a1 Laboratory of Viral, Immune and Malignant Diseases, California Institute for Medical Research, San Jose, CA 95128, USA
Selenium is an important trace element with anti-cancer properties. In the present study, the apoptosis-inducing effects of organic selenium derivatives, namely methyl-l-selenocysteine and selenomethionine, were evaluated in vitro on human tumour-derived cell lines from breast, liver, colon, brain, skin and a non-tumorigenic line of epithelial origin. Apoptosis was assessed by cell-death detection immunoassay on cytoplasmic cell lysates. Breast carcinoma cells were highly sensitive to the organic selenium compounds, manifesting apoptosis at concentrations as low as 0·113 μm (0·0205 μg/ml) selenium. By contrast, non-tumorigenic mammary epithelial cells displayed poor sensitivity to selenium, requiring a substantially high concentration of the trace element of 87·9 μm (16·0 μg/ml). The cell lines derived from hepatoma and neuroblastoma showed intermediate sensitivity, with colon carcinoma cells manifesting the lowest sensitivity to the trace element. These results indicate intrinsic differences in the sensitivity of human tumour derivatives to selenium-mediated apoptosis, providing experimental support for the development of organic selenium compounds as anti-neoplastic agents against solid tumours displaying selective apoptotic sensitivity to these compounds.
(Received March 05 2008)
(Revised April 25 2008)
(Accepted April 28 2008)
(Online publication June 13 2008)
p1 Present address: Dr Rath Research Institute, 1260 Memorex Drive, Santa Clara, CA 95050, USA.
‡ Presently at San Bruno, CA, USA.
Abbreviations: A405 nm, absorbance at 405 nm; MSC, methylselenocysteine; SeMet, selenomethionine