Role of reactive oxygen species-mediated MAPK and NF-κB activation in polygonatum cyrtonema lectin-induced apoptosis and autophagy in human lung adenocarcinoma A549 cells.

Polygonatum cyrtonema lectin (PCL), a mannose/sialic acid-binding lectin isolated from the rhizomes of Polygonatum cyrtonema Hua, has been reported to possess remarkable anti-tumour effects via inducing apoptosis and autophagy. The aim of this study was to investigate the molecular mechanisms mediating PCL-induced apoptosis and autophagy in A549 cells. Herein, we found that the treatment of A549 cells with PCL caused a remarkable generation of reactive oxygen species (ROS) and ROS scavenger N-acetyl-cysteine (NAC) inhibited PCL-induced apoptosis and autophagy. In addition, PCL treatment activated mitogen-activated protein kinase (MAPK) members extracellular signal-regulated kinase (ERK), JNK and p38, JNK inhibitor and p38 inhibitor partially reduced PCL-induced apoptosis and autophagy. Moreover, PCL administration activated NF-κB survival pathway in A549 cells, NF-κB inhibitor Bay11-7082 promoted PCL-induced apoptosis. Importantly, we found PCL may bind to the cell surface in a mannose-specific manner, and was then internalized and accumulated primarily onto the mitochondria. These findings may provide a new perspective of PCL as a potential anti-tumour drug targeting apoptosis and autophagy pathways for future cancer therapeutics.