YCD/5-FC自杀基因治疗系统对K562B白血病细胞杀伤作用的小鼠体内实验研究

Study on the in vivo killing activity of YCD/5-FC gene therapy system on K562B cells

目的 了解酵母菌胞嘧啶脱氨酶 5 氟胞嘧啶 (YCD 5 FC)系统在体内对转基因高致瘤性K5 6 2细胞 (K5 6 2B细胞 )的杀伤效应。方法 以高滴度逆转录病毒转染K5 6 2B细胞并筛选出阳性转染克隆YCD K5 6 2B ;12只SCID小鼠分为治疗及对照组 ,在小鼠左右两侧近前肢处腹部皮下注射YCD K5 6 2B及K5 6 2B细胞 ,成瘤后治疗组腹腔注射 5 0 0mg kg 5 FC共 10d ,对照组腹腔注射生理盐水 ,观察瘤体相对体积变化及病理变化。结果 瘤细胞接种第 2 1天 ,瘤体相对体积分别为 :YCD K5 6 2B +5 FC组 2 .92 2± 0 .5 81,YCD K5 6 2B +生理盐水组 2 4.434± 4.790 ,K5 6 2B +5 FC组 2 2 .70 1± 2 35 0 ,K5 6 2B +生理盐水组 2 4.46 0± 1.6 70 ;YCD K5 6 2B +5 FC组与YCD K5 6 2B +生理盐水组相比差异非常显著 (P =0 0 0 0 1) ,K5 6 2B +5 FC组及K5 6 2B +生理盐水组相比 ,差异无显著性 (P =0 .0 96 ) ,表明 5 FC对转YCD基因的K5 6 2B白血病细胞有明显的杀伤效应 ,而对未转基因细胞的生长无影响 ;YCD K5 6 2B +5 FC组瘤体于瘤细胞接种后第 12～第 15天 (5 FC治疗的第 3～第 6天 )有所缩小 (最小的相对体积为 0 .6 81) ,病理检查可见 5 FC治疗组瘤体有以小动脉血管为中心的坏死。结论 YCD 5

Objective To elucidate the killing activity of yeast cytosine deaminase /5-fluorocytosine (YCD/5-FC) gene therapy system on gene-transferred tumorigenic cell line K562B in vivo. Method K562B cell was infected with high titer virus and a gene transferred cell clone,YCD-K562B,was selected. Twelve male SCID mice of 4 week old were divided into 2 groups at random and both YCD-K562B and K562B cells were implanted to each mice. 5-FC or saline was given i.p for 10 days after tumor developed, and relative tumor volume was measured every 3 days. At the end of experiment, animals were sacrificed and the specimens were processed for histopathological examination. Results At the end of experiment (21 days after tumor cell implantation), the relative tumor volume of the 4 groups were:YCD-K562B+5-FC 2.922±0.581,YCD-K562B+saline 24.434±4.790,K562B+5-FC 22.701±2.350 and K562B+saline 24.460±1.670;t-test analysis showed that 5-FC could kill cells (YCD-K562B)in vivo(P=0.000?1),but had no effect on the growth of gene-untransferred cells (K562B) (P=0.096). In YCD-K562B+5-FC group, relative tumor volume reduced in 3～6 days after treatment(the minimum was 0.681). Necrosis around artery could be found in the tumor of YCD-K562B+5-FC group. Conclusion YCD/5-FC suicide gene therapy system has a significant in vivo killing activity to gene-transferred tumorigenic YCD-K562B cell.