Scientists have pinpointed a molecular mechanism in mice which helps skin cancer cells confound the animal’s immune system, according to a study released yesterday.

The discovery – if duplicated in humans – could one day lead to drug treatments that block this mechanism, and thus the cancer’s growth, the study reported.

In experiments on mice, researchers showed for the first time that a protein called interferon-gamma (IFN-gamma) plays a key role in the spread of melanoma, a notoriously aggressive form of cancer resistant to standard chemotherapy.

The same kind of ultraviolet radiation that leads to sunburn caused white blood cells to infiltrate the skin of the mice, explained Glenn Merlino, a scientist at the US National Cancer Institute and the main architect of the study.

The white blood cells, in turn, “can produce IFN-gamma. We believe that IFN-gamma can promote melanoma in our model system, and perhaps in people,” he said.

Injecting the mice with antibodies that block IFN-gamma interrupted this signalling process, effectively reducing the risk of UV-induced skin cancer, the researchers found.

“We are trying to develop inhibitors that are more practical than antibodies, a small molecule, for example,” Dr Merlino said.

Ideally, such a treatment would mean that someone exposed to large doses of UV radiation – long summers at the beach without protective cream, for example – could escape the potentially lethal threat of skin cancer.

“But we would never encourage intense sunbathing, even if such a treatment were available,” Merlino cautioned.

Cases of cutaneous malignant melanoma are increasing faster than any other type of cancer.