The Journal of Internal Korean Medicine 2014;35(3): 317-331.
The root of Platycodon grandiflorum (PG) has been known to possess a range of pharmacological activities including anti-cancer, anti-inflammatory, and anti-oxidant effects. The present study was designed to investigate whether or not PG-induced cell death was connected with autophagy and apoptosis in NCI-H460 human lung cancer cells.
Effects on the cell viability and apoptotic activity were quantified using MTT assays and flow cytometry analysis, respectively. Protein activation was measured by immunoblotting. Autophagy was measured by LC3 immunofluorescence and immunoblotting. ROS production and loss of mitochondria membrane potential (MMP) were checked with flow cytometry analysis.
Following exposure to PG, NCI-H460 cell proliferation decreased simultaneously inducing autophagic vacuoles and up-regulation of microtubule-associated protein 1 light chain 3 and beclin-1 protein expressions. Interestingly, pre-treated with autophagy inhibitors, 3-methyladenin or bafilomycin A1 further triggered reduction of cell viability. PG treatment also induced apoptosis that was related modulation of Bcl-2 family proteins, death receptors and activation of caspases. In addition, PG stimulation clearly enhanced loss of MMP and reactive oxygen species (ROS) generation.
Our results suggest that PG elicited both autophagy and apoptosis by increasing loss of MMP and ROS production. PG induced-autophagy may play a cell protective role. [This research was supported by Basic Science Research Program through the NRF grant funded by the Korea government(No.2013R1A1A2065537).