For more than five thousand years, humans have harnessed the power of yeast to brew beer and leaven bread, even though they may have attributed the bubbles of fermentation to mysterious forces rather than fungal micro-organisms.
Over recent decades, humble baker’s and brewer’s yeasts have made it out of the kitchen and into the research lab. Although humans and yeast inhabit completely different branches of the evolutionary tree – animals having branched off from fungi around one and a half billion years ago – we still share strong similarities with our single-celled distant cousins. Around forty percent of human genes are also found in yeast, including the fundamental genetic instructions that tell cells when to grow and divide.
While this process of cell division is highly useful (not to mention tasty) when you use yeast to make beer or bread, it also lies at the heart of human cancer. The disease is caused by cells in our own body multiplying out of control to form solid tumours such as breast, bowel or lung cancer, or “liquid cancers” affecting immune cells in the blood, more commonly known as leukaemia. And it’s not just human and yeast cells that share the same genetic drivers for division. A similar set of genes are used to control cell growth in virtually all living cells, although very simple organisms like bacteria do things differently.
Over the years, yeast has proven to be a valuable model organism to help researchers pin down these drivers, with much less mess and fuss than other life-forms. They’re easy and quick to grow in the lab, reproducing in just a few hours – human and animal cells can take a day or more – and needing little more than nutrient broth or jelly and a warm incubator to keep them happy.
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Understanding the genes that drive cell growth is essential if we’re to truly get to grips with cancer and develop more effective therapies. Two people who’ve made a huge impact in this area are Cancer Research UK scientists Professor Sir Paul Nurse and Sir Tim Hunt, who won a Nobel prize in 2001 (along with US researcher Dr Leland Hartwell) for their discovery in the early 1980s that the genes driving cell division are the same from yeast to plants, animals to humans, and how they work together to make cells multiply.
Since then, research has continued apace, and we now have a much more detailed picture of how a huge network of genes and molecules fit together to drive the “engine” of cell division. The picture is extremely complex, but clarity is starting to come. Professor Nurse and his team recently published the first comprehensive “roadmap” of the genes that coordinate the division and growth of yeast cells, helping to provide a framework for understanding how the same genes might work in healthy – and cancerous – human cells.
To construct their map, the researchers trawled through nearly 5,000 different strains of a type of brewer’s yeast known as Schizosaccharomyces pombe, each missing a single different gene, to see if the cells had problems with growth or division, or were a strange shape (usually an indicator of underlying growth problems). If cells have these problems, it’s usually because the missing gene normally plays an important role in making sure everything works properly.
The search turned up more than 500 genes involved in cell division, more than half of which hadn’t been discovered before. And nearly 900 more genes were implicated in growth, as yeast cells missing any these particular genes were misshapen. In total, the scientists investigated more than 95 percent of the total number of yeast genes – an impressive feat that provides a valuable resource for researchers working in this field.
The next step is to find out how many of these genes match to equivalent ones in human cells, and whether they work in the same way within our bodies as they do in single-celled yeast. But, based on research over the past few decades, there’s a good chance that important discoveries will be made in the coming years, which will hopefully translate into new treatments for cancer patients. For example, there are a number of drugs currently in clinical trials aimed at blocking some of the molecules first revealed by Nurse, Hunt and Hartwell back in the 1980s.
And Professor Nurse and his team are certainly in the right place to take their ideas forward. After spending a number of years in the US, he’s now returned to the UK to head up the new Francis Crick Institute, currently being built in central London. Once finished, it will house the largest biomedical research facility in Europe under one roof, bringing together scientists working on a range of challenging diseases, including cancer, stroke, immune disorders and more.
The history of scientific progress tells us that great ideas can come from collaborations across disciplines and fields. So maybe the cancer drugs of the future will come from discoveries made in tiny yeast, springing from conversations between researchers in the local pub over a pint of beer and a breadbasket.
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