Details of a unique ‘fossil molecule’ will be unveiled by Cancer Research UK scientists at a special conference in Dundee.
They believe the molecule, called the VS ribozyme – is the largest of a family of molecules that formed the basis of the original life forms on earth.
Ribozymes today are thought to have kept the same structure for some two billion years. They have escaped evolutionary change because they are so good at their job – acting as a molecular pair of scissors – a property that could be harnessed to attack cancer cells.
Lead researcher Professor David Lilley, from Cancer Research UK’s Nucleic Acid Structure Research Group at The University of Dundee says: “We think that molecules like the VS ribozyme were around long before even the simplest cells existed. They’re molecular fossils that have survived billions of years of evolution.”
In the cell, ribozymes use their scissor function to cut up molecules called RNA. These molecules play a key role in producing the proteins that are the building blocks of the cell.
When genes in the cell are switched on they give out molecular messages written in RNA to produce proteins. Researchers believe that ribozymes can be designed to attack the RNA message and effectively turn genes off.
Genes involved in the growth and formation of blood vessels around tumours could be potential targets for ribozymes. If these genes are knocked out then cancers can be starved of their vital blood supply.
But Professor Lilley warns: “Such therapeutic applications are a long way off as there are still considerable obstacles to overcome.”
The use of ribozymes in cancer treatment may be a thing of the future but scientists believe that the VS ribozyme can still unlock some secrets of our past. The molecule may hold the key to a tricky evolutionary problem.
Professor Lilley explains: “There’s a long standing mystery in how life on earth evolved. Our cells contain DNA – which provides the plan for making cells – and proteins – which provide the tool kit for putting the plan into action. But it’s hard to see how the very earliest life forms could exist with only one of the two. It’s a chicken and egg problem.
“However, our research adds weight to the theory that RNA existed long before DNA-based life, which could resolve this evolutionary paradox. Like DNA, we know that RNA can store information. Now we are beginning to find that RNA molecules, such as the VS ribozyme, can also do the job of a protein.”
Early life on earth may have passed through an evolutionary phase where RNA molecules such as the VS ribozyme acted out a double life.
Sir Paul Nurse, Chief Executive of Cancer Research UK says: “This is very interesting area of study that not only has implications for the future of cancer therapeutics but also has great importance in the understanding of our evolution at a molecular level.”
The conference ‘Ribozymes and RNA Catalysis’ was held at the University of Dundee, 23-27 August 2002