MYCN Amplification Is Associated with Reduced Expression of Genes Encoding γ-Secretase Complex and NOTCH Signaling Components in Neuroblastoma

Unraveling the genetic and singaling landscapes of pediatric cancer

Pediatric cancer (PAEC) arises from gene mutations and their disrupted pathways, often driven by genetic instability affecting cell signaling. These pathways can help identify cancer triggers. Genomic studies have examined PAEC gene etiologies and disorders, but further analysis is needed to understand tumor progression mechanisms. We systematically analyzed PAEC datasets from cBioPortal, encompassing thirteen studies with 6568 samples. We identified 827 PAEC genes with mutation frequencies over fifteen across four tiers (I-IV). Tier I (mutation frequency ≥1 %) includes 40 genes, while Tier II(0.90-0.70 %), Tier III(0.60-0.50 %), and Tier IV(0.40-0.10 %) comprise 126, 336, and 325 genes, respectively. Key Tier I genes include TP53(5 %), NRAS(2.2 %), KRAS(1.8 %), CTNNB1(1.4 %), ATM(1.3 %), CREBBP(1.2 %), JAK2 (1.1 %), PIK3CA(1 %), PTEN(1 %), BRAF(0.9 %), EGFR(0.9 %), PIK3R1(0.8 %), and PTPN11(0.8 %). These genes participate in various signaling pathways (PI3K/AKT/mTOR, RAS/RAF/MAPK, JAK/STAT, and WNT/β-catenin), which are interconnected. We compared several PAEC panels with Tier I genes, and we found that the most shared across PAEC panels were TP53 (8), PTEN (7), and ATM (4). We further examined roles of TP53 in normal cells versus PEAC tumors using digital cellular and pathological imaging data supported by Human Protein Atlas. TP53 is expressed in cytosol, nucleosol, and vesicles and during cell-cycle TP53 protein in key regulator and it is present during all major cell-cycle events. Balancing of TP53WT and TP53MUT is the hallmark of the TP53 pathophysiology with severe functional implications. Notably, genes linked to insulin metabolism disorders may be PAEC risk factors, suggesting metabolic pathways as key research targets. This study highlights the therapeutic, prognostic, and diagnostic significance of these genes and pathways, emphasizing the need for ongoing PAEC research.

EIF2S1 Silencing Impedes Neuroblastoma Development Through GPX4 Inactivation and Ferroptosis Induction

Background: Neuroblastoma (NB) is one of the most devastating malignancies in children, accounting for a high mortality rate due to limited treatment options. This study is aimed at elucidating the role of the ferroptosis-related EIF2S1 gene in NB pathogenesis and exploring its potential as a therapeutic target. Methods: We conducted comprehensive bioinformatics analyses utilizing the FerrDb database and NB-related transcriptomics data to investigate the role of EIF2S1 in NB. Changes in EIF2S1 expression were subsequently validated in NB tissues and cell lines. Loss-of-function experiments were performed in SK-N-SH and IMR-32 cell lines through shRNA-mediated EIF2S1 knockdown. The impact of EIF2S1 knockdown on the tumorigenesis of SK-N-SH cells was assessed in nude mice. Results: Bioinformatics analyses revealed a significant association between elevated EIF2S1 expression and poor prognosis in NB patients. The increased levels of EIF2S1 expression were confirmed in NB tissues and cancerous cell lines. Furthermore, EIF2S1 overexpression was linked to translational regulation and immune cell infiltration modulation. Silencing of EIF2S1 resulted in the suppression of cell proliferation, migration, and tumorigenicity in NB cells. Additionally, EIF2S1 knockdown led to an accumulation of iron and oxidative stress, as well as a reduction in GPX4 and SLC7A11 expression. Conclusion: Our findings indicate that EIF2S1 appears to facilitate the progression of NB by protecting tumor cells from ferroptosis through modulating GPX4 and SLC7A11 expression. Consequently, EIF2S1 may serve as a potential therapeutic target for the management of NB.

