自杀基因引导的旁观者效应对鼠膀胱癌的作用

Bystander effect induced by suicide gene on mouse bladder cancer

目的 研究单纯疱疹病毒胸腺嘧啶核苷激酶 (herpessimplexvirusthymidinekinase ,HSVtk)基因联合丙氧鸟苷(ganciclovir ,GCV)治疗对膀胱癌的旁观者效应。方法 用逆转录病毒载体HSVtk转染鼠源性膀胱癌细胞株T73 9,体外检测其对GCV的敏感性。将不同比例的T73 9和T73 9TK细胞共培养观察体外旁观者效应。在同基因鼠 ,将不同比例的T73 9和T73 9TK细胞混合建立膀胱癌腹腔肿瘤模型。当肿瘤B超显示 0 5～ 0 8cm ,腹腔GCV给药 6d ,然后观察肿瘤大小变化及动物存活时间。结果 转染HSVtk基因的T73 9细胞对GCV的敏感性 ,RT PCR分析证实TK基因mRNA的表达。细胞混合培养发现 ,当T73 9TK细胞占 10 %强时就可显示出明显的旁观者效应。在GCV的作用下 ,动物体内肿瘤生长受到显著抑制 ,动物存活时间明显延长 ,证明存在体内旁观者效应。结论 转染HSVtk基因的鼠膀胱癌细胞可引导产生体内外旁观者效应 。

Objective To determine the bystander effect of therapy with herpes simplex virus thymidine kinase ( HSVtk ) gene combined with ganciclovir (GCV) on mouse bladder cancer. Methods Mouse bladder cancer cell line (T739) was transfected with retroviral vector HSVtk gene. The sensitivity of T739TK cells to GCV was detected in vitro . Bystander effect in vitro in co cultured mixtures of T739TK and T739 cells at different ratios or at the same ratio in culture bottles of different size was determined. In the mouse model of bladder tumor, mixtures of T739 and T739TK cells were implanted beneath the peritonea of syngeneic mice. When tumors grew to the size of 0 5-0 8 cm, intraperitoneal administration of GCV was carried out for 6 d. Changes of tumor size and survival rate of mice were observed. Results T739 cells retrovirally transfected with the HSVtk gene became sensitive to low concentrations of GCV. Analysis by RT PCR confirmed HSVtk expression in the transfected T739TK cells. An absolute bystander effect was observed in the mixed culture of cells in vitro when the HSVtk gene transferred cells were at the ratio of above 10%. The tumor growth in the animal model was significantly inhibited by GCV, demonstrating the existence of bystander effect in vivo . The survival time of mice was prolonged after administration of GCV. Conclusion The in vitro and in vivo bystander effects exist in mouse bladder cancer transfected with HSVtk gene, enhancing the role of HSVtk /GCV system for the treatment of bladder carcinoma.