Copy Number Analysis Reveal Genetic Risks of Penile Cancer

Objectives

To evaluate copy number alterations (CNAs) in genes associated with penile cancer (PeC) and determine their correlation and prognostic ability with PeC.

Methods

Whole-exome sequencing was performed for tumor tissue and matched normal DNA of 35 patients diagnosed with penile squamous cell carcinoma from 2011 to 2016. Somatic CNAs were detected using the Genome Analysis Toolkit (GATK). Retrospective clinical data were collected and analyzed. All the data were statistically analyzed using SPSS 16.0 software. The cancer-specific survival rates were estimated by Kaplan-Meier curves and compared with the log-rank test.

Results

CNAs in the MYCN gene was detected in 19 (amplification: 54.29%) patients. Other CNAs gene targets were FAK (amplification: 45.72%, deletion: 8.57%), TP53 (amplification: 2.86%, deletion: 51.43%), TRKA (amplification: 34.29%, deletion: 2.86%), p75NTR (amplification: 5.71%, deletion: 42.86%), Miz-1 (amplification: 14.29%, deletion: 20.00%), Max (amplification: 17.14%, deletion: 2.86%), Bmi1 (amplification:14.29%, deletion: 48.57%), and MDM2 (amplification: 5.71%, deletion: 45.72%). The CNAs in MYCN and FAK correlated significantly with patient prognosis (P<0.05). The 3-year Recurrence-free survival rate was 87.10% among patients followed up. The 5-year survival rate of patients with MYCN amplification was 69.2%, compared to 94.4% in the non-amplification group. The 5-year survival rate of patients with FAK amplification was 65.6%, compared to 94.7% in the non-amplification group. The PPI network showed that TP53 and MYCN might play meaningful functional roles in PeC.

Conclusion

MYCN and FAK amplification and TP53 deletion were apparent in PeC. MYCN and TP53 were hub genes in PeC. MYCN and FAK amplification was also detected and analyzed, and the findings indicated that these two genes are predictors of poor prognosis in PeC.

Occurrence of Esophageal Atresia With Tracheoesophageal Fistula in Siblings From Three-Generation Family Affected by Variable Expressivity MYCN Mutation: A Case Report

The MYCN oncogene encodes a transcription factor belonging to the MYC family. It is primarily expressed in normal developing embryos and is thought to be critical in brain and other neural development. Loss-of-function variants resulting in haploinsufficiency of MYCN, which encodes a protein with a basic helix-loop-helix domain causes Feingold syndrome (OMIM 164280, ORPHA 391641). We present an occurrence of esophageal atresia (EA) with tracheoesophageal fistula in siblings from a three-generation family affected by variable expressivity of MYCN mutation p.(Ser90GlnfsTer176) as a diagnostic effect of searching the cause of familial esophageal atresia using NGS-based whole-exome sequencing (WES). All of our affected patients showed microcephaly and toe syndactyly, which were frequently reported in the literature. Just one patient exhibited clinodactyly. None of the patients exhibited brachymesophalangy or hypoplastic thumbs. The latest report noted that patients with EA and Feingold syndrome were also those with the more complex and severe phenotype. However, following a thorough review of the present literature, the same association was not found, which is also confirmed by the case we described. The variable phenotypic expression of the patients we described and the data from the literature guide a careful differential diagnosis of Feingold syndrome even in cases of poorly expressed and non-specific symptoms.

Cell-Based Methods for the Identification of Myc-Inhibitory Small Molecules

Oncoproteins encoded by dominant oncogenes have long been considered as targets for chemotherapeutic intervention. However, oncogenic transcription factors have often been dismissed as "undruggable." Members of the Myc family of transcription factors have been identified as promising targets for cancer chemotherapy in multiple publications reporting the requirement of Myc proteins for maintenance of almost every type of tumor. Here, we describe cell-based approaches to identify c-Myc small molecule inhibitors by screening complex libraries of diverse small molecules based on Myc functionality and specificity.

