It used to be fashionable. It was even promoted as medicinal. We now know smoking causes cancer. How it does this is less clear. To find out, researchers examined human lung tissue from non-smokers (pictured) and smokers. They focused on two cell types that could divide and so potentially repair damaged tissue, namely alveolar progenitors (shown in magenta) and basal stem cells. Exposing these cells to radiation caused their DNA to break, as detected using a protein marker (green). In tissue from smokers, the stem cells sprung into action, dividing and repairing the breaks. But the alveolar cells didn’t respond much. While the stem cells appear to be the heroes, the way they repaired their DNA was prone to errors, making mutations more likely. Toxic chemicals released by smoking tobacco could therefore trigger these stem cells to come to the rescue, inadvertently leading to a build-up of mutations that cause cancer.
Written by Lux Fatimathas
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