Cell Proliferation in Neuroblastoma

Repurposing disulfiram, an alcohol-abuse drug, in neuroblastoma causes KAT2A downregulation and in vivo activity with a water/oil emulsion

Neuroblastoma, the most common type of pediatric extracranial solid tumor, causes 10% of childhood cancer deaths. Despite intensive multimodal treatment, the outcomes of high-risk neuroblastoma remain poor. We urgently need to develop new therapies with safe long-term toxicity profiles for rapid testing in clinical trials. Drug repurposing is a promising approach to meet these needs. Here, we investigated disulfiram, a safe and successful chronic alcoholism treatment with known anticancer and epigenetic effects. Disulfiram efficiently induced cell cycle arrest and decreased the viability of six human neuroblastoma cell lines at half-maximal inhibitory concentrations up to 20 times lower than its peak clinical plasma level in patients treated for chronic alcoholism. Disulfiram shifted neuroblastoma transcriptome, decreasing MYCN levels and activating neuronal differentiation. Consistently, disulfiram significantly reduced the protein level of lysine acetyltransferase 2A (KAT2A), drastically reducing acetylation of its target residues on histone H3. To investigate disulfiram's anticancer effects in an in vivo model of high-risk neuroblastoma, we developed a disulfiram-loaded emulsion to deliver the highly liposoluble drug. Treatment with the emulsion significantly delayed neuroblastoma progression in mice. These results identify KAT2A as a novel target of disulfiram, which directly impacts neuroblastoma epigenetics and is a promising candidate for repurposing to treat pediatric neuroblastoma.

Analysis of High-Risk Neuroblastoma Transcriptome Reveals Gene Co-Expression Signatures and Functional Features

Neuroblastoma represents a neoplastic expansion of neural crest cells in the developing sympathetic nervous system and is childhood's most common extracranial solid tumor. The heterogeneity of gene expression in different types of cancer is well-documented, and genetic features of neuroblastoma have been described by classification, development stage, malignancy, and progression of tumors. Here, we aim to analyze RNA sequencing datasets, publicly available in the GDC data portal, of neuroblastoma tumor samples from various patients and compare them with normal adrenal gland tissue from the GTEx data portal to elucidate the gene expression profile and regulation networks they share. Our results from the differential expression, weighted correlation network, and functional enrichment analyses that we performed with the count data from neuroblastoma and standard normal gland samples indicate that the analysis of transcriptome data from 58 patients diagnosed with high-risk neuroblastoma shares the expression pattern of 104 genes. More importantly, our analyses identify the co-expression relationship and the role of these genes in multiple biological processes and signaling pathways strongly associated with this disease phenotype. Our approach proposes a group of genes and their biological functions to be further investigated as essential molecules and possible therapeutic targets of neuroblastoma regardless of the etiology of individual tumors.

A light-operated dual-mode method for neuroblastoma diagnosis based on a Tb-MOF: from biometabolite detection to logic devices

Tb-DBA can not only serve as a light-operated dual-mechanism driven platform to detect VMA (an early pathological feature of neuroblastoma), but can also produce a different fluorescence response to epinephrine (EP, the metabolic precursor of VMA).

Brown adipocytes promote epithelial mesenchymal transition of neuroblastoma cells by inducing PPAR-γ/UCP2 expression

Neuroblastoma (NB) is an embryonic malignant tumour of the sympathetic nervous system, and current research shows that activation of brown adipose tissue accelerates cachexia in cancer patients. However, the interaction between brown adipose tissues and NB remains unclear. The study aimed to investigate the effect of brown adipocytes in the co-culture system on the proliferation and migration of NB cells. Brown adipocytes promoted the proliferation and migration of Neuro-2a, BE(2)-M17, and SH-SY5Y cells under the co-culture system, with an increase of the mRNA and protein levels of UCP2 and PPAR-γ in NB cells. The UCP2 inhibitor genipin or PPAR-γ inhibitor T0090709 inhibited the migration of NB cells induced by brown adipocytes. Genipin or siUCP2 upregulated the expression of E-cadherin, and downregulated the expression of N-cadherin and vimentin in NB cells. We suggest that under co-cultivation conditions, NB cells can activate brown adipocytes, which triggers changes in various genes and promotes the proliferation and migration of NB cells. The PPAR-γ/UCP2 pathway is involved in the migration of NB cells caused by brown adipocytes.

