| Summary: | 碩士 === 國立臺灣海洋大學 === 食品科學系 === 104 === Polycyclic aromatic hydrocarbons (PAHs), such as benzo[α]pyrene (B[α]P; BaP), is a potent lung carcinogen derived from tobacco smoking and food. BaP also has latent capability to activate caspase activity for inducing cell death. Taurine and vitamin C have potent antioxidative activities that protect cells from oxidative stress and cellular damage. The objectives of the present study were to investigate the adverse effects of BaP on human pulmonary epithelial cell line (A549), the potential protective effects of taurine and vitamin C against BaP-induced cellular damage, and the molecular mechanisms of actions. Therefore, A549 cells were exposed to different doses of Bap (2-50 μM) for determining direct toxic effects on the cell apoptosis . It is found that BaP induces apoptosis in a p53-mediated and caspase 3 and caspase 7 dependent manner, which relate to the accumulation of the G0/G1 phase of the cell cycle. BaP treatment resulted in a significant decrease in the protein expression of Bcl-2 and Bcl-xl, whereas protein expression of Bax and Bak and cytochrome c activity were significantly increased. Further, A549 cells were induced a significant increase in the activities of caspase 3 and caspase 7 as well as the number of apoptotic cells by BaP exposure. BaP also caused oxidative stress by increasing reactive oxygen species (ROS) production and reducing mitochondrial membrane potential (MMP). Meanwhile, A549 cells were damaged and induced to produce genomic DNA ladder after exposing BaP. Taurine and vitamin C prevented cells from BaP- induced cell cycle arrest and growth inhibition, and significantly suppressed DNA fragmentation. Taurine and vitamin C significantly restored survival of BaP exposed cells. Taurine and vitamin C could reverse some of these BaP-mediated alterations and therefore be effective natural compounds against the adverse effects of BaP in lung cells.
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