Novel Radiolytic Rotenone Derivative, Rotenoisin B with Potent Anti-Carcinogenic Activity in Hepatic Cancer Cells.

Rotenone, isolated from roots of derris plant, has been shown to possess various biological activities, which lead to attempting to develop a potent drug against several diseases. However, recent studies have demonstrated that rotenone has the potential to induce several adverse effects such as a neurodegenerative disease. Radiolytic transformation of the rotenone with gamma-irradiation created a new product, named rotenoisin B. The present work was designed to investigate the anticancer activity of rotenoisin B with low toxicity and its molecular mechanism in hepatic cancer cells compared to a parent compound, rotenone. Our results showed rotenoisin B inhibited hepatic cancer cells' proliferation in a dose dependent manner and increased in apoptotic cells. Interestingly, rotenoisin B showed low toxic effects on normal cells compared to rotenone. Mitochondrial transmembrane potential has been decreased, which leads to cytochrome c release. Down regulation of anti-apoptotic Bcl-2 levels as well as the up regulation of proapoptotic Bax levels were observed. The cleaved PARP (poly ADP-ribose polymerase) level increased as well. Moreover, phosphorylation of extracellular signal regulated kinase (ERK) and p38 slightly up regulated and intracellular reactive oxygen species (ROS) increased as well as cell cycle arrest predominantly at the G2/M phase observed. These results suggest that rotenoisin B might be a potent anticancer candidate similar to rotenone in hepatic cancer cells with low toxicity to normal cells even at high concentrations compared to rotenone.

Centipedegrass extract induces apoptosis through the activation of caspases and the downregulation of PI3K/Akt and MAPK phosphorylation in leukemia cells.

Acute lymphoblastic leukemia (ALL), which involves the blood and bone marrow, is the most common type of cancer in children younger than 5 years of age. Previous studies have investigated the effects of centipedegrass extract (CGE), which is mainly composed of maysin and its derivatives, and have demonstrated that it has various biological activities, including antioxidant and anti­inflammatory activities, pancreatic lipase inhibitory activity, anti-adipogenic activity and insecticidal activity. To the best of our knowledge, this study is the first to investigate the anticancer effects of CGE in ALL cell lines and to elucidate the mechanisms underlying these effects. Cell viability was measured by thiazolyl blue tetrazolium blue (MTT) assay. Apoptosis, cell cycle progression and mitochondrial membrane potential (∆Ψm) were determined by flow cytometry. The effects of CGE on the phosphatidylinositol 3­kinase (PI3K)/Akt pathway and mitogen­activated protein kinases (MAPKs) were assessed by immunoblotting. PI3K, MAPK and caspase inhibitors were used to further confirm the molecular mechanisms involved. Our results clearly demonstrated that the proliferation of the ALL cells was significantly inhibited by CGE in a dose­dependent manner. Apoptosis was accompanied by the induction of significant G1 cell cycle arrest. The resulting alteration of the ∆Ψm increased the activity of caspase­3/7. The induction of apoptosis was enhanced by the combined treatment of CGE with a PI3K inhibitor or an extracellular signal-regulated kinase (ERK) inhibitor, whereas the CGE­induced apoptosis was inhibited in the presence of caspase inhibitors, such as z­VAD­fmk and z­IETD­fmk. Furthermore, CGE inhibited PI3K activity by decreasing the levels of phosphorylated (p­)Akt, p­BAD, and Bcl­2 together with the levels of MAPKs, including p­ERK and p­JNK, but demonstrated no effects on p38 MAPK. Thus, our data suggest that CGE may be a novel natural compound with potential for use as an antitumor agent in ALL.

Molecular mechanism of apoptosis induction in skin cancer cells by the centipedegrass extract.

BACKGROUND: Centipedegrass extract (CGE) is mainly composed of maysin and its derivatives, which are recognized internationally as natural compounds. Compared to other flavonoids, maysin has a unique structure in that mannose is bound to the flavonoid backbone. CGE exhibits some biological properties in that it can function as an anti-oxidant, anti-inflammatory, anti-adipogenic, and insecticidal. Whether CGE has other biological functions, such as anti-cancer activity, is unknown. METHODS: B16F1 (mouse) and SKMEL-5 (human) cells were treated with CGE, and their subsequent survival was determined using MTT assay. We performed a cell cycle analysis using propidium iodide (PI), and detected apoptosis using double staining with annexin V-FITC/PI. In addition, we examined mitochondrial membrane potentials using flow cytometry, as well as signaling mechanisms with an immunoblotting analysis. RESULTS: CGE inhibited skin cancer cell growth by arresting the cell cycle in the G2/M phase, and increased both early and late apoptotic cell populations without affecting normal cells. Furthermore, we observed mitochondrial transmembrane depolarization, increased cytochrome-c release, caspase-3 and caspase-7 activation, and increased poly ADP-ribose polymerase degradation. CGE also downregulated activation of p-AKT, p-glycogen synthase kinase-3ß (GSK-3ß), and p-BAD in a time-dependent manner. LY294002 inhibition of phosphoinositide 3-kinase (PI3K) significantly sensitized skin cancer cells, which led to an increase in CGE-induced apoptosis. CONCLUSIONS: CGE controlled skin cancer cell growth by inhibiting the PI3K/AKT/GSK-3ß signaling pathway and activating the effector caspases. This study is the first to demonstrate anti-cancer properties for CGE, and that CGE may be an effective therapeutic agent for treating skin cancer.