3D biocomposite culture enhances differentiation of dopamine-like neurons from SH-SY5Y cells: A model for studying Parkinson's disease phenotypes

Studies of underlying neurodegenerative processes in Parkinson's Disease (PD) have traditionally utilized cell cultures grown on two-dimensional (2D) surfaces. Biomimetic three-dimensional (3D) cell culture platforms have been developed to better emulate features of the brain's natural microenvironment. We here use our bioengineered brain-like tissue model, composed of a silk-hydrogel composite, to study the 3D microenvironment's contributions on the development and performance of dopaminergic-like neurons (DLNs). Compared with 2D culture, SH-SY5Y cells differentiated in 3D microenvironments were enriched for DLNs concomitant with a reduction in proliferative capacity during the neurodevelopmental process. Additionally, the 3D DLN cultures were more sensitive to oxidative stresses elicited by the PD-related neurotoxin 1-methyl-4-phenylpyridinium (MPP). MPP induced transcriptomic profile changes specific to 3D-differentiated DLN cultures, replicating the dysfunction of neuronal signaling pathways and mitochondrial dynamics implicated in PD. Overall, this physiologically-relevant 3D platform resembles a useful tool for studying dopamine neuron biology and interrogating molecular mechanisms underlying neurodegeneration in PD.

Protein Tyrosine Phosphatases in Neuroblastoma: Emerging Roles as Biomarkers and Therapeutic Targets

Neuroblastoma is a type of cancer intimately related with early development and differentiation of neuroendocrine cells, and constitutes one of the pediatric cancers with higher incidence and mortality. Protein tyrosine phosphatases (PTPs) are key regulators of cell growth and differentiation by their direct effect on tyrosine dephosphorylation of specific protein substrates, exerting major functions in the modulation of intracellular signaling during neuron development in response to external cues driving cell proliferation, survival, and differentiation. We review here the current knowledge on the role of PTPs in neuroblastoma cell growth, survival, and differentiation. The potential of PTPs as biomarkers and molecular targets for inhibition in neuroblastoma therapies is discussed.

Integrated Genomic Profiling and Drug Screening of Patient-Derived Cultures Identifies Individualized Copy Number-Dependent Susceptibilities Involving PI3K Pathway and 17q Genes in Neuroblastoma

Neuroblastoma is the commonest extracranial pediatric malignancy. With few recurrent single nucleotide variations (SNVs), mutation-based precision oncology approaches have limited utility, but its frequent and heterogenous copy number variations (CNVs) could represent genomic dependencies that may be exploited for personalized therapy. Patient-derived cell culture (PDC) models can facilitate rapid testing of multiple agents to determine such individualized drug-responses. Thus, to study the relationship between individual genomic aberrations and therapeutic susceptibilities, we integrated comprehensive genomic profiling of neuroblastoma tumors with drug screening of corresponding PDCs against 418 targeted inhibitors. We quantified the strength of association between copy number and cytotoxicity, and validated significantly correlated gene-drug pairs in public data and using machine learning models. Somatic mutations were infrequent (3.1 per case), but copy number losses in 1p (31%) and 11q (38%), and gains in 17q (69%) were prevalent. Critically, in-vitro cytotoxicity significantly correlated only with CNVs, but not SNVs. Among 1278 significantly correlated gene-drug pairs, copy number of GNA13 and DNA damage response genes CBL, DNMT3A, and PPM1D were most significantly correlated with cytotoxicity; the drugs most commonly associated with these genes were PI3K/mTOR inhibitor PIK-75, and CDK inhibitors P276-00, SNS-032, AT7519, flavopiridol and dinaciclib. Predictive Markov random field models constructed from CNVs alone recapitulated the true z-score-weighted associations, with the strongest gene-drug functional interactions in subnetworks involving PI3K and JAK-STAT pathways. Together, our data defined individualized dose-dependent relationships between copy number gains of PI3K and STAT family genes particularly on 17q and susceptibility to PI3K and cell cycle agents in neuroblastoma. Integration of genomic profiling and drug screening of patient-derived models of neuroblastoma can quantitatively define copy number-dependent sensitivities to targeted inhibitors, which can guide personalized therapy for such mutationally quiet cancers.

