Tumor-targeting Salmonella typhimurium, a natural tool for activation of prodrug 6MePdR and their combination therapy in murine melanoma model
Tumor-targeting Salmonella typhimurium, a natural tool for activation of prodrug 6MePdR and their combination therapy in murine melanoma model
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DOI：
10.1007/s00253-012-4321-8
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发表时间：
2013-05-01
影响因子：
5
通讯作者：
Hua, Zi-Chun
中科院分区：
文献类型：
--
作者：
Chen, Guo;Tang, Bo;Hua, Zi-Chun
PNP/6-甲基嘌呤2‘-脱氧核苷(6MePdR)系统是一种高效的基因导向酶前药治疗系统，具有显著的抗肿瘤活性。在这个系统中，大肠杆菌嘌呤核苷磷酸化酶(EPNP)激活无毒的6MePdR生成有效的抗肿瘤药物6-甲基嘌呤(6MeP)。鼠伤寒沙门氏菌PNP(SPNP)基因与ePNP有96%的序列同源性，并具有将6MePdR转化为6MeP的能力。在本研究中，我们利用结构性表达内源性PNP基因的肿瘤靶向性鼠伤寒沙门氏菌VNP20009来激活6MePdR，并在B16F10黑色素瘤模型中进行细菌和前药的联合治疗。用高效液相色谱法分析鼠伤寒沙门氏菌将6MePdR转化为6MeP的情况，并用四唑盐比色法(四唑盐比色法)和四甲基偶氮唑蓝细胞毒试验(四甲基偶氮唑蓝比色法)检测sPNP的体外细胞毒作用。在给小鼠全身注射VNP20009后，细菌在肿瘤中大量积累并特异性地运送内源性sPNP。与VNP20009或6MePdR单独应用相比，VNP20009和6MePdR联合应用显著延缓了B16F10肿瘤的生长，增加了CD8(+)T细胞的浸润。综上所述，我们的结果表明，鼠伤寒沙门氏菌和前药6MePdR的联合治疗是一种很有前途的癌症治疗策略。
The PNP/6-methylpurine 2'-deoxyriboside (6MePdR) system is an efficient gene-directed enzyme prodrug therapy system with significant antitumor activities. In this system, Escherichia coli purine nucleoside phosphorylase (ePNP) activates nontoxic 6MePdR into potent antitumor drug 6-methylpurine (6MeP). The Salmonella typhimurium PNP (sPNP) gene has a 96-% sequence homology in comparison with ePNP and also has the ability to convert 6MePdR to 6MeP. In this study, we used tumor-targeting S. typhimurium VNP20009 expressing endogenous PNP gene constitutively to activate 6MePdR and a combination treatment of bacteria and prodrug in B16F10 melanoma model. The conversion of 6MePdR to 6MeP by S. typhimurium was analyzed by HPLC and the enzyme activity of sPNP was confirmed by in vitro (tetrazolium-based colorimetric assay) MTT cytotoxicity assay. After systemic administration of VNP20009 to mice, the bacteria largely accumulated and specifically delivered endogenous sPNP in the tumor. In comparison with VNP20009 or 6MePdR treatment alone, combined administration of VNP20009 followed by 6MePdR treatment significantly delayed the growth of B16F10 tumor and increased the CD8(+) T-cell infiltration. In summary, our results demonstrated that the combination therapy of S. typhimurium and prodrug 6MePdR is a promising strategy for cancer therapy.