Ethanol extract of Dunaliella salina induces cell cycle arrest and apoptosis in A549 human non-small cell lung cancer cells

The ethanol extract of Dunaliella salina (EDS) on proliferation and apoptosis in the A549 human lung cancer cell line and their associated protein expressions were investigated. After 24 and 48 h treatment, MTT assay showed that 25 μg/ml of EDS significantly reduced A549 cell proliferation by 25.2% (p<0.05) and 48.3% (p<0.01), respectively. To explore its molecular mechanisms in regulating cell proliferation, we first showed that EDS markedly reduced A549 proliferation via inhibition of BrdU incorporation at 25 μg/ml by 65.8% (p<0.001). By cytometric analysis, EDS was found to induce apoptosis and cell cycle arrest in the G0/G1 phase. In the DNA gel electrophoresis assay, EDS (25, 50 and 100 μg/ml) induced significant apoptosis at 48 h. Annexin V/Propodium iodide double staining demonstrated that administration of EDS (25 μg/ ml) in 12, 24 and 48 h induces apoptosis of 27.7%, 30.7%, and 38.7%. Western blotting assay demonstrated that EDS significantly increased the expression of cyclin-dependent kinase (CDK) inhibitors p53 and p21 and death-receptor proteins Fas and FasL. Bax expression was also elevated by treatment with EDS. Our data suggested that EDS could influence the antiproliferative effects and induce cell cycle G0/G1 arrest and apoptosis of A549 lung cancer cells.