Forskolin up-regulates metastasis-related phenotypes and molecules via protein kinase B,but not PI-3K,in H7721 human hepato-carcinoma cell line

Forskolin (FSK) is known as an up-regulator of intracellular cAMP and inhibitor of cancer growth and metastasis. The effects of FSK on the metastasis potential and its mechanisms were studied using a human hepatocarcinoma cell line, H7721. It was found that FSK stimulated cell growth, increased cAMP in the cells, and enhanced the metastasis-related phenotypes, including adhesion to laminin (Ln) and human umbilical vein epithelial cells (HUVEC), chemotactic migration and invasion. These effects were supposed to result from the increase of the SLe^x expression induced by FSK, since only the monoclonal antibody of SLe^x showed a significant attenuation of the enhanced metastasis-associated phenotypes. Using H7721 cells transfected with the sense or antisense cDNA of protein kinase B (PKB) and some inhibitors of signal transduction, it was discovered that FSK up-regulated the expression of SLe^x via PKB, but it was independent of phosphotidylinositide-3-kinase (PI-3K). A subtype of atypical protein kinase C (-PKC) might also participate in the up-regulation of SLe^x expression by FSK, and cAMP/PKA pathway is a negative regulator of SLe^x expression on H7721 cells. It can be concluded that FSK shows a metastasis-promoting effect ex vivo.     

Effect of the sialyl Lewis X (SLe(x)) moiety on splenic accumulation of SLe(x)-carboxymethylpullulan conjugate

Sialyl Lewis X (SLe(x)), an E-selectin ligand, was conjugated with carboxymethylpullulan (CMPul) and the disposition characteristics of this conjugate after intravenous administration were investigated using mice with ear edema. The concentration of 3H-labeled SLe(x)-CMPul in the spleen was significantly high. When CMPul was modified with a saccharide unable to bind to E-selectin, this splenic accumulation was not observed. The uptake of radiolabeled SLe(x)-CMPul by the spleen was completely inhibited by a 100-fold molar of cold SLe(x)-CMPul but not by a sialyl N-acetyllactosamine-CMPul conjugate (SLN-CMPul). Microautoradiography analyses revealed that SLe(x)-CMPul accumulated in the marginal zone of the spleen.     

Habitat-Suitability Models for Cavity-Nesting Birds in a Postfire Landscape

ABSTRACT Models of habitat suitability in postfire landscapes are needed by land managers to make timely decisions regarding postfire timber harvest and other management activities. Many species of cavity-nesting birds are dependent on postfire landscapes for breeding and other aspects of their life history and are responsive to postfire management activities (e.g., timber harvest). In addition, several cavity nesters are designated as species at risk. We compare the ability of 2 types of models to distinguish between nest and non-nest locations of 6 cavity-nesting bird species (Lewis's woodpecker [Melanerpes lewis], black-backed woodpecker [Picoides arcticus], hairy woodpecker [P. villosus], northern flicker [Colaptes auratus], western bluebird [Sialia mexicana], and mountain bluebird [S. currucoides]) in the early postfire years for a ponderosa pine (Pinus ponderosa) forest in Idaho, USA. The 2 model sets consisted of 1) models based on readily available remotely sensed data and 2) models containing field-collected data in addition to remotely sensed data (combination models). We evaluated models of nesting habitat by quantifying the model's ability to correctly identify nest and non-nest locations and by determining the percentage of correctly identified nest locations. Additionally, we developed relative habitat-suitability maps for nesting habitat of black-backed and Lewis's woodpeckers from the best models. For all species except Lewis's woodpeckers, model performance improved with the addition of field-collected data. Models containing remotely sensed data adequately distinguished between nest and non-nest locations for black-backed woodpecker and Lewis's woodpecker only, whereas models containing both field-collected and remotely sensed data were adequate for all 6 species. Improvements in the availability of more accurate remote sensing technology would likely lead to improvements in the ability of the models to predict nesting locations. External validation with data from other wildfires is necessary to confirm the general applicability of our habitat-suitability models to other forests. Land managers responsible for maintaining habitat for cavity-nesting birds in postfire landscapes can use these models to identify potential nesting areas for these species and select areas in burned forests where postfire salvage logging is most likely to have minimal impacts on cavity-nesting bird habitats.     

