ABSTRACT
OBJECTIVE@#To explore the relationship between TK gene expression regulated by enhanced suicide gene vector and telomerase activity in nasopharyngeal carcinoma cells.@*METHOD@#The reformed reconstructed enhanced vector, pGL3-basic-EGFP-TK-hTRETp-CMV enhancer, and hTERT mono-promoter vector, pGL3-basic-EGFP-TK-hTRETp(as controls), were transfected into telomerase(+) nasopharyngeal carcinoma 5-8F cell lines, telomerase(+) human breast cancer MCF-7 cell lines and telomerase(-) normal vascular endothelium cell lines respectively. TK gene green fluorescent protein was observed by fluorescence microscope. The expression of TK gene mRNA was measured by the real-time fluorescent quantified PCR and the telomerase activity was determined by the method of TRAP argentation in malignant tumour cells pre- and post-transfected by enhanced vector. Meanwhile the relationship between TK and telomerase was analyzed.@*RESULT@#(1) A strong TK gene fluorescent show and TK mRNA expression were displayed after the enhanced suicide gene vector was transfected into nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which were more stronger than those of mono-promoter group, pGL3-basic-EGFP-TK-hTRETp, and ECV cells transfected by enhanced suicide gene vector. Meanwhile,real-time fluorescent quantified PCR showed that the A value of enhanced vector group was higher than that of controls. (2) Telomerase activity after transfection of enhanced vector and GCV was lower than those before by the method of TRAP argentation in nasopharyngeal carcinoma cell lines,but no change in normal control cells after transfection of enhanced vector and GCV. (3) After adding GCV, the obvious inhibitory effect of tumour cells growth induced by pGL3-basic-EGFP-TK-hTRETp-CMV enhancer were observed in nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which was higher than those of mono-promoter, pGL3-basic-EGFP-TK-hTRETp, pGL3-basic-EGFP3 and blank controls, but without inhibitory effect in ECV cells transfected by enhanced vector.@*CONCLUSION@#TK gene expression is regulated by hTERT promoter and CMV enhancer, and then the telomerase activity is reduced and the cancer cells are specifically killed. But it is unclear how the telomerase are down-regulated by TK gene.
Subject(s)
Humans , Cell Death , Cell Line , Cell Line, Tumor , Gene Expression Regulation , Genes, Transgenic, Suicide , Genetic Vectors , Green Fluorescent Proteins , Genetics , Nasopharyngeal Neoplasms , Genetics , Metabolism , Promoter Regions, Genetic , Regulatory Sequences, Nucleic Acid , Telomerase , Genetics , Metabolism , Thymidine Kinase , Genetics , TransfectionABSTRACT
Objective:To explore the relationship between TK gene expression regulated by enhanced suicide gene vector and telomerase activity in nasopharyngeal carcinoma cells.Method:The reformed reconstructed enhanced vector, pGL3-basic-EGFP-TK-hTRETp-CMV enhancer, and hTERT mono-promoter vector, pGL3-basic-EGFP-TK-hTRETp(as controls), were transfected into telomerase(+) nasopharyngeal carcinoma 5-8F cell lines,telomerase(+) human breast cancer MCF-7 cell lines and telomerase(-) normal vascular endothelium cell lines respectively. TK gene green fluorescent protein was observed by fluorescence microscope. The expression of TK gene mRNA was measured by the real-time fluorescent quantified PCR and the telomerase activity was determined by the method of TRAP argentation in maligment tumour cells pre- and post-transfected by enhanced vector . Meanwhile the relationship beteewn TK and telomerase was analyzed.Result:①A strong TK gene fluorescent show and TK mRNA expression were displayed after the enhanced suicide gene vector was transfected into nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which were more stronger than those of mono-promoter group,pGL3-basic-EGFP-TK-hTRETp,and ECV cells transfected by enhanced suicide gene vector. Meanwhile,real-time fluorescent quantified PCR showed that the A value of enhanced vector group was higher than that of controls. ②Telomerase activity after transfection of enhanced vector and GCV was lower than those before by the method of TRAP argentation in nasopharyngeal carcinoma cell lines,but no change in normal control cells after transfection of enhanced vector and GCV.③ After adding GCV, the obvious inhibitory effect of tumour cells growth induced by pGL3-basic-EGFP-TK-hTRETp-CMV enhancer were observed in nasopharyngeal carcinoma 5-8F cell lines and human breast cancer MCF-7 cell line, which was higher than those of mono-promoter, pGL3-basic-EGFP-TK-hTRETp,pGL3-basic-EGFP3 and blank controls, but without inhibitory effect in ECV cells transfected by enhanced vector. Conclusion:TK gene expression is regulated by hTERT promoter and CMV enhancer, and then the telomerase activity is reduced and the cancer cells are specifically killed.But it is unclear how the telomerase are down-regulated by TK gene.
ABSTRACT
AIM To examine antithrombotic effects of arecoline on the arterial thrombosis induced by carrageenin in mice through modulating the functions of endothelium and determine its mechanisms from hemostatic system, the platelet aggregative functions and the bioactive factors released by vascular endothelial cells. METHODS Kappa carrageenin was given ip in mice and mice were fed at the temperature of 20 to 21 degrees and at the humidity of 30 percent to 50 percent. RESULTS On the foregoing models of thrombosis, arecoline could antagonize the formation of thrombosis through activating the endothelial target for acetylcholine in a dose dependent manner and its antithrombotic potency was 250 to 500 times greater than aspirin; while under the same conditions, pilocarpine could not antagonize the formation of thrombosis. The levels of TT, PT, KPTT and MAR had no prominent changes compaired with control groups. The levels of t-PA became higher greatly than normal and the levels of PAI 1 became lower greatly than normal 2 hours after intravenous injection of arecoline in rats. Arecoline could decrease the higher plasma levels of thromboxane A2 and increase the lower plasma levels of prostacyclin in a dose dependent manner in the mice tail thrombosis induced by carrageenin. CONCLUSION The antithrombotic effects of arecoline are associated with activating the endothelial target for acetylcholine closely, but are not associated with muscarinic receptors,and not relevant to hemostatic systems or functions of platelet aggregation directly.