An international team of researchers from the University of Cambridge (United Kingdom) and Oregon Health and Science University (USA) has identified a previously unknown mechanism by which cancer cells escape the immune system. According to the study published in the journal Science, tumors release large amounts of antioxidants that create a chemical barrier capable of neutralizing the body's defenses and preventing the action of T cells, the white blood cells responsible for fighting tumor threats.
The research revealed that T cells require small controlled amounts of reactive oxygen species (ROS), commonly known as free radicals, as an indispensable chemical signal to activate and trigger the destructive response against the tumor. To neutralize this mechanism, cancer produces and releases peroxiredoxin 1 (PRDX1) protein into the tumor fluid, a highly effective natural antioxidant that systematically eliminates ROS from the surrounding environment, depriving T cells of the necessary stimulus and leaving them inactive.
To validate the hypothesis, the team used CRISPR gene editing technology in animal models, creating cancer cells unable to synthesize the PRDX1 protein. Without this antioxidant for protection, T cell activity was significantly enhanced and tumor growth showed marked slowing. The mechanism was also confirmed in humans through the analysis of proteins released by cell lines, the study of gene activity in thousands of tumors, and the evaluation of fluid collected during tumor removal surgeries.
The discovery is viewed with great anticipation by the scientific community, particularly because many cancers show resistance or do not respond to current immunotherapy treatments. As Robert Eil, researcher at the University of Oregon and co-author of the study, noted, the results reveal that antioxidants are not always beneficial in the cancer context, opening a completely new avenue to explore in the development of more effective treatments.
