Lipopolysaccharide exacerbates to the migration, invasion, and epithelial-mesenchymal transition of esophageal cancer cells by TLR4/NF-κB axis.

Previous studies have shown the role of bacterial lipopolysaccharide (LPS) in promoting tumor progression. Our previous study found that the community richness of LPS-producing bacteria was significantly increased in the fresh stool samples of esophageal cancer (EC) patients, but the relative LPS levels and underlying mechanism in EC progression remain unknown. In this study, an case-control study found that the content of LPS was higher in serum of EC patients. Functional experiments of CCK8 assay and transwell assay showed that LPS contributed to the proliferation, migration, invasion of EC109 cells. Meanwhile, LPS induced EC109 to secrete IL-6 and TGF-β1. Western blot analysis revealed the level of TLR4 and NF-κB increased significantly after LPS treatment. Epithelial marker E-cadherin was significantly down-regulated and interstitial marker N-cadherin and Vimentin were up-regulated after LPS treatment. However, TAK242 (TLR4 inhibitor) or PDTC (NF-κB inhibitor) could eliminate the inflammatory and EMT-promoting effects of LPS. In total, our results suggested that LPS exacerbated to the migration, invasion, and epithelial-mesenchymal transition of EC109 cells by TLR4/NF-κB axis. High level LPS may have a critical effect on the occurrence and development of EC.