Increasing Dietary Selenium Elevates Reducing Capacity and ERK Activation Associated with Accelerated Progression of Select Mesothelioma Tumors.

Department of Cellular and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
American Journal Of Pathology (Impact Factor: 4.6). 01/2014; 184(4). DOI: 10.1016/j.ajpath.2013.12.008
Source: PubMed

ABSTRACT Dietary selenium is an essential micronutrient. To study the effect of increasing dietary selenium on malignant mesothelioma (MM) progression, we cultured four different MM cell lines in media containing increasing amounts of sodium selenite (30, 50, and 80 nmol/L). Increasing the amounts of selenium increased density-dependent proliferation and mobility for CRH5 and EKKH5, but not AB12 and AK7. Comparison of these cell lines showed that extracellular regulated kinase (ERK) phosphorylation was sensitive to a selenium increase in CRH5 and EKKH5, but not AB12 and AK7 cells. Stable expression of a dominant-negative mutant ERK eliminated the effects of increasing selenium. Because ERK is redox sensitive, we compared the MM cell lines in terms of glutathione levels and the capacity to reduce exogenous hydrogen peroxide. Increasing selenium levels led to higher glutathione and reducing capacity in CRH5 and EKKH5, but not AB12 and AK7. The reducing agent N-acetylcysteine eliminated the effects of selenium on ERK activation, proliferation, and mobility. Mice fed diets containing increasing levels of selenium (0.08, 0.25, and 1.0 ppm) showed increased tumor progression for CRH5, but not AB12, MM cells, and in vivo N-acetylcysteine treatment eliminated these effects. Data suggest that the effects of dietary selenium on MM tumor progression depend on the arising cancer cells' redox metabolism, and the tumors able to convert increased selenium into a stronger reducing capacity actually benefit from increased selenium intake.

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Jul 15, 2014