Biology subjects

Mayoh, C.

Publications and source records attributed to Mayoh, C..

13 recordsLinked to original sources

bioRxiv2026

METTL1 gene dosage and catalytic activity define a targetable vulnerability in pediatric cancers

METTL1 is responsible for catalyzing N7-methylguanosine (m7G) methylation of tRNAs. METTL1-dependent oncogenic mechanisms include both its methyltransferase catalytic activity and, in specific instances, non-catalytic interactions that maintain aminoacylated tRNA levels in malignant cells. We show that METTL1 copy number gain and elevated expression are a feature of pediatric tumors that are METTL1 dependent, using Cas13-mediated RNA to reduce the threshold of METTL1 mRNA and protein, which disrupts both catalytic and non-catalytic functions. In cell lines with METTL1 gene amplification, specific degradation of METTL1 mRNA impaired colony formation, triggered cell death, and decreased the translation efficiency of a subset of genes enriched for codons decoded m7G-modified tRNAs. METTL1 inhibition was accompanied by downregulation of c-MYC, n-MYC and MCL-1 protein expression. METTL1 silencing synergizes with drugs targeting anti-apoptotic members of the BCL2 family, notably BCL-xL. Importantly, the catalytic activity of METTL1 was required to rescue cells from the deleterious consequences of METTL1 silencing. We conclude that inhibiting the catalytic activity of METTL1 has potential therapeutic efficacy, particularly in tumors with METTL1 amplification. Synergistic combinations with BH3-mimetic drugs may be a promising therapeutic combination.

cancer biology↗

bioRxiv2026

Preclinical trial supports dual inhibition of BCL2 and Aurora kinase A for MYCN-amplified high-risk neuroblastoma

Purpose: Treatment for children with high-risk neuroblastoma relies on conventional chemotherapy and anti-GD2 immunotherapy. However, 5-year survival is only 50%, with high rates of late effects. Targeted therapy combinations are a major priority for these patients. The BCL2 inhibitor venetoclax, in combination with cyclophosphamide/topotecan, has clinical activity in relapsed and refractory neuroblastoma. We sought more effective and safer venetoclax combinations through systematic preclinical testing. Experimental design: Synergistic combinations were identified by high-throughput screening using patient-derived xenograft (PDX) models and confirmed in vivo. The leading combination (venetoclax-alisertib) was compared to combination chemotherapy in a clinical trial-like study using 22 PDX models, in scheduling experiments designed to reduce short-term toxicity, and in combination with anti-GD2 immunotherapy. BCL2 and Bim-BCL2 complex protein levels were assessed as predictors of sensitivity. Results: In vitro synergy with venetoclax was observed for standard-of-care chemotherapies and targeted agents, including DNA topoisomerase, microtubule, HDAC and Aurora kinase A (AURKA) inhibitors. Venetoclax-alisertib was particularly effective in vivo. In an n=1 study, venetoclax-alisertib induced objective response in all models. Activity was most striking in models of MYCN-amplified disease (n=12), doubling median survival time compared to cyclophosphamide/topotecan, and outperforming venetoclax-cyclophosphamide-topotecan. Efficacy was maintained with discontinuous schedules, minimizing hematological toxicity without substantially compromising activity. PDX-engrafted animals treated with venetoclax-alisertib and anti-GD2 immunotherapy survived tumor-free long-term. BCL2 expression and BCL2-Bim complex levels were of limited value for predicting response. Conclusion: Our findings support advancement of BCL2-AURKA inhibition to clinical trial for neuroblastoma with or without anti-GD2 immunotherapy, particularly in patients with MYCN amplified disease.

cancer biology↗

bioRxiv2025

Single-cell RNA-sequencing of cerebral spinal fluid identifies circulating tumour cells in children with brain cancer

Paediatric central nervous system (CNS) tumours are the leading cause of cancer-related death in children, yet disease monitoring remains challenging. Conventional approaches, including imaging and cytology, lack sensitivity, delaying intervention. Liquid biopsy offers a minimally invasive alternative, but the utility of circulating tumour cells (CTCs) in paediatric CNS tumours as biomarkers is poorly defined. We developed a CTC detection and characterisation workflow from cerebrospinal fluid (CSF) utilising single-cell RNA-sequencing (scRNA-seq) and applied this to ten CNS tumour subtypes in 16 patients. CTCs were identified in all cases, with higher burdens in pineoblastoma, medulloblastoma and atypical teratoid rhabdoid tumours. Longitudinal profiling revealed CTC dynamics correlated with clinical disease course and anticipated relapse. Critically, scRNA-seq uncovered a sub-clonal canonical driver alteration at diagnosis that only became detectable by bulk RNA-seq at progression, underscoring its potential to resolve clonal dynamics. This workflow enables real-time molecular profiling, offering a transformative strategy for disease monitoring and personalised therapy in paediatric brain tumours.

