“What can chickens teach us about cancer?”
30 Aug 2021
Written by York Against Cancer Research Fellow – Doctor Andrew Mason.
As a researcher of human cancers, it often raises an eyebrow when I tell people I spent my PhD studying chickens. The eyebrow can often get lost in the hairline when I say there’s no real difference between humans and chickens at all!
Whilst a little glib, as a bioinformatician, studying the long strings of As, Ts, Cs and Gs which represent the DNA in all organisms, it is largely true. The chicken genome is smaller than the human genome (about one third the size), but shares many of the same genes, and is prone to similar methods of DNA damage which can lead to cancer. For example, retroviruses are viruses which integrate (combine) into the host DNA as part of their infective life cycle, and are commonly “oncogenic” (cancer causing). Retroviruses drive cancer formation by turning on genes which would usually be kept silenced.
In chickens I studied the role of “endogenous” retroviruses – retroviruses which have become “stuck” in the host DNA and are now inherited from generation to generation, sometimes impacting healthy development, leading to spontaneous tumours, and affecting how the chicken handles new viral infections (and not just other retroviruses).
And how does this relate to humans? Well, approximately 8% of our DNA is made up of thousands of copies of endogenous retroviruses, collected over our evolution. This is truly staggering, when you consider that only 2% of our DNA is responsible for all the proteins and molecules needed to fully construct and maintain us. Most human endogenous retroviruses (HERVs) are now defunct, but HERVs become active in cancers, where they can influence tumour growth and spread, as well as treatment success. The Jack Birch Unit has a particular interest in urothelial cancers where, so far, the impact of HERVs is unknown. Drawing on my previous research I plan to examine the importance of HERVs in urothelial cancers as my York Against Cancer-funded research fellowship continues.
Dr Andrew Mason, York Against Cancer research fellow – with credit for the brilliant cartoon to Alex Hawley (Andrew’s father-in-law)