Naringenin suppresses growth of human placental choriocarcinoma via reactive oxygen species-mediated P38 and JNK MAPK pathways

Background: Human placental choriocarcinoma is a gestational trophoblastic tumor with high rates of metastasis and reoccurrence. However, some patients with choriocarcinoma are chemoresistance to conventional chemotherapeutic agents. Hypothesis: Naringenin increases apoptosis in human placental choriocarcinoma cells. Methods: We investigated the effects of naringenin on proliferation and migration of JAR and JEG3 cells, and performed TUNEL and Annexin V/PI staining assays to examine apoptotic effects of naringenin on both cells. In addition, we studied the loss of mitochondrial membrane potential (MMP) and the production of mitochondrial reactive oxygen species (ROS) to determine the specific reason for apoptosis of choriocarcinoma cells being mediated via mitochondria. Consistent with the induction of production of ROS by naringenin in both choriocarcinoma cell lines, we investigated lipid peroxidation and glutathione levels in both JAR and JEG3 cells since both are affected by ROS. We next determined dose-dependent effects of naringenin and its pharmacological inhibitors on signal transduction pathways in JAR and JEG3 cells by western blot analyses. Results: Naringenin reduced viability and migratory functions of both cell lines, and increased mitochondria related apoptosis induced by ROS and lipid peroxidation, decreased glutathione and decreased mitochondrial membrane potential MMP in a dose-dependent manner. We also determined naringenin activated phosphorylation of ERK1/2, P38, JNK and P70S6K in JAR and JEG3 cells in a dose-response manner. Although naringenin induced phosphorylation of AKT proteins in JAR cells, it suppressed phosphorylation of the protein in JEG3 cells. In addition, we confirmed the mechanism of naringenin-induced cell signaling by using a combination of naringenin and pharmacological inhibitors of the PI3K and MAPK pathways, as well as a ROS inhibitor in JAR and JEG3 cell lines. Conclusions: Collectively, results of this study indicate that naringenin is a potential therapeutic molecule with anti-cancer effects on choriocarcinoma cells by inducing generation of ROS and activation of the MAPK pathways.