Characteristics of Microbiome in Lung Adenocarcinoma Tissue from Patients in Southwestern China

Abstract

Background:Increasing evidences have unveiled the connection between microbiome and lung cancer. This study aims to identify the characteristics of microbial communities in the lung cancer tissues from patients in southwestern China, and to compare the distinct microbial genes at different clinical stages of lung cancer for uncovering potential immunotherapy targets.Methods:Forty samples of primary lung adenocarcinoma tissue were performed by 16S rRNA gene sequencing. The subjects were grouped according to TNM stages (T and N group), clinical stage and smoke status. To identify the taxa composition of each sample, Operational Taxonomic Units (OTUs) were classified on the Effective Tags with 97% identity. The linear discriminant analysis effect size (LEfSe) method was utilized to compare relative abundances of all bacterial taxa between non-metastasis group and metastasis group. The Shannon index of the 97% identity OTUs was calculated to evaluate alpha diversity. Beta diversity measurement was calculated using Principal Co-ordinates Analysis (PCoA).Results:A total of 951 OTUs were identified in the cancer tissues, including 224 overlapping genera. No significant difference has been found in the alpha diversity within all the groups. Beta diversity was significantly different in N group, T group and clinical stage group. By LEfSe analysis, nine differential species were identified in the N group, of which the relative abundance of genus Bifidobacterium was 10.78%±11.59% in the N0 group and 20.15%±13.44% in the N+ group (p<0.05). In the T1 and T2 group, the LEfSe result identified 4 phylum and 10 genera. The differential genera were Moraxella, Dolosigranulum, Corynebacteriaceae and Citrobacter in the T2 group and Bifidobacterium, Alistipes, Akkermansia, Blautia, Lactobacillus as well as Facelibacterium in the T1 group. Differential bacterial composition and abundance were also observed in the clinical stage group.Conclusions:In conclusion, by 16S RNA sequencing, we identified dominant species of lung cancer tissue in different groups of AD patients. Bifidobacterium plays important role both in lymph node metastasis and tumor progression, which could provide specific immunotherapy strategy for lung cancer.