Cancer cells tricked into suicide by gene therapy

Scientists have performed a "con trick" on cancer by persuading tumour cells to self- destruct after treatment with a new form of gene therapy.

The researchers said that the technique was a potential breakthrough in cancer treatment, which could be applied to many types of tumour that were currently difficult or impossible to treat.

Although the scientists have so far only done the research in the test tube, they believe that early results show that it could become a powerful new tool for treating cancer within five to 10 years.

Gene therapy, in which genes are manipulated to treat a medical condition, is still in its infancy but the Glasgow University team believes that the first clinical trials on cancer patients using the new technique could begin within two years.

"I feel very strongly that our research represents a potential breakthrough, with implications for the treatment of a variety of common cancers," said Dr Nicol Keith, who led the team from the Cancer Research Campaign's Beatson Laboratories in Glasgow.

"People have discussed similar kinds of gene therapy system before, but we've now made significant progress by moving from talking about the theory to actually killing cancer cells in a very efficient manner," Dr Keith said.

The research, published today in the journal Oncogene, involves introducing a gene into cancer cells that has the effect of switching on another gene that kills the cell. Ordinary cells are left untouched because the introduced gene contains a genetic switch that is only usually turned on in cancer cells.

"With a bit of genetic trickery, we've managed to fool cancer cells to their doom without harming normal cells. I'm optimistic that we could soon have targeted treatments that spare cancer patients the side-effects that many suffer today," Dr Keith said.

Cancer cells are known to switch on a gene called telomerase, which causes the cells to replicate uncontrollably. By attaching the switch for telomerase to a cancer toxin gene called nitroreductase, the scientists can selectively kill tumour cells without harming healthy tissue.

"We're using a sleight of hand to convince cancer cells that they're switching on the telomerase gene which they need for their survival when they're actually switching on a gene that will ultimately kill them," Dr Keith said.

Nitroreductase does not destroy tumours directly but converts a drug, called CB1954, which is normally harmless, into a toxin that rapidly kills cancer cells. Healthy cells will not produce nitroreductase and will not be harmed unless they are directly adjacent to a cancer cells that is producing the toxin.

Gordon McVie, director general of the Cancer Research Campaign, said: "I'm looking forward to seeing it developed for patients as soon as possible. If it works in one kind of cancer, it should be effective in many others."