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Preparation Of Radionuclide Labeled Peptides K237 And The Experimental Study On Molecular Imaging And Targeting Therapy In Nude Mice Bearing Human Lung Cancer

Posted on:2012-03-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:J X ZhengFull Text:PDF
GTID:1114330335474185Subject:Clinical Laboratory Science
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Part 1 Study on preparation of 99Tcm-K237 and it's biodistribution in miceObjective A novel peptide K237, which was isolated from a phage-displayed peptide library, can inhibit tumor growth and metastasis by blocking the binding of vascular endothelial growth factor(VEGF) to it's KDR receptor.The aim of this study was to explore the method of the radiolabeling of peptides K237 with 99Tcm and investigate the stability of 99Tcm-K237 and its distribution in mice.Methods Peptide K237 was labeled directly with 99Tcm. The labeling rate, the radiochemic purity, the in vitro stability and the biologic activity of Tcm-K237 were studied under various conditions.99Tcm-K237 was injected through tail vein of normal mice with 2.96 MBq in a volume of 0.1 ml. Those mice were killed at different stages after injection and their blood and other major organs were taken out, then the radioactivity count of these organs were measured to investigate the biodistribution. 99Tcm-K237 of 0.1 ml 5.55 MBq was injected into the tail vein of tumor bearing nude mice, then imaged at 1,2,3,5 and 8 h.Results Under the conditions of SnCl2·2H2O 100μg, K237 100μg, pH value 6.0, reaction time 10~30 min and reaction temperature 4~37℃, the labeling rate and the radiochemic purity of 99Tcm-K237 were more than 95%. The specific binding efficiency of 99Tcm-K237 with human umbilical vein endothelial cell (HUVEC) was 40.36%. After 99Tcm-K237 was placed in physiologic saline and in blood serum, the radiochemic purity was respectively (89.1±1.4)% and (88.3±1.1)% at 24 h, while there was no significant difference between the two groups(t=1.56, P>0.05). In the first 24 h postinjection, the biodistribution in mice showed rapid blood and renal clearance with gradually excreted in other organs or tissues including heart, liver, lungs, stomach and muscle, most of the radioactivity was observed in renal. In imaging, the uptake ratios of tumor to background (T/B) at 1,2,3,5 and 8 h were 1.25±0.11,3.13±0.26,3.97±0.31,1.34±0.29 and 1.18±0.25, respectively.Conclusion 99Tcm-K237, which is an easily prepared and labeled compound with high labeling rate and stability, will be a potential tumor imaging agent.Part 2 Study on preparation of 131I-K237 and it's biodistribution in nude mice bearing human lung cancerObjective To explore the method of the radiolabeling of peptide K237 with 131I and investigate the stability of 131I-K237 and its distribution in nude mice bearing human lung cancer.Methods Iodogen method was used for 131I labeling K237. The bioactivity of 131I-K237 was tested by HUVEC proliferation inhibitory assay and the affinity of 131I-K237 was examined by competition binding studies.131I-K237 was injected through tail vein of nude mice with 2.96 MBq in a volume of 0.1 ml to investigate the biodistribution. Those mice were killed at different stages after injection and their blood and other major organs were taken out, then the radioactivity counts of these organs were measured to investigate the biodistribution.Results The labeling rate of 131I-K237 was 60.16%, radiochemical purity was above 95%. The inhibition rate of HUVEC proliferation had no significant difference between radiolabeled K237 and unlabeled K237(P>0.05). After 131I-K237 was placed in physiologic saline and in blood serum, the radiochemic purity was>95%,respectively. The ratios of tumor to muscle(T/N) were 2.12,2.32,2.51,2.70,3.03,4.31and 4.19 at 30min,1 h,2 h,4 h,8 h,12 h and 24 h, respectively.Conclusion 131I-K237, which is an easily prepared and labeled compound with high labeling rate and stability, will be a potential targeting tumor imaging and treating agent.Part 3 Experimental study on targeting therapy in nude mice bearing human lung cancer with 131I-K237Objective To investigate the targeted therapeutic efficiency of 131I radiolabeled peptide K237 (131I-K237) on nude mice bearing human lung cance.Methods Human lung cancer xenografts with positive KDR expression were established in nude mice. All 25 mice models were divided into five groups randomly, including physiologic saline group, 131I-K237 group intravenously,131I-K237 group intratumorally, K237 group and 131I group. Thirty-one days after infusion, the tumor growth inhibition rate was calculated.The inhibited effect and the radiation breakdown of 131I-K.237 on nude mice were determined by biochemical, immunohistochemical and pathohistology methods.Results Tthe inhibition rate of HUVEC proliferation had no significant difference between radiolabeled K237 and unlabeled K237(t=1.67, P> 0.05). The growth of transplanted lung cancer was inhibited by 75.01%, 78.99%,31.15% and 12.61% at groups treated with 131I-K237 intravenously, 131I-K237 intratumorally, K237 and 131I, respectively. The average tumor volume of the 131I-K237 trial groups less than that of the control, K237 and 131I group (P<0.01). Irreversible destruction of tumor cells in 131I-K237 trial groups and K237 group was found under light and electron microscope. There was no effect of radiation breakdown on liver, kidney, spleen and blood-cell in nude mice.Conclusion 131I-K237 can effectively inhibit the growth of tumor in nude mice bearing human lung cancer, with little obvious side effects.
Keywords/Search Tags:Peptide K237, Neoplasms, Angiogenesis, Isotope labeling, Pharmacokinetics, mice, Molecular imaging, Targeting therapy
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