Anti-proliferation effect of Scutellaria barbata D. Don extract on lung cancer

Purpose: To investigate the effect of Scutellaria barbata D. Don extract (SBDE) on apoptosis and proliferation in A549 human lung cancer cells. Methods: Inverted microscope was used to observe morphological changes in A549 cells after exposure to SBDE. Trypan blue staining of living cells was applied to construct cell growth curve after treatment with varying concentrations of SBDE. The influence of SBDE on cell proliferation, apoptosis and cell cycle was determined by MTT assay while protein expressions of key apoptosis-related enzymes were evaluated by immuno-cytochemical method. Results: SBDE inhibited the growth of A549 lung cancer cells at a concentration range of 20 - 160 mu g/mL. Flow cytometry showed that SBDE induced apoptosis in the A549 cells. The proportion of cells in G0/G1-phase increased significantly (p < 0.01), while the proportion of cells in S-phase and G2/M-phase decreased correspondingly, indicating that the cells were in G0/G1-phase arrest. Cell cycle arrest and apoptosis-inducing effect gradually increased with increase in SBDE concentration. With increasing concentrations of SBDE, there were significant increases in the expressions of caspase-3 (p < 0.05), caspase-8 (p < 0.01) and caspase-9 (p < 0.05), and significant decreases in Ki-67 (p < 0.01) and p21 ras protein (p < 0.01). Conclusion: SBDE exerts significant inhibitory effect on the proliferation of A549 lung cancer cells, which can be developed for the treatment of lung cancer patients.