Exposure to a mixture of cigarette smoke carcinogens disturbs gut microbiota and influences metabolic homeostasis in A/J mice

An increased risk of developing lung cancer has been associated with exposure to cigarette smoke carcinogens and alteration in the gut microbiota. However, there is limited understanding about the impact of exposure to NNK and BaP, the two important components of cigarette smoke carcinogens, on gut microbiota in lung cancer. The present study characterized the influence of exposure to a mixture of NNK plus BaP on lung cancer, feces metabolite composition, and gut microbiota in the A/J mice. The A/J mice were administered NNK plus BaP, and the changes in gut microbiota and feces metabolic profiles were characterized using 16S rRNA gene sequencing and metabolomics, respectively. Results presented here illustrated that a mixture of NNK plus BaP exposure triggered lung carcinogenesis as shown by light microscopy and histopathological evaluation. 16S rRNA sequencing of gut microbiota indicated that exposure to NNK plus BaP could modified fecal bacterial composition. Elevated levels of Actinobacteria, Bifidobacterium, and Intestinimonas and reduced levels of Alistipes, Odoribacter, and Acetatifactor are associated with NNK plus BaP triggered lung cancer. In addition, metabolomics profile revealed the regulation of metabolism including purine metabolism, phenylalanine metabolism, primary bile acid biosynthesis, steroid hormone biosynthesis, biosynthesis of unsaturated fatty acids, linoleic acid metabolism, and others. In conclusion, the results provide some guidance for using gut microbes as biomarkers to assess the progression of lung cancer, and lead to interventional targets to control the development of the disease in the future.