Intratumoural microbiome-derived lipopolysaccharides contributes to non-small-cell lung cancer progression via activating TLR4-mTOR-NF-κB-IL-6 axis

Background: As emerging component of the tumor microenvironment, intratumoural microbiota imperceptibly influences the progression of various human malignancies. However, the critical intratumoural microbiota and its role in non-small-cell lung cancer (NSCLC) progression has not been fully elucidated. Results: Herein, we reveal significant abnormalities in the intratumoural microbiota of NSCLC by analyzing the microbiota profiles of tumor and non-malignant tissues from NSCLC patients. Specifically, Gram-negative bacteria were significantly increased in intratumoural bacteria, and network analysis revealed that Escherichia-Shigella and unclassified_f__Enterobacteriaceae, which had strong ability to synthesize bacterial toxin lipopolysaccharides (LPS), could significantly promote tumor proliferation. Mechanistically, we found that Escherichia-Shigella and unclassified_f__Enterobacteriaceae-derived LPS activated the TLR4-mTOR-NF-κB-IL-6 axis to facilitate the proliferation of NSCLC, while rapamycin could effectively postpone LPS-induced tumor proliferation through in vitro cell culture and in vivo murine model. In addition, the receiver operating characteristic (ROC) curves showed that the combined diagnosis of intratumoural bacterial concentration, Escherichia-Shigella, and unclassified_f__Enterobacteriaceae had higher diagnostic validity than the individual diagnosis in predicting the probability of NSCLC, and their detection in blood has the potential to be combined with imaging for non-invasive diagnosis of NSCLC. Conclusions: Collectively, this research discovered increased Gram-negative bacteria Escherichia-Shigella, and unclassified_f__Enterobacteriaceae in NSCLC tumors, and clarified the mechanism of these bacteria-derived LPS in promoting tumor development, providing new strategies for the treatment and diagnosis of NSCLC from a microbial perspective.