Isolinderalactone sensitizes oxaliplatin-resistance colorectal cancer cells through JNK/p38 MAPK signaling pathways.

BACKGROUND:Isolinderalactone (ILL), a sesquiterpene lactone compound, can be extracted from the root of Lindera aggregate. Physiological activities of ILL, including anti-inflammatory and anti-proliferative effects, have been investigated in multiple diseases. Nevertheless, little is known regarding its anti-cancer activities and the mechanism of action of ILL in targeting human CRC cells. PURPOSE:To determine ILL-mediated anti-proliferative effects on oxaliplatin (Ox)-sensitive and resistant colorectal cancer (CRC) cells and underlying mechanisms involved in its effects focusing on signal transduction. METHODS:Inhibitory effect of ILL on CRC cells was evaluated by analyzing mitochondrial membrane potential (MMP) dysfunction and multi-caspase activity. Apoptosis-regulating proteins and JNK/p38 signaling molecules were monitored by Western blotting. ROS-dependent physiological modifications by ILL were confirmed by pretreatment with N-acetylcysteine (NAC). Moreover, the involvement of JNK/p38 signaling in ROS-mediated apoptosis was verified by treatment with SP600125 (JNK inhibitor) and SB203580 (p38 inhibitor). RESULTS:ILL decreased cell viability and colony formation in both CRC Ox-sensitive (HCT116 and HT29) and Ox-resistant (OxR) (HCT116-OxR and HT29-OxR) cells. ILL induced G2/M phase cell cycle arrest, ROS generation, phosphorylated (p)JNK/p38 MAPK activation, mitochondrial membrane potential (MMP) depolarization, and multi-caspase activation, which eventually triggered apoptotic cell death of CRC cells. In addition, combined treatment with ILL and SP600125, SB203580, or pan-caspase inhibitor (Z-VAD-FMK) prevented decreases in cell viability seen after treatment with ILL alone. Pretreatment with NAC attenuated ILL-mediated apoptosis, ROS production, and p-JNK/p38 expression. CONCLUSION:Taken together, our results suggest that ILL can exert its anticancer effect in CRC Ox-sensitive and OxR cells by inducing ROS-mediated apoptosis through JNK/p38 MAPK signaling pathways. This is the first study demonstrating that ILL has a potential to improve drug efficacy against resistance mechanisms, providing a new insight into therapeutic strategies targeting drug-resistant CRC.