Identification of MYCN-Related Gene as a Potential Biomarker for Neuroblastoma Prognostic Model by Integrated Analysis and Quantitative Real-Time PCR

Neuroblastoma (NB) has the highest incidence of all extracranial solid tumors in children and is highly lethal. This study aims to establish a prognostic model of NB with MYCN-related genes. We determined the gene expression profiles of 900 NB samples from the UCSC database and four Gene Expression Omnibus (GEO) data sets, and performed a comprehensive bioinformatics analysis and clinical sample verification. After univariate Cox regression, least absolute shrinkage and selection operator (Lasso), and multivariate Cox regression analyses, four (AKR1C1, CHD5, PDE4DIP, and PRKACB) genes were finally selected and used to construct a risk score prognostic model. In the UCSC data set, the high-risk group exhibited a significantly worse prognosis than the low-risk group. In addition, the nomogram, which includes prognostic markers and clinical factors, demonstrates high prognostic value. Finally, the differential expression of the four genes in the model was verified by quantitative real-time PCR in clinical tissues. These findings of MYCN-related genes provide a new and reliable prognostic model for NB related to MYCN.

Growth inhibition and suppression of the mTOR and Wnt/β-catenin pathways in T-acute lymphoblastic leukemia by rapamycin and MYCN depletion

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy. Understanding of the molecular pathogenesis may lead to novel therapeutic targets. Rapamycin, the mammalian target of rapamycin (mTOR) inhibitor, showed inhibitory effects on T-ALL cells. In this study, we showed that rapamycin significantly reduced MYCN mRNA and protein in a concentration-dependent manner in T-ALL cells. Selective knockdown of MYCN by small interfering RNA had similar effects to rapamycin to inhibit T-ALL proliferation and colony formation and to induce G1-phase cell-cycle arrest and apoptosis. The inhibitory effects of rapamycin and MYCN depletion were also found in a Molt-4 xenograft model. Rapamycin and MYCN inhibition suppressed both Wnt/β-catenin and mTOR signaling pathways. The results suggest the effects of rapamycin on adult T-ALL is likely mediated by downregulation of MYCN. The findings suggest MYCN a potential target for the treatment of adult T-ALL. Additionally, dual targeting of mTOR and Wnt/β-catenin pathways may represent a novel strategy in the treatment of adult T-ALL.

Reciprocal Induction of MDM2 and MYCN in Neural and Neuroendocrine Cancers

MYC family oncoproteins MYC, MYCN, and MYCL are deregulated in diverse cancers and via diverse mechanisms. Recent studies established a novel form of MYCN regulation in MYCN-overexpressing retinoblastoma and neuroblastoma cells in which the MDM2 oncoprotein promotes MYCN translation and MYCN-dependent proliferation via a p53-independent mechanism. However, it is unclear if MDM2 also promotes expression of other MYC family members and has similar effects in other cancers. Conversely, MYCN has been shown to induce MDM2 expression in neuroblastoma cells, yet it is unclear if MYC shares this ability, if MYC family proteins upregulate MDM2 in other malignancies, and if this regulation occurs during tumorigenesis as well as in cancer cell lines. Here, we report that intrinsically high MDM2 expression is required for high-level expression of MYCN, but not for expression of MYC, in retinoblastoma, neuroblastoma, small cell lung cancer, and medulloblastoma cells. Conversely, ectopic overexpression of MYC as well as MYCN induced high-level MDM2 expression and gave rise to rapidly proliferating and MDM2-dependent cone-precursor-derived masses in a cultured retinoblastoma genesis model. These findings reveal a highly specific collaboration between the MDM2 and MYCN oncoproteins and demonstrate the origin of their oncogenic positive feedback circuit within a normal neuronal tissue.

The glycosphingolipid GD2 as an effective but enigmatic target of passive immunotherapy in children with aggressive neuroblastoma (HR-NBL)

Neuroblastoma (NBL), the most frequent and lethal pediatric cancer of children in pre-school age, is considered enigmatic in view of its extreme heterogeneity, from spontaneous regression in the IV-S form to incurable disease in approx. 40% of cases (High Risk, HR-NBL). It has an embryonal origin and a very heterogeneous genomic landscape, hampering the success of targeted strategies. The glycosphingolipid GD2 was shown to be expressed on NBL cells and utilized as target for passive immunotherapy with anti-GD2 antibodies (GD2-IMT). An international protocol was established with GD2-IMT, which increases remission length and survival in HR-NBL. By reviewing the different biological and molecular aspects of NBL and GD2-IMT, this mini-review questions the present lack of association between GD2-IMT and the underlying molecular landscape. The alternative model of Micro-Foci inducing virus (MFV) is presented, since MFV infection can induce extensive genomic aberrations (100X NMYC DNA-amplification). Since this family of viruses uses molecules for cell penetration similar to GD2 (i.e., GM2), it is hypothesized that GD2 is the port-of-entry for MFV and that success of anti-GD2 therapies is also associated to inhibition of this clastogenic virus in HR-NBL.

