珍珠菜提取物抗肿瘤作用的初步研究

观察灌服珍珠菜提取物对小鼠肉瘤 ( S1 80 )的抑制作用 ,用相同方法跟踪珍珠菜的抗肿瘤有效部位。用紫外分光光度法 ,观察了珍珠菜提取物对环磷酰胺造成骨髓抑制的保护作用 ;采用 MTT法观察不同浓度珍珠菜提取物对人白血病 HL - 6 0及 K 5 6 2细胞的体外抑制作用。结果表明珍珠菜浸膏 ( 40 0 0 m g/ kg· d)、石油醚部位 ( 2 0 0 m g/kg· d)、氯仿部位 ( 2 0 0 m g/ kg· d)、乙酸乙酯 ( 2 0 0 mg/ kg· d)部位、正丁醇部位 ( 2 0 0 mg/ kg· d)及水溶性部位 ( 2 0 0mg/ kg· d)对小鼠肉瘤 ( S1 80 )抑瘤率分别为 5 2 .74%,16 .5 1%,2 8.41%,42 .17%,48.2 1%,2 5 .2 4%;小鼠灌服环磷酰胺 ( 2 5 mg/ kg· d)能引起骨髓抑制而使骨髓中 DNA含量下降 ,如同时灌服珍珠菜浸膏 ( 2 0 0 0 m g/ kg· d)则可使小鼠骨髓 DNA含量恢复至接近正常水平 ;珍珠菜总黄酮提取物 ( 2 10μg/ m L )、乙酸乙酯部位 ( 180μg/ m L )、正丁醇部位 ( 2 10μg/ m L )作用 48h对 HL - 6 0细胞的抑制率分别为 35 .6 6 %,45 .85 %,42 .36 %;IC5 0分别为 92 .85 ,16 4.93,40 2 .6 1μg/ m L ;对 K5 6 2细胞抑制率为 5 9.94%,70 .34%,77.98%;IC5 0分别为 17.6 4,5 2 .5 3,6 4.70μg/ m L。因此 ,珍珠菜提取物对小鼠肉瘤 ( S180 )有显     

眼镜蛇毒细胞毒素的抗肿瘤作用

目的　研究眼镜蛇毒细胞毒素（ Ｃ Ｖ Ｃ Ｔ Ｘ）的体内抗肿瘤作用。方法　小鼠皮下、腹腔接种 Ｓ１８０ 、 Ｅ Ａ Ｃ后, 于接种部位注射不同剂量的 Ｃ Ｖ Ｃ Ｔ Ｘ, 每天 １ 次, 连续１０ 天, 观察瘤重抑制率和生命延长率。结果　适当剂量（０２～０８ｍ ｇ／ｋｇ） 的 Ｃ Ｖ Ｃ Ｔ Ｘ 能明显抑制肿瘤的生长 （ Ｐ＜ ００１）,小鼠的存活时间明显延长（ Ｐ ＜ ００１）。结论　 Ｃ Ｖ Ｃ Ｔ Ｘ 在小鼠体内对 Ｓ１８０ 、 Ｅ Ａ Ｃ有明显地抗肿瘤作用。     

Anti-tumour components of the culture filtrates from Tricholoma sp.

The anti-tumour component (Fraction A) found in the culture filtrates of a local mushroom, Tricholoma sp. (strain STC20-T1), was purified using DEAE-cellulose ion exchange chromatography and Sepharose CL-4B gel filtration. Of its two purified sub-fractions, A-1 and A-2, only the latter showed anti-tumor activity. When Fraction A-2 was treated with cetyltrimethylammonium hydroxide and chloroform/butanol (24:1, v/v), it behaved as a proteinbound polysaccharide, with a molecular mass estimated to be 154 kDa by gel filtration. It contained 40% polysaccharide, which consisted of fucose, galactose, glucose, arabinose and mannose, and 30.5% protein, the amino-acid composition of which was determined. Fraction A-2 could inhibit the growth of Sarcoma-180 implanted in mice intraperitoneally and subcutaneously, with no sign of toxicity, at a dose of 20 mg/kg.day for 10 days.     

