Targeting MYC through next generation structure-function

Background: It is estimated that dysregulation of MYC occurs in over 70% of all human cancers, making it one of the most enticing targets for cancer drug development. However, no efficacious small molecule inhibitors have reached clinical stage development for this challenging target. Through CRUK Pioneer funding, we have shown that the N-terminus of MYC is absolutely required for tumour maintenance.

We performed a site-saturation structure function screen, identifying 19 different N-terminal residues that are crucial to function, many of which involve novel sites. Aims: We plan to validate these mutations for oncogenic function in a variety of in vitro and in vivo tumour models.

We hypothesise these mutations disrupt specific protein-protein interactions, and we aim to identify the direct MYC binding partners that are crucial for function.

Lastly, we aim to build a 3-dimensional model of the specific protein-protein interface of MYC with its binding partner.

Methods: The 19 different mutations will be individually validated for their ability to rescue cell growth in MYC-off T-ALL cell lines, neuroblastoma lines and breast cancer cell lines.

We will test the transformation potential of these mutations in an in vivo model of MYC-induced T-cell acute lymphoblastic leukaemia in the zebrafish.

Using BioID, we will characterise the protein binding partners of MYC and MYC mutants, enabling us to identify the specific direct interactors of MYC that are crucial for its oncogenic function.

Lastly, we will characterise the protein-protein interface using HDX-MS and generate a crystal structure of MYC together with its binding partner.

How results will be used: characterising the specific protein-protein interface of MYC with a critical partner protein will provide a framework for rational drug design and enable direct small molecule screens for inhibitors that interrupt formation of the complex.