SNHG16 knockdown inhibits tumorigenicity of neuroblastoma in children via miR-15b-5p/PRPS1 axis

Neuroblastoma is an important problem in children. Long noncoding RNAs (lncRNAs) exhibit important roles in tumorigenicity of neuroblastoma. However, the role and mechanism of lncRNA small nucleolar RNA host gene 16 (SNHG16) in neuroblastoma tumorigenicity remain poorly understood. Forty-six neuroblastoma samples and 28 normal tissues were harvested. The levels of SNHG16, microRNA-15b-5p (miR-15b-5p), and phosphoribosyl pyrophosphate synthetase 1 (PRPS1) were detected via quantitative reverse transcription PCR or western blot. Cell proliferation as well as cycle distribution were measured via 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide or flow cytometry. Cell metastasis was investigated via epithelial-mesenchymal transition or transwell assay. The target relationship of miR-15b-5p and SNHG16 or PRPS1 was explored via starBase and dual-luciferase reporter assay. The role of SNHG16 in neuroblastoma in vivo was analyzed using a xenograft model. We found SNHG16 and PRPS1 levels were increased in neuroblastoma tissues and cells. SNHG16 knockdown inhibited cell proliferation, increased the cell cycle distribution at G0/G1 phase, and decreased the cells at S phase. SNHG16 overexpression caused an opposite effect. SNHG16 silence suppressed neuroblastoma cell metastasis. PRPS1 knockdown constrained cell proliferation and metastasis and regulated cell cycle distribution. miR-15b-5p was sponged by SNHG16 and directly targeted PRPS1. miR-15b-5p knockdown or PRPS1 overexpression mitigated the influence of SNHG16 silence on cell cycle, proliferation, and metastasis. SNHG16 knockdown reduced xenograft tumor growth. In conclusion, SNHG16 downregulation suppressed neuroblastoma tumorigenicity by regulating cell cycle, proliferation, and metastasis via miR-15b-5p/PRPS1 axis.

An overview of neuroblastoma cell lineage phenotypes and in vitro models

This review was conducted to present the main neuroblastoma (NB) clinical characteristics and the most common genetic alterations present in these pediatric tumors, highlighting their impact in tumor cell aggressiveness behavior, including metastatic development and treatment resistance, and patients' prognosis. The distinct three NB cell lineage phenotypes, S-type, N-type, and I-type, which are characterized by unique cell surface markers and gene expression patterns, are also reviewed. Finally, an overview of the most used NB cell lines currently available for in vitro studies and their unique cellular and molecular characteristics, which should be taken into account for the selection of the most appropriate model for NB pre-clinical studies, is presented. These valuable models can be complemented by the generation of NB reprogrammed tumor cells or organoids, derived directly from patients' tumor specimens, in the direction toward personalized medicine.

Autophagic flux inhibition enhances cytotoxicity of the receptor tyrosine kinase inhibitor ponatinib

Background

Despite reported advances, acquired resistance to tyrosine kinase inhibitors still represents a serious problem in successful cancer treatment. Among this class of drugs, ponatinib (PON) has been shown to have notable long-term efficacy, although its cytotoxicity might be hampered by autophagy. In this study, we examined the likelihood of PON resistance evolution in neuroblastoma and assessed the extent to which autophagy might provide survival advantages to tumor cells.