PROTAC Bromodomain Inhibitor ARV-825 Displays Anti-Tumor Activity in Neuroblastoma by Repressing Expression of MYCN or c-Myc

Neuroblastoma (NB) is one of the most common solid tumors in childhood. To date, targeting MYCN, a well-established driver gene in high-risk neuroblastoma, is still challenging. In recent years, inhibition of bromodomain and extra terminal (BET) proteins shows great potential in multiple of Myc-driven tumors. ARV-825 is a novel BET inhibitor using proteolysis-targeting chimera (PROTAC) technology which degrades target proteins by the proteasome. In this study, we investigated the effect of ARV-825 in neuroblastoma in vitro and in vivo. Our results showed that ARV-825 treatment robustly induced proliferative suppression, cell cycle arrest, and apoptosis in NB cells. Moreover, ARV-825 efficiently depleted BET protein expression, subsequently repressing the expression of MYCN or c-Myc. In the NB xenograft model, ARV-825 profoundly reduced tumor growth and led to the downregulation of BRD4 and MYCN expression in mice. Taken together, these findings provide evidence that PROTAC BET inhibitor is an efficient way to achieve MYCN/c-Myc manipulation, and ARV-825 can be used as a potential therapeutic strategy for the treatment of neuroblastoma.

Identification of VRK1 as a New Neuroblastoma Tumor Progression Marker Regulating Cell Proliferation

Neuroblastoma (NB) is one of the most common pediatric cancers and presents a poor survival rate in affected children. Current pretreatment risk assessment relies on a few known molecular parameters, like the amplification of the oncogene MYCN. However, a better molecular knowledge about the aggressive progression of the disease is needed to provide new therapeutical targets and prognostic markers and to improve patients' outcomes. The human protein kinase VRK1 phosphorylates various signaling molecules and transcription factors to regulate cell cycle progression and other processes in physiological and pathological situations. Using neuroblastoma tumor expression data, tissue microarrays from fresh human samples and patient-derived xenografts (PDXs), we have determined that VRK1 kinase expression stratifies patients according to tumor aggressiveness and survival, allowing the identification of patients with worse outcome among intermediate risk. VRK1 associates with cell cycle signaling pathways in NB and its downregulation abrogates cell proliferation in vitro and in vivo. Through the analysis of ChIP-seq and methylation data from NB tumors, we show that VRK1 is a MYCN gene target, however VRK1 correlates with NB aggressiveness independently of MYCN gene amplification, synergizing with the oncogene to drive NB progression. Our study also suggests that VRK1 inhibition may constitute a novel cell-cycle-targeted strategy for anticancer therapy in neuroblastoma.

The Role of MYCN in Symmetric vs. Asymmetric Cell Division of Human Neuroblastoma Cells

Asymmetric cell division (ACD) is an important physiological event in the development of various organisms and maintenance of tissue homeostasis. ACD produces two different cells in a single cell division: a stem/progenitor cell and differentiated cell. Although the balance between self-renewal and differentiation is precisely controlled, disruptions to ACD and/or enhancements in the self-renewal division (symmetric cell division: SCD) of stem cells resulted in the formation of tumors in Drosophila neuroblasts. ACD is now regarded as one of the characteristics of human cancer stem cells, and is a driving force for cancer cell heterogeneity. We recently reported that MYCN controls the balance between SCD and ACD in human neuroblastoma cells. In this mini-review, we discuss the mechanisms underlying MYCN-mediated cell division fate.

The Tumor Microenvironment in Neuroblastoma: New Players, New Mechanisms of Interaction and New Perspectives

The contribution of the tumor microenvironment (TME) to cancer progression has been well recognized in recent decades. As cancer therapeutic strategies are increasingly precise and include immunotherapies, knowledge of the nature and function of the TME in a tumor becomes essential. Our understanding of the TME in neuroblastoma (NB), the second most common solid tumor in children, has significantly progressed from an initial focus on its Schwannian component to a better awareness of its complex nature, which includes not only immune but also non-immune cells such as cancer-associated fibroblasts (CAFs), the contribution of which to inflammation and interaction with tumor-associated macrophages (TAMs) is now recognized. Recent studies on the TME landscape of NB tumors also suggest significant differences between MYCN-amplified (MYCN-A) and non-amplified (MYCN-NA) tumors, in their content in stromal and inflammatory cells and their immunosuppressive activity. Extracellular vesicles (EVs) released by cells in the TME and microRNAs (miRs) present in their cargo could play important roles in the communication between NB cells and the TME. This review article discusses these new aspects of the TME in NB and the impact that information on the TME landscape in NB will have in the design of precise, biomarker-integrated clinical trials.

