Fusobacterium Nucleatum Stimulates the Progression of Oral Squamous Cell Carcinoma through CCL20

Abstract

Background: This study aimed to verify the effect of Fusobacterium nucleatum (F. nucleatum) in oral squamous cell carcinoma (OSCC) and explore the possible molecular mechanism. Methods: The abundance of F. nucleatum was analyzed by 16S rRNA sequencing and fluorescence in situ hybridization (FISH). Human normal oral keratinocytes (HOK), human OSCC cell lines CAL-27 and SCC-9 cells were cultured and infected with F. nucleatum, respectively. The proliferation, migration and invasion of cells were detected by Cell Counting Kit-8 (CCK-8), wound healing, transwell migration and invasion assay. A mouse OSCC model induced by 4-nitroquinolin-1 oxide (4NQO) was constructed. F. nucleatum was applied to the oral cavity of mice. Tumor number, volume and body weight were recorded. The promotion of F. nucleatum on 4NQO-induced OSCC in mice was evaluated by hematoxylin-eosin (HE) staining and immunohistochemistry (IHC). The chemokines with the highest differential expression in CAL-27 cells after infection of F. nucleatum were screened out by transcriptomics. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot and small interfering RNA (siRNA) interference assay were used to verify the mechanism of the selected chemokines in the tumor-promoting process of F. nucleatum. Results: Compared with paracancerous tissues, the abundance of F. nucleatum was higher in OSCC. F. nucleatum could regulate the proliferation, migration, and invasion of CAL-27 cells and promote the progression of OSCC in mice. Transcriptomic analysis showed that chemokine ligand 20 (CCL20) was the most differentially expressed chemokine in CAL-27 cells infected by F. nucleatum, consistent with the qRT-PCR and western blot results. siRNA interference experiment showed that the migration and invasion ability of CAL-27 cells was significantly weakened after the reduction of CCL20 expression. Conclusions: This study confirmed that F. nucleatum was enriched in OSCC and can promote the progression of OSCC through CCL20.