不同发育时期小鼠胚泡表面Lewis寡糖抗原的表达

在胚泡表面表达的Lewis寡糖抗原 (LewisX ,LewisY)在胚胎发育以及着床过程中起重要作用 .应用免疫印迹和免疫荧光等方法对着床前小鼠胚泡表面的Lewis寡糖抗原进行分析 .结果发现 :小鼠胚泡LewisX寡糖蛋白有 2 7kD、2 9kD、6 8kD和 80kD 4种 ,LewisY寡糖蛋白有 70kD和 90kD 2种 ;2种寡糖抗原均在 8细胞时期开始表达 ,其中 ,LewisY寡糖抗原在胚泡表面的表达持续升高 ,直至胚泡着床 ;而LewisX寡糖抗原的表达则在桑椹期后逐渐降低 ,但仍在胚胎期的囊胚腔侧的顶端可见有部分表达 ;应用RT PCR的分析结果显示 ,LewisX合成的关键糖基转移酶FUT9基因在 4细胞及桑椹期高表达 ,到胚泡期虽然强度明显减弱 ,但仍有表达 ;而LewisY合成关键酶FUT1基因在 4细胞未见表达 ,在桑椹和胚泡阶段均有表达并逐渐升高 ,表达趋势与相应寡糖的表达趋势基本一致 .结果说明 ,在小鼠胚泡表面表达的Lewis寡糖抗原的表达受到相应糖基转移酶基因转录的调控     

Combination of rapamycin and IL-2 do not affect antigen presentation ability of rat B cell and could promote Tregs proliferation and inhibitory activity

Rapamycin (RPM), a powerful agent used clinically in transplant recipients, induces CD4⁺CD25⁺ regulatory T cells (Tregs) which play an important role in induction of immune tolerance. However, long-term use of RPM has negative side effects. In this report, we found that combination with the low dose RPM and high dose IL-2 did not affect antigen presentation of rat B cells to Tregs, and could efficiently promote Tregs proliferation and enhance their inhibitory activities in vitro. In addition, the combination of low dose RPM and high dose IL-2 enhanced mRNA expression of Foxp3, TGF-β1 and Pim-2 in Tregs but not in CD4⁺CD25⁻ T effector cells (Teffs). The Tregs inhibitory activity is positively associated with mRNA expressions of TGF-β1 and Pim-2 while unrelated to the Foxp3 mRNA expression. Our present study offers one approach to expand functional Tregs in vitro, which maybe used for clinical immune tolerance induction.     

Modification of oligosaccharides by reactive oxygen species decreases sialyl lewis x-mediated cell adhesion

Modification of cell surface oligosaccharides by reactive oxygen species (ROS) and the biological effect of such modifications on cell adhesion were investigated. Treatment of HL60, a human promyelocyte leukemia cell line, with ROS, generated by a combination of hypoxanthine and xanthine oxidase (HX/XO), decreased the sialic acid content on the cell surface, as indicated by a flow cytometric analysis involving sialic acid-specific lectins, and a concomitant increase of free sialic acid was observed in the supernatant. A cell adhesion assay showed that the HX/XO treatment of HL60 cells decreases their capability of binding to human umbilical vein endothelial cells (HUVEC), probably because of an impairment of the interaction involving E-selectin, whereas the decrease in the binding was canceled by the addition of superoxide dismutase (SOD) and catalase. In fact, cell surface sialyl lewis x (sLe x), but not lewis x (Le x), was decreased by HX/XO treatment. Thus, it is more likely that the impaired interaction is based on diminished levels of the selectin ligand. Cleavage of sialic acid by ROS was further verified by the degradation of 4MU-Neu5Ac by HX/XO in the presence of hydrogen peroxide and iron ion. These results indicate that glycosidic linkage of sialic acid is a potential target for superoxide and other related ROS. It is well known that ROS cause cellular damages such as lipid peroxidation and protein oxidation, but, as suggested by the findings reported in the literature, ROS may also regulate cell adhesion via the structural alteration of sialylated oligosaccharides on the cell surface.     

小鼠正常肺细胞和肺癌细胞之间的力学特性比较研究

该实验通过鬼笔环肽染色技术观察并比较了小鼠正常肺细胞和肺癌细胞的微丝差异,利用荧光抗体染色技术测定了小鼠单个正常肺细胞和肺癌细胞的α-SMA蛋白含量变化,以及利用CTFM法测定了小鼠正常肺细胞和肺癌细胞的牵引力变化。结果发现,小鼠肺细胞癌变后,细胞内微丝骨架发生了变化,影响了细胞的形态;α-SMA蛋白含量明显下降并且变得分散：细胞投影面积显著减少,大约减少27％,细胞牵引力也显著减小,均方根值大约减少49％。这说明细胞骨架、细胞的形态、α-SMA蛋白和细胞牵引力均与细胞的癌变过程密切相关。