Dr Christopher Runchel investigates the surprising role of the fruit fly in medical research.

Tuesday 9 September 2014      Research blog
A small male Drosophila melanogaster fly (fruit fly)

The Drosophila melanogaster fly, commonly known as the fruit fly, can be an excellent tool for medical research. Image credit: André Karwath

You’ll probably know fruit flies as the small flying pests that feed and live on your decomposing leftovers in the bin or compost pile. But you might be surprised to hear that this little insect has also saved numerous human lives. This isn’t because having them around gives us any kind of health benefit, but because they are an excellent tool for medical research.

Fruit flies and life-saving drugs

Research conducted in fruit flies, or Drosophila melanogaster as they are called by scientists, has had an immense impact on our understanding of biology which has directly contributed to the development of many of the life-saving drugs that we today use to treat serious diseases. Fruit flies have been used for more than a century to study biology, and today thousands of scientists around the world are using this insect in their research.

Why do scientists use flies in their research?

It may seem strange, but although we don’t exactly look or behave like flies, we are actually very similar to them in terms of biology. We share an astounding 60% of our genes with flies. This means that if something works in a certain way in flies, it is very likely to work in the same way in humans. By studying the biology of flies, we can learn about ourselves.

Fruit flies are used primarily for “basic” research, which is entirely curiosity driven with the aim to increase our fundamental understanding of biology. It is this type of science that is the foundation for developing treatments for diseases such as breast cancer.

Fruit flies are useful for this kind of research because in addition to being biologically similar to us, they are very easy to keep, they reproduce quickly and they develop fast, ultimately speeding up the pace at which experiments can be performed. Also, because flies have been used in research for so many years there is a wide range of genetic tools and tricks available that allows scientists to get to the bottom of how biology works. For example, using a powerful technique called the UAS-GAL4 system, scientists can very precisely switch genes on or off in whichever tissue they want. This is so specific that a gene can be manipulated in a very small group of cells, or even in a single cell. By switching off a gene, scientists can observe changes in cell behaviour and thereby get an idea of the gene’s function.

Do flies get cancer?

Fruit flies only live up to two months, so they don’t exactly get tumours in the same way as humans, but there are many similarities. By manipulating the genetics of a fruit fly it is possible to mutate certain genes to make their cells start growing out of control so they form tumours. In fact, many genes that regulate growth of tissues and the development of cancer were first identified in fruit flies.

An example of this is the Hippo signalling pathway, which is a group of genes that work together to control how big tissues grow. Disrupting the activity of this group of genes can cause tissues to grow out of control, which is a hallmark of cancer. Most of these genes were initially discovered in fruit flies, which lead to the later identification of the same genes in humans.

Further studies in humans have shown that genes in the Hippo pathway can promote breast cancer growth and scientists are now working actively to develop drugs targeting genes in the pathway. The fast-paced characterisation of this pathway in humans and the promising prospect of the development of new drugs would not have been possible without the initial research in fruit flies.

The cell death programme

Another aspect of cancer research that can be studied in fruit flies is how cells die. Almost all cells in our body contain a suicide programme, called apoptosis, which is activated when the cell senses something is wrong. For example, if a cell picks up genetic mutations which could lead to cancer, it can activate apoptosis to kill itself and prevent the disease from starting. Some cancer cells can develop ways to switch apoptosis off, meaning they fail to die when they should and begin to grow out of control. This is a characteristic of cancer and a problem which can make cancer cells extremely hard to kill.

Pioneering research in fruit flies, conducted by Professor Pascal Meier at the Toby Robins Breast Cancer Research Centre and other leading scientists around the world, has provided key insights into how the cell death programme is activated and executed. Based on this work, scientists discovered a gene in humans called SMAC, which directly activates the suicide programme in cells, causing them to die. This led to the development of a type of drug called SMAC mimetics, which mimics the biological activity of SMAC and cause cancer cells to kill themselves. These drugs are now in clinical trials for several cancers, including breast cancer, and are showing very promising results.

In praise of the humble fruit fly – a research pioneer

Funding research in fruit flies is something that at first glance might seem strange, but the past has shown us that it can lead to breakthrough discoveries that have a direct effect on cancer treatment. So next time you see a fruit fly buzzing around the bin, think about the amazing work it’s relatives are doing to help us understand the biology of cancer.

Dr Christopher Runchel was Breakthrough's Research Officer. (Editor's note 2016: now Breast Cancer Now

Breast Cancer Now agrees with the policy on animal research advocated by the Association of Medical Research Charities (AMRC) of which we are a member. They state that scientists should only use animals in research when there is no alternative. This is a requirement by law.