Background Benzoapyrene-7, 8-diol-9, 10-epoxide (BPDE) is an environmental carcinogen that can cause cell apoptosis and oxidatve stress. Chlorogenic acid (CGA) is an antoxidant, but its effect on BPDE-induced apoptosis is unclear.
Objective BPDE exposure is administered to mimic the damage of tobacco to bronchial epithelial cells. Then CGA interventon is administered to explore its ant-apoptotc effect and its potental molecular mechanism.
Methods In the pre-experiment, 16HBE cells were treated with CGA at fnal concentratons of 0, 50, 100, 150, and 200 μmol/L for 2, 4, and 8 h. Based on the results of the pre-experiment, cells were pretreated with CGA 50μmol/L for 4h, and then were induced by BPDE 0.5μmol/L for 12h. There were four groups:control group, CGA exposure group (CGA 50 μmol/L), BPDE exposure group (BPDE 0.5 μmol/L), and CGA interventon group (CGA 50 μmol/L+BPDE 0.5 μmol/L). Cell apoptosis was measured by Annexin V/PI staining and flow cytometry; intracellular reactve oxygen species (ROS) was detected with DCFH-DA probes; the expressions of apoptosis markers including Cleaved caspase-3, Cleaved caspase-9, p53, and p21 were detected by Western blot.
Results Compared with the 0 μmol/L CGA group, the cell viabilites were not different in the 50 and 100 μmol/L CGA groups at various tme points (P>0.05), but reduced in the 150 and 200 μmol/L CGA groups at 8 h (P < 0.05). Compared with the BPDE exposure group, the CGA interventon group showed reduced cell apoptosis rate (17.63% vs 9.21%, P < 0.05), relatve expression levels of Cleaved caspase-3 (1.81 vs 1.34, P < 0.05) and Cleaved caspase-9 (2.13 vs 1.37, P < 0.05), dichlorofluorescein fluorescence intensity (250.21±8.13 vs 199.14±6.74, P < 0.05), and relatve expression levels of p53 (1.66 vs 1.25, P < 0.05) and p21 (1.64 vs 1.23, P < 0.05).
Conclusion CGA can inhibit apoptosis in 16HBE cells induced by BPDE and reduce intracellular ROS level. Its mechanism may be related to caspase-9/caspase-3 mediated endogenous mitochondrial pathway and inhibited protein expressions of p53 and p21 induced by BPDE.
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