The discovery of air pollution that could revolutionize the fight against cancer

Researchers say they have discovered how air pollution leads to cancer, in a discovery that completely transforms our understanding of how tumors arise.

The team at the Francis Crick Institute in London showed that rather than causing damage, air pollution was waking up damaged old cells.

One of the world’s leading experts on the subject, Professor Charles Swanton said the breakthrough marks a “new era”. And now it may be possible to develop drugs that prevent cancers from forming.

The findings could explain how hundreds of carcinogens act in the body.

The classic view of cancer starts with a healthy cell. It acquires more and more mutations in its genetic code, or DNA, until it reaches a tipping point. Then it becomes a cancer and grows wildly.

But there are problems with this idea: cancerous mutations are found in apparently healthy tissue, and many substances known to cause cancer — including air pollution — don’t seem to damage people’s DNA.

So what’s the problem?

The researchers produced evidence for a different idea. The damage is already in our cell’s DNA, picked up as we grow and age, but something has to pull the trigger that actually makes it cancerous.

The discovery came from investigating why non-smokers get lung cancer. The overwhelming majority of lung cancers are caused by smoking, yet one in ten cases in the UK is due to air pollution.

Francis Crick scientists focused on a form of pollution called particulate matter 2.5 (known as PM2.5), which is much smaller than the diameter of a human hair. and animals, they showed that:

• Locations with higher levels of air pollution had more non-smoking lung cancers
• Breathing in PM2.5 leads to the release of a chemical alarm (interleukin-1-beta) in the lungs
• This causes inflammation and activates cells in the lungs to help repair any damage.
• But about one in every 600,000 cells in the lungs of a 50-year-old already contains potentially cancerous mutations.
• They are acquired as we age, but appear completely healthy until they are activated by the chemical alarm and become cancerous.
• Crucially, the researchers were able to prevent cancer from forming in mice exposed to air pollution by using a drug that blocks the alarm signal.

The results are a double step forward, both for understanding the impact of air pollution and for the fundamentals of how we get cancer.

Emilia Lim, one of the researchers at the Francis Crick Institute, said people who had never smoked but developed lung cancer often had no idea why.

“Giving them some clues as to how this might work is very, very important,” says Lim.

“It’s super important, 99% of people in the world live in places where air pollution exceeds WHO guidelines, so it really affects us all.”

rethinking cancer

But the results also showed that mutations alone are not always enough to cause cancer. They may need an extra element.

Professor Swanton said this was the most exciting discovery his lab has found, as it “really rethinks our understanding of how tumors are initiated”. He says this would usher in a “new era” of molecular cancer prevention.

The idea of ​​taking a pill to block cancer if you live in a highly polluted area is not completely fanciful.

Doctors have already tested an interleukin-1-beta drug in cardiovascular disease and found, quite by accident, that it reduces the risk of lung cancer.

The latest findings are being presented to scientists at a European Society of Medical Oncology conference.

Speaking to the BBC of the conference, Professor Swanton said: “Pollution is a beautiful example, but there will be 200 more examples of it in the next 10 years.”

And he said we needed to even rethink how smoking causes cancer — is it just the known DNA damage caused by tobacco chemicals, or does the smoke also cause inflammation?

Interestingly, the idea that mutated DNA is not enough and cancers need another trigger to grow was first proposed by scientist Isaac Berenblum in 1947.

“Philosophically, it’s fascinating. These amazing biologists did this work 75 years ago and it was largely ignored,” says Lim.

Michelle Mitchell, chief executive of Cancer Research UK, emphasized that “smoking remains the biggest cause of lung cancer”.

But she added: “Science, which takes years of painstaking work, is changing our thinking about how cancer develops. We now have a much better understanding of the driving forces behind lung cancer.”

This text was originally published here.