Non-tumor adjacent tissue of advanced stage from CRC shows activated antioxidant response

Colorectal cancer (CRC) is a leading cause of malignant cancer-related morbidity and mortality, with a higher incidence in developed countries and a high mortality rate mainly attributable to metastases. The aim of the present study was to determine the metabolic adaptations related to oxidative stress in tumor tissue from advanced stages (III and IV) of CRC and whether they could be used as potential biomarkers for clinical applications. To tackle this aim, we have analyzed the protein expression levels related to oxidative stress and the enzymatic activities of MnSOD and catalase, comparing samples of non-tumor adjacent tissue and tumor tissue of CRC patients in stages III and IV. The results showed no differences between stage III and IV in tumor tissues for any of the proteins studied. However, some differences were found between samples of non-tumor adjacent tissue and tumor tissue for some of the antioxidant enzymes. Overwhelmingly, the greatest differences were detected when comparing samples of non-tumor adjacent tissue from stage III and stage IV. To the best of our knowledge, this is the first study where differences between the non-tumor adjacent tissues of CRC patients from different cancer stages were determined. This study suggests that the parameters analyzed should be evaluated as biomarkers for the evolution of CRC. Furthermore, tumor tissue status should not be of sole importance for the prognosis of CRC, as the non-tumor adjacent tissues could also merit consideration.