Bingya Yang

Synergistic antitumor activity of oridonin and arsenic trioxide on hepatocellular carcinoma cells.

Although arsenic trioxide (As2O3) has been successfully employed in treatment of patients with APL (acute promyelocytic leukemia), the sensitivity of solid tumor cells to this treatment was much lower than APL cells. The single agent of As2O3 was inefficient for treatment of hepatocellular carcinoma (HCC) in phase II trial demonstrating that new modalities of treatment with enhanced therapeutic effect are needed. In this study, we showed that oridonin, a diterpenoid isolated from traditional Chinese medicine Rabdosia rubescences, greatly potentiated apoptosis induced by As2O3 in hepatocellular carcinoma cells. The synergistic pro-apoptosis effect of combination of these two drugs led to increase in intracellular reactive oxygen species (ROS) level and N-acetyl-L-cysteine (NAC), a thiol-containing anti-oxidant, was able to completely block the effect. The combination treatment induced ROS-dependent decrease in mitochondrial membrane potential (MMP) decrease, and relocation of Bax and cytochrome C. Besides, oridonin dramatically increased the intracellular Ca2+ overload triggered by As2O3. Furthermore, the co-treatment of oridonin and As2O3 induced ROS-mediated down-regulation of Akt and XIAP, and inhibition of NF-κB activation. The two drug combination enhanced tumor suppression activity in murine HCC model compared with single agent treatment in vivo. These findings demonstrate that oridonin can sensitize hepatocellular carcinoma cells to As2O3 treatment and will facilitate the optimization of As2O3 therapy for HCC patients.

Protective Effect of Procyanidin B2 against CCl4-Induced Acute Liver Injury in Mice

Procyanidin B2 has demonstrated several health benefits and medical properties. However, its protective effects against CCl4-induced hepatotoxicity have not been clarified. The present study aimed to investigate the hepatoprotective effects of procyanidin B2 in CCl4-treated mice. Our data showed that procyanidin B2 significantly decreased the CCl4-induced elevation of serum alanine aminotransferase activities, as well as improved hepatic histopathological abnormalities. Procyanidin B2 also significantly decreased the content of MDA but enhanced the activities of antioxidant enzymes SOD, CAT and GSH-Px. Further research demonstrated that procyanidin B2 decreased the expression of TNF-α, IL-1β, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), as well as inhibited the translocation of nuclear factor-kappa B (NF-κB) p65 from the cytosol to the nuclear fraction in mouse liver. Moreover, CCl4-induced apoptosis in mouse liver was measured by (terminal-deoxynucleotidyl transferase mediated nick end labeling) TUNEL assay and the cleaved caspase-3. Meanwhile, the expression of apoptosis-related proteins Bax and Bcl-xL was analyzed by Western blot. Results showed that procyanidin B2 significantly inhibited CCl4-induced hepatocyte apoptosis, markedly suppressed the upregulation of Bax expression and restored the downregulation of Bcl-xL expression. Overall, the findings indicated that procyanidin B2 exhibited a protective effect on CCl4-induced hepatic injury by elevating the antioxidative defense potential and consequently suppressing the inflammatory response and apoptosis of liver tissues.

Use of 16S rRNA Gene-Targeted Group-Specific Primers for Real-Time PCR Analysis of Predominant Bacteria in Mouse Feces

ABSTRACT Mouse models are widely used for studying gastrointestinal (GI) tract-related diseases. It is necessary and important to develop a new set of primers to monitor the mouse gut microbiota. In this study, 16S rRNA gene-targeted group-specific primers for Firmicutes, Actinobacteria, Bacteroidetes, Deferribacteres, “Candidatus Saccharibacteria,” Verrucomicrobia, Tenericutes, and Proteobacteria were designed and validated for quantification of the predominant bacterial species in mouse feces by real-time PCR. After confirmation of their accuracy and specificity by high-throughput sequencing technologies, these primers were applied to quantify the changes in the fecal samples from a trinitrobenzene sulfonic acid-induced colitis mouse model. Our results showed that this approach efficiently predicted the occurrence of colitis, such as spontaneous chronic inflammatory bowel disease in transgenic mice. The set of primers developed in this study provides a simple and affordable method to monitor changes in the intestinal microbiota at the phylum level.

