Fusobacterium nucleatum present in the saliva of oral cancer subjects can activate niche defense of oral squamous cell carcinoma

Abstract

Oral cancer is a subset of head and neck cancer (HNC), has a high incidence rate in this malignancy group. Cancer Stem Cells (CSCs) are population of the heterogeneous malignant cells present within oral tumor microenvironment. CSCs stemness permits them to control several signaling pathways and so play a role in cancer progression and relapse. A number of studies have recently demonstrated the presence of specific oral bacteria populations and their lipopolysaccharides (LPS) in the tumor microenvironment. The precise mechanism of action in the initiation, progression, and relapse of oral cancer by the oral bacteria are yet to be determined. We previously reported pathogenic bacterial internalization in CSCs. Based on the findings; we have developed an in-vitro model to investigate how oral microbiota may integrate into the tumor microenvironments CSC population and control its activity. Notably, we found that live bacteria and their LPS, mostly Fusobacterium nucleatum isolated from clinical subjects, were capable of invading CSCs in the in-vitro experimental design setup. Post the host-pathogen interaction; it enabled the activation of a niche modulatory tumor stemness defense (TSD) phenotype in the CSCs. These aggressive CSCs with the TSD phenotype have been found to have a critical role in the progression and relapse of oral cancer.