Manganese superoxide dismutase expressed in silkworm larvae,Bombyx mori L enhances the NK activity and splenocyte proliferation against Sarcoma 180 tumor cells in vivo

Natural killer cell (NK) is known as a major immune system in body through mediating cell death via several possible pathways, and one of three subpopulations of lymphocytes functioning as scavenger of tumor, virus infected cells etc. Our present results found that the SOD-contained silkworm larvae powder caused an enhancement of the effect on NK cell cytotoxicity, which implied this material modulated the immune system in mice in vivo. The NK cell activities of S180 tumor modeled mice treated with silkworm powder including SOD were enhanced significantly ranging from 30% to 48%, respectively, compare to a distilled water feeding control and silkworm powder without SOD. Meanwhile, the ConA-stimulated splenocyte proliferation of all three treated groups was higher than that of the control both in T cells or B cells. The average tumor weight of S180 modeled mice treated with doses of SOD-contained silkworm powder was lighter than that of water control showing the tumor inhibition rates (IR) reached to 22.51% to 37%, respectively. In conclusion, these findings demonstrate that administration of silkworm larvae powder containing SOD results in activation of NK cells and immune T-cell and B-cell, suggesting the silkworm larvae powder containing SOD play a positive role in tumor inhibition.     

纳米中药对S180荷瘤小鼠肠道菌群影响的研究及其防治作用

目的研究纳米中药对S180荷瘤小鼠肠道菌群的影响及其抑制作用。方法将S180荷瘤瘤株以2×105/(0.2 m l.鼠)用注射器接种于小鼠右前肢腋下,建立实体瘤模型,肿瘤发生率为100%。观察小鼠的一般状态,用梯度稀释法和培养法测定小鼠4种肠道正常菌群,即乳酸杆菌、双歧杆菌、肠球菌、肠杆菌。用电子天平称瘤重并计算瘤抑制率。病理行HE(苏木精-伊红)染色,在光学显微镜下观察。结果与模型组比较,纳米中药组双歧杆菌和乳酸杆菌数量明显升高,肠球菌和肠杆菌数量明显减少,肿瘤坏死因子数量增加,抑瘤率达64%,病理显示肿瘤组织间坏死灶明显,有大量的炎性细胞浸润。结论纳米中药提高机体免疫屏障功能,增强药物的靶向性,扶植机体正常菌群的生长,实现抗肿瘤的目的。     

Rapamycin decreases tau phosphorylation at Ser214 through regulation of cAMP-dependent kinase

Preventing or reducing tau hyperphosphorylation is considered to be a therapeutic strategy in the treatment of Alzheimer’s disease (AD). Rapamycin may be a potential therapeutic agent for AD, because the rapamycin-induced autophagy may enhance the clearance of the hyperphosphorylated tau. However, recent rodent studies show that the protective effect of rapamycin may not be limited in the autophagic clearance of the hyperphosphorylated tau. Because some tau-related kinases are targets of the mammalian target of rapamycin (mTOR), we assume that rapamycin may regulate tau phosphorylation by regulating these kinases. Our results showed that in human neuroblastoma SH-SY5Y cells, treatment with rapamycin induced phosphorylation of the type IIα regulatory (RIIα) subunit of cAMP-dependent kinase (PKA). Rapamycin also induced nuclear translocation of the catalytic subunits (Cat) of PKA and decreases in tau phosphorylation at Ser214 (pS214). The above effects of rapamycin were prevented by pretreatment with the mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) inhibitor U0126. In addition, these effects of rapamycin might not depend on the level of tau expression, because similar results were obtained in both the non-tau-expressing wild type human embryonic kidney 293 (HEK293) cells and HEK293 cells stably transfected with the longest isoform of recombinant human tau (tau441; HEK293/tau441). These findings suggest that rapamycin decreases pS214 via regulation of PKA. Because tau phosphorylation at Ser214 may prime tau for further phosphorylation by other kinases, our findings provide a novel possible mechanism by which rapamycin reduces or prevents tau hyperphosphorylation.     

Time-resolved quantitative analysis of CCK1 receptor-induced intracellular calcium increase

Cholecystokinin (CCK) is a gastrointestinal hormone, which regulates many physiological functions such as satiety by binding to the CCK receptor (CCKR). Molecules, which recognize this receptor can mimic or block CCK signaling and thereby influence CCKR-mediated processes. We have set up a quantitative heterologous assay with CHO cells over-expressing the rat CCK1 receptor to screen for such candidate molecules. Receptor activation, induced by agonist binding, is followed by an intracellular calcium increase, which was monitored using a fluorescent sensor dye. For quantification of the calcium increase, a population average technique using a fluorescence plate reader was optimized and subsequently compared with a single-cell approach using confocal microscopy. With both strategies, dose-response curves were generated for the natural agonist CCK-8S, the partial agonist JMV-180 as well as the antagonist lorglumide. Significant differences were found between the ligands and a strong correspondence was observed between both methods in terms of maximum response and median effect concentrations. Both highly sensitive methods proved complementary: whereas the plate reader assay allowed faster, high throughput screening, the confocal microscopy identified single-cell variations and revealed factors that reduce specificity and sensitivity.     

