Effects of green tea on miRNA and microbiome of oral epithelium

Abstract

Consumption of green tea (GT) extracts or purified catechins has shown the ability to prevent oral and other cancers and inhibit cancer progression in rodent models, but the evidence for this in humans is mixed. Working with humans, we sought to understand the source of variable responses to GT by examining its effects on oral epithelium. Lingual epithelial RNA and lingual and gingival microbiota were measured before and after 4 weeks of exposure in tobacco smokers, whom are at high risk of oral cancer. GT consumption had on average inconsistent effects on miRNA expression in the oral epithelium. Only analysis that examined paired miRNAs, showing changed and coordinated expression with GT exposure, provided evidence for a GT effect on miRNAs, identifying miRNAs co-expressed with two hubs, miR-181a-5p and 301a-3p. An examination of the microbiome on cancer prone lingual mucosa, in contrast, showed clear shifts in the relative abundance of Streptococcus and Staphylococcus, and other genera after GT exposure. These data support the idea that tea consumption can consistently change oral bacteria in humans, which may affect carcinogenesis, but argue that GT effects on oral epithelial miRNA expression in humans vary between individuals.

Association of oral dysbiosis with oral cancer development (Review)

“…All these food-derived miRNAs can presumably interact with oral and gut microbiota (167,168). On this basis, exogenous miRNAs may act as bacterial small RNA to interfere with bacterial gene expression modulating the entire microbiome (169,170).…”

Health Functions and Related Molecular Mechanisms of Tea Components: An Update Review

“…Several clinical trials also demonstrated the anticancer effect of tea and its components [110][111][112]. It was reported that green tea consumption (5 × 1 cup/day, four weeks) changed oral bacteria, which might be related to oral carcinogenesis [110].…”

“…Several clinical trials also demonstrated the anticancer effect of tea and its components [110][111][112]. It was reported that green tea consumption (5 × 1 cup/day, four weeks) changed oral bacteria, which might be related to oral carcinogenesis [110]. In another clinical trial involving 70 Algerian prostate cancer patients and 120 age-matched healthy subjects, daily consumption of 5 cups of infusion prepared from 2 g green tea for 6 months significantly decreased oxidative stress and prevented prostate cancer initiation [111].…”

Gut/Oral Bacteria Variability May Explain the High Efficacy of Green Tea in Rodent Tumor Inhibition and Its Absence in Humans

“…After 4 weeks of GT drinking, human tissue exposed to probably the highest concentration of undiluted tea in the body, the tongue epithelium, showed on average no changes in gene expression due to inter-subject variability in levels of miRNA. Only after differential co-expression analysis, which can correct for a lack of a response in some subjects, did GT-induced changes in miRNA expression become evident [ 48 , 49 , 50 , 51 ]. Non-supervised hierarchical clustering of oral epithelial sample miRNA revealed a group of 5 out of 14 subjects who, after consuming GT, differed most from control subjects who did not consume GT [ 48 ].…”