Salmonella-mediated tumor-targeting TRAIL gene therapy significantly suppresses melanoma growth in mouse model.

Attenuated Salmonella typhimurium (S. typhimurium) strains can selectively grow and express exogenous genes in tumors for targeted therapy. We engineered S. typhimurium strain VNP20009 to secrete tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) under the control of a hypoxia‐induced nirB promoter and examined the efficacy of Salmonella‐mediated targeted expression of TRAIL in mice bearing melanoma tumor and in TRAIL‐resistant RM‐1 tumor. We found that VNP preferentially accumulated in tumor tissues and the nirB promoter effectively drove targeted expression of TRAIL. Compared with recombinant TRAIL protein and VNP20009 combination therapy, VNP20009 expressing TRAIL significantly suppressed melanoma growth but failed to suppress RM‐1 tumor growth. Furthermore, we confirmed that VNP20009 expressing TRAIL yielded its antitumor effect by inducing melanoma apoptosis. Our findings indicate that Salmonella‐mediated tumor‐targeted therapy with TRAIL could reduce tumor growth and extend host survival. (Cancer Sci 2012; 103: 325–333)

Regulation of Protein Kinase C Inactivation by Fas-associated Protein with Death Domain

Background: PKC is extremely important for a wide array of cellular processes. However, its inactivation is poorly understood. Results: FADD deficiency or phosphoryl-mimicking mutation (FADD-D) leads to accumulation of phosphorylated PKC and sustained signaling. Conclusion: The apoptotic adapter FADD is required for PKC dephosphorylation, degradation and signaling inactivation and may be regulated by its phosphorylation. Significance: FADD is critical for PKC dephosphorylation, stability, and signaling termination. Protein kinase C (PKC) plays important roles in diverse cellular processes. PKC has been implicated in regulating Fas-associated protein with death domain (FADD), an important adaptor protein involved in regulating death receptor-mediated apoptosis. FADD also plays an important role in non-apoptosis processes. The functional interaction of PKC and FADD in non-apoptotic processes has not been examined. In this study, we show that FADD is involved in maintaining the phosphorylation of the turn motif and hydrophobic motif in the activated conventional PKC (cPKC). A phosphoryl-mimicking mutation (S191D) in FADD (FADD-D) abolished the function of FADD in the facilitation of the turn motif and hydrophobic motif dephosphorylation of cPKC, suggesting that phosphorylation of Ser-191 negatively regulates FADD. We show that FADD interacts with PP2A, which is a major phosphatase involved in dephosphorylation of activated cPKC and FADD deficiency abolished PP2A mediated dephosphorylation of cPKC. We show that FADD deficiency leads to increased stability and activity of cPKC, which, in turn, promotes cytoskeleton reorganization, cell motility, and chemotaxis. Collectively, these results reveal a novel function of FADD in a non-apoptotic process by modulating cPKC dephosphorylation, stability, and signaling termination.

In situ electrical-field-induced growth and properties of Bi3TiNbO9 ferroelectric thin films

With Bi3TiNbO9 (BTN) ferroelectric samples, in situ electrical-field-induced growth of ferroelectric thin films was demonstrated to control the films’ microstructure and manipulate their ferroelectric properties. BTN films on Ti/SiO2/Si substrates were grown at a relatively low temperature (650 °C) with a biased electrical field during pulsed-laser deposition. The (001) orientation of the films, which makes no contribution to their polarization, was effectively reduced by the in situ electrical field of strength of 70 V/cm. This results in a large increase of remnant polarization from 1.1 to 6.2 μC/cm2, and reduction of the coercive field from 70 to 50 kV/cm, comparing the films grown freely under the same condition. Furthermore, the films showed an excellent fatigue-free property of up to 1010 switching cycles.

Tumor-targeting Salmonella typhimurium, a natural tool for activation of prodrug 6MePdR and their combination therapy in murine melanoma model.