cancer biology↗

bioRxiv2025

CBL mutations in pediatric solid and CNS tumors are a marker of receptor tyrosine kinase activation and a potential therapeutic target

Mutations in CBL, an E3 ubiquitin ligase that negatively regulates receptor tyrosine kinases (RTKs) and potentiates intracellular signaling, have been extensively characterized in hematological malignancies. However, the impacts are unknown in other cancer types. We have identified established and novel aberrations in CBL in molecularly diverse pediatric CNS and solid tumors. Additionally, we present novel CBL splice mutations, including in the germline of a high-grade glioma patient, and alternative CBL splicing without corresponding genomic alterations. Functionally, we demonstrate that CBL exon 8/9{Delta}, typically associated with acute myeloid leukemia, is RTK activating in neuroblastoma and that novel CBL variants, CBL E366_E373del and CBL C384G, can cooperate with overexpression of EGFR to transform Ba/F3 cells. Collectively, these data represent a novel form of RTK activation in pediatric patients with solid and CNS tumors who might benefit from RTK-targeted therapies. Statement of significanceMolecularly targeted therapies improve childhood cancer outcomes. Therapies targeting genes called receptor tyrosine kinases are particularly effective. We have identified new genetic alterations that may be a marker for receptor tyrosine kinase activation and drug sensitivity, enabling more patients to benefit from targeted treatments.

cancer biology↗

bioRxiv2025

Expanding the utility of transcriptome analysis for mutation detection in high-risk childhood precision oncology

In precision oncology, whole transcriptome sequencing (RNA-seq) excels at identifying oncogenic fusions. Here, using a cohort of 477 high-risk paediatric tumours, we demonstrate that RNA-seq can identify all mutation classes found previously using whole genome sequencing (WGS) and provides additional functional insights into their pathogenicity. By incorporating reference-guided fusion, and reference-free structural variant (SV) detection algorithms with RNA abundance assessment, RNA-seq identified 96% of SVs and resolved 33 complex SVs that WGS failed to identify. Furthermore, RNA-seq identified 92% of all single nucleotide variants and small insertions and deletions. Importantly RNA-seq informed the pathogenicity assessment in 22% of variants through identification of allele specific expression or the functional consequence of splice-altering variants. The utility of RNA-seq extends beyond fusion identification to the interpretation of mutation pathogenicity and the discovery of important mutations that would otherwise go undetected. We propose that RNA-seq is an indispensable companion to WGS in precision medicine.

genomics↗

bioRxiv2025

OnCorr: A pan-cancer mRNA-protein correlation tool for precision oncology

Proteins are ultimately responsible for cellular phenotypes and are targeted by most anticancer drugs. However, beyond immunohistochemistry, proteins are not typically measured in precision oncology, meaning transcriptomics is used as a proxy. To determine how informative mRNA is for guiding personalised treatments, mRNA-protein correlations were analysed in three large pan-cancer datasets and made available in a web portal (https://procan.shinyapps.io/OnCorr/). OnCorr can be integrated into precision medicine programs to augment transcriptomics.

cancer biology↗

bioRxiv2024

Engineered paediatric tumours retain patient tumour genotype and phenotype for precision medicine.

Precision medicine for paediatric and adult cancers that includes drug sensitivity profiling, can identify effective therapies for individual patients. However, obtaining adequate biopsy samples for high-throughput (HTP) screening remains challenging, with tumours needing to be expanded in culture or patient-derived xenografts - this is time-consuming and often unsuccessful. Herein, we have developed paediatric patient-derived tumour models using an engineered extracellular matrix (ECM) tissue mimic hydrogel system and HTP 3D bioprinting. Gene expression analysis from neuroblastoma and sarcoma patients identified key components of the ECM in these tumour types. Engineered hydrogels with ECM-mimic peptides were used to create patient-specific tumour organoids, modelling tumour growth conditions. Expanded tumour organoids recapitulated the genetic and phenotypic characteristics of the original tumours and retained tumourgenicity. Screening of these models identified individualised drug sensitivities. Our approach offers a timely and clinically relevant technology platform for precision medicine in paediatric cancers, potentially transforming preclinical testing across cancer types.