Methods

The effects of PON in inducing autophagy were determined both in vitro, using SK-N-BE(2), SH-SY5Y, and IMR-32 human neuroblastoma cell lines, and in vivo, using zebrafish and mouse models. Single and combined treatments with chloroquine (CQ)—a blocking agent of lysosomal metabolism and autophagic flux—and PON were conducted, and the effects on cell viability were determined using metabolic and immunohistochemical assays. The activation of the autophagic flux was analyzed through immunoblot and protein arrays, immunofluorescence, and transmission electron microscopy. Combination therapy with PON and CQ was tested in a clinically relevant neuroblastoma mouse model.

Results

Our results confirm that, in neuroblastoma cells and wild-type zebrafish embryos, PON induces the accumulation of autophagy vesicles—a sign of autophagy activation. Inhibition of autophagic flux by CQ restores the cytotoxic potential of PON, thus attributing to autophagy a cytoprotective nature. In mice, the use of CQ as adjuvant therapy significantly improves the anti-tumor effects obtained by PON, leading to ulterior reduction of tumor masses.

Conclusions

Together, these findings support the importance of autophagy monitoring in the treatment protocols that foresee PON administration, as this may predict drug resistance acquisition. The findings also establish the potential for combined use of CQ and PON, paving the way for their consideration in upcoming treatment protocols against neuroblastoma.

LncRNA DLX6-AS1 Promotes the Progression of Neuroblastoma by Activating STAT2 via Targeting miR-506-3p

Background

Neuroblastoma (NB) is a common malignant tumor of the sympathetic nervous system, mainly disturbing children. Long non-coding RNAs (lncRNAs) serving as promising cancer biomarkers have been well recognized. Our study intends to explore the functions of lncRNA X–inactive specific transcript (DLX6-AS1) in NB and provide a potential action mechanism.

Methods

The expression of DLX6-AS1, miR-506-3p and signal transducer and activator of transcription 2 (STAT2) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and colony formation assay. Cell cycle distribution was determined by flow cytometry assay. The protein level of cell cycle-related markers and STAT2 was detected by Western blot. Glycolysis progress was evaluated according to glucose consumption, lactate production and ATP level. The target genes were predicted by the online database Starbase3.0 and verified by dual-luciferase reporter assay.

Results

DLX6-AS1 expression was highly elevated in NB tissues and cells. DLX6-AS1 deficiency inhibited NB cell proliferation, cell cycle and glycolysis in vitro. MiR-506-3p was a target of DLX6-AS1, and miR-506-3p absence partly reversed the effects of DLX6-AS1 deficiency. Besides, STAT2 was targeted by miR-506-3p, and its expression was regulated by DLX6-AS1 through miR-506-3p. MiR-506-3p restoration also inhibited NB cell malignant behaviors, and STAT2 overexpression partially abolished the role of miR-506-3p restoration. Moreover, DLX6-AS1 deficiency weakened tumor growth in vivo.

Conclusion

DLX6-AS1 regulated cell proliferation, cell cycle and glycolysis in vitro and tumor growth in vivo to promote the development of NB by upregulating STAT2 via targeting miR-506-3p.

Hypoxia Predicts Poor Prognosis in Neuroblastoma Patients and Associates with Biological Mechanisms Involved in Telomerase Activation and Tumor Microenvironment Reprogramming

The biological and clinical heterogeneity of neuroblastoma (NB) demands novel biomarkers and therapeutic targets in order to drive the most appropriate treatment for each patient. Hypoxia is a condition of low-oxygen tension occurring in poorly vascularized tumor tissues. In this study, we aimed to assess the role of hypoxia in the pathogenesis of NB and at developing a new clinically relevant hypoxia-based predictor of outcome. We analyzed the gene expression profiles of 1882 untreated NB primary tumors collected at diagnosis and belonging to four existing data sets. Analyses took advantage of machine learning methods. We identified NB-hop, a seven-gene hypoxia biomarker, as a predictor of NB patient prognosis, which is able to discriminate between two populations of patients with unfavorable or favorable outcome on a molecular basis. NB-hop retained its prognostic value in a multivariate model adjusted for established risk factors and was able to additionally stratify clinically relevant groups of patients. Tumors with an unfavorable NB-hop expression showed a significant association with telomerase activation and a hypoxic, immunosuppressive, poorly differentiated, and apoptosis-resistant tumor microenvironment. NB-hop defines a new population of NB patients with hypoxic tumors and unfavorable prognosis and it represents a critical factor for the stratification and treatment of NB patients.