The PNP/6-methylpurine 2′-deoxyriboside (6MePdR) system is an efficient gene-directed enzyme prodrug therapy system with significant antitumor activities. In this system, Escherichia coli purine nucleoside phosphorylase (ePNP) activates nontoxic 6MePdR into potent antitumor drug 6-methylpurine (6MeP). The Salmonella typhimurium PNP (sPNP) gene has a 96-% sequence homology in comparison with ePNP and also has the ability to convert 6MePdR to 6MeP. In this study, we used tumor-targeting S. typhimurium VNP20009 expressing endogenous PNP gene constitutively to activate 6MePdR and a combination treatment of bacteria and prodrug in B16F10 melanoma model. The conversion of 6MePdR to 6MeP by S. typhimurium was analyzed by HPLC and the enzyme activity of sPNP was confirmed by in vitro (tetrazolium-based colorimetric assay) MTT cytotoxicity assay. After systemic administration of VNP20009 to mice, the bacteria largely accumulated and specifically delivered endogenous sPNP in the tumor. In comparison with VNP20009 or 6MePdR treatment alone, combined administration of VNP20009 followed by 6MePdR treatment significantly delayed the growth of B16F10 tumor and increased the CD8+ T-cell infiltration. In summary, our results demonstrated that the combination therapy of S. typhimurium and prodrug 6MePdR is a promising strategy for cancer therapy.

Growth of completely (110)- and (111)-oriented MgO films on H-terminated (100) silicon substrate by pulsed laser deposition

Abstract Thin films of MgO have been grown on H-terminated Si (100) substrates by pulsed laser deposition. The completely (110)-oriented films were obtained at ambient pressure of 10−3 Pa and at various substrate temperatures from 400 to 750°C. If the ambient pressure is higher, the prepared MgO films are (111)-oriented. The (110)-oriented films have a larger lattice constant along the [110] direction comparing to that of the bulk MgO; while the lattice constant of the (111)-oriented films along the [111] direction is almost the same as that of the bulk MgO. Atomic force microscopy measurements showed the surface of deposited films is smooth with roughness less than 30 nm. These results are explained by taking into account of the interactions between MgO species and substrate surface.

Role of Fas-Associated Death Domain-containing Protein (FADD) Phosphorylation in Regulating Glucose Homeostasis: from Proteomic Discovery to Physiological Validation

Fas-associated death domain-containing protein (FADD), a classical apoptotic signaling adaptor, participates in different nonapoptotic processes regulated by its phosphorylation. However, the influence of FADD on metabolism, especially glucose homeostasis, has not been evaluated to date. Here, using both two-dimensional electrophoresis and liquid chromatography linked to tandem mass spectrometry (LC/MS/MS), we found that glycogen synthesis, glycolysis, and gluconeogenesis were dysregulated because of FADD phosphorylation, both in MEFs and liver tissue of the mice bearing phosphorylation-mimicking mutation form of FADD (FADD-D). Further physiological studies showed that FADD-D mice exhibited lower blood glucose, enhanced glucose tolerance, and increased liver glycogen content without alterations in insulin sensitivity. Moreover, investigations on the molecular mechanisms revealed that, under basal conditions, FADD-D mice had elevated phosphorylation of Akt with alterations in its downstream signaling, leading to increased glycogen synthesis and decreased gluconeogenesis. Thus, we uncover a novel role of FADD in the regulation of glucose homeostasis by proteomic discovery and physiological validation.

Four regions of the propagation of the plume formed in pulsed laser deposition by optical-wavelength-sensitive CCD photography

Abstract Propagation of the plume formed by pulsed laser ablation of PbTiO3 in an ambient of oxygen and argon was studied by using a CCD camera. Two optical filters with different transmittance bands were used to distinguish the atomic processes in the plume. The results show that, if a strong shock wave is formed, the propagation of the plume formed in pulsed laser deposition in oxygen ambient can be classified into four successive regions from the target to the substrate: (1) the plasma region nearby the target surface; (2) the shock wave forming region in which the interactions between ablated species and ambient oxygen are not chemically reactive; (3) the shock wave propagation region in which the excitations, dissociations, and ionizations, as well as gas-phase chemical reactions between ablated species and ambient oxygen occur; and (4) sound wave region.