Podophyllotoxin (PT), a
lignan compound from the roots and rhizomes of Podophyllum peltatum, has diverse pharmacological activities including anticancer effect in several types of
cancer. The molecular mechanism of the anticancer effects of PT on
colorectal cancer cells has not been reported yet. In this study, we sought to evaluate the anticancer effect of PT on human
colorectal cancer HCT116 cells and identify the detailed molecular mechanism. PT inhibited the growth of cells and colony formation in a concentration-dependent manner and induced apoptosis as determined by the
annexin V/7-aminoactinomycin D double staining assay. PT-induced apoptosis was accompanied by cell cycle arrest in the G2/M phase and an increase in the generation of
reactive oxygen species (ROS). The effects of PT on the induction of ROS and apoptosis were prevented by pretreatment with
N-acetyl-L-cysteine (NAC), indicating that an increase in ROS generation mediates the apoptosis of HCT116 cells induced by PT. Furthermore, Western blot analysis showed that PT upregulated the level of phospho (p)-p38
mitogen-activated protein kinase (MAPK). The treatment of
SB203580, a p38 inhibitor, strongly prevented the apoptosis induced by PT, suggesting that PT-induced apoptosis involved the
p38 MAPK signaling pathway. In addition, PT induced the loss of mitochondrial membrane potential and multi-
caspase activation. The results suggested that PT induced cell cycle arrest in the G2/M phase and apoptosis through the
p38 MAPK signaling pathway by upregulating ROS in HCT116 cells.