胞苷脱氨酶基因对小鼠大剂量化疗的保护作用

Protection of cytidine deaminase gene gainst toxicity of high-dose chemotherapy in mice

目的:将人胞苷脱氨基酶基因(CD)导入小鼠骨髓细胞后,观察小鼠对大剂量阿糖胞苷(Ara—C)的耐受性,探讨骨髓耐受联合化疗的可行性. 方法:以反转录病毒为载体,将人胞苷脱氨基酶基因(CD)通过共培养转染入小鼠骨髓干细胞,观察共培养后的骨髓细胞及受体小鼠骨髓移植后经药物处理后的骨髓细胞耐Ara—C CFU—GM生成情况;从转基因小鼠骨髓细胞提取DNA,用PCR检测转基因小鼠骨髓细胞耐药基因的表达;观察转基因小鼠经大剂量Ara—C化疗后血象、体质量及生存率的变化. 结果:骨髓移植前共培养后供体的骨髓细胞和骨髓移植后受体含有耐药基因(SFG—CD)的骨髓细胞均有耐药克隆的形成(52%,54%;与对照组相比X2分别为124.62, 126.26,P均<0.01),并明显增加了对Ara—C的耐受性:与对照组比较含耐药基因组动物经大剂量化疗后, 生存率明显提高(X2=7.42,P<0.01),血象、体质量下降幅度较小而恢复较快;转基因小鼠骨髓细胞经PCR检测,显示有CD基因条带. 结论:耐药基因可以进入小鼠骨髓细胞并且获得共表达,提高了造血细胞对Aar—C的耐受性.

AIM： To observe the tolerance to high-dose cytarabine （Ara-C） in mice after the cytidine deaminase （CD） gene is transfected into mouse bone marrow cells, and to explore the feasibility of chemotherapy combined with the tolerance of myelosuppression. METHODS： Human cytidine deaminase gene was transfected into mouse bone marrow cells by retroviral vector. Then the colony-forming unit granulocyte-macrophage （CFU-GM） was observed in the cells of marrow donor and acceptor mice treated with Ara-C. DNA was extracted from the cells and the drug-resistant genes were detected by polymerase chain reaction （PCR）. The blood cell count, weight and survival rate of the mice treated with Ara-C were analyzed. RESULTS： Drug-resistant colonies appeared both in the bone marrow cells of donor and acceptor mice treated with Ara-C, and the CFU-GMs were 52% and 54% respectively, which were significantly higher than those ofthe controls （x^2 = 124.62, 126.26; both P〈0.01）. The survival rate was significantly higher in CD-transfected mice as compared with that in the controls （x^2 = 7.42, P〈0.01 ）,and the blood cell count and body weight decreased less and recovered sooner. CD gene was expressed in the bone marrow cells of transfected mice. CONCLUSION： Drug-resistant gene can not only integrate and express in mouse bone marrow cells, but also promote the tolerance to high-dose Ara-C.