Very little is known about the factors that lead to the development of cancer in children. Our overall strategy is to dissect the mechanisms of cancer initiation and progression and to use this information to develop more effective treatments and prevention strategies for childhood cancer.
Our objectives are to:
• study the factors in the pre- and perinatal environment which may represent the prenatal origins of child cancer
• better understand the molecular basis of embryonal cancer initiation and molecular modelling of embryonal cancer initiation
• characterise novel small molecules that overcome MYCN-initiated cell-death resistance in embryonic cells as childhood cancer prevention strategies
• identify and target novel onco-factors of the MYCN oncogene for neuroblastoma treatment
• decipher mechanisms of neuroblastoma tumorigenesis using single cell profiling
• develop more effective combination chromatin-modifier therapies for neuroblastoma treatment
Our funding sources include the National Health and Medical Research Council (NHMRC), Cancer Institute NSW and Cancer Council NSW.
Head of Program
HEAD OF TRANSLATIONAL RESEARCH
Dr Belamy Cheung
MYCN is a major oncoprotein that contributes to the progression of many paediatric and adult cancers. MYCN oncogene amplification and consequent N-Myc mRNA and protein over-expression, are seen as a clonal feature in a quarter of tumours, and correlate with poorer prognosis in patients with neuroblastoma. Deregulation is frequently associated with poor prognosis and unfavourable patient survival.
The ubiquitin-proteasomal mechanism has been characterised to control the levels and the activities of MYCN. Ubiquitin-specific proteases (USPs), such as USP28, USP36, and USP37 have been shown to stabilise and enhance c-MYC protein activity, and USP7 has been shown to deubiquitinate and stabilise N-MYC in neuroblastoma. Recently, we identified a number of small molecule drugs which enhance the anticancer activity of histone deacetylase inhibitors (HDACI). In combination with HDACIs these drugs inhibit cancer cell growth by targeting USP levels and MYCN protein for degradation, thus inhibiting tumour growth in TH-MYCN transgenic mice.
We hypothesise that USPs are specifically enhancing the stability and activity of MYCN oncogenesis. The overall aim of this study is to characterise the mechanisms by which USPs regulate the deubiquitination of MYCN, develop selective and potent inhibitors of USPs, and evaluate the efficacy of combination therapies for the treatment of MYCN-driven cancer.
Dr Belamy Cheung
Neuroblastoma (NB) is an embryonal child cancer with heterogenous phenotypes, ranging from spontaneous regression to highly aggressive, incurable tumours. NB arises due to defects in sympathetic neuron (SN) differentiation occurring during foetal development. Our group uses genetically engineered mouse models to investigate the genesis of child cancer. In this project we will examine the role of factors such as maternal diet in the prenatal initiation of embryonal child cancer.
Recent findings from our lab and collaborators suggest that environmental factors such as high birth weight, certain maternal dietary supplements, and nitrous oxide exposure during neonatal age, are associated with an increased occurrence of childhood cancer. The molecular mechanisms behind these associations are unknown; thus, we are establishing in vitro and in vivo models to better understand these associations in relation to initiation and development of child cancer.
This project is suitable for PhD/Honours students and has the following aims:
- Evaluate impacts of dietary supplements, hormone and vitamins during pregnancy on initiation and development of NB in mice offspring.
- Carry out in vitro studies to understand initiation and development of NB in the presence/absence of different environmental factors, using cell lines and neurospheres.
Dr Belamy Cheung
MYC is the most frequently amplified oncogene and is implicated in more than 70% of human malignancies. As it lacks a defined catalytic or regulatory site amenable to small molecule inhibition, there has yet to be an effective treatment for MYC-driven cancers, despite extensive research. We are investigating indirect approaches to suppress MYC expression by targeting MYC regulatory proteins that are essential for its stability and oncogenic function. Previous research in our lab uncovered a novel MYCN binding protein, PA2G4, which stabilises MYCN and prevents it from targeted degradation, hence driving neuroblastoma tumorigenesis. Treatment of cells with a PA2G4 inhibitor called WS6 decreases both PA2G4 and MYCN expression in vivo and in vitro. WS6 is hypothesised to disrupt the PA2G4/MYCN interaction by binding to PA2G4. This decreases MYCN stability, enabling targeted degradation and reducing the malignant phenotype.
Translation of this research to a c-MYC-driven neuroblastoma model showed promising preliminary results. High and low levels of c-MYC expression correlated with high and low PA2G4 expression levels respectively. High PA2G4 levels were also associated with increased cell viability in neuroblastoma cells with high c-MYC. These results demonstrate a possible interaction between c-MYC and PA2G4. This study, therefore, aims to further investigate the interaction of c-MYC and PA2G4 in c-MYC-driven malignancies. Since c-MYC is implicated in more than 70% of human malignancies, this research will pave the way for better treatment of numerous human cancers.
HEAD OF PROGRAMProfessor Glenn Marshall AM
CLINICAL RESEARCH FELLOW
Dr Toby Trahair
Dr Hassina Massudi
Dr Zsuzsanna Nagy
Dr Ritu Mittra
Dr Amit Lalwani
Dr Mukesh Raipuria
Dr Anushree Balachandran
Jiunn Fung Cheong