Scientists at Johns Hopkins have found that Fusobacterium nucleatum, a bacterium associated with gum disease, can travel to breast tissue via the bloodstream, causing DNA damage and accelerating tumor growth and spread. The effect is particularly pronounced in cells with BRCA1 mutations. The research highlights a potential connection between oral health and breast cancer risk.
Researchers from the Johns Hopkins Kimmel Cancer Center and the Bloomberg~Kimmel Institute for Cancer Immunotherapy have identified a link between Fusobacterium nucleatum and breast cancer. Published in Cell Communication and Signaling, the study shows this oral bacterium can enter breast tissue, trigger inflammation, and induce early cellular changes such as metaplastic and hyperplastic lesions, along with DNA damage and increased cell proliferation. In mouse models of human breast cancer, the bacterium sped up tumor growth and promoted metastasis to the lungs when introduced via the bloodstream or directly into breast ducts. It also activated error-prone DNA repair mechanisms like nonhomologous end joining, elevating levels of the PKcs protein, which enhanced cancer cell invasion, stem-like properties, and chemotherapy resistance. Cells with BRCA1 mutations were more vulnerable due to higher levels of the surface sugar Gal-GalNAc, facilitating greater bacterial uptake and retention across generations. Lead researcher Dipali Sharma stated, 'The key takeaway is that this oral microbe can reside in breast tissue and that there is a connection between this pathogen and breast cancer.' First author Sheetal Parida, Ph.D., added, 'We wanted to dig deeper and see if we could uncover the underlying connections.' Sharma further noted, 'Our findings reveal a link between oral microbes and breast cancer risk and progression, particularly in genetically susceptible individuals.' The study, inspired by prior associations between periodontal disease and breast cancer, suggests F. nucleatum may act as an environmental factor cooperating with genetic risks like BRCA1 mutations. More research is needed on implications for oral health in cancer prevention. The team included Deeptashree Nandi, Deepak Verma, and others, with funding from the Breast Cancer Research Foundation and Department of Defense grants.
