Saturday, November 12, 2011

Genome modification used for treating cancer

A novel treatment that focuses on altering the structure of our DNA was found to be effective in patients suffering from lung cancer. It works on an epigenetic level. That means it works by altering the activity of genes, without actually touching the genetic code. The epigenetic treatment was given in concert with ordinary treatment, in cancer patients that suffered from metastasis, and were already pretreated for a long time. The epigenetic therapy was found to prolong patient life, and one participant even fully recovered and is still alive, two years after he joined the study.

The therapy works by altering the structure of the genome. Chemical compounds called methyl and acetyl are able to bind to DNA and histones, the latter being structures that are used to wind up the DNA. Adding methyl and acetyl groups can cause the structure of the DNA on the 'spools' to change. They become tighter, which renders the cellular machinery that is involved with transcription of genes to protein unable to reach the genetic code, which effectively silences the genes.

From right to left: genetic code being wound up into a histone structure.
In their study, the scientists used a cocktail of ordinary cancer treatment with inhibitors of DNA methylation and histone deacetylation. That means that adding a methyl group to the DNA, and removing an acetyl group from the histone structure was slowed down by the drugs. Correspondingly, the scientists found that four genes, that were previously silenced by epigenetic factors, were activated by the treatment, and improved patient survival. The genes in question are known to play a role in slowing down cancer development. The median survival rate of the patients that participated in the clinical trials was 6.4 months.

Epigenetics is an emerging field that has been increasing in popularity over the last 20 years. Scientists found that certain mechanisms influence the genome without actually affecting the code itself, but rather the structure that holds it. It is related to genetics because epigenetic modifications are also inherited: the pattern of methyl and acetyl groups that are attached to specific parts of the DNA can be passed down parents to their offspring, just like what happens to the actual genetic code. The newly developed therapy for cancer patients is prove that studying epigenetics makes sense.

In previous studies, scientists have shown that epigenetic modification can be inherited. An example is the living conditions in which you've grown up: this is reflected in your DNA. In an animal study, scientists have found that a longer life span caused by epigenetic alterations can be inherited, as well as a form of obesity.

No comments:

Post a Comment