<http://news.bbc.co.uk/1/hi/health/3646745.stm>

Last Updated: Thursday, 22 April, 2004, 01:32 GMT 02:32 UK

E-mail this to a friend    Printable version
GM bacteria used to fight cancer

E.coli was used to "smuggle" the enzyme into cells

A genetically altered version of the food poisoning bug E.coli could be
used to destroy cancer cells, say scientists.

Cancer Research UK experts used a neutralised version of the bacteria to
deliver a cancer-killing enzyme directly into the cells.

It provides scientists with a method of breaking through the previously
impenetrable barriers around the cells.

In tests using E.coli, over 90% of cancer cells were destroyed.

Using bacteria to treat tumours is an innovative new approach to the
problem

Professor Robert Souhami, Cancer Research UK

The bacteria were carrying an enzyme called purine nucleoside
phosphorylase into cancer cells.

It works in conjunction with a powerful anti-cancer drug called 6-MPDR.
The drug cannot be activated until the enzyme is inside the cancer
cells.

When researchers targeted mouse tumours with the bacteria and drug
combination , it appeared to slow down tumour growth and cause large
numbers of cancer cells to die.

'Efficient delivery'

E. coli bacteria are found naturally in the human gut and only a few
strains are harmful.

The research by experts at the Cancer Research UK Molecular Oncology
Unit at Barts and the London Queen Mary's School of Medicine and
Dentistry used a version of E coli that had been modified so it could no
longer grow, divide or cause disease.

Scientists added a gene called invasin, which gives E. coli the power to
enter human cells by passing through their outside membranes - which it
cannot normally do.

They also added a second gene, called listeriolysin O, which instructs
the E.coli bacteria to release the cargo it is carrying once it is
inside the cancer cell.

Dr Georges Vassaux, of the Cancer Research UK Molecular Oncology Unit,
who led the research, said: "It's notoriously difficult to get some
types of therapeutic molecule inside cancer cells, which is why we
turned to living organisms to do the job for us.

"With a few important genetic modifications, we were able to turn
bacteria into efficient delivery capsules, able to penetrate the outside
membrane of cancer cells and protect their precious cargo until safely
inside."

He said the therapy may also attack cancer cells a second way.

"We also think that introducing bacteria into a patient's body, albeit
harmless, neutered ones, will provoke the immune system and help to
direct it against the tumour."

Professor Robert Souhami, Cancer Research UK's director of clinical and
external affairs, said: "Developing new drugs tends to grab the
headlines, but equally important is the development of new systems to
efficiently deliver treatments to cancer cells.

"Using bacteria to treat tumours is an innovative new approach to the
problem and may offer the potential to target cancer cells with a range
of different therapeutic molecules.

"It could open up exciting new avenues of cancer treatment."

The research is published online by the journal Gene Therapy.

E-mail this to a friend    Printable version

LINKS TO MORE HEALTH STORIES