Human cells evolved to reduce cancer risk

Researchers at the Samuel Lunenfeld Research Institute of Mount Sinai Hospital, University of Toronto, The Institute of Cancer Research (UK) and the University of California have found that as animals moved up the evolutionary chain they progressively shed molecules that are linked to cancer development. The cells of humans and other animals have likely evolved to reduce the chance of triggering cancers and other diseases, according to research published today in the journal Science.

"This research highlights how studying evolution can help us better understand human disease,” states Dr. Gary Bader, Associate Member of the Samuel Lunenfeld Research Institute and author on the paper. “The observations in this paper help us better understand how specific changes in proteins can rewire cell networks to cause disease."

As animals have become more biologically complex they have acquired more variants of tyrosine kinases, a class of enzymes that control the behaviour of cells. Tyrosine kinases are necessary for survival as their effect on an amino acid called tyrosine alters proteins, sending instructions to cells about when to move, grow and die – but they can also become damaged and send the wrong signals, causing cancer and other diseases.
 
The research team found that, in an apparent effort to compensate for this increased risk, the cells of more complex animals have reduced the amount of tyrosine they allow in their proteins – leaving less opportunity for the kinases to malfunction.

Tyrosine levels in animals – including a worm, sea squirt, fly, mosquito, two species of pufferfish, frog, chicken, dog, cow, mouse, rat, chimpanzee and humans – were evaluated relative to other amino acids. A “striking” progressive reduction in tyrosine concentrations was found to occur higher up the evolutionary chain.

The research was led by the Samuel Lunenfeld Research Institute of Mount Sinai Hospital, in collaboration with the University of Toronto, The Institute of Cancer Research (UK) and the University of California, San Francisco, US.