Antioxidants May Offer a New Way to Help Defeat Cancer

Cancer cells may defend themselves by chemically suffocating the immune cells that attack them. A joint study by the University of Cambridge in the United Kingdom and Oregon Health and Science University in the United States found that tumors release antioxidants that can prevent T cells from activating.

Scientists examined the fluid surrounding cells inside tumors. They found that tumors release large amounts of Peroxiredoxin 1, or PRDX1, a naturally occurring antioxidant protein. By neutralizing reactive oxygen species, PRDX1 removes signals that specialized immune cells need to launch an attack.

T cells hunt and destroy cancer cells, but they require small amounts of reactive oxygen species to activate their tumor-killing abilities, said Xan Wesolowski of Cambridge’s Department of Pathology. The study challenges the view that these molecules are simply harmful by-products of metabolism. In this setting, they also serve as signals for immune activity.

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Our immune system keeps us healthy by identifying and destroying harmful elements, such as invading bacteria and viruses, as well as cancer cells.

“When we block this process, malignant cells that do not respond to certain immunotherapies begin to be destroyed by the treatment,” said Rahul Roychoudhuri, also of Cambridge’s Department of Pathology. The researchers said their findings identify a new potential therapeutic target and could improve the effectiveness of cancer immunotherapies.

The study appeared in Science. Funding came largely from the Medical Research Council, the European Research Council, Wellcome and the U.S. National Institutes of Health, including the National Cancer Institute.

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When we block this process, malignant cells that do not respond to certain immunotherapies begin to be destroyed by the treatment.