[The role of caveolin-1 for carbon black nanoparticles uptake in vitro].

Objective To investigate the protein expression of caveolin-1 in type Ⅱ alveolar epithelial cells (A549) exposed to carbon black nanoparticles (CB NPs) and the role of caveolin in the endocytosis of CB NPs.Methods A549 cells were exposed to 0,25,50,100,200,and 400 μg/ml CB NPs for 24 h; then,trypan blue assay was applied to determine the cell viability.A549 cells were also exposed to 0,25,50,and 100 μg/ml CB NPs for 24 h,then,transmission electron microscopy (TEM) and flow cytometry were applied to observe the morphological change of cells and cellular side scatter (SSC),and Western blot was used to analyze the effect of CB NPs on the protein expression of caveolin-1.A549 cells were co-exposed to 1 μg/ml filipin and 100 μg/ml CB NPs for 24 h,then,the cellular SSC was observed.Results Compared with controls,the A549 ceils exposed to 200 and 400 μg/ml CB NPs had the cell viability decreased by 38.2％ and 46.6％,respectively (P＜0.05),while those exposed to 25,50,and 100 μg/ml CB NPs showed no significant decrease in cell vitality (P＞0.05).The protein expression of caveolin-1 was significantly higher in the cells exposed to 50 and 100 μg/ml CB NPs than in controls (P＜0.05).The TEM showed that plasmalemmal vesicles containing black particles were found in the cytoplasm of the cells exposed to 50 and 100 μg/ml CB NPs.The flow cytometry showed that the cellular SSC ratio increased from 1.007 to 1.331 as the dose of CB NPs rose within 0～100 μg/ml and fell to 1.25 after the cells were co-exposed to 1 μg/ml filipin and 100 μg/ml CB NPs.Conclusion Carbon black nanoparticles can be transferred into A549 cells by endocytosis,but caveolin-mediated endocytic pathway plays a minor role in this process. Key words: Carbon black nanoparticles;  Pulmonary alveolar;  Epithelial cells;  Caveolin-1