Structurally diverse alkaloids from Buxus sempervirens with cardioprotective activity.

Extensive phytochemical study of the methanol extract of twigs and leaves of Buxus sempervirens resulted in the identification of 17 Buxus alkaloids, including 12 new ones, namely buxusemines A-L (1-12). Their structures were delineated by detailed analysis of the HRESIMS and NMR data, as well as quantum chemical NMR calculations. Buxusemine A (1) represents the second Buxus alkaloid with a unique spiro[4.6]undecatriene moiety, buxusemines B-C (2-3) are a rarely occurring class of Buxus alkaloids featured with an additional five-membered ring through the ether or lactone linkage between C-10 and C-23, and buxusemines D-F (4-6) are another rare type of Buxus alkaloids with an epoxy motif. In the assessment of their bioactivities, buxusemine F (6) and buxanoldine (17) displayed more potent protective effects than the positive control cyclovirobuxinum D in the doxorubicin-induced cardiac injury model.

LYG-202 augments tumor necrosis factor-α-induced apoptosis via attenuating casein kinase 2-dependent nuclear factor-κB pathway in HepG2 cells.

Tumor necrosis factor-α (TNF-α) is being used as an antineoplastic agent in treatment regimens of patients with locally advanced solid tumors, but TNF-α alone is only marginally active. In clinical use, it is usually combined with other chemical agents to increase its tumor response rate. Our previous studies reported that LYG-202 (5-hydroxy-8-methoxy-7-(4-(4-methylpiperazin-1-yl)butoxy)-2-phenyl-4H-chromen-4-one), a synthesized flavonoid with a piperazine substitution, has antiproliferative, antiangiogenic, and proapoptotic activities in multiple cancer cell lines. Here we evaluated the antineoplastic effect of TNF-α and analyzed the mechanism underlying its combination with LYG-202. Our results indicated that LYG-202 significantly increased the cytostatic and proapoptotic activity of TNF-α in HepG2 cells and heightened the protein level of apoptosis-related genes including caspase-3, caspase-8/9, cleaved poly(ADP-ribose) polymerase, and Bid. The fact that LYG-202 had a fitness score similar to that of the casein kinase 2 (CK2) inhibitor naphthyridine-8-carboxylate (CX-4945) implied to us that it may serve as a potential candidate for CK2 inhibitor, and the kinase activity assay suggested that LYG-202 significantly inhibited CK2 activity. Moreover, the electrophoretic mobility shift assay and luciferase assay showed that LYG-202 blocked the TNF-α-induced nuclear factor-κB (NF-κB) survival signaling pathway primarily by inactivating protein kinase CK2. In murine xenograft models, we also found that LYG-202 enhanced TNF-α antineoplastic activity and inhibited CK2 activity and NF-κB-regulated antiapoptotic gene expression. All these results showed that LYG-202 enhanced TNF-α-induced apoptosis by attenuating the CK2-dependent NF-κB pathway and probably is a promising agent in combination with TNF-α.

Reactive oxygen species-mitochondria pathway involved in FV-429-induced apoptosis in human hepatocellular carcinoma HepG2 cells.

FV-429 is a newly synthesized flavonoid with a bis(2-hydroxyethyl) amino propoxy substitution. In this study, we investigate the anticancer effect of FV-429 both in vivo and in vitro. These data have shown that FV-429 could significantly inhibit tumor growth in mice inoculated with Heps hepatoma cells without evident toxicity. After the treatment of FV-429 (40 mg/kg), the inhibitory rate of tumor weight was 52.12%. Then, we performed diamidinophenylindole staining and annexin V/propidium iodide double-staining assay to investigate the apoptosis induced by FV-429 in HepG2 cells. Further research revealed that FV-429 induced apoptosis through the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl-2 ratios, collapse of mitochondrial membrane potential, the transposition of apoptotic-inducing factor and cytochrome c, caspase-3 and caspase-9 activation, and degradation of poly (ADP-ribose) polymerase. The accumulation of reactive oxygen species induced by FV-429 in HepG2 cells was also observed. Moreover, the mitogen-activated protein kinases, the downstream effect of reactive oxygen species accumulation including c-Jun N-terminal kinase and p38 mitogen-activated protein kinases, could be activated by FV-429. Taken together, our results provided a mechanistic framework for further exploration of FV-429 as a novel chemotherapy for human tumors.

Structure-Based Pharmacophore Modeling from Multicomplex: a Comprehensive Pharmacophore Generation of Protein Kinase CK2 and Virtual Screening Based on it for Novel Inhibitors.

Protein kinase CK2, a member of the serine/threonine kinase family, is an attractive therapeutic target for anticancer combination therapy. A multiple structure-based modeling approach complemented with shape components was taken to build a reliable pharmacophore model for ATP-competitive CK2 inhibitors. The final model consisted of one hydrogen bond acceptor (HBA), one hydrogen bond donor (HBD), two hydrophobic (HY) features, several excluded volumes and shape constraints. In the validation study, this model yielded an enrichment factor of 10.22 and performed fairly well in distinguishing active compounds. SPECS database was searched based on this query and sixteen compounds were retained after multiple filtrations for biological test. 4 compounds with IC50 values less than 10 µM were disclosed, providing 2 new chemical scaffolds as CK2 inhibitors. It is expected that the information provided here is helpful for discovering more potential CK2 inhibitors.