cancer biology↗

bioRxiv2024

Chromatin remodeling with combined FACT and BET inhibition disrupts oncogenic transcription in Diffuse Midline Glioma

Aberrant epigenetic regulation is a hallmark of Diffuse Midline Glioma (DMG), an incurable pediatric brain tumor. The H3K27M driver histone mutation leads to transcriptional dysregulation, indicating that targeting the epigenome and transcription may be key therapeutic strategies against this highly aggressive cancer. One such target is the Facilitates Chromatin Transcription (FACT) histone chaperone. We found FACT to be enriched at developmental gene promoters, coinciding with regions of open chromatin and binding motifs of core DMG regulatory transcription factors. Furthermore, FACT interacted and co-localized with the Bromodomain and Extra-Terminal Domain (BET) protein BRD4 at promoters and enhancers, suggesting functional cooperation between FACT and BRD4 in DMG. In vitro, a combinatorial therapeutic approach using the FACT inhibitor CBL0137, coupled with BET inhibition revealed potent and synergistic cytotoxicity across a range of DMG cultures. These results were recapitulated in vivo, significantly extending survival in three independent orthotopic PDX models of DMG. Mechanistically, we show that CBL0137 treatment decreased chromatin accessibility, synergizing with BET inhibition to cause broad transcriptional collapse, silencing several key oncogenes including MYC, PDGFRA, MDM4 and SOX2, as well as causing alterations to the splicing landscape. Notably, this combination also elicited immune-related effects, including activation of the interferon response and antigen presentation mechanisms in DMG cells and induction of an activated state in macrophages and T cells, as demonstrated in an immunocompetent setting with spatial transcriptomics. Altogether, our data highlights the therapeutic promise of simultaneously targeting FACT and BET proteins in DMG, offering a dual tumor-intrinsic and immune-mediated strategy for combating this devastating pediatric brain tumor.

cancer biology↗

bioRxiv2024

The polyamine transporter ATP13A3 mediates DFMO-induced polyamine uptake in neuroblastoma

High-risk neuroblastomas, often associated with MYCN oncogene amplification, are addicted to polyamines, small polycations vital for cellular functioning. We have shown that neuroblastoma cells increase polyamine uptake when exposed to the polyamine biosynthesis inhibitor DFMO, currently in clinical trial, and that this mechanism limits the efficacy of the drug. While this finding resulted in the clinical development of polyamine transport inhibitors including AMXT 1501, presently under clinical investigation in combination with DFMO, the mechanisms and transporters involved in DFMO-induced polyamine uptake are unknown. Knockdown of ATP13A3, a member of the P5B-ATPase family, limited basal and DFMO-induced polyamine uptake, attenuated MYCN-amplified and non-MYCN-amplified neuroblastoma cell growth and potentiated the inhibitory effects of DFMO. Overexpression of ATP13A3 in neuroblastoma cells increased polyamine uptake, which was inhibited by AMXT 1501, highlighting ATP13A3 as a key target of the drug. The association between high ATP13A3 expression and poorer survival in neuroblastoma further supports a role of this transporter in neuroblastoma progression. Thus, this study identified ATP13A3 as a critical regulator of basal and DFMO-induced polyamine uptake and a novel therapeutic target for neuroblastoma. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/581161v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@11bef78org.highwire.dtl.DTLVardef@106c250org.highwire.dtl.DTLVardef@bf39b1org.highwire.dtl.DTLVardef@64d05f_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Comprehensive multi-platform tyrosine kinase profiling reveals novel actionable FGFR aberrations across pediatric and AYA sarcomas

No targeted agents are approved for pediatric sarcomas. Tyrosine kinase (TK) inhibitors represent attractive therapeutic candidates, however, beyond rare TK-activating fusions or mutations, predictive biomarkers are lacking. RNA overexpression of TKs is more commonly observed in pediatric sarcomas, however, an unresolved question is when upregulated TK expression is associated with kinase activation and signaling dependence. We explored the TK molecular landscape of 107 sarcoma patients from the ZERO Childhood Cancer precision medicine program using whole genomic and transcriptomic sequencing. Phosphoproteomic analyses of tyrosine phosphorylation (pY) and functional in vitro and in vivo assays were also performed in cell lines and patient-derived xenografts (PDXs). Our integrated analysis shows that although novel genomic driver lesions are rare, they are present and therapeutically actionable in selected patients as exemplified by a novel LSM1-FGFR1 fusion identified in an osteosarcoma patient. We further show that in certain contexts, TK expression data can be used to indicate TK pathway activity and predict TK-inhibitor sensitivity. We exemplify the utility of FGFR-inhibitors in PAX3-FOXO1 fusion-positive rhabdomyosarcomas (FP-RMS) mediated by high FGFR4 and FGF8 RNA expression levels, and overt activation of FGFR4 (FGFR4_pY). We demonstrate marked tumor growth inhibition in all FP-RMS PDXs treated with single agent FGF401 (FGFR4-specific inhibitor) and single agent lenvatinib (multi-kinase FGFR-inhibitor). Clinical benefit of lenvatinib in a relapsed metastatic FP-RMS patient further exemplifies that FGFR-inhibitors deserve additional investigation in FP-RMS patients. Statement of significanceOur multi-omic interrogation of sarcomas in the ZERO Childhood Cancer program illustrates how an RNA-expression biomarker signature (FGFR4+/FGF8+) in association with FGFR4 activation identifies that PAX3-FOXO1-positive rhabdomyosarcoma patients could benefit from FGFR-inhibitors.

