Screening of Health-Associated Oral Bacteria for Anticancer Properties

While extensive literature exists about the role of oral bacterial pathogens like and in oral squamous cell carcinoma (OSCC), the role of health-associated species has been largely unexplored. In this study, we assessed the effect of , and on proliferation and expression of marker genes (IL-6, TNF-α, MMP3, CD36, CCD1, and NANOG) in OSCC cell lines CAL27, SCC25, and SCC4. was included as a pathogenic control. Both bacterial lysates (3 concentrations) and live cells (3 MOIs) were tested. , and resulted in substantial, dose-dependent reduction of proliferation, which was found to be mediated by HO for the former and intracellular infection in the latter two species. However, only showed differential antiproliferative effect against the cancer cell lines vs. the normal control (TIGKs). In the gene expression assays, the health-associated species mostly downregulated CD36, a gene that plays an important role in tumor growth and metastasis, while upregulated it. IL6 and TNF expression, on the other hand, was upregulated by almost all species, particularly the Gram-negatives including . The effect on other genes was less evident and varied significantly by cell line. This exploratory study is the first insight into how health-associated bacteria may interact with OSCC. Further studies to explore whether the observed effects may have implications for the prevention or treatment of oral cancer are warranted.