Expression of selenium-containing proteins in human colon carcinoma tissue.

Selenium may be beneficial in reducing the risk of cancer incidence and mortality in many cancer types such as liver, prostate, colorectal and lung. However, despite the extensive recent research on selenium and selenium-containing proteins, there are still open questions concerning their expression in certain human cancer types, including colorectal carcinoma. Therefore, the expression level of the selenoproteins thioredoxin reductases 1 and 2 (TRXR-1 and TRXR-2) and glutathione peroxidases 1 and 4 (GPX1 and GPX4) in human colon carcinoma tissues was investigated. Up-regulation of TRXR-1 in the colon carcinoma specimens was found both in disease stage-dependent and independent analyses. No differences were found for TRXR-2 expression levels. GPX1 was up-regulated in carcinoma tissues at both the protein and mRNA levels. GPX4 was also up-regulated at the protein level, except for the samples derived from stage III patients. The expression of TRXR-1, GPX1 and GPX4, but not TRXR-2 is differently regulated in cancer as compared to healthy colonic tissue.