脂质体包裹99Tcm-HYNIC-survivin ASODN中胞嘧啶含量对荷肝癌裸鼠显像的影响

摘要

目的 研究胞嘧啶(C)含量对反义探针肿瘤特异性聚集的影响,为最佳反义显像碱基序列的筛选提供帮助.方法 以survivin为靶序列制备3种(A1、A2、A3)C含量不同(10％、20％、30％)的20个碱基单链ASODN,耦联HYNIC,经99 Tcm标记、Cellufine GH-25纯化、脂质体包裹后获得3种标记化合物.分别对荷肝癌裸鼠行反义显像,各组计量资料比较采用Kruskal-Wallis H检验.结果 注射后4h,3种标记化合物在荷肝癌裸鼠体内均表现为肝、肾高摄取.随着C含量升高,3种标记化合物的肾脏摄取依次升高,分别为(1.50±0.06)、(2.80±0.09)和(3.96±0.03) ％ID/g;肿瘤摄取依次降低,分别为(2.08±0.08)、(1.69±0.01)和(1.20±0.09) ％ID/g;体内显像的T/NT比值分别为4.49～4.93、4.12～4.21和3.35～ 3.85,差异有统计学意义(H=12.50,P＜0.05);生物分布的T/NT比值分别为4.08 ～ 4.94、4.02～4.18和3.66～3.85,差异有统计学意义(H=10.82,P＜0.05).结论 Survivin ASODN中的C含量越低,标记化合物的肾内滞留率越低,肿瘤特异性结合率越高,显像质量越好.%Objective To investigate whether specific cellular uptake of 99Tcm-survivin-ASODN in nude mice bearing human HCC is influenced by its cytosine content.Methods Three kinds(A1,A2,A3) of synthesized survivin ASODN with three cytosine contents(10％,20％,30％),20 bases per single-strand were prepared.They were labeled with 99Tcm by conjugating with a bifunctional chelator HYNIC,purified through Cellufine GH-25 and then encapsulated with liposome.Antisense gene imaging and the biodistribution of 99Tcm-HYNIC-survivin ASODN in nude mice bearing HCC were performed.The data were analysed by Kruskal-Wallis H test.Results At 4 h post injection,all the 3 labelled compounds showed increased uptake by tumor,liver and kidney.With increase in cytosine content,the uptake increased in kidney (％ID/g:1.50±0.06,2.80±0.09 and 3.96±0.03),and decreased in tumor (％ID/g:2.08±0.08,1.69±0.01 and 1.20±0.09).T/NT in imaging (4.49-4.93,4.12-4.21,3.35-3.85;H=12.50,P＜0.05) and in biodistribution (4.08-4.94,4.02-4.18,3.66-3.85;H=10.82,P＜0.05) were all significantly different.Conclusion ASODN with lower cytosine content shows higher uptake by HCC tumor cells and less stasis in kidneys,thus providing better quality in antisense gene imaging.