EFFECT OF SELENIUM ON GROWTH, S-ADENOSYLMETHIONINE AND POLYAMINE BIOSYNTHESIS IN HUMAN COLON-CANCER CELLS

Selenium metabolism and polyamine biosynthesis are linked in their com mon requirement for S-adenosylmethionine. The effects of selenium supp lementation (0.1 to 6.0 ppm) on growth, polyamine biosynthesis and S-a denosylmethionine are examined in two human colon cancer cell lines, W iDr and HT29. WiDr cells were very sensitive to selenium with a signif icant decrease in H-3-thymidine incorporation and cell number to doses above 0.25 ppm. HT29 cells were less sensitive. In HT29 cells, ornith ine decarboxylase activity and its product putrescine decreased in par allel with the growth inhibitory effects of selenium. Similar changes were not noted in WiDr cells. Spermidine and spermine content were con served in both cell lines exposed to cytotoxic doses of selenium. S-ad enosylmethionine was increased in HT29 cells at cytotoxic doses of sel enium (1.0 to 6.0 ppm).