Abstract Neural stem cell (NSC)-based gene therapies have been recently developed as effective strategies for treating brain tumors through inherent tumor tropism. However, this methodology has two considerable challenges: preventing NSCs from dying from the therapeutic agents encoded by their equipped genes before reaching tumor sites and the clearance of exogenous NSCs after therapeutic treatments. For these purposes, we established a novel doxycycline-inducible retroviral plasmid pTRE3G-TKGFP. A herpes simplex type 1 thymidine kinase (HSV1TK)-green fluorescent protein (GFP) fusion protein coding sequence was integrated into the multiple cloning site II (MCS II) of the pQcXIX vector, and the CMV IE promoter (PCMV IE) of pQcXIX was replaced with the doxycycline-inducible TRE3G promoter (PTRE3G). We then cloned the coding sequences of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and soluble interleukin 6 receptor (sIL-6R) into MCS I to combine HSV1TK (TK)/ganciclovir (GCV)-based suicide gene therapy against tumorigenic C6 glioma cells. TNF-α, IL-6 and sIL6R could efficiently induce tumorigenic C6 glioma cell differentiation, resulted in down-regulating the cell proliferation rate and the tumorigenicity of glioma cells and up-regulating the production of differentiation markers, such as connexin-43. Furthermore, gap junctions could enhance the bystander effect in suicide gene therapy. Consequently, we found that the retroviral plasmid transfected NSCs exerted stronger remedial effects on tumorigenic C6 glioma cells through the combination of differentiation and suicide gene therapy than by suicide gene therapy alone. This study is also the first case applying NSCs to conduct the combination of differentiation and TK/GCV-based suicide gene therapy on glioma cells.

中文翻译：

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基于多西环素诱导 C17.2 神经干细胞的分化和自杀基因治疗组合，用于体外致瘤性 C6 神经胶质瘤模型

摘要 基于神经干细胞 (NSC) 的基因疗法最近被开发为通过固有的肿瘤趋向性治疗脑肿瘤的有效策略。然而，这种方法有两个相当大的挑战：防止 NSCs 在到达肿瘤部位之前死于由其配备的基因编码的治疗剂，以及在治疗后清除外源性 NSCs。为此，我们建立了一种新型强力霉素诱导型逆转录病毒质粒 pTRE3G-TKGFP。将单纯疱疹1型胸苷激酶（HSV1TK）-绿色荧光蛋白（GFP）融合蛋白编码序列整合到pQcXIX载体的多克隆位点II（MCS II）中，pQcXIX的CMV IE启动子（PCMV IE）为替换为强力霉素诱导型 TRE3G 启动子 (PTRE3G)。然后我们将肿瘤坏死因子-α (TNF-α)、白介素 6 (IL-6) 和可溶性白介素 6 受体 (sIL-6R) 的编码序列克隆到 MCS I 中以结合 HSV1TK (TK)/更昔洛韦 (GCV)-基于针对致瘤性 C6 神经胶质瘤细胞的自杀基因治疗。TNF-α、IL-6 和 sIL6R 可有效诱导致瘤性 C6 胶质瘤细胞分化，导致细胞增殖率和胶质瘤细胞的致瘤性下调，并上调分化标志物如 connexin-43 的产生。此外，间隙连接可以增强自杀基因治疗中的旁观者效应。因此，我们发现逆转录病毒质粒转染的神经干细胞通过分化和自杀基因治疗的组合比单独的自杀基因治疗对致瘤性 C6 神经胶质瘤细胞发挥更强的治疗作用。