AIM: The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS: The effect of AFP on the...AIM: The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS: The effect of AFP on the proliferation of NIH 3T3 cells was measured by incorporation of 3H-TdR. Receptor-binding assay of 125I-AFP was performed to detect the properties of AFP receptor in NIH 3T3 cells. The influences of AFP on the [cAMP]i and the activities of protein kinase A (PKA) were determined. Western blot was used to detect the change of K-ras P21 protein expression. RESULTS: The proliferation of NIH 3T3 cells treated with 0-80 mg/L of AFP was significantly enhanced. The Scatchard analysis indicated that there were two classes of binding sites with KD of 2.722 x 10(-9)M (Bmax=12810 sites per cell) and 8.931 x 10(-8)M (Bmax=119700 sites per cell) respectively. In the presence of AFP (20 mg/L), the content of cAMP and activities of PKA were significantly elevated . The level of K-ras P21 protein was upregulated by AFP at the concentration of 20 mg/L. The monoclonal antibody against AFP could reverse the effects of AFP on the cAMP content, PKA activity and the expression of K-ras p21 gene. CONCLUSION: The effect of AFP on the cell proliferation was achieved by binding its receptor to trigger the signal transduction pathway of cAMP-PKA and alter the expression of K- ras p21 gene.展开更多
AIM: To clone the cDNA fragment of human TRAIL (TNF-related apoptosis inducing ligand) into a tetracycline-regulated gene expression system, the RevTet-On system, transduce expression vectors into a gastric carcinoma ...AIM: To clone the cDNA fragment of human TRAIL (TNF-related apoptosis inducing ligand) into a tetracycline-regulated gene expression system, the RevTet-On system, transduce expression vectors into a gastric carcinoma cell line-NCI-N87 and examine the effects of controlled expression of TRAIL in vitro on the gastric carcinoma cells. METHODS: The full-length cDNA of TRAIL was inserted into a vector under the control of the tetracycline-responsive element (TRE) to obtain the plasmid pRevTRE-TRAIL, which was transfected into a packaging cell line PT67. In addition, vector pRev-Tet On and pRevTRE were also transfected into PT67 separately. After hygromycin and G418 selection, the viral titer was determined. The medium containing retroviral vectors was collected and used to transduce a gastric carcinoma cell line NCI-N87. The resulting cell line NCI-N87-Tet On TRE-TRAIL and a control cell line, NCI-N87 Tet On-TRE, were established. TRAIL expression in the cell line was induced by incubating cells with doxycycline (Dox), which is a tetracycline analogue. The killing effect on gastric carcinoma cells was analyzed after induction. RESULTS: The recombinant plasmid pRev-TRE-TRAIL was constructed. After hygromycin or G418 selection, the producer cell lines PT67-TRE, PT67-TRE-TRAIL and PT67-Tet On were obtained,with titers of about 10(8)CFU.L(-1). By transducing NCI-N87 cells with retroviral vectors from these cell lines, stable cell lines NCI-N87-Tet-On TRE-TRAIL (NN3T) and control cell line NCI-N87-Tet-On-TRE (NN2T) were established. The growth curves of the selected cell lines were the same with the wild type NCI-N87. When Dox was added, cell death was obvious in the test groups (29%-77%), whereas no difference was observed in control and wild type cell lines. With the addition of a medium from the test group, human leukemia cell line Jurkat was activated till death (83%), indicating the secretion of active TRAIL proteins from the test cells to the medium. CONCLUSION: With the use of the RevTet-On system, a regulated expression system for TRAIL was constructed. Using this system, the selected killing effect of TRAIL on gastric carcinoma cell line NCI-N87 could be observed.展开更多
Purpose： This study aims to establish a new framework for evaluating science and technology （S＆T） competitiveness that is appropriate to meet the needs of provincial academies of sciences （PASs） in China.Design/...Purpose： This study aims to establish a new framework for evaluating science and technology （S＆T） competitiveness that is appropriate to meet the needs of provincial academies of sciences （PASs） in China.Design/methodology/approaches： An evaluation index, including such assessing indicators as research strength, research impact, research development and trends, and regional contributions, is developed for China＇s PASs. Taking the Jiangxi Academy of Sciences （JXAS） as an example, we first explain how to apply this framework to analyze the strengths and weaknesses of PASs in China. Then, we compare the results of all 17 PASs in order to get a comprehensive understanding of their competitiveness.Findings： Our results show the development path, current status, innovation advantages, and weaknesses of JXAS very clearly. Based on our comparative analysis, we ranked the 17 PASs from the perspective of different dimensions, by which their competitiveness strengths and weaknesses can be highlighted for improvement.Research limitations： In this analysis, we did not take S＆T policies, S＆T systems, or historical factors into consideration. Thus, we may have ignored the influence of the soft individual differences of different PASs in China..Practical implications： The evaluation index developed in this paper provides a useful insight into an analytical method that can be used by PASs or other provincial research institutions （PRIs） to assess their competitiveness.Originality/value： Compared with existing evaluation frameworks, our method has two main characteristics： First, we added three new dimensions, including the PASs＇ applicable research outputs, regional contributions, and comparative advantages; second, we conducted a comparative analysis of local research institutes in their different advantaged industrial areas, which makes our analytical method more comprehensive for local research institutions.展开更多
基金This work was supported by National NaturalScience Fundation of China(No.39760077).
