Effects of Selenium Dioxide on Apoptosis, Bcl-2 and p53 Expression, Intracellular Reactive Oxygen Species and Calcium Level in Three Human Lung Cancer Cell Lines

Objective: To evaluate the anti-tumor effects of SeO₂ and its mechanisms on three human lung cancer cell lines. Methods: Three lung cancer cells A549, GLC-82 and PG were treated with 3-30 μmol/L SeO₂. Flow cytometry was used to detect apoptosis, and analyze the changes of expression of p53 and Bcl-2, as well as ROS and Ca²⁺ level within cells. Results: SeO₂ markedly inhibited cell proliferation and viability, and prompted apoptosis after 48 h treatment. SeO₂ at 10 μmol/L induced 47.8% apoptosis in A549 cells, 40.8% in GLC-82 cells, 18.2% in PG cells. SeO₂ at 30 μmol/L induced 37.8% apoposis in PG cells,but did not increase apoptotic raes in other two cells. SeO₂ could down-regulate the mean fluorescent intensity of Bcl-2 from 65.8 to 9.6 in A549, but not in GLC-82 and in PG cells, up-regulate wild type p53 level in all three cells. SeO₂ decreased the ROS and Ca²⁺ level markedly within three tested cells. Conclusion: SeO₂ showed anti-tumor effect via apoptosis pathway in three lung cancer cell lines. The decrease of ROS and Ca²⁺ level within cells as well as regulation of Bcl-2 and p53 expression may play important roles in above apoptotic procedure.