Maclurin exerts anti-cancer effects on PC3 human prostate cancer cells via activation of p38 and inhibitions of JNK, FAK, AKT, and c-Myc signaling pathways

Maclurin is a phenolic compound extracted from purple mangosteen and mulberry twigs. Earlier reports indicated that it exerts antioxidant activity. We hypothesized that maclurin exerts antioxidant activity and anti-cancer effects in small cell neuroendocrine carcinomas (SCNCs), a very aggressive type of human prostate cancer. To verify our hypothesis, we selected PC3 cells as a model system and investigated the antioxidant activity and anti-cancer effects of maclurin. In the reactive oxygen species (ROS) detection assay for the verification of antioxidant activity, we observed the unexpected prooxidant activity of maclurin in PC3 cells. For the anti-cancer activities, we investigated the effects of maclurin on induction of apoptosis and inhibition of metastatic characteristics of PC3 cells. In the apoptosis assay, maclurin significantly induced apoptosis of PC3 cells. Maclurin also showed significant anti-metastatic effects. Maclurin inhibited cell migration in a dosage-dependent manner. In addition, the gelatin zymography assay indicated that maclurin inhibited activities of matrix metalloproteinase-2 and 9 (MMP-2 and MMP-9) that affect cell migration and extracellular matrix (ECM) degradation. Then, we investigated the effects of maclurin on the cancer-related signaling molecules. Maclurin activated p38 signaling and inhibited c-Jun N-terminal kinase (JNK), focal-adhesion kinase (FAK), AKT, and c-Myc signalings in PC3 cells. Finally, we observed prooxidant activity and anti-SCNC effects of maclurin in DU145 cells. This suggests that the effects of maclurin may not be specifically limited to PC3 cells. Our findings suggest that maclurin exerts anti-cancer effects on SCNC cells via activation of p38 and inhibitions of JNK, FAK, AKT and c-Myc signalings.