Methanol Extract of Petasites japonicus Promotes Apoptosis via the MAPK and ROS-dependent Signaling Pathways

Background: Petasites japonicus (PJ), also known as Butterbur, has a rich history as a traditional healing remedy across numerous countries. Objectives: This study was designed to evaluate the potential anti-cancer properties of the methanol extract derived from PJ (PJE). Materials and Methods: Cell viability was measured with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide. Cell cycle analysis, caspase activity assays, western blotting, and reactive oxygen species (ROS) assays were also used to investigate the anticancer effects of PJE on cancer cells. Results: It was shown that PJE inhibited the cell viability of the colon carcinoma cell line Caco-2 (half-maximal inhibitory concentration [IC50]: 268.4 µg/mL), of the hepatocellular carcinoma cell line Hep3B (IC50: 420.2 µg/mL), and of the bladder carcinoma cell line 5637 (IC50: 99.43 µg/mL). Analysis of DNA content indicated an increase in the sub-G1 population of 5637 cells as a result of PJE treatment. Furthermore, PJE caused a reduction in mitochondrial membrane potential and the ratio of Bcl-2 to Bax. Moreover, PJE enhanced the levels of various components involved in the proapoptotic cascade, such as caspase-3, caspase-9, and poly-adenosine diphosphate-ribose polymerase. Moreover, it was observed that PJE modulated mitogen-activated protein kinases (MAPKs) activation and induced an elevation in intracellular production of ROS. Conclusion: These combined results strongly suggest that PJE possesses significant proapoptotic properties as an herbal medicine, acting through ROS-dependent MAPK signaling pathways in bladder cancer cells.