WHOLE MOUTH FLUID MICROBIOME: A NEW FRONTIER IN CANCER RESEARCH

Divya Gopinath^1*Asmaa Wajeeh Issa²Ji'An Liu³Zhengrui Li³

• ¹Ajman University, Ajman, United Arab Emirates
• ²University of Michigan, Ann Arbor, United States
• ³Shanghai Jiao Tong University, Shanghai, China

Recent years have witnessed the emergence of evidence on the association of an altered indigenous microbiome (dysbiosis) with many cancers. A variety of new platforms, including 16S rRNA gene sequencing and metagenomic approaches, have provided a large amount of new information. The temporal stability exhibited by the salivary bacteriome and ease in sample collection when compared to the fecal, make saliva/whole mouth fluid (WMF) a promising tool for diagnostic and therapeutic applications in the field of microbiomics. This review summarizes current evidence on the reported association between an altered salivary bacteriome and several human cancers. While numerous epidemiological studies have highlighted disparities in relative abundances of dominant taxa in the saliva of cancer patients and controls, no specific archetype of dysbiosis has yet been identified in association with any of the cancers studied. Nevertheless, associations between some oral bacteria detected in WMF, particularly those implicated in the development of periodontitis, such as Fusobacterium nucleatum and Porphyromonas gingivalis, have been reported by many investigators and are speculated to play a key role in the aetiopathogenesis of colorectal cancer and pancreatic cancer, respectively. Streptococcus sanguis was shown to modify the TNF-α and NF-κB pathways and to upregulate genes associated with EBV lytic activation in Nasopharyngeal carcinoma thus playing an indirect role. With our existing knowledge of genomic alterations in carcinogenesis, deciphering the role of the bacterial community should enhance our understanding of the complex process of initiation and progression of cancer.