论文部分内容阅读
Objective: The application of radiotherapy is currently limited by the side-effects such as the radiation-induced damages of the normal tissues nearby and the radiation-resistance of certain tumors.To solve these problems, a recombinant baculovirus containing Egr-1 promoter and human plasminogen Kringle5 gene was constructed in our study.After Egr-1 promoter activated by the radiation, its downstream gene, Kringle 5 will start its transcription and protein expression.Thus, suppression of tumor vessels by Kringle5 and the direct killing of tumor cells by radiation will work simultaneously.18F-FDG PET/CT as well as 18F-FLT PET/CT were used to evaluate the treatment effect in order to further confirm its feasibility.Methods: 1、 The recombinant plasmid pGL3-Egr-1-EGFP was constructed to identify the activity of Egr-1 promoter after radiation.Then generate the recombinant baculovirus B ac Egr-1-Kringle5 and the control groups according to Bac-to-Bac baculovirus expression system.2、 In vitro, after infected by Bac Egr-1-K5, human lung adenocarcinoma A549 cell line was accepted radiation.We analyze the transcription of K5 mRNA、 expression of K5 protein and apoptosis percentage of HUVEC cell lines.3、 In vivo, The animal models were built.GD (growth delay time) and the inhibition rates for tumor growth were calculated.18F-FDG PET/CT as well as 18F-FLT PET/CT were used to evaluate treatment effect on d0, d7 and d14.The SUVmax was analyzed to get the agreement with the results of GD analysis, and the expression level of VEGF, CD31 and Ki-67 detected by IHC also.Results: 1、 We proved the activity of Egr-1 promoter induced by radiation.2、 In vitro, the transcription of K5 mRNA and the K5 protein expression were elevated with the dose of X-radiation (P<0.05).But the transcription of K5 mRNA in different X-radiation dose groups has no significant difference after three consecutive irradiation (P>0.05).The apoptosis percentage of HUVEC cell line in radiotherapy combined with Bac Egr-1-Kringle5 group was significantly higher than that of HUVEC cell line with radiation alone.3、 In vivo, FDG and FLT metabolism of implanted tumors after treatment were markedly decreased compared with the control groups detected by Micro PET/CT.And the SUVmax was significantly correlated with the GD as well as with the expression of Ki-67, VEGF and CD31.Conclusion: 18F-FDG PET/CT as well as 18F-FLT PET/CT can be applied in the assessment of tumor treatment.Radiation therapy and anti-angiogenesis therapy work simultaneously when Egr-1 promoter was activated by radiation in our research.It would decrease the dose of radiation,so as to protect the normal tissues and increase the suppression of tumors at the same time.And low dose and more times would be better.It would provide a promising way for tumor treatment.