慢病毒介导双自杀基因对乳腺癌细胞的体内杀伤作用

Killing Effect of Lentivirus-mediated Double Suicide Genes on Human Breast Cancer Cells in vivo

目的:研究慢病毒介导的KDR启动子驱动的胞嘧啶脱氨酶(CD)/胸苷激酶(TK)融合基因系统(FGW-KDRP-CD/TK)对乳腺癌细胞的体内杀伤作用。方法:培养乳腺癌MCF-7细胞,建立裸鼠荷瘤模型。荷瘤后将裸鼠随机分为4组。Ⅰ组:空白对照,荷瘤但不施加任何处理;Ⅱ组:注射慢病毒与前药(5-FC+GCV);Ⅲ组:仅注射慢病毒;Ⅳ组:仅注射前药。观察肿瘤生长速度,测量瘤体大小及重量;用RT-PCR法鉴定双自杀基因在转基因瘤组织中的表达;取肿瘤组织进行HE及PCNA免疫组化染色;流式细胞技术进行细胞周期检测。结果:第Ⅱ组裸鼠移植瘤的生长显著受到抑制,第Ⅰ、Ⅲ、Ⅳ组肿瘤生长情况无明显差异。经RT-PCR检测发现转基因瘤组织有目的基因的表达。与第Ⅰ组(空白对照组)相比,第Ⅱ组瘤组织的PCNA表达明显下调。流式细胞仪检测细胞周期分析显示治疗后G_1期细胞比率增多,G_2/M期细胞减少。结论:FGW-KDRP-CD/TK联合前药5-FC及GCV在体内可明显抑制移植瘤的生长,细胞周期阻滞,该作用可能与抑制PCNA表达有关。

Objective： To evaluate the killing effect of lentivirus mediated CD/TK fusion gene controlled by kinase insert domain-containing receptor （KDR） promoter on human breast cancer cells in vivo. Methods： Nude mice were used as hosts for cell line MCF-7 xenografts to establish the animal model of breast cancer. The tumor-bearing mice were randomly divided into 4 groups. Group Ⅰ were blank controls with tumor-bearing mice with no treatment. Group Ⅱ was injected with lentivirus and prodrug （ 5-FC＋ GCV ）. Group Ⅲ was injected with lentivirus. Group Ⅳ was injected with prodrug. Tumor growth rate, tumor size and weight were observed. The expression of double suicide genes in xenografl tumors was examined by RT-PCR. The tumor tissue was analyzed by hematoxylin-eosin staining and PCNA immunohistochemistry. Flow cytometry （FCM） was used for cell cycle analysis. Results： Tumor growth was obviously inhibited in group Ⅱ. But there was no significant difference in tumor growth among group Ⅰ, group Ⅲ, and group Ⅳ. RT-PCR demonstrated the existence of CD/TK gene in genetically modified xenograft tumor cells. The expression of PCNA was lower in tumor tissue of group Ⅱ than in group Ⅰ. Flow cytometry analysis showed that the proportion of G, phase cells was increased and the proportion of G2-M phase cells was decreased. Conclusion： Combined with the prodrug, FGW-KDRP-CD/TK can significantly inhibit the growth of implanted breast cancer cells in nude mice and cell cycle arrest, which may be related to its inhibitory effect on PCNA expression.