Emetine exerts anticancer effects in U2OS human osteosarcoma cells via activation of p38 and inhibition of ERK, JNK, and ß-catenin signaling pathways.

Osteosarcoma (OS) is a primary bone neoplasm that is highly malignant. As advances in chemotherapy for the treatment of OS have stagnated, discovery of new reagents is required. Emetine is a phytochemical which can be isolated from a medicinal herb Cephaelis ipecacuanha and is traditionally used for amoebicides. Previous studies have demonstrated that emetine can possibly be repositioned for use in anticancer reagents. However, any anticancer effects and underlying mechanisms of emetine on human OS are not yet well understood. In this study, we analyzed the anticancer effects and involved cellular mechanisms after treatment with emetine to U2OS human OS cells. Emetine significantly reduced both the viability and proliferation, and induced apoptosis via activation of caspase-3 and caspase-7 in U2OS cells. Emetine effectively inhibited the migration and invasion of U2OS cells. Gelatinase activities of matrix metalloproteinase 2 (MMP-2) and MMP-9 were reduced by emetine. MMP-9 was transcriptionally inhibited, while MMP-2 was posttranscriptionally repressed, via the reduced expression of membrane-type I-matrix metalloproteinase (MT1-MMP). p38, which is closely related with induction of apoptosis, was stimulated by emetine. Extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and ß-catenin, which are linked with expression of MMPs, were downregulated. Emetine exerted anticancer effects on MG63 human OS cells as well. Taken together, our study demonstrated the anticancer and antimetastatic potential of emetine in treating human OS for the first time. It is expected that emetine may be a promising drug candidate to be repositioned for chemotherapy of OS.

Therapeutic Potential of Ursonic Acid: Comparison with Ursolic Acid.

Plants have been used as drugs to treat human disease for centuries. Ursonic acid (UNA) is a naturally occurring pentacyclic triterpenoid extracted from certain medicinal herbs such as Ziziphus jujuba. Since the pharmacological effects and associated mechanisms of UNA are not well-known, in this work, we attempt to introduce the therapeutic potential of UNA with a comparison to ursolic acid (ULA), a well-known secondary metabolite, for beneficial effects. UNA has a keto group at the C-3 position, which may provide a critical difference for the varied biological activities between UNA and ULA. Several studies previously showed that UNA exerts pharmaceutical effects similar to, or stronger than, ULA, with UNA significantly decreasing the survival and proliferation of various types of cancer cells. UNA has potential to exert inhibitory effects in parasitic protozoa that cause several tropical diseases. UNA also exerts other potential effects, including antihyperglycemic, anti-inflammatory, antiviral, and antioxidant activities. Of note, a recent study highlighted the suppressive potential of UNA against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Molecular modifications of UNA may enhance bioavailability, which is crucial for in vivo and clinical studies. In conclusion, UNA has promising potential to be developed in anticancer and antiprotozoan pharmaceuticals. In-depth investigations may increase the possibility of UNA being developed as a novel reagent for chemotherapy.

Ursonic acid exerts inhibitory effects on matrix metalloproteinases via ERK signaling pathway.

Ursonic acid is a pentacyclic triterpenoid compound that can be extracted from Ziziphus jujuba Mill., a traditional medicine. Matrix metalloproteinases (MMPs) are involved in cancer metastasis and skin aging. Regulation of various MMPs is closely associated with mitogen-activated protein kinases (MAPKs), including ERK, p38, and JNK MAPKs. In this study, we investigated the possibility of ursonic acid as an anti-cancer/anti-skin aging agent targeting MMPs. Cytotoxic effects of ursonic acid were analyzed by cell counting kit-8 (CCK-8) assay. Invasive abilities of ursonic acid-treated A549 and H1299 non-small cell lung cancer (NSCLC) cells were tested with Boyden chamber assay. Effects of ursonic acid on MMPs were analyzed by zymography assays and quantitative real time polymerase chain reaction (qRT-PCR). We also conducted flow cytometry and western blot analysis to elucidate the mechanisms of MMP regulation by ursonic acid. Our results revealed that ursonic acid inhibited transcriptional expression of gelatinases (MMP-2 and MMP-9) via inhibition of ERK and CREB signaling pathways in NSCLC cells. Moreover, ursonic acid reduced mRNA levels of collagenase (MMP-1) via suppression of ERK and c-Fos signaling pathways in HaCaT keratinocytes. These results suggest that ursonic acid could be a potential candidate for development of an effective novel anti-cancer and anti-wrinkle agent.

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.