The MDM2 inhibitor CGM097 combined with the BET inhibitor OTX015 induces cell death and inhibits tumor growth in models of neuroblastoma

Background

Neuroblastoma (NB) is the most common extracranial solid tumor in infants and children, with amplification of the oncogene MYCN being a hallmark of high‐risk disease and poor prognosis. Although less frequent, overexpression of MYC is similarly an indicator of poor prognosis. Most NB tumors initially respond to chemotherapy, however, most will relapse, resulting in chemoresistant disease. After relapse, there is growing evidence of p53 inactivation. MYC/MYCN and MDM2 have been shown to interact and contribute to NB growth and disease progression. MDM2 inhibitors and Bromodomain and Extra‐Terminal domain (BET) inhibitors have both shown promise in treating NB by increasing the expression of p53 and decreasing MYC/MYCN expression, respectively. Our study focuses on the combined treatment of a MDM2 inhibitor (CGM097) with a BET inhibitor (OTX015) in neuroblastoma.

Methods

Two p53 wild‐type and two p53 mutant established neuroblastoma cells lines were used to test this combination. Ray design assays were used to test whether this combination was synergistically cytotoxic to NB cells. Western blots were performed to check signaling pathways of interest after drug treatment. IncuCyte imaging and flow cytometry were utilized to quantify the apoptotic and cytostatic effects of these drugs on NB cells. In vivo studies were carried out to test the antitumor effect of this combination in a living host.

Results

The combination of CGM097 and OTX015 resulted in p53 activation, decreased expression of MYC family proteins and a subsequent synergistic increase in NB cell death.

Conclusion

This study warrants further investigation into the combination of MDM2 inhibitors and BET inhibitors for the treatment in NB.

New Prognostic Indicators in Pediatric Adrenal Tumors: Neuroblastoma and Adrenal Cortical Tumors, Can We Predict When These Will Behave Badly?

Pediatric adrenal tumors are unique entities with specific diagnostic, prognostic, and therapeutic challenges. The adrenal medulla gives rise to peripheral neuroblastic tumors (pNTs), pathologically defined by their architecture, stromal content, degree of differentiation, and mitotic-karyorrhectic index. Successful risk stratification of pNTs uses patient age, stage, tumor histology, and molecular/genetic aberrations. The adrenal cortex gives rise to adrenocortical tumors (ACTs), which present diagnostic and prognostic challenges. Histologic features that signify poor prognosis in adults can be meaningless in children, who have superior outcomes. The key clinical, pathologic, and molecular findings of pediatric ACTs have yet to be completely identified.

Genetic variation associated with childhood and adult stature and risk of MYCN-amplified neuroblastoma

Background

Neuroblastoma is the most common pediatric solid tumor. MYCN‐amplification is an important negative prognostic indicator and inherited genetic contributions to risk are incompletely understood. Genetic determinants of stature increase risk of several adult and childhood cancers, but have not been studied in neuroblastoma despite elevated neuroblastoma incidence in children with congenital overgrowth syndromes.

Methods

We investigated the association between genetic determinants of height and neuroblastoma risk in 1538 neuroblastoma cases, stratified by MYCN‐amplification status, and compared to 3390 European‐ancestry controls using polygenic scores for birth length (five variants), childhood height (six variants), and adult height (413 variants). We further examined the UK Biobank to evaluate the association of known neuroblastoma risk loci and stature.

Results

An increase in the polygenic score for childhood stature, corresponding to a ~0.5 cm increase in pre‐pubertal height, was associated with greater risk of MYCN‐amplified neuroblastoma (OR = 1.14, P = .047). An increase in the polygenic score for adult stature, corresponding to a ~1.7 cm increase in adult height attainment, was associated with decreased risk of MYCN‐amplified neuroblastoma (OR = 0.87, P = .047). These associations persisted in case‐case analyses comparing MYCN‐amplified to MYCN‐unamplified neuroblastoma. No polygenic height scores were associated with MYCN‐unamplified neuroblastoma risk. Previously identified genome‐wide association study hits for neuroblastoma (N = 10) were significantly enriched for association with both childhood (P = 4.0 × 10⁻³) and adult height (P = 8.9 × 10⁻³) in >250 000 UK Biobank study participants.

Conclusions

Genetic propensity to taller childhood height and shorter adult height were associated with MYCN‐amplified neuroblastoma risk, suggesting that biological pathways affecting growth trajectories and pubertal timing may contribute to MYCN‐amplified neuroblastoma etiology.