A First-in-Class High-Throughput Screen to Discover Modulators of the Alternative Lengthening of Telomeres (ALT) Pathway

Telomeres are a protective cap that prevents chromosome ends from being recognized as double-stranded breaks. In somatic cells, telomeres shorten with each cell division due to the end replication problem, which eventually leads to senescence, a checkpoint proposed to prevent uncontrolled cell growth. Tumor cells avoid telomere shortening by activating one of two telomere maintenance mechanisms (TMMs): telomerase reactivation or alternative lengthening of telomeres (ALT). TMMs are a viable target for cancer treatment as they are not active in normal, differentiated cells. Whereas there is a telomerase inhibitor currently undergoing clinical trials, there are no known ALT inhibitors in development, partially because the complex ALT pathway is still poorly understood. For cancers such as neuroblastoma and osteosarcoma, the ALT-positive status is associated with an aggressive phenotype and few therapeutic options. Thus, methods that characterize the key biological pathways driving ALT will provide important mechanistic insight. We have developed a first-in-class phenotypic high-throughput screen to identify small-molecule inhibitors of ALT. Our screen measures relative C-circle level, an ALT-specific biomarker, to detect changes in ALT activity induced by compound treatment. To investigate epigenetic mechanisms that contribute to ALT, we screened osteosarcoma and neuroblastoma cells against an epigenetic-targeted compound library. Hits included compounds that target chromatin-regulating proteins and DNA damage repair pathways. Overall, the high-throughput C-circle assay will help expand the repertoire of potential ALT-specific therapeutic targets and increase our understanding of ALT biology.

Notch signaling pathway in cancer: from mechanistic insights to targeted therapies

Notch signaling, renowned for its role in regulating cell fate, organ development, and tissue homeostasis across metazoans, is highly conserved throughout evolution. The Notch receptor and its ligands are transmembrane proteins containing epidermal growth factor-like repeat sequences, typically necessitating receptor-ligand interaction to initiate classical Notch signaling transduction. Accumulating evidence indicates that the Notch signaling pathway serves as both an oncogenic factor and a tumor suppressor in various cancer types. Dysregulation of this pathway promotes epithelial-mesenchymal transition and angiogenesis in malignancies, closely linked to cancer proliferation, invasion, and metastasis. Furthermore, the Notch signaling pathway contributes to maintaining stem-like properties in cancer cells, thereby enhancing cancer invasiveness. The regulatory role of the Notch signaling pathway in cancer metabolic reprogramming and the tumor microenvironment suggests its pivotal involvement in balancing oncogenic and tumor suppressive effects. Moreover, the Notch signaling pathway is implicated in conferring chemoresistance to tumor cells. Therefore, a comprehensive understanding of these biological processes is crucial for developing innovative therapeutic strategies targeting Notch signaling. This review focuses on the research progress of the Notch signaling pathway in cancers, providing in-depth insights into the potential mechanisms of Notch signaling regulation in the occurrence and progression of cancer. Additionally, the review summarizes pharmaceutical clinical trials targeting Notch signaling for cancer therapy, aiming to offer new insights into therapeutic strategies for human malignancies.

Target Genes of c-MYC and MYCN with Prognostic Power in Neuroblastoma Exhibit Different Expressions during Sympathoadrenal Development

Deregulation of the MYC family of transcription factors c-MYC (encoded by MYC), MYCN, and MYCL is prevalent in most human cancers, with an impact on tumor initiation and progression, as well as response to therapy. In neuroblastoma (NB), amplification of the MYCN oncogene and over-expression of MYC characterize approximately 40% and 10% of all high-risk NB cases, respectively. However, the mechanism and stage of neural crest development in which MYCN and c-MYC contribute to the onset and/or progression of NB are not yet fully understood. Here, we hypothesized that subtle differences in the expression of MYCN and/or c-MYC targets could more accurately stratify NB patients in different risk groups rather than using the expression of either MYC gene alone. We employed an integrative approach using the transcriptome of 498 NB patients from the SEQC cohort and previously defined c-MYC and MYCN target genes to model a multigene transcriptional risk score. Our findings demonstrate that defined sets of c-MYC and MYCN targets with significant prognostic value, effectively stratify NB patients into different groups with varying overall survival probabilities. In particular, patients exhibiting a high-risk signature score present unfavorable clinical parameters, including increased clinical risk, higher INSS stage, MYCN amplification, and disease progression. Notably, target genes with prognostic value differ between c-MYC and MYCN, exhibiting distinct expression patterns in the developing sympathoadrenal system. Genes associated with poor outcomes are mainly found in sympathoblasts rather than in chromaffin cells during the sympathoadrenal development.