Bachelor Thesis

Selenosulfate toxicity in human liver and bladder cells

Franziska Geist (11/2012-07/2013)

Support: Britta Planer-Friedrich, Sinikka Hinrichsen

Selenium, like other essential trace elements, does not only have nutritional benefits, but is also toxic depending on its concentration and chemical form. Little is known about the toxicity of the inorganic species selenosulfate. Selenosulfate is used e.g. to produce Se0-nanoparticles, but has also been proposed as anticancerogenic agent in chemotherapy. In the present work the influence of selenosulfate on the cell viabilities of human urothelial cells (UROtsa) and hepatoma cells (HepG2) was investigated by means of an MTT assay in comparison to selenite. Both cell types were treated with 0-30 μM selenosulfate and 0-100 μM selenite. Selenosulfate was synthesised from selenite, GSH and sulfite in a mixing ratio of 1:4:4 at ambient temperature. In pre-tests, its stability over the duration of the toxicological experiments was confirmed visually, since its oxidation yields red elemental selenium. The toxicity tests revealed that selenosulfate was slightly less toxic than selenite for UROtsa cells (LC50 (24h) 2.8 μM and 2.2 μM, respectively). However, selenosulfate was considerably more toxic than selenite for HepG2 cells (LC50 (24h) 2.0 μM and 20 μM, respectively). This effect is attributed either to differences in the associated organs (badder versus liver) or the different origin of the cells (normal tissue versus carcinoma). Further investigations need to clarify whether the higher toxicity of selenosulfate for the HepG2 cells is truly based on their carcinogenic origin and is only beneficial for its application in cancer treatment.