De novo evolved gene product NCYM in the pathogenesis and clinical outcome of human neuroblastomas and other cancers

NCYM is an antisense transcript of MYCN oncogene and promotes tumor progression. NCYM encodes a de novo protein whose open reading frame evolved from noncoding genomic regions in the ancestor of Homininae. Because of its topology, NCYM is always co-amplified with MYCN oncogene, and the mutual regulations between NCYM and MYCN maintain their expressions at high levels in MYCN-amplified tumors. NCYM stabilizes MYCN by inhibiting GSK3β, whereas MYCN stimulates transcription of both NCYM and MYCN. NCYM mRNA and its noncoding transcript variants MYCNOS have been shown to stimulate MYCN expression via direct binding to MYCN promoter, indicating that both coding and noncoding transcripts of NCYM induce MYCN expression. In contrast to the noncoding functions of NCYM, NCYM protein also promotes calpain-mediated cleavage of c-MYC. The cleaved product called Myc-nick inhibits cell death and promotes cancer cell migration. Furthermore, NCYM-mediated inhibition of GSK3β results in the stabilization of β-catenin, which promotes aggressiveness of bladder cancers. These MYCN-independent functions of NCYM showed their clinical significance in MYCN-non-amplified tumors, including adult tumors. This year is the 30th anniversary of the identification of NCYM/MYCNOS gene. On this special occasion, we summarize the current understanding of molecular functions and the clinical significance of NCYM and discuss future directions to achieve therapeutic strategies targeting NCYM.

Amino Acids Regulate Cisplatin Insensitivity in Neuroblastoma

Simple Summary

Neuroblastomas mostly show poor response to the Cisplatin therapy. Amino acids serve as building blocks for proteins, which are acquired either through diet or protein breakdown. Our study reveals high amino acid pools and dependence of Cisplatin-tolerant neuroblastomas cells on amino acids for their survival, especially, in drug treated conditions. Our study also demonstrates that response of neuroblastomas to Cisplatin can be improved by decreasing cellular amino acid levels either by reducing amino acid supplements or by applying autophagy inhibitor, Hydroxychloroquine. Thus, our findings establish that neuroblastomas can be sensitized to Cisplatin by targeting amino acid metabolism.

Abstract

Neuroblastoma are pediatric, extracranial malignancies showing alarming survival prognosis outcomes due to their resilience to current aggressive treatment regimens, including chemotherapies with cisplatin (CDDP) provided in the first line of therapy regimens. Metabolic deregulation supports tumor cell survival in drug-treated conditions. However, metabolic pathways underlying cisplatin-resistance are least studied in neuroblastoma. Our metabolomics analysis revealed that cisplatin-insensitive cells alter their metabolism; especially, the metabolism of amino acids was upregulated in cisplatin-insensitive cells compared to the cisplatin-sensitive neuroblastoma cell line. A significant increase in amino acid levels in cisplatin-insensitive cells led us to hypothesize that the mechanisms upregulating intracellular amino acid pools facilitate insensitivity in neuroblastoma. We hereby report that amino acid depletion reduces cell survival and cisplatin-insensitivity in neuroblastoma cells. Since cells regulate their amino acids levels through processes, such as autophagy, we evaluated the effects of hydroxychloroquine (HCQ), a terminal autophagy inhibitor, on the survival and amino acid metabolism of cisplatin-insensitive neuroblastoma cells. Our results demonstrate that combining HCQ with CDDP abrogated the amino acid metabolism in cisplatin-insensitive cells and sensitized neuroblastoma cells to sub-lethal doses of cisplatin. Our results suggest that targeting of amino acid replenishing mechanisms could be considered as a potential approach in developing combination therapies for treating neuroblastomas.

MYCN drives chemoresistance in small cell lung cancer while USP7 inhibition can restore chemosensitivity

Small cell lung cancer (SCLC) is an aggressive neuroendocrine cancer characterized by initial chemosensitivity followed by emergence of chemoresistant disease. To study roles for MYCN amplification in SCLC progression and chemoresistance, we developed a genetically engineered mouse model of MYCN-overexpressing SCLC. In treatment-naïve mice, MYCN overexpression promoted cell cycle progression, suppressed infiltration of cytotoxic T cells, and accelerated SCLC. MYCN overexpression also suppressed response to cisplatin-etoposide chemotherapy, with similar findings made upon MYCL overexpression. We extended these data to genetically perturb chemosensitive patient-derived xenograft (PDX) models of SCLC. In chemosensitive PDX models, overexpression of either MYCN or MYCL also conferred a switch to chemoresistance. To identify therapeutic strategies for MYCN-overexpressing SCLC, we performed a genome-scale CRISPR-Cas9 sgRNA screen. We identified the deubiquitinase USP7 as a MYCN-associated synthetic vulnerability. Pharmacological inhibition of USP7 resensitized chemoresistant MYCN-overexpressing PDX models to chemotherapy in vivo. Our findings show that MYCN overexpression drives SCLC chemoresistance and provide a therapeutic strategy to restore chemosensitivity.

