Figure 1.

Oral microbiota dysbiosis is associated with oral cancer development through different mechanisms. Oral infections and dysbiosis are responsible for the instauration of a pro-inflammatory microenvironment of which inflammatory cytokines and matrix metalloproteinases favor the development and progression of tumors. Furthermore, the bacteria host in the oral cavity produces oxygen and nitrogen reactive species, as well as oncogenic metabolites (e.g., nitrosamines) to induce genetic damage to cells composing the oral mucosa. Another mechanism of neoplastic transformation mediated by oral dysbiosis is the alteration of the epithelial barriers predisposing the individuals for the development of chronic pre-cancerous lesions. Finally, oral dysbiosis is responsible for several epigenetic alterations predisposing the development of tumors (e.g., alteration of onco-miR or DNA methylation phenomena).