Alkaloids and Polyacetylenes from Hippobroma longiflora with Antiangiogenesis Properties.

Four new alkaloids, hippobrines A-D (1-4), along with three new polyacetylenes, hippobrenes A-C (5-7), were isolated from Hippobroma longiflora. Compounds 1-3 possess an unprecedented carbon skeleton. All of the new structures were determined by analyzing their mass and NMR spectroscopic data. The absolute configurations of 1 and 2 were confirmed by single-crystal X-ray analyses, and the absolute configurations of 3 and 7 were deduced using their ECD spectra. Plausible biogenetic pathways of 1 and 4 were proposed. In regard to bioactivities, all compounds (1-7) exhibited weak antiangiogenic activity against human endothelial progenitor cells, with IC50 values ranging from 21.1 ± 1.1 to 44.0 ± 2.3 µg/mL.

ZnO Nanoparticles Induced Caspase-Dependent Apoptosis in Gingival Squamous Cell Carcinoma through Mitochondrial Dysfunction and p70S6K Signaling Pathway.

Zinc oxide nanoparticles (ZnO-NPs) are increasingly used in sunscreens, food additives, pigments, rubber manufacture, and electronic materials. Several studies have shown that ZnO-NPs inhibit cell growth and induce apoptosis by the production of oxidative stress in a variety of human cancer cells. However, the anti-cancer property and molecular mechanism of ZnO-NPs in human gingival squamous cell carcinoma (GSCC) are not fully understood. In this study, we found that ZnO-NPs induced growth inhibition of GSCC (Ca9-22 and OECM-1 cells), but no damage in human normal keratinocytes (HaCaT cells) and gingival fibroblasts (HGF-1 cells). ZnO-NPs caused apoptotic cell death of GSCC in a concentration-dependent manner by the quantitative assessment of oligonucleosomal DNA fragmentation. Flow cytometric analysis of cell cycle progression revealed that sub-G1 phase accumulation was dramatically induced by ZnO-NPs. In addition, ZnO-NPs increased the intracellular reactive oxygen species and specifically superoxide levels, and also decreased the mitochondrial membrane potential. ZnO-NPs further activated apoptotic cell death via the caspase cascades. Importantly, anti-oxidant and caspase inhibitor clearly prevented ZnO-NP-induced cell death, indicating the fact that superoxide-induced mitochondrial dysfunction is associated with the ZnO-NP-mediated caspase-dependent apoptosis in human GSCC. Moreover, ZnO-NPs significantly inhibited the phosphorylation of ribosomal protein S6 kinase (p70S6K kinase). In a corollary in vivo study, our results demonstrated that ZnO-NPs possessed an anti-cancer effect in a zebrafish xenograft model. Collectively, these results suggest that ZnO-NPs induce apoptosis through the mitochondrial oxidative damage and p70S6K signaling pathway in human GSCC. The present study may provide an experimental basis for ZnO-NPs to be considered as a promising novel anti­tumor agent for the treatment of gingival cancer.

Internalization of mesoporous silica nanoparticles induces transient but not sufficient osteogenic signals in human mesenchymal stem cells.

The biocompatibility of nanoparticles is the prerequisite for their applications in biomedicine but can be misleading due to the absence of criteria for evaluating the safety and toxicity of those nanomaterials. Recent studies indicate that mesoporous silica nanoparticles (MSNs) can easily internalize into human mesenchymal stem cells (hMSCs) without apparent deleterious effects on cellular growth or differentiation, and hence are emerging as an ideal stem cell labeling agent. The objective of this study was to thoroughly investigate the effect of MSNs on osteogenesis induction and to examine their biocompatibility in hMSCs. Uptake of MSNs into hMSCs did not affect the cell viability, proliferation and regular osteogenic differentiation of the cells. However, the internalization of MSNs indeed induced actin polymerization and activated the small GTP-bound protein RhoA. The MSN-induced cellular protein responses as believed to cause osteogenesis of hMSCs did not result in promotion of regular osteogenic differentiation as analyzed by cytochemical stain and protein activity assay of alkaline phosphatase (ALP). When the effect of MSNs on ALP gene expression was further examined by reverse transcriptase polymerase chain reaction, MSN-treated hMSCs were shown to have significantly higher mRNA expression than control cells after 1-hour osteogenic induction. The induction of ALP gene expression by MSNs, however, was absent in cells after 1-day incubation with osteogenic differentiation. Together our results show that the internalization of MSNs had a significant effect on the transient protein response and osteogenic signal in hMSCs, thereby suggesting that the effects of nanoparticles on diverse aspects of cellular activities should be carefully evaluated even though the nanoparticles are generally considered as biocompatible at present.

Highly efficient cellular labeling of mesoporous nanoparticles in human mesenchymal stem cells: implication for stem cell tracking.

Tracking the distribution of stem cells is crucial to their therapeutic use. However, the usage of current vectors in cellular labeling is restricted by their low internalizing efficiency. Here, we reported a cellular labeling approach with a novel vector composed of mesoporous silica nanoparticles (MSNs) conjugated with fluorescein isothiocyanate in human bone marrow mesenchymal stem cells and 3T3-L1 cells, and the mechanism about fluorescein isothiocyanate-conjugated MSNs (FITC-MSNs) internalization was studied. FITC-MSNs were efficiently internalized into mesenchymal stem cells and 3T3-L1 cells even in short-term incubation. The process displayed a time- and concentration-dependent manner and was dependent on clathrin-mediated endocytosis. In addition, clathrin-dependent endocytosis seemed to play a decisive role on more internalization and longer stay of FITC-MSNs in mesenchymal stem cells than in 3T3-L1 cells. The internalization of FITC-MSNs did not affect the cell viability, proliferation, immunophenotype, and differentiation potential of mesenchymal stem cells, and 3T3-L1 cells. Finally, FITC-MSNs could escape from endolysosomal vesicles and were retained the architectonic integrity after internalization. We conclude that the advantages of biocompatibility, durability, and higher efficiency in internalization suit MSNs to be a better vector for stem cell tracking than others currently used.

Induction of mitotic arrest and apoptosis in human prostate cancer pc-3 cells by evodiamine.

PURPOSE: Although evodiamine, an alkaloid isolated from Evodiae fructus, has been reported to exert anticancer activities, to our knowledge its target and mechanism of action have not yet been explored. We examined the anticancer activities and action mechanism of evodiamine. MATERIALS AND METHODS: Human prostate cancer PC-3 cells were used in this study. The cytotoxic effect and cell growth inhibition were examined using the MTT (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay and sulforhodamine B assay, respectively. The apoptotic effect was determined using TUNEL assay and the progression of cells through the cell cycle and cell apoptosis were examined by FACScan flow cytometry (Becton Dickinson, Sunnyvale, California). In situ mitotic spindle detection and in vitro tubulin polymerization assay were performed by immunofluorescence staining for beta-tubulin and CytoDYNAMIX ScreenTM3 (CDS-03) kits (Cytoskeleton, Denver, Colorado). RESULTS: It was found that treatment of PC-3 cells with evodiamine decreased the cell number in a concentration and time dependent manner, and effectively inhibited PC-3 cell growth via the induction of cell cycle arrest at the G2/M phase and subsequent apoptosis. In an in situ assay we found that evodiamine inhibited microtubule spindle formation. In a cell-free assay system of tubulin polymerization evodiamine inhibited the polymerization of microtubules in a concentration dependent manner. CONCLUSIONS: These data suggest that evodiamine shows anticancer activity through inhibition of tubulin polymerization. This antitubulin activity might make evodiamine a potential anticancer drug.