Cancer's sweet tooth

Otto Warburg

One of the best things about being a scientist is discovering something no one has ever done or seen before. Whether it be the creation of a new man-made plastic, or the discovery of the Higgs boson, science is tirelessly expanding our collective knowledge. Sometimes however, we're so busy focusing on the horizon and the next scientific breakthrough that we forget to look over our shoulder and examine in sufficient detail what has come before.

Cancer detection through imaging

A German scientist, Otto Warburg made the discovery in the 1920s that cancer cells consume sugar in far greater amounts than normal healthy cells.  It's only recently though that we have started to use this discovery to our advantage.  By designing drugs that curtail this 'addiction' to sugar it is hoped that we can stop these cancer cells from growing. We also take advantage of cancer's sweet tooth during diagnosis. Following injection of a radioactive sugar into the bloodstream, clinicians can detect cancer using a scan that measures where that sugar is being used in the body.  An example is shown to the left, with the tumour indicated by the arrow.  It is now thought that cancer cells use the sugar to protect against harmful waste products, for energy, and to create building blocks to form new cells.

Following in the footsteps of Warburg, a team of French scientists made the discovery in the late 70s/early 80s that cancer cells save some of this sugar for a rainy day - when extra energy is needed, or to keep the cells alive when the supply of sugars from elsewhere runs out. This discovery is fascinating given that sugar stores are normally only found in the liver and muscle. Cancer cells that originate from say the breast or ovary seem to acquire the ability to store these sugars through, as of yet, unknown mechanisms. These findings have been largely ignored until now. In a research article published this month in Cancer Research, myself and my colleagues at Imperial College London further explore this phenomenon, some 30 years later.  We showed that cancer cells store more sugar when they stop growing and that we can detect these sugar stores through imaging. A picture of these sugar stores are shown below, indicated by the intense orange/yellow dots within the cancer cells. The identification of these stores has wider implications as cancer cells that grow more slowly are typically more resistant to traditional chemotherapy. It's hoped that this new imaging method might be able to detect these slower growing cells that we can then target with different drugs. Although this technique hasn't been tested in humans yet, we are hoping scans, similar to the one shown above, will be performed in the next few years.  There is also hope that this technique can be used to detect other sugar storage diseases such as diabetes.

Cancer's sugar stores

For more information, the research article, 'A Novel Radiotracer to Image Glycogen Metabolism in Tumors by Positron Emission Tomography' can be found here.