Cynaropicrin induces the apoptosis of colorectal cancer cells by elevating reactive oxygen species and activating the JNK/p38 MAPK

The development of new therapeutics for colorectal cancer (CRC) is urgently needed to address the limitations of current treatments. This study was performed to investigate the anticancer activity of cynaropicrin (a natural product) in CRC HCT116 cells and an oxaliplatin (Ox)-resistant HCT116 strain (HCT116-OxR). MTT cell viability assays showed that cynaropicrin inhibited the growth of HCT116 and HCT116-OxR cells in a dose- and time-dependent manner. Cynaropicrin also induced apoptosis, as identified by an Annexin V-FITC/PI double staining, and this apoptosis was accompanied by the phosphorylations of JNK and p38 MAPK. In addition, treatment with the kinase-specific inhibitors SP600125 and SB203580 confirmed that this apoptosis was mediated by JNK and p38 MAPK. Flow cytometry analysis using the CellROX™ kit showed cynaropicrin increased reactive oxygen species (ROS) levels, and N-acetylcysteine pretreatment confirmed ROS mediated the cytotoxicity of cynaropicrin. Flow cytometry with propidium iodide staining and western blot analysis indicated that cynaropicrin induced cell cycle arrest at the G2/M phase by modulating cell cycle regulators, and western blot analysis revealed that cynaropicrin altered the balance of Bcl-2 family proteins. Also, flow cytometry using the Muse™ Multi-Caspase Kit showed cynaropicrin activated multiple caspases, the crucial roles of which were confirmed using the pan-caspase inhibitor Z-VAD-FMK. In conclusion, cynaropicrin demonstrated anticancer activity against CRC cells by elevating ROS levels, activating JNK and p38 MAPK, and inducing cell cycle arrest leading to apoptosis. Further studies are warranted to evaluate the therapeutic potential of cynaropicrin in CRC.