cancer biology↗

bioRxiv2022

A novel transcriptional signature identifies T-cell infiltration in high-risk paediatric cancer

Molecular profiling of the tumour immune microenvironment (TIME) has enabled the rational choice of immunotherapies in some adult cancers. In contrast, the TIME of paediatric cancers is relatively unexplored. We speculated that a more refined appreciation of the TIME in childhood cancers, rather than a reliance on commonly used biomarkers such as tumour mutation burden (TMB), neoantigen load and PD-L1 expression, is an essential prerequisite for improved immunotherapies in childhood solid cancers. We combined immunohistochemistry (IHC) and molecular profiling to develop an alternative, expression-based signature associated with CD8+ T-cell infiltration of the TIME in high-risk paediatric tumours. Using this novel 15-gene immune signature, Immune Paediatric Signature Score (IPASS), we estimate up to 31% of high-risk cancers harbour infiltrating T-cells. Our data provides new insights into the variable immune-suppressive mechanisms dampening responses in paediatric solid cancers. Effective immune-based interventions in high-risk paediatric cancer will require individualised analysis of the TIME.

cancer biology↗

bioRxiv2022

RNA binding is essential for NONO condensates to modulate pre-mRNA processing in neuroblastoma

High-risk neuroblastoma patients have poor survival rates and require better therapeutic options. High expression of a multifunctional DNA and RNA binding protein, NONO, in neuroblastoma is associated with poor patient outcome, however there is little understanding of the mechanism of NONO-dependent oncogenic gene regulatory activity in neuroblastoma. Here, we used cell imaging, biophysical and molecular analysis to reveal complex NONO-dependent regulation of gene expression, finding that NONO forms RNA- and DNA-tethered phase-separated condensates throughout the nucleus. CLIP analyses show that NONO mainly binds to the 5 end of pre-mRNAs and modulates pre-mRNA processing, dependent on its RNA binding activity. NONO preferentially regulates super enhancer-associated genes, including HAND2 and GATA2. In the absence of functional NONO-RNA condensates, inefficient pre-mRNA processing at these loci leads to decreased expression of HAND2 and GATA2. Thus, future development of agents that target RNA binding activity of NONO may have therapeutic potential in this cancer context.

cell biology↗

bioRxiv2019

Genomic landscape of 261 childhood cancer patient-derived xenograft models

Accelerating cures for children with cancer remains an immediate challenge due to extensive oncogenic heterogeneity between and within histologies, distinct molecular mechanisms evolving between diagnosis and relapsed disease, and limited therapeutic options. To systematically prioritize and rationally test novel agents in preclinical murine models, researchers within the Pediatric Preclinical Testing Consortium are continuously developing patient-derived xenografts (PDXs) from high-risk childhood cancers, many refractory to current standard-of-care treatments. Here, we genomically characterize 261 PDX models from 29 unique pediatric cancer malignancies and demonstrate faithful recapitulation of histologies, subtypes, and refine our understanding of relapsed disease. Expression and mutational signatures are used to classify tumors for TP53 and NF1 inactivation, as well as impaired DNA repair. We anticipate that these data will serve as a resource for pediatric oncology drug development and guide rational clinical trial design for children with cancer.\n\nHighlightsO_LIMultiplatform genomic analysis defines landscape of 261 pediatric cancer patient derived xenograft (PDX) models\nC_LIO_LIPediatric patient derived xenografts faithfully recapitulate relapsed disease\nC_LIO_LIInferred TP53 pathway inactivation correlates with pediatric cancer copy number burden\nC_LIO_LISomatic mutational signatures predict impaired DNA repair across multiple histologies\nC_LI

genomics↗