Fusobacterium nucleatum promotes epithelial‐mesenchymal transiton through regulation of the lncRNA MIR4435‐2HG/miR‐296‐5p/Akt2/SNAI1 signaling pathway

• Published in: The FEBS journal 2020-09, Vol.287 (18), p.4032-4047
• Main Authors: Zhang, Shuwei, Li, Chen, Liu, Junchao, Geng, Fengxue, Shi, Xiaoting, Li, Qian, Lu, Ze, Pan, Yaping
• Format: Article
• Language: English
• Subjects: AKT2 protein; Cadherins - genetics; Cadherins - metabolism; Carcinoma, Squamous Cell - genetics; Carcinoma, Squamous Cell - metabolism; Carcinoma, Squamous Cell - microbiology; Cell adhesion & migration; Cell cycle; Cell Line, Tumor; Cell migration; Cell proliferation; Cytoplasm; Epithelial cells; Epithelial-Mesenchymal Transition - genetics; epithelial–mesenchymal transition; E‐cadherin; Fusobacterium Infections - genetics; Fusobacterium Infections - metabolism; Fusobacterium Infections - microbiology; Fusobacterium nucleatum; Fusobacterium nucleatum - physiology; Gene Expression Regulation, Neoplastic; Host-Pathogen Interactions; Humans; Infections; Mesenchyme; MicroRNAs - genetics; MIR4435‐2HG; Mouth Neoplasms - genetics; Mouth Neoplasms - metabolism; Mouth Neoplasms - microbiology; Opportunist infection; Oral carcinoma; Oral squamous cell carcinoma; Original; Periodontitis; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - metabolism; Regular Paper; Signal transduction; Signal Transduction - genetics; Signaling; siRNA; Snail Family Transcription Factors - genetics; Snail Family Transcription Factors - metabolism; Snail protein; SNAIL1; Vimentin
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.15233

Fusobacterium nucleatum, an anaerobic oral opportunistic pathogen associated with periodontitis, has been considered to be associated with the development of oral squamous cell carcinoma (OSCC). However, the initial host molecular alterations induced by F. nucleatum infection which may promote predisposition to malignant transformation through epithelial–mesenchymal transition (EMT) have not yet been clarified. In the present study, we monitored the ability of F. nucleatum to induce EMT‐associated features, and our results showed that F. nucleatum infection promoted cell migration in either noncancerous human immortalized oral epithelial cells (HIOECs) or the two OSCC cell lines SCC‐9 and HSC‐4, but did not accelerate cell proliferation or cell cycle progression. Mesenchymal markers, including N‐cadherin, Vimentin, and SNAI1, were upregulated, while E‐cadherin was decreased and was observed to translocate to the cytoplasm. Furthermore, FadA adhesin and heat‐inactivated F. nucleatum were found to cause a similar effect as the viable bacterial cells. The upregulated lncRNA MIR4435‐2HG identified by the high‐throughput sequencing was demonstrated to negatively regulate the expression of miR‐296‐5p, which was downregulated in F. nucleatum‐infected HIOECs and SCC‐9 cells. The binding of MIR4435‐2HG and miR‐296‐5p was validated via a dual‐luciferase reporter assay. Additionally, knockdown of MIR4435‐2HG with siRNA leads to a decrease in SNAI1 expression, while miR‐296‐5p could further negatively and indirectly regulate SNAI1 expression via Akt2. Therefore, our study demonstrated that F. nucleatum infection could trigger EMT via lncRNA MIR4435‐2HG/miR‐296‐5p/Akt2/SNAI1 signaling pathway, and EMT process may be a probable link between F. nucleatum infection and initiation of oral epithelial carcinomas. Fusobacterium nucleatum is an anaerobic oral opportunistic pathogen; its precise role in inducing epithelial–mesenchymal transition (EMT) has not been clarified. Here, we reported that F. nucleatum upregulated the expression of MIR4435‐2HG, which could specifically bind with miR‐296‐5p, weakening its ability to silence Akt2. In turn, this could then activate SNAI1 expression and eventually contribute to EMT in the infected oral epithelial cells.