Selenium is effective in inducing lymphocyte progression through cell cycle in cancer patients: potential mechanisms for its activity.

Epidemiologic evidence in humans suggests a role for selenium in reducing cancer incidence and mortality. The aim of the present study was that to assess the ability of selenium dioxide (SeO2) to enhance the lymphocyte progression through the cell cycle in patients with advanced (stage IV) cancer. Ten patients (mean age 51.9 years, range: 32-74; M/F ratio: 3/7) with tumors at different sites were included in the study. The addition into culture of SeO2 1.5 microM enhanced significantly the progression into S phase of PBMCs isolated from cancer patients, whilst no significant effect was observed on PBMCs isolated from controls. ROS levels were significantly higher, whereas GPx activity was significantly lower in cancer patients than controls. Serum levels of IL-6 and TNFalpha were significantly higher in cancer patients than controls. Our results show the ability of selenium to induce a progression of PBMCs from cancer patients into the cell cycle, which is an essential prerequisite for the physiological functioning of the immune system and thus positively influence the immune status of advanced cancer patients. The mechanism of action of selenium could be to downregulate the production and release of proinflammatory cytokines, which have a role in cancer progression and particularly in the onset of cachexia.