Effect of a synthetic cannabinoid agonist on the proliferation and invasion of gastric cancer cells

Although cannabinoids are associated with antineoplastic activity in a number of cancer cell types, the effect in gastric cancer cells has not been clarified. In the present study, we investigated the effects of a cannabinoid agonist on gastric cancer cell proliferation and invasion. The cannabinoid agonist WIN 55,212‐2 inhibited the proliferation of human gastric cancer cells in a dose‐dependent manner and that this effect was mediated partially by the CB₁ receptor. We also found that WIN 55,212‐2 induced apoptosis and down‐regulation of the phospho‐AKT expression in human gastric cancer cells. Furthermore, WIN 55,212‐2 treatment inhibited the invasion of gastric cancer cells, and down‐regulated the expression of MMP‐2 and VEGF‐A through the cannabinoid receptors. Our results open the possibilities in using cannabinoids as a new gastric cancer therapy. J. Cell. Biochem. 110: 321–332, 2010. © 2010 Wiley‐Liss, Inc.     

Hymenobacter perfusus sp. nov., Hymenobacter flocculans sp. nov. and Hymenobacter metalli sp. nov. three new species isolated from an uranium mine waste water treatment system

Three red-pink pigmented strains, designated A1-12(T), A2-50A(T) and A2-91(T), were recovered from two different sites in a uranium mine. For all strains, the optimum growth temperature was 25°C, the optimum pH was 6.0-6.5 and the DNA G+C contents were between 60 and 63.4 mol%. The major respiratory quinone was menaquinone 7 (MK-7) and the fatty acid profiles contained iso- and anteiso-branched C15 fatty acids, summed feature 3 (16:1 ω6c and/or ω7c and/or 15:0 iso 2-OH), summed feature 4 (17:1 anteiso B and/or iso I) and the unsaturated fatty acid 16:1 ω5c as the major components. Phylogenetic analysis of the 16S rRNA gene sequences showed that these organisms represented three distinct branches within the family Flexibacteraceae most closely related to the members of the genus Hymenobacter. Strain A1-12(T) formed a distinct phylogenetic line along with H. rigui KCTC 12533(T) and they shared approximately 98.9% 16S rRNA gene sequence similarity. However, these two strains shared only 14.7% pairwise similarity in their genomic DNA. Strains A2-50A(T) and A2-91(T) formed two distinct lineages, related to the species H. soli KCTC 12607(T), sharing about 95.5% 16S rRNA gene sequence similarity between themselves, and 88.3 and 92.0% with other members of the genus Hymenobacter. Based on the phylogenetic analysis and physiological and biochemical characteristics, these isolates were considered to represent three novel species for which we propose the names Hymenobacter perfusus for strain A1-12(T) (=CIP 110166=LMG 26000), Hymenobacter flocculans for strain A2-50A(T) (=CIP 110139=LMG 25699) and Hymenobacter metalli for strain A2-91(T) (=CIP 110140=LMG 25700).     

AtCML8, a calmodulin-like protein, differentially activating CaM-dependent enzymes in Arabidopsis thaliana

Plants express many calmodulins (CaMs) and calmodulin-like (CML) proteins that sense and transduce different Ca²⁺ signals. Previously, we reported divergent soybean (Glycine max) CaM isoforms (GmCaM4/5) with differential abilities to activate CaM-dependent enzymes. To elucidate biological functions of divergent CaM proteins, we isolated a cDNA encoding a CML protein, AtCML8, from Arabidopsis. AtCML8 shows highest identity with GmCaM4 at the protein sequence level. Expression of AtCML8 was high in roots, leaves, and flowers but low in stems. In addition, the expression of AtCML8 was induced by exposure to salicylic acid or NaCl. AtCML8 showed typical characteristics of CaM such as Ca²⁺-dependent electrophoretic mobility shift and Ca²⁺ binding ability. In immunoblot analyses, AtCML8 was recognized only by antiserum against GmCaM4 but not by GmCaM1 antibodies. Interestingly, AtCML8 was able to activate phosphodiesterase (PDE) but did not activate NAD kinase. These results suggest that AtCML8 acts as a CML protein in Arabidopsis with characteristics similar to soybean divergent GmCaM4 at the biochemical levels.     

