中文摘要：

目的：构建Tet调节的自杀基因HSVtk重组逆转录病毒，探讨其治疗乳腺癌的作用机制。方法：构建重组逆转录病毒RevTRE／HSVtk与RevTet—On感染乳腺癌细胞株MCF-7。Southern杂交检测细胞中HSVtk基因的整合。应用倒置荧光显微镜、流式细胞术、TUNEL、苔盼蓝排斥试验观察分析在Tet调控下，重组病毒对感染的乳腺癌细胞杀伤作用机制。以MCF-7细胞构建裸鼠乳腺癌模型。观察Tet调控下病毒对肿瘤细胞的杀伤作用．并对瘤体进行病理分析。结果：重组病毒感染乳腺癌细胞株MCF-7后，乳腺癌细胞随着DOX浓度的增高和GCV作用后，细胞死亡增加并呈现细胞凋亡等特征。乳腺癌裸鼠在DOX诱导7天GCV治疗30天后与对照组比较，在Tet调控下乳腺癌裸鼠肿瘤体积减小并可诱导乳腺癌细胞凋亡。结论：重组逆转录病毒在DOX诱导GCV作用下对病毒感染的MCF-7细胞具有诱导细胞凋亡的作用．能有效地杀伤肿瘤细胞。

英文摘要：

Objective： To improve the antineoplastic activity of suicide gene therapy and to investigated the antitumor mechanism of this therapy in breast cancer controlled by Tet regulation system. Methods： Recombinant retroviruses containing HSVtk and Tet-On gene were constructed and transduced into MCF-7 cells. Target gene was inserted into the host cells and performed by Southern-blotting. The antiproliferative effect on infected MCF-7 ceils was detected by trypan-blue exclusion assay, observed morphological aspect of apoptosis by inverted fluorescent microscope and assessed apoptosis rate by flow cytometric method. To examine the therapy effect on the BALB/C nude mice of breast cancer under the Tet-On induction, retroviruses were injected into the tumors and pathological analysis virus-infected MCF-7 cells under higher induction of Doxycycline （DOX）. After treatment .of different concentration of DOX, inhibition rate of proliferation and apoptosis rate of MCF-7 cells were increased. Seven days after DOX induction and 30 days following GCV treatment, tumorous size of nude mice was decreased remarkably and apoptosis could be detected in tumor cells. Conclusions： Recombinant retrovirus containing Tet regulation system and HSVtk gene can successfully infect MCF-7 cells and induce apoptosis in vivo and in vitro of tumor cells.