malformations or with low-grade CNS tumors.

CONCLUSIONS

Our results suggest that the use of bevacizumab is safe for the youngest children.

The role of intracellular calcium for the development and treatment of neuroblastoma

Neuroblastoma is the second most common paediatric cancer. It developsfrom undifferentiated simpatico-adrenal lineage cells and is mostly sporadic; however, theaetiology behind the development of neuroblastoma is still not fully understood. Intracellularcalcium ([Ca2+]i) is a secondary messenger which regulates numerous cellular processesand, therefore, its concentration is tightly regulated. This review focuses on the role of[Ca2+]i in differentiation, apoptosis and proliferation in neuroblastoma. It describes themechanisms by which [Ca2+]i is regulated and how it modulates intracellular pathways.Furthermore, the importance of [Ca2+]i for the function of anti-cancer drugs is illuminatedin this review as [Ca2+]i could be a target to improve the outcome of anti-cancer treatmentin neuroblastoma. Overall, modulations of [Ca2+]i could be a key target to induce apoptosisin cancer cells leading to a more efficient and effective treatment of neuroblastoma.

A critical evaluation of PI3K inhibition in Glioblastoma and Neuroblastoma therapy

Members of the PI3K/Akt/mTor signaling cascade are among the most frequently altered proteins in cancer, yet the therapeutic application of pharmacological inhibitors of this signaling network, either as monotherapy or in combination therapy (CT) has so far not been particularly successful. In this review we will focus on the role of PI3K/Akt/mTOR in two distinct tumors, Glioblastoma multiforme (GBM), an adult brain tumor which frequently exhibits PTEN inactivation, and Neuroblastoma (NB), a childhood malignancy that affects the central nervous system and does not harbor any classic alterations in PI3K/Akt signaling. We will argue that inhibitors of PI3K/Akt signaling can be components for potentially promising new CTs in both tumor entities, but further understanding of the signal cascade's complexity is essential for successful implementation of these CTs. Importantly, failure to do this might lead to severe adverse effects, such as treatment failure and enhanced therapy resistance.

A critical evaluation of PI3K inhibition in Glioblastoma and Neuroblastoma therapy

Members of the PI3K/Akt/mTor signaling cascade are among the most frequently altered proteins in cancer, yet the therapeutic application of pharmacological inhibitors of this signaling network, either as monotherapy or in combination therapy (CT) has so far not been particularly successful. In this review we will focus on the role of PI3K/Akt/mTOR in two distinct tumors, Glioblastoma multiforme (GBM), an adult brain tumor which frequently exhibits PTEN inactivation, and Neuroblastoma (NB), a childhood malignancy that affects the central nervous system and does not harbor any classic alterations in PI3K/Akt signaling. We will argue that inhibitors of PI3K/Akt signaling can be components for potentially promising new CTs in both tumor entities, but further understanding of the signal cascade's complexity is essential for successful implementation of these CTs. Importantly, failure to do this might lead to severe adverse effects, such as treatment failure and enhanced therapy resistance.