Combination of pharmacophore model development and binding mode analyses: identification of ligand features essential for IκB kinase-beta (IKKß) inhibitors and virtual screening based on it.

IκB kinase ß (IKKß) is an important anti-cancer target that plays crucial role in activating the transcription factor NF-κB in response to various inflammatory stimuli. In order to discover novel IKKß inhibitors, a 3D chemical-feature-based QSAR pharmacophore model was established. A homology model of IKKß enzyme was also developed to study the binding mode of IKKß and its inhibitors. The two models were consistent in predicting the binding conformation of IKKß inhibitor. Based on the virtual screening using the pharmacophore model, 16 compounds from SPECS database were selected after multiple filtrations for biological test. Two compounds with IC(50) values lower than 10 µM were discovered.

DHF-18, a new synthetic flavonoid, induced a mitochondrial-mediated apoptosis of hepatocarcinoma cells in vivo and in vitro.

A new synthetic flavonoid DHF-18, synthesized with a piperazine substitution, has been recently found to show potent anti-tumor activities both in vivo and in vitro. In this study, we demonstrated that DHF-18 significantly inhibited tumor growth in mice inoculated with Heps hepatoma cells without evident toxicity. After the treatment of 40mg/kg DHF-18, the inhibitory rate of tumor weight was 53.69%. To investigate whether apoptosis induction contributed to the anti-tumor effects of DHF-18, DAPI (diamidino-phenyl-indole) staining and Annexin V/PI (Propidium iodide) double staining were performed in our tests. The data showed that DHF-18 could induce the apoptosis cell death in HepG2 cells. Moreover, the apparent increase of intracellular reactive oxygen species levels and the reduction of mitochondria ΔΨm were both observed in HepG2 cells after DHF-18 treatment. Meanwhile, the transposition of apoptotic inducing factor (AIF) from mitochondria to nuclei, the release of cytochrome c from mitochondria and the activation of caspase-3, -9 were also detected, indicating that DHF-18 may induce apoptosis through a mitochondrial-mediated pathway. Additionally, DHF-18 decreased the expression of Bcl-2 protein, whereas the levels of Bax and Bak were found to increase after DHF-18 treatment. Moreover, the activation of caspase-8, the increase of TNF-R1 (Tumor necrosis factor receptor) and Bid were found. Taken together, our results suggested that DHF-18 may induce HeG2 cells apoptosis through a mitochondrial-dependent and independent pathway.

Reactive oxygen species-mitochondria pathway involved in LYG-202-induced apoptosis in human hepatocellular carcinoma HepG(2) cells.

Previously, we demonstrated that LYG-202, a newly synthesized flavonoid with a piperazine substitution, exhibited obvious antitumor activity in vivo and in vitro. The exact mechanism of this new compound remains unclear. In the present study, we examined the effects of LYG-202 on reactive oxygen species (ROS) production and the downstream signaling pathway in the apoptosis of human hepatocellular carcinoma HepG(2) cells. Pretreatment with NAC (N-acetylcysteine), a ROS production inhibitor, partly inhibited the apoptosis induced by LYG-202 via blocking the ROS generation. Further data revealed that LYG-202 induced ROS accumulation followed by a decrease in mitochondrial membrane potential (MMP), release of cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) to cytosol, which induced apoptosis of the cells. Moreover, the mitogen-activated protein kinases (MAPK), the downstream effect of ROS accumulation including c-Jun N-terminal kinase (JNK) and p38 MAPK, could be activated by LYG-202. Taken together, the generation of ROS might play an important role in LYG-202-induced mitochondrial apoptosis pathway, which provided further support for LYG-202 as a novel anticancer therapeutic candidate.

Isolation and characterization of cancer stem like cells in human glioblastoma cell lines.

To identify and compare the features of stem like cells in human glioblastoma cell lines U251, U87MG, A172 with primary cultured glioblastoma stem cells, the ratio of CD133+ cells, the ability of tumor sphere formation, and self-renewing capacity of U251, U87MG, A172 cells in serum free medium plus EGF, bFGF and B27 supplement were detected. The results suggested that there might be more cancer stem like cells in U251 cells compared with others. CD133+ cells enriched in SP cells and in U251 cells cultured with the serum free medium. They expressed the neural stem cell markers CD133 and Nestin, but lacked of neuronal and astrocyte marker MAP2, beta-III tubulin and GFAP. They could apparently generate both neurons and glial cells after serum retrieved in vitro. Gli1, Bmi1, Notch2 and PTEN were also found expressed highly in them. Moreover, CD133+ cells were more resistant to hypoxia, irradiations and some chemotherapeutics than CD133-cells. So we suggested that glioblastoma stem like cells were existed in CD133+ cells in U251 cell line with characteristics of self-renew and generation of an unlimited progeny of non-tumorigenic cells. Molecular and functional characterization of such a tumorigenic population may be exploited in the development of novel cancer therapeutic drugs.