Scientists use genetic fingerprints to collar cancer culprits

Environmental chemical ‘suspects' cause characteristic mutations in DNA that can be used to identify them, a study has found.

A new library of DNA “fingerprints” could help detective scientists close in on the environmental culprits behind cancer.

UK experts have created a database of the mutation markers, which include those left by tobacco chemicals in lung-cancer tumours.

In total the scientists identified the “prints” of 41 environmental agents linked to cancer, such as tobacco smoke, sunlight, and air pollution from road vehicles.

Each of the chemicals triggers a specific change in the molecular structure of DNA that can lead to cancer.

Dr Serena Nik-Zainal, from the Medical Research Council Cancer Unit at Cambridge University, who co-led the research, said: “Mutational signatures are the fingerprints that carcinogens leave behind on our DNA, and just like fingerprints, each one is unique.

“They allow us to treat tumours as a crime scene and, like forensic scientists, allow us to identify the culprit, and their accomplices, responsible for the tumour.”

At the start of the study the scientists exposed skin-derived stem cells to 79 known or suspected environmental carcinogens, or cancer triggers.

The cells had been reprogrammed back to an embyronic-like “pluripotent” state, giving them the potential to become any type of cell in the body.

The researchers then looked at the patterns of changes caused by the chemical “suspects”.

They found that 41 left a characteristic, unique, fingerprint on the stem cells’ DNA.

Among them were mutations known to occur in the lung tumours of smokers, allowing scientists for the first time to identify the tobacco chemicals responsible.

Other “fingerprints” were left by common chemotherapy drugs, some dietary chemicals, and chemicals present in diesel exhaust fumes.

The research demonstrates just how vulnerable human DNA is to chemical agents that pervade the world we live in, say the scientists whose findings are reported in the journal Cell.

Dr Nik-Zainal said: “Our reference library will allow doctors in future to identify those culprits responsible for causing cancer.

“Such information could be invaluable in helping inform measures to reduce people’s exposure to potentially dangerous carcinogens.”

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