Alteration of cadherin isoform expression and inhibition of gap junctions in stomach carcinoma cells

To explore cell malignant phenotype correlated changes of cell surface adhesion molecules and cell-cell communication in carcinogenesis, human stomach transformed and cancer cell lines were investigated. Expressions of E-cadherin, N-cadherin,α-catenin, β-catenin as well as gap junction (GJ) protein Cx32 were studied by utilization of immunoblotting, immunocytochemical and fluorescent dye transfer methods. Mammalian normal stomach mucosal cells expressed E-cadherin but not N-cadherin. E-cadherin im-munofluorescence was detected at cell membranous adher-ens junctions (AJ) where colocalization with immunofluo-rescent staining of inner surface adhesion plaque proteins αnd β-catenins was observed. The existence of E-cadherin/ catenin (α-, β-) protein complexes as AJ was suggested. In transformed and stomach cancer cells E-cadherin was inhibited, instead, N-cadherin was expressed and localized at membranous AJ where co-staining with α- and β-catenin fluorescence was observed. Formation of N-cadherin/catenin (α-, β-) protein complex at AJs of transformed and cancer cells was suggested. The above observations were further supported by immunoblotting results. Normal stomach muscosal and transformed cells expressed Cx32 at membranous GJ and were competent of gap junction communication (GJIC). In stomach cancer cells, Cx32 was inhibited and GJIC was defective. The results suggested that changes of signal pathways mediated by both cell adhesion and cell communication systems are associated intracellular events of stomach carcinogenesis. The alteration of cadherin isoform from E- to N-cadherin in transformed and stomach cancer cells is the first report.     

Expression of green fluorescent protein gene with baculovirus vector in insect cells

The green fluorescence of bioluminescent jellyfishAequorea victoria is due to the presence of the green fluorescent protein (GFP). To examine whether the GFP gene can be applied as a reporter gene in insect cells, a baculovirus transfer vector containing the neomycin resistance gene (neo) was established. The GFP gene was subcloned into the vector downstream of the polyhedrin gene (ocu) promoter. In the presence of G418, the recombinant virus can be purified. Expression of the GFP gene in the recombinant virus should give rise to synthesis of the GFP with a molecular weight of 30×10³ dalton, and is observable by the strong green light irradiated by ultraviolet or blue light in viable intact insect cells. The GFP produced in insect cells has typical fluorescent spectra indistinguishable from those of the purified native GFP. The GFP gene as a good reporter gene can be applied to the baculovirus-insect cell expression system. Supported by the National Natural Science Foundation of China Hu Jianhong: born in July, 1972, Master graduate student     

小鼠嗅鞘细胞的分离、纯化和免疫细胞化学特性

目的:对小鼠嗅鞘细胞的体外分离、纯化和免疫细胞化学特性进行研究.方法:分离新生小鼠嗅鞘细胞,综合运用差速贴壁法、阿糖胞苷抑制和丝裂原刺激等方法对其进行纯化,并用免疫细胞化学方法对其进行检测.结果:体外培养的新生小鼠嗅鞘细胞主要为双极或三极细胞.纯化培养后其纯度可以达到88.7%以上,污染细胞中有星形胶质细胞、神经元、少突胶质细胞和成纤维细胞.免疫组化结果提示,嗅鞘细胞呈P75和CNP免疫阳性,GFAP和Nestin阴性.结论:本研究对新生小鼠嗅鞘细胞的形态学和免疫细胞化学特性提供了部分数据.但不同的取材时间,不同的培养条件对嗅鞘细胞的影响尚需进一步研究.     

His-猪生长激素融合基因在Bm-N细胞和蚕体内的表达与纯化

用构建的带有His—Tag pgh融合基因的重组杆状病毒Bm—BacPAK6—pgh研究了Bm—BacPAK6—pgh在家蚕细胞(Bm—N)和蚕体内的表达，并对蚕体表达产物进行了纯化．SDS—PAGE电泳分析显示，重组病毒Bin—BacPAK6—pgh在Bin—N细胞、蚕体中得到了融合表达，Western blot分析表明，Bm—N细胞、蚕体中表达的融合蛋白与大肠杆菌表达的猪生长激素具有相同的抗原性．Bm-BacPAK6-pgh在Bin—N细胞内的表达始于24h，而蚕体中的表达始于72h，二者的表达峰分别在96h和120h．经40％饱和度硫酸铵盐析和Ni—NTA Agarose亲和柱二步纯化可获得SDS—PA(正电泳纯的具有抗原性的重组猪生长激素融合蛋白。     