Accelerating drug development for neuroblastoma: Summary of the Second Neuroblastoma Drug Development Strategy forum from Innovative Therapies for Children with Cancer and International Society of Paediatric Oncology Europe Neuroblastoma

Only one class of targeted agents (anti-GD2 antibodies) has been incorporated into front-line therapy for neuroblastoma since the 1980s. The Neuroblastoma New Drug Development Strategy (NDDS) initiative commenced in 2012 to accelerate the development of new drugs for neuroblastoma. Advances have occurred, with eight of nine high-priority targets being evaluated in paediatric trials including anaplastic lymphoma kinase inhibitors being investigated in front-line, but significant challenges remain. This article reports the conclusions of the second NDDS forum, which expanded across the Atlantic to further develop the initiative. Pre-clinical and clinical data for 40 genetic targets and mechanisms of action were prioritised and drugs were identified for early-phase trials. Strategies to develop drugs targeting TERT, telomere maintenance, ATRX, alternative lengthening of telomeres (ALT), BRIP1 and RRM2 as well as direct targeting of MYCN are high priority and should be championed for drug discovery. Promising pre-clinical data suggest that targeting of ALT by ATM or PARP inhibition may be potential strategies. Drugs targeting CDK2/9, CDK7, ATR and telomere maintenance should enter paediatric clinical development rapidly. Optimising the response to anti-GD2 by combinations with chemotherapy, targeted agents and other immunological targets are crucial. Delivering this strategy in the face of small patient cohorts, genomically defined subpopulations and a large number of permutations of combination trials, demands even greater international collaboration. In conclusion, the NDDS provides an internationally agreed, biologically driven selection of prioritised genetic targets and drugs. Improvements in the strategy for conducting trials in neuroblastoma will accelerate bringing these new drugs more rapidly to front-line therapy.

SP1-induced HOXD-AS1 promotes malignant progression of cholangiocarcinoma by regulating miR-520c-3p/MYCN

The purpose of this article is to explore the function and mechanism of HOXD-AS1 in cholangiocarcinoma. TCGA, StarBase and JASPAR were applied to predict the differential expression and molecular mechanism. The qRT-PCR was conducted to detect molecular expression. The effect of HOXD-AS1 on tumor proliferation, metastasis and stemness was measured through corresponding experiments. ChIP, luciferase reporter and RIP assays were implemented to explore the regulatory mechanism of HOXD-AS1 in CCA. In this study, HOXD-AS1 expression was significantly upregulated in CCA tissues and cells compared with control groups, respectively. Increased HOXD-AS1 was markedly correlated with lymph node invasion, advanced TNM stage and poor survival of CCA patients. Moreover, HOXD-AS1 was confirmed to be an unfavorable independent prognostic factor for CCA patients. Functionally, gain- and loss-of-function experiments demonstrated that HOXD-AS1 facilitated tumor proliferation, migration, invasion, EMT, stemness and drug resistance in vitro and in vivo. For the mechanism, transcription factor SP1-induced HOXD-AS1 upregulated oncogene MYCN through competitively binding to miR-520c-3p. Furthermore, HOXD-AS1-induced malignant phenotypes were rescued by interfering miR-520c-3p and MYCN, respectively. SP1/HOXD-AS1/miR-520c-3p/MYCN plays a vital role in initiation and progression of CCA, and HOXD-AS1 is expected to be an efficient biomarker and therapeutic target.

