Researchers at the University of Minnesota have discovered that a naturally occurring human antiviral enzyme causes DNA mutations that lead to several forms of cancer.
The discovery, reported in the July 14 issue of Nature Genetics, follows the team’s earlier finding that the enzyme, called APOBEC3B, is responsible for more than half of breast cancer cases. The new study shows that the enzyme appears to contribute to bladder, cervical, head and neck, and two forms of lung cancer as well.
APOBEC3B is part of a family of antiviral proteins that lead researcher Reuben Harris, Ph.D., has studied for more than a decade.
“We are very excited about this discovery because it indicates that a single enzyme is one of the largest known contributors to cancer mutation, possibly even eclipsing sources such as UV rays from the sun and chemicals from smoking,” says Harris, a member of the Masonic Cancer Center, University of Minnesota and a professor in the College of Biological Sciences.
Findings from these studies are counterintuitive because the enzyme, which is produced by the immune system, is supposed to protect cells from HIV and other viruses — not harm our own genomic DNA.
Harris believes that APOBEC3B is a biological “double-edged sword” that protects some cells from viruses such as HIV and produces mutations that give rise to cancer in others. In the future, he hopes to find a way to block APOBEC3B from causing DNA mutations.