Ginsenoside Rg3 enhances the anticancer effect of 5‑FU in colon cancer cells via the PI3K/AKT pathway

Chemotherapy is one of the most commonly used treatments for patients with advanced colon cancer, yet the toxicity of chemotherapy agents, such as 5-fluorouracil (5-FU), limits the effectiveness of chemotherapy. Ginsenoside Rg3 (Rg3) is an active ingredient isolated from ginseng. Rg3 has been shown to display anticancer effects on a variety of malignancies. Yet, whether Rg3 synergizes the effect of 5-FU to inhibit the growth of human colon cancer remains unknown. The present study was designed to ascertain whether Rg3 is able to enhance the anti-colon cancer effect of 5-FU. The results revealed that combined treatment of Rg3 and 5-FU significantly enhanced the inhibition of the proliferation, colony formation, invasion and migration of human colon cancer cells (SW620 and LOVO) in vitro. We also found that combined treatment of Rg3 and 5-FU significantly enhanced the apoptosis of colon cancer cells by activating the Apaf1/caspase 9/caspase 3 pathway and arrested the cell cycle of the colon cancer cells in G0/G1 by promoting the expression of Cyclin D1, CDK2 and CDK4. In addition, the PI3K/AKT signaling pathway in colon cancer cells was suppressed by Rg3 and 5-FU. In vivo, Rg3 synergized the effect of 5-FU to inhibit the growth of human colon cancer xenografts in nude mice. Similarly, combined treatment of Rg3 and 5-FU altered the expression of colon cancer protein in vivo and in vitro. Collectively, the present study demonstrated that ginsenoside Rg3 enhances the anticancer effect of 5-FU in colon cancer cells via the PI3K/AKT pathway.

Neuroblastoma-targeted nanoparticles and novel nanotechnology-based treatment methods

Neuroblastoma is a complicated pediatric tumor, originating from the neural crest, which is the most prevalent in adrenal glands, but may rarely be seen in some other tissues as well. Studies are focused on developing new strategies through novel chemo- and immuno-therapeutic drug targets. Different types of oncogenes such as MYCN, tumor suppressor genes such as p53, and some structural genes such as vascular endothelial growth factor are considered as targets for neuroblastoma therapy. The individual expression patterns in NB cells make them appropriate for this purpose. The combined effect of nano-drug delivery systems and specific drug targets will result in lower systemic side effects, prolonged therapeutic effects, and improvements in the pharmacokinetic properties of the drugs. Some of these novel drug delivery systems with a focus on liposomes as carriers are also discussed. In this review, genes and protein products that are beneficial as drug targets in the treatment of neuroblastoma have been discussed.

Growth and neurite stimulating effects of the neonicotinoid pesticide clothianidin on human neuroblastoma SH-SY5Y cells

Neonicotinoids are one of most widely used pesticides targeting nicotinic acetylcholine receptors (nAChRs) of insects. Recent epidemiological evidence revealed increasing amounts of neonicotinoids detected in human samples, raising the critical question of whether neonicotinoids affect human health. We investigated the effects of a neonicotinoid pesticide clothianidin (CTD) on human neuroblastoma SH-SY5Y cells as in vitro models of human neuronal cells. Cellular and functional effects of micromolar doses of CTD were evaluated by changes in cell growth, intracellular signaling activities and gene expression profiles. We examined further the effects of CTD on neuronal differentiation by measuring neurite outgrowth. Exposure to CTD (1-100 μM) significantly increased the number of cells within 24 h of culture. The nAChRs antagonists, mecamylamine and SR16584, inhibited this effect, suggesting human α3β4 nAChRs could be targets of neonicotinoids. We observed a transient intracellular calcium influx and increased phosphorylation of extracellular signal-regulated kinase 1/2 shortly after exposure to CTD. Transcriptome analysis revealed that CTD down-regulated genes involved in neuronal function (e.g., formation of filopodia and calcium ion influx) and morphology (e.g., axon guidance signaling and cytoskeleton signaling); these changes were reflected by a finding of increased neurite length during neuronal differentiation. These findings provide novel insight into the potential risks of neonicotinoids to the human nervous system.

