LONDON (Reuters) - British scientists have discovered a new way to improve the effectiveness of drugs used to treat prostate cancer.

Researchers at the Weatherall Institute of Molecular Medicine in Oxford found that blocking the action of a gene called IGF1R makes prostate cancer cells more sensitive to radiotherapy and certain chemotherapy treatments.

"This is the first study to show that silencing the IGF1R gene can improve the effectiveness treatments for prostate cancer," Dr Val Macaulay, who headed the research team, said on Friday.

Prostate is one of the most common cancers in men. Each year 543,000 new cases are reported worldwide and the disease kills 200,000 mostly older men in developed countries.

Starving the cancer of male hormones works in the early stages but the disease eventually becomes hormone-independent and the treatment ceases to work.

"Prostate cancer is very resistant to essentially all forms of chemotherapy, so there is an urgent need for new ways to tackle the disease," Macaulay told Reuters. "Chemotherapy drugs have very limited activity and we are looking for ways to make them more effective," she added.

Macaulay and her colleagues found that switching off the gene in prostate cancer cells with a genetic technique called RNA interference doubled their sensitivity to radiotherapy.

It also made cancerous cells that were resistant to hormone-based therapy vulnerable to chemotherapy drugs that damage DNA.

The scientists blocked production of the protein produced by the IGF1R gene. Pharmaceutical companies are also working on compounds that inhibit the protein's function.

Macaulay is now testing the technique on animals. If it is successful, her team plans to begin human trials. The research, which is funded by the charities Cancer Research UK and the Health Foundation, is reported in Cancer Gene Therapy.

"It is another step toward making prostate cancer cells more sensitive to chemotherapy by using a molecular agent which is specific for this growth-promoting protein," said Macaulay.

The gene and its protein are involved in many cancers so the technique could be useful in treating other types of the disease.

"IGF1R sustains many types of cancer cell, so blocking the gene could prove a powerful new way of treating tumors. This is early stage research, but holds great promise in the fight against not only prostate cancer but other forms of the disease," said Professor Robert Souhami of Cancer Research UK.

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