| Description: |
When the A549 cells were exposed to CSE at 0.01 vol/vol% for 36 h, they exhibited a phenotype that is typical of cellular senescence (i.e., an increase in SA β-gal activity) , a distinct, flat, and enlarged morphology, and an increase in lysosomal mass. When A549 cells were exposed to 0.01 vol/vol% of CSE solution before growth stimulation with 10% FCS, cellular uptake of BrdU was reduced to half the uptake by the control cells, suggesting that irreversible growth arrest had occurred. When cells were exposed to CSE at 0.01 vol/vol% for 36 h, washed with PBS, and then stimulated with 10% FCS for a long period of time, a reduction of BrdU uptake was still observed ,confirming the irreversibility of CSE-induced growth arrest. Quantitative analyses for cellular senescence showed that exposure of A549 cells to CSE caused a dose-dependent and timedependent increase in SA-β-gal activity, with 60% of the A549 cells expressing SA-β-gal activity after exposure to 0.05 vol/vol% of CSE solution for 36 h. Exposure of A549 cells to CSE also increased the total number of cells expressing SA-β-gal, indicating that the increase in the percentage of cells expressing SA-β-gal was not merely due to a decrease in overall cell number that may have occurred after cell death. |