A naturally occuring triterpene saponin ardisiacrispin B displayed cytotoxic effects in multi-factorial drug resistant cancer cells via ferroptotic and apoptotic cell death

Abstract

IntroductionMultidrug resistance of cancer cells constitutes a serious problem in chemotherapy and a challenging issue in the discovery of new cytotoxic drugs. Many saponins are known to display anti-cancer effects. In this study, the cytotoxicity and the modes of action of a naturally occuring oleanane-type tritepene saponin, ardisiacrispin B isolated from the fruit of Ardisia kivuensis Taton (Myrsinaceae) was evaluated on a panel of 9 cancer cell lines including various sensitive and drug-resistant phenotypes. MethodsResazurin reduction assay was used to evaluate cytotoxicity and ferroptotic cell death of samples; caspase-Glo assay was used to detect the activation of caspases in CCRF–CEM leukemia cells. Flow cytometry was used for cell cycle analysis and detection of apoptotic cells by annexin V/PI staining, analysis of mitochondrial membrane potential (MMP) and measurement of reactive oxygen species (ROS). ResultsArdisiacrispin B displayed significant cytotoxic effects in the 9 tested cancer cell lines with IC50 values below 10 µM. The IC50 values ranges were 1.20 µM (towards leukemia CCRF–CEM cells) to 6.76 µM [against heptocarcinoma HepG2 cells] for ardisiacrispin B and 0.02 µM (against CCRF–CEM cells) to 122.96 µM (against resistant CEM/ADR5000 leukemia cells) for doxorubicin. Collateral sensitivity of resistant HCT116p53−/− colon adenocarcinoma cells to ardisiacripsin B was observed. Ardisiacrispin B induced apoptosis in CCRF–CEM cells via activation of inititator caspases 8 and 9 and effector caspase 3/7, alteration of MMP and increase in ROS production. Ferroptosis also contributed to the cytotoxicity of ardisiacrispin B. ConclusionsThe studied oleanane-type triterpene saponin is a good cytotoxic molecule that deserve more detailed exploration in the future, to develop novel cytotoxic drugs to combat both sensitive and drug-resistant cancers.