Intratumoral Gram-negative Bacteria Promote NPC Progression via an LPS-PLAUR-HIF1A Axis
Nasopharyngeal carcinoma (NPC) is a common malignant tumor in China and Southeast Asia, with a complex etiology. While viral factors are known to contribute to NPC pathogenesis, the presence and role of intratumoral bacteria has not been fully elucidated. Here, we aimed to identify and characterize viable intratumoral bacteria in NPC and elucidate their role in tumor progression. The presence of viable intratumoral bacteria in NPC tissues is evaluated using several approaches, including bacterial culture, 16S rRNA fluorescent in situ hybridization, single-cell RNA sequencing, electron microscopy, and quantitative PCR. Multi-cohort 16S rRNA sequencing revealed that NPC tissues harbored a distinct intratumoral microbiota dominated by gram-negative bacteria, in contrast to nasopharyngeal lymphatic hyperplasia or matched surface swabs. Notably, high intratumoral gram-negative bacterial burden and elevated bacterial lipopolysaccharide (LPS) levels correlate with poor clinical outcomes. Functionally, LPS stimulation promotes NPC cell proliferation and enhances invasive and metastatic capabilities in vitro and in vivo. Mechanistically, vesicle-released LPS from gram-negative intratumoral bacteria activates the PLAUR-PI3K/AKT-HIF-1A signaling pathway, driving glycolytic reprogramming and epithelial-mesenchymal transition. These findings uncover a previously underappreciated microbial mechanism in NPC progression and suggest gram-negative intratumoral bacteria and LPS as potential prognostic biomarkers and novel therapeutic targets for NPC.