Wednesday, December 28, 2011

New mechanism reveals how body prevents cancer

Scientists from the University of Zurich showed that the body possesses a repair mechanism that is supposed to prevent our cells to become cancerous. They found a molecule that repairs damage in our genetic code, induced by factors that can for example be released by smoking. If this particular repair mechanism does not function properly, genetic damage persists and can alter cellular behaviour. While most cells die, some actually become cancerous. While we possess more of these DNA repairing molecules, the discovery of this particular one is important. By improving its functionality, we might be able to prevent cancer.

Oxidative stress
DNA damaged by so-called oxidative stress is repaired by the molecule that the researchers from Zurich found. Oxidative stress occurs when the body produces 'radical' oxygen molecules. These special pieces of oxygen are very reactive, and interact with almost everything they come in contact to. This causes damage: when radicals react with the cell membrane, for example, the cell might start leaking. Equally so, oxygen radicals are able to damage the DNA, which is where the newly discovered molecule comes in.

DNA repair
Our genetic code is build up from four distinct building blocks, abbreviated by their first letter. They are known as A, T, C and G. The repair molecule, called Pol λ, focuses on repairing misconstructed G's in the DNA. However, Pol λ can be targeted and degraded, leaving it unable to perform repairs. However, in some parts of the cell cycle it is stabilized, which makes repairs much easier. The balance between stabilization and degradation is important, and needs to be investigated further.

Tumours can develop because cellular mechanisms that protect the cell from acquiring damage and grow uncontrollably are broken. With the right set of mutations in the DNA, cells gain the capability to focus almost exclusively on growth. When DNA repair mechanisms are active, cells do not get the chance to build up mutations.

It is known that smoking causes oxidative stress, and can lead to cancer. That immediately reveals why this discovery is important. By reducing the genetic damage caused by oxygen radicals, cancer may be prevented. For this, we need Pol λ, which makes it an interesting therapeutic target. While the researchers from Zurich have merely discovered a fundamental cellular mechanism, one can easily see how this may become useful in the future. 

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