Structure–activity relationships of carbocyclic 6-benzylthioinosine analogues as subversive substrates of Toxoplasma gondii adenosine kinase

Carbocyclic 6-benzylthioinosine analogues were synthesized and evaluated for their binding affinity against Toxoplasma gondii adenosine kinase [EC.2.7.1.20]. Various substituents on the aromatic ring of the 6-benzylthio group resulted in increased binding affinity to the enzyme as compared to the unsubstituted compound. Carbocyclic 6-(p-methylbenzylthio)inosine 9n exhibited the most potent binding affinity. Docking simulations were performed to position compound 9n into the T. gondii adenosine kinase active site to determine the probable binding mode. Experimental investigations and theoretical calculations further support that an oxygen atom of the sugar is not critical for the ligand-binding. In agreement with its binding affinity, carbocyclic 6-(p-methylbenzylthio)inosine 9n demonstrated significant anti-toxoplasma activity (IC₅₀ = 11.9 μM) in cell culture without any apparent host-toxicity.     

An Arabidopsis splicing RNP variant STEP1 regulates telomere length homeostasis by restricting access of nuclease and telomerase

Telomere is an essential DNA-protein complex composed of repetitive DNA and binding proteins to protect the chromosomal ends in eukaryotes. Telomere length is regulated by a specialized RNA-dependent DNA polymerase, telomerase and associated proteins. We show here a potential role of STEP1 that was previously isolated by affinity chromatography in controlling telomere length. While STEP1 requires both RNA-binding domains for telomere binding and subsequent DNA protection, it requires only one RBD to interact with telomerase. The differential telomerase inhibitory activity depending on STEP1 concentrations may suggest that STEP1 contributes to controlling telomere length homeostasis, likely by limiting the accessibility of nuclease or telomerase to telomeric DNA.     

Protein expression changes in human monocytic THP-1 cells treated with lipoteichoic acid from Lactobacillus plantarum and Staphylococcus aureus

Lipoteichoic acid (LTA) from Staphylococcus aureus (aLTA) and from Lactobacillus plantarum LTA (pLTA) are both recognized by Toll-like receptor 2 (TLR2), but cause different stimulatory effects on the innate immune and inflammatory responses, and their underlying cellular mechanisms are unknown. In this study, comparative proteome analysis was performed using two-dimensional gel electrophoresis and mass spectrometry on protein extracts from human monocyte THP-1 cells stimulated with either aLTA or pLTA. Differentially expressed proteins might be involved in innate immunity and inflammation. Cells treated with aLTA and with pLTA showed different protein expression profiles. Of 60 identified proteins, 10 were present only in treated cells (8 in aLTA-treated only, and 2 in pLTA-treated only), 1 protein (IMPDH2) was suppressed by pLTA, and 49 were up- or down-regulated more than three-fold by aLTA- or pLTA- stimulation. Several proteins involved in immunity or inflammation, antioxidation, or RNA processing were significantly changed in expression by aLTA- or pLTA-stimulation, including cyclophilin A, HLA-B27, D-dopachrome tautomerase, Mn- SOD, hnRNP-C, PSF and KSRP. These data demonstrated that aLTA and pLTA had different effects on the protein profile of THP-1 cells. Comparison of the proteome alterations will provide candidate biomarkers for further investigation of the immunomodulatory effects of aLTA and pLTA, and the involvement of aLTA in the pathogenesis of Staphylococcus aureus sepsis.     

