Artificial moles could serve as cancer warning system

Scientists have developed a synthetic gene network that serves as an early warning system against cancer, producing visible moles on the skin as soon as the system detects the development of a tumour in the body.

Cancer has become one of the top causes of death in industrialised countries. Many of those affected are diagnosed only after a tumour has developed extensively. This often reduces the chance of recovery significantly.

The ability to detect such tumours reliably and early would not only save lives, but also reduce the need for expensive, stressful treatment.

The gene network, developed by researchers from ETH Zurich in Switzerland, recognises the four most common types of cancer - prostate, lung, colon and breast cancer - at a very early stage when the level of calcium in the blood is elevated due to a developing tumour.

The early warning system comprises a genetic network that researchers integrate into human body cells, which in turn are inserted into an implant.

This encapsulated gene network is then implanted under the skin where it constantly monitors the blood calcium level.

As soon as the calcium level exceeds a particular threshold value over a longer period of time, a signal cascade is triggered that initiates production of the body's tanning pigment melanin in the genetically modified cells. The skin then forms a brown mole that is visible to the naked eye.

The mole appears long before cancer becomes detectable through conventional diagnosis.

"An implant carrier should then see a doctor for a further evaluation after the mole appears," said Martin Fussenegger, a professor at ETH Zurich.

The mole does not mean that the person is likely to die soon, he said. It simply means that clarification and if necessary treatment is needed.

The researchers used calcium as the indicator of the development of the four types of cancer, as it is regulated strongly in the body. Bones serve as a buffer that can balance out concentration differences.

However, when too much calcium is detected in the blood, this may serve as a sign for one of the four cancers.

Early detection increases the chance of survival significantly. For example, if breast cancer is detected early, the chance of recovery is 98 percent.

However, if a tumour is diagnosed too late, only one in four women has a good chance of recovery.

"Nowadays, people generally go to the doctor only when a tumour begins to cause problems. Unfortunately, by that point it is often too late," Fussenegger said.

The implant is intended primarily for self-monitoring, making it very cost effective, he said.

The disadvantage is that the service life of such an implant is limited.

"Encapsulated living cells last for about a year, according to other studies. After that, they must be inactivated and replaced," Fussenegger said.

The researchers have tested their early warning system in a mouse model and on pig skin. It functioned reliably during these tests. Moles developed only when the calcium concentration reached a high level.