Bugs help scientists fight cancer

From: http://news.bbc.co.uk/2/hi/health/6347057.stm

Feb 11, 2007

The bacterium took drugs right into cancer cells

A bacterium which is closely related to bugs that cause gangrene, tetanus and food poisoning could help scientists beat cancer.

A US team is using Clostridium novyi-NT to release cancer-fighting drugs once they have been delivered directly into the tumour.

Early tests in mice proved promising and more work is planned, Science magazine reports.

The team are confident many different cancers could be treated in this way.

The strategy they used exploits some of the unique features of tumours and Clostridium.

Cancers tend to be relatively low in oxygen compared to other tissues because their blood supply is often not as good.

And the blood vessels that do supply the tumour tend to be quite leaky.

Breaking down walls

Dr Ian Cheong and his team, at the Howard Hughes Medical Institute and the Johns Hopkins Kimmel Comprehensive Cancer Center in Baltimore, used agents called liposomes to carry the cancer-fighting drugs into the tumour.

Liposomes, being relatively large particles, pass through the leaky blood vessels and into the tumour, but are generally too big to escape from blood vessels in the surrounding healthy tissue.

However, liposomes are fairly robust and take a while to break down and release their drugs once they have arrived at their target.

To speed up the process, the scientists used Clostridium, which is a low-oxygen loving bacterium that is good at breaking down the walls of particles and in this case, fortuitously, liposomes.

Specifically, the bacterium releases a protein called a liposomase, which ruptures the liposome, the researchers found.

Many of the mice treated in this way had their bowel cancers completely eradicated with a single dose of the therapy.

The mice also appeared to tolerate the treatment well and showed no obvious side effects.

The researchers said their findings offered exciting possibilities, but acknowledged more work was needed to see if the same strategy could treat cancer in humans.

Ed Yong, science information officer at Cancer Research UK, agreed that proof in humans would be needed, adding: "If they can do this, then bacteria, or at least their proteins, may become the latest recruits in the fight against cancer."