Distinct Roles for Rho Versus Rac/Cdc42 GTPases Downstream of Vav2 in Regulating Mammary Epithelial Acinar Architecture

Non-malignant mammary epithelial cells (MECs) undergo acinar morphogenesis in three-dimensional Matrigel culture, a trait that is lost upon oncogenic transformation. Rho GTPases are thought to play important roles in regulating epithelial cell-cell junctions, but their contributions to acinar morphogenesis remain unclear. Here we report that the activity of Rho GTPases is down-regulated in non-malignant MECs in three-dimensional culture with particular suppression of Rac1 and Cdc42. Inducible expression of a constitutively active form of Vav2, a Rho GTPase guanine nucleotide exchange factor activated by receptor tyrosine kinases, in three-dimensional MEC culture activated Rac1 and Cdc42; Vav2 induction from early stages of culture impaired acinar morphogenesis, and induction in preformed acini disrupted the pre-established acinar architecture and led to cellular outgrowths. Knockdown studies demonstrated that Rac1 and Cdc42 mediate the constitutively active Vav2 phenotype, whereas in contrast, RhoA knockdown intensified the Vav2-induced disruption of acini, leading to more aggressive cell outgrowth and branching morphogenesis. These results indicate that RhoA plays an antagonistic role to Rac1/Cdc42 in the control of mammary epithelial acinar morphogenesis.     

HIV-1 Transmission by Dendritic Cell-specific ICAM-3-grabbing Nonintegrin (DC-SIGN) Is Regulated by Determinants in the Carbohydrate Recognition Domain That Are Absent in Liver/Lymph Node-SIGN (L-SIGN)

In this study, we identify determinants in dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) necessary for human immunodeficiency virus, type 1 (HIV-1), transmission. Although human B cell lines expressing DC-SIGN efficiently capture and transmit HIV-1 to susceptible target cells, cells expressing the related molecule liver/lymph node-specific ICAM-3-grabbing nonintegrin (L-SIGN) do not. To understand the differences between DC-SIGN and L-SIGN that affect HIV-1 interactions, we developed Raji B cell lines expressing different DC-SIGN/L-SIGN chimeras. Testing of the chimeras demonstrated that replacement of the DC-SIGN carbohydrate-recognition domain (CRD) with that of L-SIGN was sufficient to impair virus binding and prevent transmission. Conversely, the ability to bind and transmit HIV-1 was conferred to L-SIGN chimeras containing the DC-SIGN CRD. We identified Trp-258 in the DC-SIGN CRD to be essential for HIV-1 transmission. Although introduction of a K270W mutation at the same position in L-SIGN was insufficient for HIV-1 binding, an L-SIGN mutant molecule with K270W and a C-terminal DC-SIGN CRD subdomain transmitted HIV-1. These data suggest that DC-SIGN structural elements distinct from the oligosaccharide-binding site are required for HIV-1 glycoprotein selectivity.     

Temperature-dependent threshold shear stress of red blood cell aggregation

Red blood cell (RBC) aggregation is becoming an important hemorheological parameter, which exhibits a unique temperature dependence. However, further investigation is still required for understanding the temperature-dependent characteristics of hemorheology that includes RBC aggregation. In the present study, blood samples were examined at 3, 10, 20, 30, and 37 °C. When the temperature decreases, the whole-blood and plasma viscosities increase, whereas the aggregation indices (AI, M, and b) yield contrary results. Since these contradictory results are known to arise from an increase in the plasma viscosity as the temperature decreases, aggregation indices that were corrected for plasma viscosity were examined. The corrected indices showed mixed results with the variation of the temperature. However, the threshold shear rate and the threshold shear stress increased as the temperature decreased, which is a trend that agrees with that of the blood viscosity. As the temperature decreases, RBC aggregates become more resistant to hydrodynamic dispersion and the corresponding threshold shear stress increases as does the blood viscosity. Therefore, the threshold shear stress may help to better clarify the mechanics of RBC aggregation under both physiological and pathological conditions.