Expression of matrix metalloproteinase-28 in human normal cytotrophoblast cells and a choriocarcinoma cell line,JEG-3

There are striking similiarities present between the behavior of invasive placental cells and that of invasive cancer cells. Matrix metalioproteinases (MMPs) are one of the most important mediators. MMP-28, the new member ofMMPs, was sequenced and identified recently. Expression of MMP-28 mRNA and protein in the cytotrophoblast cells anda choriocarcinoma cell line, JEG-3 cell, was conducted by zymography, RT-PCR and Northern blot. There is MMP-28mRNA expression in both the cytotrophoblast cells and JEG-3 cells by RT-PCR. The activity of MMP-28 in cytotrophoblast cells was significantly weaker than that in JEG-3 (P < 0.01) by zymography. Furthermore, mRNA expression of MMP-28 was significantly stronger (P < 0.001) in JEG-3than in human cytotrophoblast cells in a time-dependent way by Northern Blot. Our results suggest that MMP-28 may play a role in some of the tissue-remodeling events associated with normal pregnancy and tumor progression.``     

Regulation of activin A in cell proliferation and hormone secretion by human normal trophoblast cells

Regulation of activin A in cell proliferation as well as hCG and progesterone secretion was investigated using primary cultured cytotrophoblast cells and normal placenta origin cytotrophoblast cell line-NPC cells in serum-free system. It was shown that activin A promoted hCG and progesterone secretion in primary cultured cytotrophoblast cells as well as progesterone secretion in NPC cells, while it had no effect on cell proliferation and hCG secretion in NPC cells. Important evidence is provided for the autocrine regulatory mechanism of activin A on hormone secretion in placental trophoblast cells at early pregnancy.     

KDR基因和Sema3基因在再障和正常人骨髓基质细胞中的表达

目的：了解激酶插入区域受体(Kinase insert domain receplor,KDR)基因和脑信号蛋白Ⅲ(Semaphorin3,Sema3)基因在再生障碍性贫血(AA)和正常人的骨髓基质细胞(BMSC)和骨髓造血细胞中的表达情况。方法：收集9例AA和33例正常骨髓标本,分离单个核细胞(MNC)后体外长期培养扩增BMSC,并收集悬浮细胞(骨髓细胞)。RT-PCR-ELISA检测KDR基因和Sema3基因在BMSC和造血细胞中的表达,分析表达率,并以管家基因β2微球蛋白(β2M)为内参照进行半定量分析。结果：KDR基因在正常对照BMSC中的表达率(97．0％)明显高于对应的骨髓细胞(70．8％,P=0．07)。I①R基因在AA的BMSC和骨髓细胞中的表达率和表达水平与正常对照比较均无显差异。Sema3基因在正常BMSC中的表达水平明显低于其对应的骨髓细胞(P=0．035)。Sema3基因在AA的BMSC和骨髓细胞中的表达率和表达水平与正常对照组比较均无显差异。KDR基因和Sema3基因的表达水平在正常造血细胞中呈显正直线相关(r=0．703,P=0．002)。结论：KDR基因在BMSC中的高表达提示其可能在维持造血微环境中有重要作用。Sema3基因在造血细胞中的高表达状态提示其可能具有维持造血细胞生存的作用。KDR基因和Sema3基因在AA中的表达变化不大。     

血管内皮生长因子基因反义核酸设计及其对HL60细胞生长的影响

目的:用计算机设计筛选出血管内皮生长因子(VEGF)的高效反义核酸;用实验方法研究VEGF反义核酸对HL60细胞生长的影响。方法:用RNAstructure(version3 7)软件,选择总自由能(Overall△G37)的相对低的反义核酸,共计7条,长度18～20核苷酸,全硫代修饰;细胞培养72h,采用胎盼蓝拒染法观察存活细胞,用ELISA法检测培养液中VEGF蛋白水平,分析反义核酸对HL60细胞的作用。结果:筛选出6条反义药物对HL60细胞生长有明显抑制作用,其中4条优于阳性对照组(A2);A7组细胞生长抑制率达41 74%。培养液中VEGF蛋白表达抑制率达47 81%。Overall△G37与反义核酸活性密切相关(r=-0 842,P<0 01)。结论:计算机辅助设计有助于获得更好的反义药物,VEGF反义核酸可抑制HL60细胞生长及VEGF蛋白表达,VEGF可能成为白血病治疗的新靶点。