我们先前的发现证实了结直肠癌(CRC)患者粪便样品中脆弱拟杆菌(BF)的高度富集。肠黏膜屏障是机体抵御共生菌群和肠道致病菌的第一道防线,与CRC的发生、发展密切相关。因此,本研究旨在探讨BF介导肠屏障损伤和CRC进展的分子机制。SW480细胞和Caco2肠屏障模型用肠毒素BF(ETBF)处理,其肠毒素(B.脆弱毒素,BFT),和非产毒BF(NTBF)。细胞计数试剂盒-8,流式细胞术,进行伤口愈合和transwell测定以分析增殖,凋亡,迁移,和SW480细胞的侵袭。透射电子显微镜,FITC-葡聚糖,和跨上皮电阻(TEER)用于分析Caco2肠屏障模型中的损伤。建立偶氮甲烷/葡聚糖硫酸钠(AOM/DSS)动物模型,以评估ETBF对肠屏障损伤和CRC进展的影响。ETBF和BFT增强了生存能力,伤口愈合率,入侵,和SW480细胞的EMT。此外,ETBF和BFT破坏了肠屏障模型中的紧密连接和绒毛结构,导致渗透率增加和TEER降低。同样,肠屏障相关蛋白(MUC2,Occludin和Zo-1)的表达受ETBF和BFT限制。有趣的是,STAT3/ZEB2轴被ETBF和BFT激活,用BrevilinA(STAT3抑制剂)或ZEB2敲低治疗限制了ETBF和BFT对SW480恶性表型的促进作用。体内实验也证实ETBF定植加速肿瘤负荷,致癌作用,AOM/DSS动物模型结肠直肠黏膜屏障损伤,用布雷维林A治疗缓解了这些过程。ETBF分泌的BFT通过激活STAT3/ZEB2轴加速肠屏障损伤和CRC。我们的发现为ETBF在CRC治疗中的应用提供了新的见解和观点。
Our previous findings confirmed the high enrichment of Bacteroides fragilis (BF) in fecal samples from patients with colorectal cancer (CRC). The intestinal mucosal barrier is the first defense of the organism against commensal flora and intestinal pathogens and is closely associated with the occurrence and development of CRC. Therefore, this study aimed to investigate the molecular mechanisms through which BF mediates intestinal barrier injury and CRC progression. SW480 cells and a Caco2 intestinal barrier model were treated with entero-toxigenic BF (ETBF), its enterotoxin (B. fragilis toxin, BFT), and non-toxigenic BF (NTBF). Cell counting kit-8, flow cytometry, wound healing and transwell assays were performed to analyze the proliferation, apoptosis, migration, and invasion of SW480 cells. Transmission electron microscopy, FITC-dextran, and transepithelial electrical resistance (TEER) were used to analyze damage in the Caco2 intestinal barrier model. The Azoxymethane/Dextran Sulfate Sodium (AOM/DSS) animal model was established to evaluate the effect of ETBF on intestinal barrier injury and CRC progression in vivo. ETBF and BFT enhanced the viability, wound healing ratio, invasion, and EMT of SW480 cells. In addition, ETBF and BFT disrupted the tight junctions and villus structure in the intestinal barrier model, resulting in increased permeability and reduced TEER. Similarly, the expression of intestinal barrier-related proteins (MUC2, Occludin and Zo-1) was restricted by ETBF and BFT. Interestingly, the STAT3/ZEB2 axis was activated by ETBF and BFT, and treatment with Brevilin A (a STAT3 inhibitor) or knockdown of ZEB2 limited the promotional effect of ETBF and BFT on the SW480 malignant phenotype. In vivo experiments also confirmed that ETBF colonization accelerated tumor load, carcinogenesis, and intestinal mucosal barrier damage in the colorectum of the AOM/DSS animal model, and that treatment with Brevilin A alleviated these processes. ETBF-secreted BFT accelerated intestinal barrier damage and CRC by activating the STAT3/ZEB2 axis. Our findings provide new insights and perspectives for the application of ETBF in CRC treatment.