Bystander effects of different enzyme-prodrug systems for cancer gene therapy depend on different pathways for intercellular transfer of toxic metabolites, a factor that will govern clinical choice of appropriate regimes
Bystander effects of different enzyme-prodrug systems for cancer gene therapy depend on different pathways for intercellular transfer of toxic metabolites, a factor that will govern clinical choice of appropriate regimes
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DOI：
10.1089/hum.1997.8.15-1825
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发表时间：
1997-10-10
影响因子：
4.2
通讯作者：
Pitts, JD
中科院分区：
文献类型：
--
作者：
Denning, C;Pitts, JD
将自杀基因转移到肿瘤细胞中使其对特定前药的细胞毒性作用敏感。我们发现单纯疱疹病毒胸苷激酶/更昔洛韦（tk/GCV）和胸苷磷酸化酶/5 ′-脱氧-5-氟尿苷（tp/DFUR）自杀基因系统均可诱导肿瘤细胞死亡。此外，在有和没有自杀基因的细胞的混合培养物中，两种细胞类型都发生死亡，表明存在旁观者效应。我们证明，在人类和啮齿动物细胞系，TK/GCV旁观者效应需要间隙连接细胞间通讯（GJIC）。当培养物缺乏GJIC时，未观察到旁观者效应。在交流文化中，GJIC水平和旁观者效应之间没有相关性，这是由于高水平的tk活性。此外，我们证明了毒性代谢物从tk（+）转移到tk（-）细胞发生在GCV应用的2小时内，并且由于在此时间之后才能检测到细胞凋亡，因此细胞凋亡是tk/GCV旁观者效应的结果，而不是原因。在tp/DFUR系统中，观察到介质介导的旁观者效应，独立于GJIC和凋亡。我们证明了在培养中结合tk/GCV和tp/DFUR自杀基因系统比单独治疗更有效。
Transfer of suicide genes into tumor cells renders them sensitive to cytotoxic effects of specific prodrugs. We show here that both the herpes simplex virus thymidine kinase/ganciclovir (tk/GCV) and thymidine phophorylase/5'-deoxy-5-fluorouridine (tp/DFUR) suicide gene systems can induce cell death in tumor cells. Additionally in mixed cultures of cells with and without the suicide gene, death occurred in both cell types, indicative of a bystander effect. We demonstrate, in human and rodent cell lines, that the tk/GCV bystander effect requires gap junctional intercellular communication (GJIC). Where cultures lack GJIC, no bystander effect was observed. In communicating cultures, no correlation between level of GJIC and bystander effect was seen and this was due to high levels of tk activity. Additionally, we demonstrate that transfer of toxic metabolites from tk(+) to tk(-) cells occurs within 2 hr of GCV application and, as no apoptosis could be detected until after this time, apoptosis is the result, not the cause, of the tk/GCV bystander effect. In the tp/DFUR system, a medium-mediated bystander effect, independent of GJIC and apoptosis, was observed. We demonstrated that combining tk/GCV and tp/DFUR suicide gene systems in culture was more effective than either therapy alone.