Bacteroidetes promotes esophageal squamous carcinoma invasion and metastasis through LPS-mediated TLR4/Myd88/NF-κB pathway and inflammatory changes.

Gut microbiota plays a crucial role in gastrointestinal tumors. Additionally, gut microbes influence the progression of esophageal cancer. However, the major bacterial genera that affect the invasion and metastasis of esophageal cancer remain unknown, and the underlying mechanisms remain unclear. Here, we investigated the gut flora and metabolites of patients with esophageal squamous cell carcinoma and found abundant Bacteroides and increased secretion and entry of the surface antigen lipopolysaccharide (LPS) into the blood, causing inflammatory changes in the body. We confirmed these results in a mouse model of 4NQO-induced esophageal carcinoma in situ and further identified epithelial-mesenchymal transition (EMT) occurrence and TLR4/Myd88/NF-κB pathway activation in mouse esophageal tumors. Additionally, in vitro experiments revealed that LPS from Bacteroides fragile promoted esophageal cancer cell proliferation, migration, and invasion, and induced EMT by activating the TLR4/Myd88/NF-κB pathway. These results reveal that Bacteroides are closely associated with esophageal cancer progression through a higher inflammatory response level and signaling pathway activation that are both common to inflammation and tumors induced by LPS, providing a new biological target for esophageal cancer prevention or treatment.