Abstract:

Objective To study the mechanisms of apoptosis of the human squamous cell carcinoma cell line A431 induced by triptolide. Methods Cultured A431 cells were treated with triptolide at different concentrations （1, 10, 100 mg/L） for various durations （12, 18, 24, 48 hours）. Various stages of apoptosis of A431 cells were quantified using flow cytometry and dual staining with Annexin V-FITC and propidium iodide （PI）. The expressions of Caspase 3, 8 and 9 in triptolide-treated or untreated A431 cells were examined by microspectrophotometry. Results As flow cytometry and fluorescence microscopy revealed, early apoptosis of A431 cells was observed 12 hours after treatment with triptolide, and typical apoptosis was noticed at 24 hours. Moreover, the apoptosis rate was positively correlated with the treatment concentration and durations of triptolide. The activities of Caspase 3, 8 and 9 commenced to increase at 12 hours, peaked at 24 hours （Caspase 3 and 9） or 18 hours （Caspase 8） after triptolide treatment, and the top activities expressed as absorbence value were 0.723, 0.850, 1.127 for Caspase 3, 1.072, 1.091 and 1.191 for Caspase-9, 0.641, 0.780 and 0.910 for Caspase 8 after treatment with triptolide of 1, 10 and 100 mg/L, respectively, which were significantly higher than those in untreated control cells at corresponding time points （all P < 0.05）. Conclusion Triptolide could induce the apoptosis of A431 cells, and the induction effect seems to be concentration- and time-dependent.