The pro-apoptotic effect and mechanism of Prunella Vulgaris extracts on thyroid cancer cell line B-CPAP / 西安交通大学学报(医学版)

ABSTRACT

Objective: To observe the pro-apoptotic effect of Prunella Vulgaris extracts (PVE) on thyroid cancer cell line B-CPAP and explore its mechanism. Methods: After cultured in PVE of different concentrations for 72 h, the cytoactive of B-CPAP cells was detected by MTT and half maximal inhibitory concentration (IC50) was calculated. Flow cytometry, TUNEL and transmission electron microscopy were used to observe the changes in apoptosis rate, apoptosis index (AI) and intracellular ultrastructure after 48-hour treatment with the IC50 concentration of PVE. Immunohistochemical staining (IHC) was used to detect the differences in bcl-2 protein expression with or without PVE treatment. Results: PVE significantly inhibited B-CPAP (F=22.815, P<0.05) in the concentration-dependent manner (r2=0.851) with IC50=1.53 mg/mL. The apoptosis rate of cells in PVE of 0.77 mg/mL and 1.53 mg/mL was 8.5% and 16.3%, respectively, which were significantly higher than that of control group (3.9%) (P<0.05). The AI of cells in medium containing PVE was 47% while AI of negative control was 29%. The B-CPAP cells treated with PVE were observed to have swollen intracellular mitochondria, non-uniform size, and an increased number of autophagosomes. Semi-quantitative analysis of IHC showed that the expression level of bcl-2 protein in the negative control group was higher than that in drug group. Conclusion: PVE can significantly promote the apoptosis of B-APAP cells in vitro. The pro-apoptotic effect of PVE may be related to the inhibition of bcl-2 protein expression.