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Perio bacteria found to spur cancer growth in mouth, say researchers

April 21, 2014

Cleveland—Two bacteria prevalent in periodontal disease form small fatty acids that incite growth of deadly Kaposi's sarcoma-related lesions and tumors in the mouth, said Case Western Reserve University researchers who discovered the potential connection.

Their discovery could be key to the development of testing and preventive treatments. Saliva testing for the bacteria may lead to early treatment and monitoring for signs of KS before malignancy develops. KS of the mouth starts as lesions on the mucosal surfaces. Early detection and treatment of these lesions increase survival rates. If not removed, the lesions can evolve into malignant tumors.

An article describing the discovery, "Short Chain Fatty Acids from Periodontal Pathogens Suppress HDACs, EZH2, and SUV39H1 to Promote Kaposi's Sarcoma-Associated Herpesvirus Replication," ran online Feb. 5 in The Journal of Virology.

People with compromised immune systems—particularly those with human immunodeficiency virus—are at significant risk for developing KS. Others at risk include people on medications to suppress rejection of transplants, cancer patients on chemotherapies and the elderly population, whose immune systems naturally weaken with age, according to researchers.

Porphyromonas gingivalis and Fusobacterium nucleatum, the bacteria associated with periodontal disease, were suspected to contribute to the replication of Kaposi's sarcoma-associated herpesvirus and the development of KS in the mouth.

The researchers recruited 21 subjects for this study. The first group of 11 participants had an average age of 50 and had severe chronic periodontal disease. The second group of 10 participants, whose average age was about 26, had healthy gums, practiced good oral health and showed no signs of bleeding or tooth loss from periodontal disease.

The researchers studied a saliva sample from each. Part of the saliva sample was separated into its components. The remaining saliva was used for DNA testing to track and identify bacteria present, and at what levels. The researchers tested by-products of the components of the saliva samples. They introduced the fatty acid by-products to cells with quiescent KSHV virus in a petri dish. They observed that, while the fatty acids allowed the virus to multiple, the process also set in motion a cascade of actions that also inhibited molecules in the body's immune system from stopping the growth of KSHV.

"The most important thing to come out of this study is that we believe periodontal disease is a risk factor for Kaposi sarcoma tumor in HIV patients," said Fengchun Ye, Ph.D., the study's lead investigator from Case Western Reserve School of Dental Medicine's Department of Biological Sciences. However, the study did not show that people with periodontal disease are actually at higher risk for developing KS lesions in the mouth.

Grants from Center for AIDS Research at Case Western Reserve University and National Institute of Dental and Craniofacial Research supported the research.