Embryonal Cancer Therapy and Prevention

Contact: Dr Belamy Cheung, bcheung@ccia.org.au

The MYC family of transcription factors, including c-Myc and MYCN, play a crucial role in cancer progression, particularly in high-risk paediatric tumours like medulloblastoma (MB) and diffuse intrinsic pontine glioma (DIPG). For many years MYC proteins, c-Myc and MYCN, were considered "undruggable" due to their essential roles in cell proliferation, but recent advances have made them viable targets for therapy. Elevated MYC protein stability is a key mechanism driving tumour initiation and progression, particularly in MYC-driven cancers with poor prognoses. MYC proteins are often overexpressed in various cancers, contributing to tumour aggressiveness and poor clinical outcomes.

Our recent research has identified potential strategies to target these proteins more effectively. UNSW-SC-22, a novel small molecule compound, has shown promise in targeting MYCN and c-Myc by enhancing their ubiquitination and reducing protein stability. Preclinical studies suggest that UNSW-SC-22 can cross the blood-brain barrier and exhibit efficacy in combination with other drugs such as chemotherapy and HDAC inhibitors (HDACi), like SAHA. These findings highlight the potential of UNSW-SC-22 as a therapeutic agent in combination with established treatments.

We are expanding on these promising findings by investigating the effectiveness of our novel drug combinations with standard therapies in preclinical models of MB and DIPG. Additionally, we are exploring the molecular mechanisms underlying the synergistic effects of these drug combinations. This preclinical study will generate essential evidence to support future clinical trials.

Contact: Dr Belamy Cheung, bcheung@ccia.org.au

To determine whether certain embryonal environmental factors, such as maternal diet, might initiate embryonal cancer, we examined the links between maternal obesity, high birth weight and neuroblastoma (NB) incidence in MYCN transgenic NB mice. We found that a high fat diet (HFD) given prior or during pregnancy, to maternal MYCN transgenic mice induced maternal obesity and hyperglycaemia which resulted in progeny with high birth weight. We found that the maternal HFD not only increased birth weight, but accelerated tumour formation and reduced tumour-free survival in their offspring. Ganglia from pups born to HFD-fed mothers demonstrated strong activation of the metabolic pathways for oxidative phosphorylation (OXPHOS) and fatty acid metabolism and several cancer related pathways including MYC transcriptional target genes.

We have identified and validated several upregulated candidate genes as molecular targets of HFD-accelerated NB tumour growth. Most importantly, we have identified a specific inhibitor of fatty acid metabolism and showed that the inhibitor induced apoptosis in a fatty acid-enriched environment in NB cells. The inhibitor of fatty acid metabolism has strong synergistic cytotoxic effects with chemotherapy drugs in the presence of fatty acids in NB cells. These ?ndings provide a rationale for developing novel therapeutic strategies targeting HFD-activated OXPHOS and fatty acid metabolism for the treatment of high-risk NB.

We hypothesise that HFD-induced maternal obesity accelerates NB initiation by activation of OXPHOS pathway and fatty acid metabolism and upregulation of MYCN transcriptional targets as the key drivers of HFD-accelerated tumour progression in MYCN-driven NB. In this study, we are using a comprehensive in vitro and in vivo strategy to determine the molecular mechanisms of HFD-accelerated tumour growth and evaluate our novel combination therapies for the treatment of high-risk NB.

Contact: Dr Belamy Cheung, bcheung@ccia.org.au

A significant percentage of children, adolescents, and young adults with sarcoma do not respond well to the standard "one-size-fits-all" chemotherapy approach. To address this challenge, there is a critical need for novel diagnostic methods capable of early identification and characterization of minor malignant subclones, enabling timely adjustments to therapy and potentially preventing progression and relapse.

While bulk tumour DNA sequencing has advanced the matching of drugs to their gene targets, single-cell RNA sequencing (scRNA-seq) provides unparalleled resolution for deciphering tumour heterogeneity and evaluating an individual patient's chemo-resistance genes. By comparing variant allele frequencies and single-cell transcriptomes from whole-exome sequencing (WES) and scRNA-seq, respectively, this approach can track the emergence and development of chemo-resistance, overcoming the limitations associated with bulk RNA and DNA approaches.

To date, no published studies have used post-chemotherapy transcriptomes to identify treatment-resistant clones and their RNA targets at the single-cell level. Our lab at the has established a high-throughput droplet-single-cell sequencing platform and conducted proof-of-principle experiments comparing osteosarcoma and neuroblastoma samples before and after chemotherapy. These experiments revealed an enrichment of chemo-resistant clones with sensitivities to drugs not commonly used in these diseases.

These findings have the potential to significantly advance our understanding of cancer progression and lay the groundwork for an individualized precision medicine diagnostic approach that introduces novel drugs early in the treatment course, potentially preventing relapse. This study aims to use single-cell analysis and combined transcriptomic/genomic analyses to better inform the treatment for children with sarcoma.