Metformin & Cancer Prevention

Diabetes drug metformin may prevent cancer   By Aaron Derfel, Postmedia News January 19, 2012 MONTREAL - The most widely prescribed drug to treat Type 2 diabetes might also help prevent colon cancer in those who are considered at high risk, suggests new research carried out by a team of Montreal scientists.

Metformin has already been shown in previous studies to cut cancer rates by 40 per cent in those taking the medication, compared with diabetics who are not.

Researchers at McGill University and the Universite de Montreal sought to understand exactly how Metformin might prevent cancer. The prevailing theory before their lab study was that since cancer cells have a voracious appetite for glucose, using a drug to lower glucose levels in the blood for the treatment of Type 2 diabetes might also inadvertently block cancer.

The researchers did confirm that the glucose-lowering action of Metformin does play a subtle role in preventing cancer. But they also made a much more important and unexpected discovery:Metformin protects cells from DNA damage that can lead to cancer.

``Surprisingly, we found that Metformin protected DNA from mutations,'' said the study's director, Dr. Michael Pollak, a professor in McGill's departments of medicine and oncology.

``It is remarkable that Metformin - an inexpensive, off-patent, safe and widely used drug - has several biological actions that may result in reduced cancer risk.''

Cells burn nutrients to produce energy. That burning-off process produces what Pollak likens to a kind of cellular exhaust, known as reactive oxygen species. It's this exhaust that can cause DNA damage inside cells, which in turn can spark cancer.

Metformin acts as a cellular exhaust ``filter,'' Pollak explained, reducing reactive oxygen species.

``The drug seems to selectively prevent (the cellular exhaust) production ... such as those found in cells with oncogenic mutations,'' said study co-author Gerardo Ferbeyre, of U de M's department of biochemistry.

The researchers made the discovery by treating pre-cancerous breast and colon cells with Metformin. The results of their study were published Wednesday in the journal Cancer Prevention Research.