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.

Identification of Potential Prognostic Genes for Neuroblastoma

Background and Objective: Neuroblastoma (NB), the most common pediatric solid tumor apart from brain tumor, is associated with dismal long-term survival. The aim of this study was to identify a gene signature to predict the prognosis of NB patients.

Materials and Methods: GSE49710 dataset from the Gene Expression Omnibus (GEO) database was downloaded and differentially expressed genes (DEGs) were analyzed using R package “limma” and SPSS software. The gene ontology (GO) and pathway enrichment analysis were established via DAVID database. Random forest (RF) and risk score model were used to pick out the gene signature in predicting the prognosis of NB patients. Simultaneously, the receiving operating characteristic (ROC) and Kaplan-Meier curve were plotted. GSE45480 and GSE16476 datasets were employed to validate the robustness of the gene signature.

Results: A total of 131 DEGs were identified, which were mainly enriched in cancer-related pathways. Four genes (ERCC6L, AHCY, STK33, and NCAN) were selected as a gene signature, which was included in the top six important features in RF model, to predict the prognosis in NB patients, its area under the curve (AUC) could reach 0.86, and Cox regression analysis revealed that the 4-gene signature was an independent prognostic factor of overall survival and event-free survival. As well as in GSE16476. Additionally, the robustness of discriminating different groups of the 4-gene signature was verified to have a commendable performance in GSE45480 and GSE49710.

Conclusion: The present study identified a gene-signature in predicting the prognosis in NB, which may provide novel prognostic markers, and some of the genes may be as treatment targets according to biological experiments in the future.

S-trityl-L-cysteine, a novel Eg5 inhibitor, is a potent chemotherapeutic strategy in neuroblastoma

Eg5 is a member of the kinesin-5 family. It is involved in the formation of the bipolar spindle and serves a crucial role in mitosis; meaning that mitotic activation may serve as a chemotherapeutic strategy. However, the anticancer activity of Eg5 inhibitors in neuroblastoma remains uncharacterized. In the present study, the expression of Eg5 was examined in clinical tissue samples and neuroblastoma cell lines, SK-N-SH, SH-SY5Y and SK-N-BE2. Additionally, the antitumor activity of the Eg5 inhibitor, S-trityl-L-cysteine (STLC), was confirmed in vitro. STLC could mediate cell apoptosis, as well as cell cycle arrest, in a dose-dependent manner, which may contribute toward its antitumor activity. STLC-mediated apoptosis and cell cycle arrest were triggered by activation of the mitogen-activated protein kinase and nuclear factor kB signaling pathways. These results suggested that STLC may have potential in the in vivo treatment of neuroblastoma.

Tumorigenic proteins upregulated in the MYCN-amplified IMR-32 human neuroblastoma cells promote proliferation and migration

