Altered selenium-binding protein levels associated with selenium resistance.

Abstract

Our previous studies have sought to elucidate the mechanism by which selenium inhibits cell growth since the mechanisms involved may be relevant to the chemopreventive properties of selenium. In a previous report, we described the isolation of a selenium-resistant cell line, B19, from a selenium-sensitive parental cell line, C57. In this report we identify biochemical changes that may be responsible for conferring selenium resistance. Altered selenium uptake and intracellular glutathione concentrations were eliminated as possible modes of resistance since these two parameters were similar between the two cell lines. However, when the selenium-containing protein complements of the two cell lines were compared by labelling with [75Se]selenite, both increases and decreases in a number of selenium-labelling proteins were found in the B19 cells. The most striking differences were the presence of two 72 kDa selenium-labelling proteins in B19 cells which could not be detected in C57 cells. The levels of a number of mRNAs encoding antioxidant or detoxification enzymes were also compared between the two cell lines but only minor changes were found. This work suggests that further analysis of the 72 kDa selenium-labelling proteins may reveal insights into the mechanisms of growth inhibition by selenium.