Wu Yuqin, Feng Zhicai, Jiang Shengnan, Chen Jing, Zhan Yuefu, Chen Jianqiang
Department of Radiology, Affiliated Haikou Hospital of Xiangya Medical College, Central South University, No. 43, Renmin Avenue, Haikou, 570208, Hainan, China.
Department of Oncology, The Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
AMB Express. 2019 Nov 21;9(1):189. doi: 10.1186/s13568-019-0910-6.
Engineered Salmonella typhimurium (S.t-ΔpG) and attenuated Salmonella typhimurium (SL: Salmonella typhimurium with a defect in the synthesis of guanine 5'-diphosphate-3'-diphosphate) exhibit similar tumor targeting capabilities (Kim et al. in Theranostics 5:1328-1342, 2015; Jiang et al. in Mol Ther 18:635-642, 2013), but S.t-ΔpG exerts superior tumor suppressive effects. The aim of this study was to investigate whether S.t-ΔpG inhibits colon cancer growth and recurrence by promoting increased IL-1β production. The CT26 tumor mouse model was used, and mice were treated in the following ways: PBS, S.t-ΔpG + IL-1βAb, SL, S.t-ΔpG, and S.t-ΔpG. Dynamic evaluation of the efficacy of S.t-ΔpG in the treatment of colon cancer was assessed by MRI. Western blot, immunofluorescence and flow cytometry analysis were used to investigate IL-1β-derived cells and IL-1β expression on tumor cells and immune cells to analyze the regulatory mechanism. IL-1β levels in tumors colonized by S.t-ΔpG were significantly increased and maintained at high levels compared to control treatments. This increase caused tumors to subside without recurrence. We examined the immune cells mediating S.t-ΔpG-induced tumor suppression and examined the major cell types producing IL-1β. We found that macrophages and dendritic cells were the primary IL-1β producers. Inhibition of IL-1β in mice treated with S.t-ΔpG using an IL-1β antibody caused tumor growth to resume. This suggests that IL-1β plays an important role in the treatment of cancer by S.t-ΔpG. We found that in St-ΔpG-treated tumors, expression of molecules involved in signaling pathways, such as NLRP3, ASC, Caspase1, TLR4, MyD88, NF-kB and IL-1β, were upregulated, while in ΔppGpp S. typhimurium treated animals, TLR4, MyD88, NF-kB and IL-1β were upregulated with NLRP3, ASC, and Caspase1 being rarely expressed or not expressed at all. Using S.t-ΔpG may simultaneously activate TLR4 and NLRP3 signaling pathways, which increase IL-1β expression and enhance inhibition of colon cancer growth without tumor recurrence. This study provides a novel platform for treating colon cancer.
工程化鼠伤寒沙门氏菌（S.t-ΔpG）和减毒鼠伤寒沙门氏菌（SL：鸟苷5'-二磷酸-3'-二磷酸合成有缺陷的鼠伤寒沙门氏菌）表现出相似的肿瘤靶向能力（Kim等人，《治疗诊断学》5:1328 - 1342，2015；Jiang等人，《分子治疗》18:635 - 642，2013），但S.t-ΔpG具有更强的肿瘤抑制作用。本研究的目的是探讨S.t-ΔpG是否通过促进白细胞介素-1β（IL-1β）产量增加来抑制结肠癌生长和复发。使用CT26肿瘤小鼠模型，小鼠接受以下处理：磷酸盐缓冲液（PBS）、S.t-ΔpG + IL-1β抗体（IL-1βAb）、SL、S.t-ΔpG和S.t-ΔpG。通过磁共振成像（MRI）动态评估S.t-ΔpG治疗结肠癌的疗效。采用蛋白质免疫印迹法、免疫荧光法和流式细胞术分析来研究IL-1β来源的细胞以及肿瘤细胞和免疫细胞上IL-1β的表达，以分析调控机制。与对照处理相比，S.t-ΔpG定植肿瘤中的IL-1β水平显著升高并维持在高水平。这种升高导致肿瘤消退且无复发。我们检查了介导S.t-ΔpG诱导的肿瘤抑制的免疫细胞，并检查了产生IL-1β的主要细胞类型。我们发现巨噬细胞和树突状细胞是主要的IL-1β产生者。使用IL-1β抗体抑制S.t-ΔpG处理小鼠中的IL-1β会导致肿瘤生长恢复。这表明IL-1β在S.t-ΔpG治疗癌症中起重要作用。我们发现，在经S.t-ΔpG处理的肿瘤中，参与信号通路的分子如NLRP3、ASC、半胱天冬酶-１（Caspase1）、Toll样受体4（TLR4）、髓样分化因子88（MyD88）、核因子κB（NF-κB）和IL-1β的表达上调，而在经ΔppGpp鼠伤寒沙门氏菌处理的动物中，TLR4、MyD88、NF-κB和IL-1β上调，而NLRP3、ASC和Caspase1很少表达或根本不表达。使用S.t-ΔpG可能同时激活TLR4和NLRP3信号通路，这会增加IL-1β表达并增强对结肠癌生长的抑制且无肿瘤复发。本研究为治疗结肠癌提供了一个新平台。