Childhood neuroblastoma is one of the most common types of extra-cranial cancer affecting children with a clinical spectrum ranging from spontaneous regression to malignant and fatal progression. In order to improve the clinical outcomes of children with high-risk neuroblastoma, it is crucial to understand the tumorigenic mechanisms that govern its malignant behaviors. MYCN proto-oncogene, bHLH transcription factor (MYCN) amplification has been implicated in the malignant, treatment-evasive nature of aggressive, high-risk neuroblastoma. In this study, we used a SILAC approach to compare the proteomic signatures of MYCN-amplified IMR-32 and non-MYCN-amplified SK-N-SH human neuroblastoma cells. Tumorigenic proteins, including fatty-acid binding protein 5 (FABP5), L1-cell adhesion molecule (L1-CAM), baculoviral IAP repeat containing 5 [BIRC5 (survivin)] and high mobility group protein A1 (HMGA1) were found to be significantly upregulated in the IMR-32 compared to the SK-N-SH cells and mapped to highly tumorigenic pathways including, MYC, MYCN, microtubule associated protein Tau (MAPT), E2F transcription factor 1 (E2F1), sterol regulatory element binding transcription factor 1 or 2 (SREBF1/2), hypoxia-inducible factor 1α (HIF-1α), Sp1 transcription factor (SP1) and amyloid precursor protein (APP). The transcriptional knockdown (KD) of MYCN, HMGA1, FABP5 and L1-CAM significantly abrogated the proliferation of the IMR-32 cells at 48 h post transfection. The early apoptotic rates were significantly higher in the IMR-32 cells in which FABP5 and MYCN were knocked down, whereas cellular migration was significantly abrogated with FABP5 and HMGA1 KD compared to the controls. Of note, L1-CAM, HMGA1 and FABP5 KD concomitantly downregulated MYCN protein expression and MYCN KD concomitantly downregulated L1-CAM, HMGA1 and FABP5 protein expression, while survivin protein expression was significantly downregulated by MYCN, HMGA1 and FABP5 KD. In addition, combined L1-CAM and FABP5 KD led to the concomitant downregulation of HMGA1 protein expression. On the whole, our data indicate that this inter-play between MYCN and the highly tumorigenic proteins which are upregulated in the malignant IMR-32 cells may be fueling their aggressive behavior, thereby signifying the importance of combination, multi-modality targeted therapy to eradicate this deadly childhood cancer.

A novel αVβ3 ligand-modified HPMA copolymers for anticancer drug delivery

The integrin α_Vβ₃ receptor emerged as one of the most promising targets owing to its high expression on the surface of various malignant tumour cells and tumour angiogenesis endothelial cells, but with little expression in mature endothelial cells and the majority of normal cells. Here, we report a new targeting ligand FQSIYPpIK (FQS) with high affinity to integrin α_Vβ₃ receptor. To take the advantage of the particular interaction between FQS and integrin α_Vβ₃ receptor, FQS was linked to N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers. A model drug doxorubicin (DOX) was simultaneously conjugated to the same HPMA copolymers via pH-sensitive hydrazone linkages (FQS-HPMA-DOX). In in vitro study, FQS-HPMA-DOX could be internalised into α_Vβ₃ receptor-overexpressed B16F10 cells via a highly specific ligand - receptor pathway (5.0 times and 4.5 times higher cellular internalisation than HPMA-DOX and a scrambled peptide (s)-FQS (sequence: SYFIPKQIp)-modified copolymers ((s)-FQS-HPMA-DOX)). It is worth noting that compared with the classical α_Vβ₃ ligand cRGDfK-modified HPMA copolymers (cRGDfK-HPMA-DOX), FQS-HPMA-DOX also showed superior targeting efficiency. In in vivo study in the B16F10 melanoma bearing mice model showed the antitumour efficiency of FQS-HPMA-DOX (83.9%) were significantly higher than HPMA-DOX (44.9%) and cRGDfK-HPMA-DOX (77.5%). These results suggest that FQS peptide can act as an effective targeting ligand for the delivery of therapeutic agents.

Didymin: an orally active citrus flavonoid for targeting neuroblastoma

Neuroblastoma, a rapidly growing yet treatment responsive cancer, is the third most common cancer of children and the most common solid tumor in infants. Unfortunately, neuroblastoma that has lost p53 function often has a highly treatment-resistant phenotype leading to tragic outcomes. In the context of neuroblastoma, the functions of p53 and MYCN (which is amplified in ~25% of neuroblastomas) are integrally linked because they are mutually transcriptionally regulated, and because they together regulate the catalytic activity of RNA polymerases. Didymin is a citrus-derived natural compound that kills p53 wild-type as well as drug-resistant p53-mutant neuroblastoma cells in culture. In addition, orally administered didymin causes regression of neuroblastoma xenografts in mouse models, without toxicity to non-malignant cells, neural tissues, or neural stem cells. RKIP is a Raf-inhibitory protein that regulates MYCN activation, is transcriptionally upregulated by didymin, and appears to play a key role in the anti-neuroblastoma actions of didymin. In this review, we discuss how didymin overcomes drug-resistance in p53-mutant neuroblastoma through RKIP-mediated inhibition of MYCN and its effects on GRK2, PKCs, Let-7 micro-RNA, and clathrin-dependent endocytosis by Raf-dependent and -independent mechanisms. In addition, we will discuss studies supporting potential clinical impact and translation of didymin as a low cost, safe, and effective oral agent that could change the current treatment paradigm for refractory neuroblastoma.

