Scientists uncover how smoking causes cancer

Washington, May 14 : While smoking has long been linked to cancer, researchers have now uncovered the yet unknown mechanism behind this process, by identifying the protein that can actually lead to genetic changes causing lung cancer.

Oregon Health and Science University Cancer Institute researchers have discovered that the production of a protein called FANCD2 is slowed when lung cells are exposed to cigarette smoke. The subsequent low levels of FANCD2 lead to DNA damage, which ultimately triggers cancer.

The study highlighted the fact that cigarette smoke inhibits the production of 'caretaker' proteins, like FANCD2, which normally prevent cancer by fixing damages in DNA and causing self-destruction of faulty cells. This discovery may also make scientists improve treatments for lung disease in the future.

"These findings show the important role FANCD2 plays in protecting lung cells against cigarette smoke, and may explain why cigarette smoke is so toxic to these cells," said lead author Laura Hays, Ph.D., research assistant professor of medicine (hematology/medical oncology) and member of the OHSU Cancer Institute.

"Dr. Hays' work shows that FANCD2 is an important protein in protecting against cancer, and cigarette smoke knocks out its production. Although there are probably other proteins involved in this process, we know this is a key one because cells with very high levels of FANCD2 were resistant to the toxic effects of the smoke," said senior author, Grover Bagby, M.D.

For the research, the authors created an artificial windpipe in the lab imitating the environment of a smoker's lung. After this, they studied the effects of cigarette smoke on different proteins in cells and found that FANCD2 levels were low enough to allow DNA damage.

FANCD2 belongs to family of proteins involved in an inherited condition called Fanconi anemia. Those having this condition are more prone to develop cancers at a young age and have low levels of these proteins.

"This interesting piece of science adds to our understanding of why smoking is so deadly. Smoking is the single biggest preventable cause of cancer and causes nine out of 10 cases of lung cancer," said Lesley Walker, Ph.D., director of cancer information at Cancer Research UK.

Walker added: "But the good news is that quitting works - after five years without smoking, your risk of a heart attack will have fallen to half that of a smoker. And after 10 years, your risk of lung cancer will have halved too."

The research will be published in the British Journal of Cancer.

ANI