文摘AIM: The existence and properties of alpha-fetoprotein (AFP) receptor on the surface of NIH 3T3 cells and the effects of AFP on cellular signal transduction pathway were investigated. METHODS: The effect of AFP on the proliferation of NIH 3T3 cells was measured by incorporation of 3H-TdR. Receptor-binding assay of 125I-AFP was performed to detect the properties of AFP receptor in NIH 3T3 cells. The influences of AFP on the [cAMP]i and the activities of protein kinase A (PKA) were determined. Western blot was used to detect the change of K-ras P21 protein expression. RESULTS: The proliferation of NIH 3T3 cells treated with 0-80 mg/L of AFP was significantly enhanced. The Scatchard analysis indicated that there were two classes of binding sites with KD of 2.722 x 10(-9)M (Bmax=12810 sites per cell) and 8.931 x 10(-8)M (Bmax=119700 sites per cell) respectively. In the presence of AFP (20 mg/L), the content of cAMP and activities of PKA were significantly elevated . The level of K-ras P21 protein was upregulated by AFP at the concentration of 20 mg/L. The monoclonal antibody against AFP could reverse the effects of AFP on the cAMP content, PKA activity and the expression of K-ras p21 gene. CONCLUSION: The effect of AFP on the cell proliferation was achieved by binding its receptor to trigger the signal transduction pathway of cAMP-PKA and alter the expression of K- ras p21 gene.
基金the National Natural Science Foundation of China,No.39870850
文摘AIM: To clone the cDNA fragment of human TRAIL (TNF-related apoptosis inducing ligand) into a tetracycline-regulated gene expression system, the RevTet-On system, transduce expression vectors into a gastric carcinoma cell line-NCI-N87 and examine the effects of controlled expression of TRAIL in vitro on the gastric carcinoma cells. METHODS: The full-length cDNA of TRAIL was inserted into a vector under the control of the tetracycline-responsive element (TRE) to obtain the plasmid pRevTRE-TRAIL, which was transfected into a packaging cell line PT67. In addition, vector pRev-Tet On and pRevTRE were also transfected into PT67 separately. After hygromycin and G418 selection, the viral titer was determined. The medium containing retroviral vectors was collected and used to transduce a gastric carcinoma cell line NCI-N87. The resulting cell line NCI-N87-Tet On TRE-TRAIL and a control cell line, NCI-N87 Tet On-TRE, were established. TRAIL expression in the cell line was induced by incubating cells with doxycycline (Dox), which is a tetracycline analogue. The killing effect on gastric carcinoma cells was analyzed after induction. RESULTS: The recombinant plasmid pRev-TRE-TRAIL was constructed. After hygromycin or G418 selection, the producer cell lines PT67-TRE, PT67-TRE-TRAIL and PT67-Tet On were obtained,with titers of about 10(8)CFU.L(-1). By transducing NCI-N87 cells with retroviral vectors from these cell lines, stable cell lines NCI-N87-Tet-On TRE-TRAIL (NN3T) and control cell line NCI-N87-Tet-On-TRE (NN2T) were established. The growth curves of the selected cell lines were the same with the wild type NCI-N87. When Dox was added, cell death was obvious in the test groups (29%-77%), whereas no difference was observed in control and wild type cell lines. With the addition of a medium from the test group, human leukemia cell line Jurkat was activated till death (83%), indicating the secretion of active TRAIL proteins from the test cells to the medium. CONCLUSION: With the use of the RevTet-On system, a regulated expression system for TRAIL was constructed. Using this system, the selected killing effect of TRAIL on gastric carcinoma cell line NCI-N87 could be observed.
基金supported by the National Science Library of the Chinese Academy of Sciences(Grant No.:Y130181001)
文摘Purpose： This study aims to establish a new framework for evaluating science and technology （S＆T） competitiveness that is appropriate to meet the needs of provincial academies of sciences （PASs） in China.Design/methodology/approaches： An evaluation index, including such assessing indicators as research strength, research impact, research development and trends, and regional contributions, is developed for China＇s PASs. Taking the Jiangxi Academy of Sciences （JXAS） as an example, we first explain how to apply this framework to analyze the strengths and weaknesses of PASs in China. Then, we compare the results of all 17 PASs in order to get a comprehensive understanding of their competitiveness.Findings： Our results show the development path, current status, innovation advantages, and weaknesses of JXAS very clearly. Based on our comparative analysis, we ranked the 17 PASs from the perspective of different dimensions, by which their competitiveness strengths and weaknesses can be highlighted for improvement.Research limitations： In this analysis, we did not take S＆T policies, S＆T systems, or historical factors into consideration. Thus, we may have ignored the influence of the soft individual differences of different PASs in China..Practical implications： The evaluation index developed in this paper provides a useful insight into an analytical method that can be used by PASs or other provincial research institutions （PRIs） to assess their competitiveness.Originality/value： Compared with existing evaluation frameworks, our method has two main characteristics： First, we added three new dimensions, including the PASs＇ applicable research outputs, regional contributions, and comparative advantages; second, we conducted a comparative analysis of local research institutes in their different advantaged industrial areas, which makes our analytical method more comprehensive for local research institutions.