Vascular endothelial cell senescence mediated by integrin beta4 in vitro

To understand whether integrin beta4 is involved in vascular endothelial cell (VEC) senescence, we examined integrin beta4 level changes, as well as P53 and reactive oxygen species (ROS) levels and alterations of phosphatidylcholine-specific phospholipase C (PC-PLC) activity before and after knocking-down integrin beta4 by small interfering RNA. We found integrin beta4, P53 and ROS levels increased significantly, while Ca(2+)-independent PC-PLC activity obviously decreased during VEC senescence. On the other hand, integrin beta4 down-regulation attenuated the senescence phenotype and reversed Ca(2+)-independent PC-PLC activity, and P53 and ROS levels. The data suggested that integrin beta4 might mediate VEC senescence through depressing Ca(2+)-independent PC-PLC and elevating the levels of P53 and ROS.     

Superoxide dismutase induces G1‐phase cell cycle arrest by down‐regulated expression of Cdk‐2 and cyclin‐E in murine sarcoma S180 tumor cells

As an efficient reactive oxygen species–scavenging enzyme, superoxide dismutase (SOD) has been shown to inhibit tumor growth and interfere with motility and invasiveness of cancer cells. In this study, the molecular mechanisms of cell cycle arrest when S180 tumor cells were exposed to high levels of SOD were investigated. Here, both murine sarcoma S180 tumor cells and NIH‐3T3 mouse fibroblasts were respectively treated with varying concentrations of Cu/Zn‐SOD for 24, 48 and 72 h to determine optimal dose of SOD, which was a concentration of 800 U/ml SOD for 48 h. It is found that SOD induced S180 cell cycle arrest at G1‐phase with decreasing level of superoxide production, whereas SOD had less effect on proliferation of NIH‐3T3 cells. Moreover, the expression rate of Proliferating Cell Nuclear Antigen (PCNA) in S180 tumor cells was suppressed after SOD treatment, which indicated the inhibition of DNA synthesis in S180 cells. Besides, there were significant down‐regulations of cyclin‐E and Cdk‐2 in S180 cells after SOD treatment, which contributed to the blockage of G1/S transition in S180 cell cycle. Together, our data confirmed that SOD could notably inhibit proliferation of S180 tumor cell and induce cell cycle arrest at G1‐phase by down‐regulating expressions of cyclin‐E and Cdk‐2. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural basis of the LOV1 dimerization of Arabidopsis phototropins 1 and 2

Phototropin (phot) is a blue-light receptor protein that triggers phototropic responses, chloroplast relocation, and stomata opening to maximize the efficiency of photosynthesis in higher plants. Phot is composed of three functional domains. The N-terminal half folds into two light-oxygen-voltage-sensing domains called LOV1 and LOV2, each binding a flavin mononucleotide to absorb blue light. The C-terminal half is a serine/threonine kinase domain that causes light-dependent autophosphorylation leading to cellular signaling cascades. LOV2 domain is primarily responsible for activation of the kinase, and LOV1 domain is thought to act as a dimerization site and to regulate sensitivity to activation by blue light. Here we show the crystal structures of LOV1 domains of Arabidopsis phot1 and phot2 in the dark at resolutions of 2.1 Å and 2.0 Å, respectively. Either LOV1 domain forms a dimer through face-to-face association of β-scaffolds in the crystallographic asymmetric unit. Three types of interactions stabilizing the dimer structures found are as follows: contacts of side chains in their β-scaffolds, hydrophobic interactions of a short helix found in the N-terminus of a subunit with the β-scaffolds of both subunits, and hydrogen bonds mediated by hydration water molecules filling the dimer interface. The critical residues for dimerization are Cys261, forming a disulfide bridge between subunits in phot1-LOV1 domain, and Thr217 and Met232 in phot2-LOV1. The topology in homodimeric associations of the LOV1 domains is discussed when referring to those of homodimers or heterodimers of light-oxygen-voltage-sensing or Per-ARNT-Sim domains. The present results also provide clues to understanding structural basis in dimeric interactions of Per-ARNT-Sim protein modules in cellular signaling.