Tyramide Signal-Amplified Immunofluorescence of MYCN and MYC in Human Tissue Specimens and Cell Line Cultures

MYC family members, MYC, MYCN, and MYCL, are oncogenic transcription factors that regulate the expression of genes involved in normal development, cell growth, proliferation, metabolism, and survival. While MYC is amplified and/or overexpressed across a variety of tissue types, MYCN is often overexpressed in tumors of the nervous system (neuroblastoma and medulloblastoma) or with neuroendocrine features (neuroendocrine prostate cancer). Given recent reports that MYCN expression is also deregulated in a variety of non-neuronal tissue types, we investigated whether MYCN was also deregulated in triple-negative breast cancer (TNBC). In contrast to previous individual immuno-fluorescence (IF) stains against higher expressing MYC family isoform protein, we developed an IF stain to simultaneously detect both MYCN- and MYC-expressing cells within the same tumor cell population. Our methodology allows for the detection of low level MYCN and MYC expression and can be multiplexed with additional protein probes. Herein, using tyramide signal amplification (TSA), we present two protocols for the IF detection of MYCN and MYC on formalin-fixed paraffin embedded (FFPE) tumor sections and in cell lines fixed in situ after growth as adherent cultures on chambered microscope slides.

Prognostic significance of MYCN related genes in pediatric neuroblastoma: a study based on TARGET and GEO datasets

Background

Neuroblastoma patients with MYCN amplification are associated with poor prognosis. However, the prognostic relevance of MYCN associated genes in neuroblastoma is unclear.

Methods

The expression profiles of MYCN associated genes were identified from Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) datasets. Enriched transcription factors and signaling pathways were determined using gene set enrichment analysis (GSEA). Kaplan-Meier plotter was used to identify the prognostic relevance of MYCN associated genes. Multivariate cox regression and Spearman’s correlation were used to determine the correlation coefficients of MYCN associated genes.

Results

In TARGET and GSE85047 datasets, neuroblastoma patients with MYCN amplification were associated with worse prognosis. Transcription factor MYC was positively associated with MYCN amplification in GSEA assay. We identified 13 MYC target genes which were increased in neuroblastoma patients with MYCN amplification in TARGET, GSE19274 and GSE85047 datasets. Moreover, six out of the 13 MYC target genes ARMC6, DCTPP1, EIF4G1, ELOVL6, FBL and PRMT1 were associated with adverse prognosis in TARGET and GSE85047 datasets. Transcription factor E2F1 was up-regulated by MYCN amplification and associated with the poor prognosis of neuroblastoma. Furthermore, RPS19 in ribosome signaling pathway was also associated with MYCN amplification and correlated with the poor prognosis of neuroblastoma. At last, we showed that most of MYCN target genes were correlated with each other. However, EIF4G1 was an independent prognostic marker. And the prognostic effects of the combination of MYCN amplification and EIF4G1 expression were more significant than MYCN or EIF4G1 alone.

Conclusions

MYCN target genes ARMC6, DCTPP1, EIF4G1, ELOVL6, FBL, PRMT1, E2F1 and RPS19 had significant prognostic effects in pediatric neuroblastoma. And neuroblastoma patients without MYCN amplification and low EIF4G1 expression had best prognosis.

MYCN expression induces replication stress and sensitivity to PARP inhibition in neuroblastoma

This study investigates the influence expression of the MYCN oncogene has on the DNA damage response, replication fork progression and sensitivity to PARP inhibition in neuroblastoma. In a panel of neuroblastoma cell lines, MYCN amplification or MYCN expression resulted in increased cell death in response to a range of PARP inhibitors (niraparib, veliparib, talazoparib and olaparib) compared to the response seen in non-expressing/amplified cells. MYCN expression slowed replication fork speed and increased replication fork stalling, an effect that was amplified by PARP inhibition or PARP1 depletion. Increased DNA damage seen was specifically induced in S-phase cells. Importantly, PARP inhibition caused a significant increase in the survival of mice bearing MYCN expressing tumours in a transgenic murine model of MYCN expressing neuroblastoma. Olaparib also sensitized MYCN expressing cells to camptothecin- and temozolomide-induced cell death to a greater degree than non-expressing cells. In summary, MYCN expression leads to increased replication stress in neuroblastoma cells. This effect is exaggerated by inhibition of PARP, resulting in S-phase specific DNA damage and ultimately increased tumour cell death. PARP inhibition alone or in combination with classical chemotherapeutics is therefore a potential therapeutic strategy for neuroblastoma and may be more effective in MYCN expressing tumours.

