Fn-Dps, a novel virulence factor of Fusobacterium nucleatum, disrupts erythrocytes and promotes metastasis in colorectal cancer

Author summaryOur previous studies have found that the CRC-associated bacterium Fn is a facultative intracellular bacterium. To date, the underlying mechanism by which Fn infection induces carcinogenesis remains largely unknown. Here, our findings revealed that Fn-Dps is a novel multifunctional Fn virulence factor that lyses and disrupts erythrocytes, enhances intracellular survival of Fn in macrophages, and promotes CRC metastasis. We also found that mucosal immunization with Fn-Dps conferred protection against Fn. A high level of serum anti-Fn-Dps antibody was prevalent in populations, and elevated anti-Fn-Dps antibody levels were observed in CRC patients. These findings reveal a novel Fn virulence factor that promotes tumor progression, providing a potential novel drug target for CRC treatment. Fusobacterium nucleatum (Fn) is a critical colorectal cancer (CRC)-associated bacterium. DNA hunger/stationary phase protective proteins (Dps) are bacterial ferritins that protect DNA from oxidative stress. However, little is known about the regulatory roles of Fn-Dps towards host cellular functions. Here, we identified Fn-Dps from the culture supernatant of Fn by mass spectrometry, and prepared the recombinant of Fn-Dps protein. We show a novel virulence protein of Fn, Fn-Dps, which lyses and disrupts erythrocytes by the competition for iron acquisition. Also, Fn-Dps facilitates intracellular survival of Fn in macrophages by upregulating the expression of the chemokine CCL2/CCL7. In addition, Fn-Dps can elicit a strong humoral immune response, and mucosal immunization with Fn-Dps conferred protection against Fn in the intestinal tract. Moreover, a high level of anti-Fn-Dps antibody was prevalent in populations, and elevated anti-Fn-Dps antibody levels were observed in CRC patients. Furthermore, Fn-Dps promotes the migration of CRC cells via the CCL2/CCL7-induced epithelial-mesenchymal transition (EMT) and promotes CRC metastasis in vivo.