miR-1303 promotes the proliferation of neuroblastoma cell SH-SY5Y by targeting GSK3β and SFRP1

Neuroblastoma (NB) is one of the most common solid tumors in children, many microRNAs regulate progression and development of NB. Here, we found miR-1303 was upregulated in NB cells and tissues, miR-1303 overexpression promoted the proliferation of SH-SY5Y NB cell investigated by MTT assay, colony formation assay and anchorage-independent growth ability assay, while miR-1303 knockdown reduced this effect. mechanism analysis suggested glycogen synthase kinase 3 beta (GSK3β) and secreted frizzled-related protein 1 (SFRP1) were the target of miR-1303, luciferase assay revealed miR-1303 directly bound to the 3'UTR of GSK3β and SFRP1. miR-1303 increased expression of MYC and CyclinD1, and decreased the expression of p21 and p27, and further demonstrated miR-1303 promotes NB proliferation. Moreover, there was a negative correlation between miR-1303 expression and GSK3β and SFRP1 expression in NB tissues, confirming GSK3β and SFRP1 were the targets of miR-1303 in NB tissues. Collectively, our findings suggested miR-1303 promotes NB proliferation by targeting GSK3β and SFRP1, and might be a target for NB therapy.

L1-CAM knock-down radiosensitizes neuroblastoma IMR-32 cells by simultaneously decreasing MycN, but increasing PTEN protein expression

Childhood neuroblastoma is one of the most malignant types of cancers leading to a high mortality rate. These cancerous cells can be highly metastatic and malignant giving rise to disease recurrence and poor prognosis. The proto-oncogene myelocytomatosis neuroblastoma (MycN) is known to be amplified in this type of cancer, thus, promoting high malignancy and resistance. The L1 cell adhesion molecule (L1-CAM) cleavage has been found upregulated in many types of malignant cancers. In the present study, we explored the interplay between L1-CAM, MycN and PTEN as well as the role played by PDGFR and VEGFR on tumorigenicity in neuroblastoma cells. We investigated the effect of L1-CAM knock-down (KD) and PDGFR/VEGFR inhibition with sunitinib malate (Sutent®) treatment on subsequent tumorsphere formation and cellular proliferation and migration in the MycN-amplified IMR-32 neuroblastoma cells. We further examined the effect of combined L1-CAM KD with Sutent treatment or radiotherapy on these cellular functions in our cells. Tumorsphere formation is one of the indicators of aggressiveness in malignant cancers, which was significantly inhibited in IMR-32 cells after L1-CAM KD or Sutent treatment, however, no synergistic effect was observed with dual treatments, rather L1-CAM KD alone showed a greater inhibition on tumorsphere formation compared to Sutent treatment alone. In addition, cellular proliferation and migration were significantly inhibited after L1-CAM KD in the IMR-32 cells with no synergistic effect observed on the rate of cell proliferation when combined with Sutent treatment. Again, L1-CAM KD alone exhibited greater inhibitory effect than Sutent treatment on cell proliferation. L1-CAM KD led to the simultaneous downregulation of MycN, but the upregulation of PTEN protein expression. Notably, radiotherapy (2 Gy) of the IMR-32 cells led to significant upregulation of both L1-CAM and MycN, which was abrogated with L1-CAM KD in our cells. In addition, L1-CAM KD radiosensitized the cells as exhibited by the synergistic effect on the reduction in cell proliferation compared to radiotherapy alone. Taken together, our data show the importance of L1-CAM interplay with MycN and PTEN on the MycN amplified neuroblastoma cell radioresistance, proliferation and motility.