Vacuolization and apoptosis induced by nano-selenium in HeLa cell line

Selenium (Se), a potential drug candidate for cancer prevention, has a special property: Its nutritional dosage and tolerable upper intake level appear in a narrow range, while the therapeutic use of this mineral may depend on a higher body intake level. Nano-selenium (nano-Se) particles, however, preserve the selenium element's low toxicity characteristic but give a high biochemical activity effect of selenium compounds. In the present study different morphologies of synthesized nano-Se were evaluated concerning its anti-proliferation and apoptosis-inducing effect. Then nano-Se (sphere) were picked out to investigate its influence on two significant events involved in apoptosis, cell cycle arrest and mitochondrial membrane potential disruption. Furthermore, massive vacuolization of HeLa cells treated by nano-Se (sphere) was observed and more methods were used to measure the level of vacuolization. Such vacuolization needs energy supply and has been demonstrated to be related to Se endocytosis. These results suggest a possible mechanism to trigger apoptosis initiation.