Elimination of MYCN-Amplified Neuroblastoma Cells by Telomerase-Targeted Oncolytic Virus via MYCN Suppression

Neuroblastoma (NB) is a primary malignant tumor of the peripheral sympathetic nervous system. High-risk NB is characterized by MYCN amplification and human telomerase reverse transcriptase (hTERT) rearrangement, contributing to hTERT activation and a poor outcome. For targeting hTERT-activated tumors, we developed two oncolytic adenoviruses, OBP-301 and tumor suppressor p53-armed OBP-702, in which the hTERT promoter drives expression of the viral E1 gene for tumor-specific virus replication. In this study, we demonstrate the therapeutic potential of the hTERT-driven oncolytic adenoviruses OBP-301 and OBP-702 using four human MYCN-amplified NB cell lines (IMR-32, CHP-134, NB-1, LA-N-5) exhibiting high hTERT expression. OBP-301 and OBP-702 exhibited a strong antitumor effect in association with autophagy in NB cells. Virus-mediated activation of E2F1 protein suppressed MYCN expression. OBP-301 and OBP-702 significantly suppressed the growth of subcutaneous CHP-134 tumors. Thus, these hTERT-driven oncolytic adenoviruses are promising antitumor agents for eliminating MYCN-amplified NB cells via E2F1-mediated suppression of MYCN protein.

Limited antitumor activity of combined BET and MEK inhibition in neuroblastoma

BACKGROUND

The treatment of high-risk neuroblastoma continues to present a formidable challenge to pediatric oncology. Previous studies have shown that Bromodomain and extraterminal (BET) inhibitors can inhibit MYCN expression and suppress MYCN-amplified neuroblastoma in vivo. Furthermore, alterations within RAS-MAPK (mitogen-activated protein kinase) signaling play significant roles in neuroblastoma initiation, maintenance, and relapse, and mitogen-activated extracellular signal-regulated kinase (MEK) inhibitors demonstrate efficacy in subsets of neuroblastoma preclinical models. Finally, hyperactivation of RAS-MAPK signaling has been shown to promote resistance to BET inhibitors. Therefore, we examined the antitumor efficacy of combined BET/MEK inhibition utilizing I-BET726 or I-BET762 and trametinib in high-risk neuroblastoma.

PROCEDURE

Utilizing a panel of genomically annotated neuroblastoma cell line models, we investigated the in vitro effects of combined BET/MEK inhibition on cell proliferation and apoptosis. Furthermore, we evaluated the effects of combined inhibition in neuroblastoma xenograft models.

RESULTS

Combined BET and MEK inhibition demonstrated synergistic effects on the growth and survival of a large panel of neuroblastoma cell lines through augmentation of apoptosis. A combination therapy slowed tumor growth in a non-MYCN-amplified, NRAS-mutated neuroblastoma xenograft model, but had no efficacy in an MYCN-amplified model harboring a loss-of-function mutation in NF1.

CONCLUSIONS

Combinatorial BET and MEK inhibition was synergistic in the vast majority of neuroblastoma cell lines in the in vitro setting but showed limited antitumor activity in vivo. Collectively, these data do not support clinical development of this combination in high-risk neuroblastoma.

Association of heterogeneous MYCN amplification with clinical features, biological characteristics and outcomes in neuroblastoma: A report from the Children's Oncology Group

PURPOSE

MYCN amplification (MNA) is associated with poor outcomes in neuroblastoma. Less is known about heterogeneous MNA within a tumour. We compared clinical characteristics, biologic features and clinical outcomes of patients with heterogeneous MNA to patients with either homogeneous MNA or MYCN wild-type tumours.

PATIENTS AND METHODS

In this retrospective cohort study, we categorized patients as having tumours with MYCN wild-type, homogeneous MNA (>20% amplified tumour cells) or heterogeneous MNA (≤20% amplified tumour cells). We used chi-squared or Fisher's exact tests to compare features between groups. We used log-rank tests and Cox models to compare event-free survival (EFS) and overall survival (OS) between groups.

RESULTS

MYCN status and heterogeneity status (if amplified) could be ascertained in diagnostic tumour samples from 5975 patients, including 57 (1%) with heterogeneous MNA, 981 (16.4%) with homogeneous MNA, and 4937 (82.6%) with MYCN wild-type tumours. Multiple clinical and biological features differed between patients with heterogeneous vs. homogeneous MNA, including enrichment for thoracic primary sites and paucity of 1p loss of heterozygosity with heterogeneous MNA (p < 0.0001). Importantly, EFS and OS were not significantly different between patients with heterogeneous vs. homogeneous MNA. Further, EFS and OS for patients with heterogeneous MNA were significantly inferior to patients with wild-type MYCN.

CONCLUSION

Although neuroblastomas with heterogeneous MNA demonstrate significantly different biological and clinical patterns compared with homogeneous MNA, prognosis is similar between the two groups. These results support current practice that treats patients with heterogeneous MNA similarly to patients with homogeneous MNA.