METHODS: The C57BL/6N mice were chosen to establish the Lewis lung cancer models. The broad-spectrum antibiotics (ABX) group was set up to estimate the effect of microbiota composition on metastasis. The therapeutic effects of different doses of SSG in treating lung metastasis were investigated through histopathology, immunohistochemistry, and Western blot analysis methods. Additionally, the phenotype of tumor-associated macrophages (TAMs) in the lung and blood was evaluated by flow cytometry. The fecal microbiota transplantation (FMT) and negative control (ABX plus high dose SSG group) experiments were also designed to assess intestinal microbiota\'s role in SSG intervention\'s outcome in lung metastasis. The 16S rRNA amplicon sequencing and Untargeted metabolomic analysis were used to analyze intestinal microbiota and metabolite changes mediated by SSG in tumor-bearing mice with lung metastasis.
RESULTS: ABX could observably lead to intestinal microbiota dysbiosis and enhance metastasis. SSG showed a significant chemopreventive effect in lung metastasis, reduced metastatic nodules and the expression levels of pre-metastatic niche biomarkers, and enriched the ratio of CD86+F4/80+CD11b+ cells, while FMT delayed metastasis similarly. The analysis of microbiota and metabolites revealed that SSG significantly enriched probiotics in feces, including Akkermansia muciniphila, Lachnoclostridium sp YL32, Limosilactobacillus reuteri, and potential anti-cancer serum metabolites, including Ginsenoside Rb1, Isoquinoline, Betulin and so on. We also investigated the mechanism of SSG protection against lung metastasis and showed that SSG regulated microbiota, improved TAMs polarization, and inhibited the expression of the NF-κB pathway.
CONCLUSIONS: The results presented in our article demonstrated that SSG improved TAMs polarization and inhibited the NF-κB pathway by alleviating intestinal microbiota imbalance and metabolic disorders in tumor-bearing mice, resulting in delayed lung metastasis.
方法:选择C57BL/6N小鼠建立Lewis肺癌模型。建立广谱抗生素(ABX)组以评估微生物群组成对转移的影响。通过组织病理学研究不同剂量SSG治疗肺转移的疗效。免疫组织化学,和Westernblot分析方法。此外,通过流式细胞术评估肺和血液中肿瘤相关巨噬细胞(TAMs)的表型.还设计了粪便微生物群移植(FMT)和阴性对照(ABX加高剂量SSG组)实验,以评估肠道微生物群在SSG干预肺转移结局中的作用。使用16SrRNA扩增子测序和非靶向代谢组学分析来分析患有肺转移的荷瘤小鼠中由SSG介导的肠道微生物群和代谢物变化。
结果:ABX可观察到导致肠道菌群失调并增强转移。SSG对肺转移有明显的化学预防作用,转移结节减少和转移前生态位生物标志物的表达水平,富集了CD86+F4/80+CD11b+细胞的比例,而FMT延迟转移相似。对微生物群和代谢产物的分析表明,SSG显著富集了粪便中的益生菌,包括Akkermansiamuciniphila,LachnosclostridiumspYL32,Limosilactobacillusreuteri,和潜在的抗癌血清代谢物,包括人参皂苷Rb1,异喹啉,Betulin等。我们还研究了SSG对肺转移的保护机制,并表明SSG调节微生物群,改进的TAM极化,并抑制NF-κB通路的表达。
结论:我们文章中的结果表明,SSG通过减轻荷瘤小鼠的肠道菌群失衡和代谢紊乱,改善TAMs极化并抑制NF-κB通路,导致肺转移延迟。