• Posted November 8, 2023

Smoking Undermines Human DNA That Would Normally Prevent Cancer

Everyone knows smoking to be a major cause of cancer.

Now, exactly how tobacco smoke triggers tumor development just got a bit clearer, thanks to new Canadian research.

According to a team at the Ontario Institute for Cancer Research (OICR) in Toronto, smoking appears to prevent the formation of proteins that work to keep runaway cell development in check.

According to Nina Adler, a University of Toronto PhD student who led the study, smoking gives rise to what are known as "stop-gain" mutations in cellular DNA. In essence, the mutations tell the body to stop making these protective proteins.

Without these proteins, tumors are more likely to occur.

"Our study showed that smoking is associated with changes to DNA that disrupt the formation of tumor suppressors,"said Adler, who led the study during her postgraduate research in Dr. Jüri Reimand's lab at OICR.

"Without them, abnormal cells are allowed to keep growing unchecked by the cell's defenses and cancer can develop more easily," she explained in an OICR news release.

The Toronto team already knew that a history of smoking leaves a unique imprint in a smoker's DNA. In their research, they compared that genetic legacy to DNA collected from 12,000 tumor samples across 18 different types of cancer.

They found that smoking appeared strongly connected to stop-gain mutations that leave people more vulnerable to cancer.

And the longer and more intensely a person had smoked, the more stop-gain mutations were found in his or her tumors, Adler's team found.

"Tobacco does a lot of damage to our DNA, and that can have a major impact on the function of our cells,"said Reimand, an OICR Investigator and an associate professor at the University of Toronto.

"Our study highlights how tobacco smoking actually deactivates critical proteins, which are the building blocks of our cells, and the impact that can have on our long-term health," he said.

Other lifestyle habits, such as drinking alcohol and eating an unhealthy diet, might also boost stop-gain mutations, Reimand said, although more research is needed to confirm that.

Smoking is most certainly connected, however.

"Everyone knows that smoking can cause cancer, but being able to explain one of the ways this works at a molecular level is an important step in understanding how our lifestyle affects our risk of cancer,"Adler said.

The study was published Nov. 3 in the journal Science Advances.

More information

Finding out more about the strong link between smoking and cancer at the American Institute for Cancer Research.

SOURCE: Ontario Institute for Cancer Research, news release, Nov. 3, 2023