proteins and DNA strand
The MYC gene codes for a protein that functions as a transcription factor. These proteins (pictured in purple) bind to DNA (blue) in the cell and help control cell growth. (Photo: iStock)

Cancer is a genetic disease – one that results from changes, known as mutations, to our DNA and genes.

When it comes to promoting cancer, not all mutations are equal. This is because cancer-causing mutations affect certain genes far more frequently than others.

One of these genes is known as MYC, which codes for the MYC protein. Over half of all cancers show changes to levels of MYC – a distinction that has led to it being referred to as one of the "hallmarks of cancer."

Because MYC is involved in so many different cancers, targeting it would be a promising strategy to stop the growth of cancer. However, to date, and despite extensive efforts, drugs developed to block MYC have failed in experimental models.

New findings by Dr. Linda Penn, a Senior Scientist at the Princess Margaret Cancer Centre, have overcome this hurdle. Her latest work, published in Cancer Cell, reveals a new way to target MYC – one that is based on new insights into how the MYC protein functions in the cell.

Along with her collaborators, Dr. Penn's team identified a protein – known as G9a, a histone H3K9-methyltransferase complex – that binds to and works together with the MYC protein to promote the growth of cancer.

"By identifying that MYC binds to G9a to repress the expression of specific genes, we have overcome a long-standing mystery in the field and identified a potential new anticancer target," says Dr. Penn.

"Importantly, we were able to show in various experimental and preclinical models that targeting G9a slows MYC-driven tumour growth. This is a major advancement because MYC has been declared 'undruggable' using traditional drug development approaches.

"Our work suggests that, by targeting a key partner protein of MYC, anticancer drugs for MYC-driven cancers could be developed."

This work was supported by the Canadian Institutes of Health Research, the Ontario Institute for Cancer Research, the Terry Fox Research Institute and The Princess Margaret Cancer Foundation. LZ Penn holds a Tier 1 Canada Research Chair in Molecular Oncology. C Arrowsmith holds a Tier 1 Canada Research Chair in Structural Proteomics.

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