19 March 2012
ByAppeared in BioNews 649
A gene known to protect from cancer might also prevent obesity, a study from the Spanish National Cancer Research Centre has found. The researchers had set out to search for a link between the Pten gene and a longer lifespan in mice, but to their surprise, a double dose of the gene also led the mice to be 28 percent thinner than their normal counterparts.
The study used transgenic mice, engineered to have an extra copy of their normal Pten gene. Pten is known to be an important tumour suppressor gene, protecting cells from becoming cancerous. It also plays an important part in regulating cell growth.
Three similar tumour suppressor genes are thought to not only protect cells from cancer, both also from ageing. A gene similar to Pten has been shown to increase the lifespan of worms and flies, but this is the first time a tumour suppressor gene has increased longevity in experiments on mammals.
The researchers started out by confirming that an extra copy of the Pten gene protected the transgenic mice from cancer. As expected, the transgenic mice also lived longer normal mice. This was even true when Pten's protective effect on cancer was taken into account.
'What we are seeing is that tumour suppressor genes not only protect against cancer but also against the damage that builds up in the body over time', Dr Manuel Serrano, who led the study, explained.
The real surprise was that the transgenic mice were thinner, even when eating more or being fed a high fat diet. The researchers found that this was due to heightened activity of brown fat, a type of fat which burns rather than stores energy. Brown fat is especially abundant in animals that hibernate, and in newborn babies, but less so in adults.
The transgenic mice in this experiment not only had more brown fat, meaning that they burned more energy, but the fat also burned energy at a higher rate.
Despite these encouraging findings, brown fat appears to be less important in humans than mice and so using it to combat obesity may be problematic.
Nonetheless, the team has developed a compound that has the same effect on mice as the double dose of the Pten gene. Dr Serrano thinks it is now possible to imagine 'a pill that boosts our tumour suppressors or one that makes us burn off excess nutrients'.