Metagenomic Approach Studying The Associations Between Gut Microbiota And Non-small-cell Lung Cancer

Objectives: The Gut microbiota plays an crucial role in the occurrence and progression of lung cancer through regulating metabolism,inflammation and immune response.After radiotherapy,chemotherapy and immunotherapy,the gut microbiota of non-small cell lung cancer(NSCLC)patients will be disordered,but its correlation with clinical indicators is still need to be elucidated.This study aims to explore the changes of gut microbiota in NSCLC patients before and after radiotherapy and analyze its correlation with clinical characteristics,which providing clinic reference for the diagnosis and prevention of NSCLC.Methods: In the present study,we consecutively recruited 10 NSCLC patients(pathologically diagnosed)from Sichuan Cancer Hospital.Fecal samples were collected before and after radiotherapy,detect inflammatory markers,extract genomic DNA,construct libraries and perform paired-end sequencing via illumina Hiseq2000.Metagenome assembly of the sequencing data,gene prediction after database comparison,corresponding species annotation,and gene function prediction analysis were performed to analyze the intestinal microecological community and metabiolic functions.SPSS 19.0was used for statistical analysis.Result:1.Research objectA total of 10 NSCLC patients were recruited,including 6 males and 4females.Pathological classification: 5 cases of adenocarcinoma,4 cases of squamous cell cacinoma and 1case of undifferentiated carcinoma.Stage:3cases of stage IIIA,1 case of stage IIIB,3 cases of stage IIIC and 3 cases of stage IVA.Evaluation after radiotherapy: 6 cases of PR and 4cases of PD.2.Correlation between gut microbiota and clinical characteristics in NSCLC patientsResulst showed that no obvious correlation between the gut microbiota and patient age,smoking,pathological type,nutrition status,and inflammatory markers(NLR,PLR,LMR)was founded.was not related to patient age,smoking,pathological type,nutrition status,and inflammatory markers(NLR,PLR,LMR).3.Variation of gut microbiota in NSCLC patients before and after radiotherapy(1)Multi-level LEfSe analysis of bio-markers found that harmful bacteria increased after radiotherapy.Among these,the abundances of Actinobacteria(LDA value: 4.2> 4)and Streptococcus(LDA value: 5.23> 4)were the most increased.(2)At the level of phylum,the abundance of Bacteroidetes was increased after radiotherapy,the proportion of Firmicutes and Bacteroidetes was the highest.While Bifidobacterium was decreased after radiotherapy at the genus level.(3)There was no correlation between the diversity of gut microbiota of each sample and the sensitivity of the tumor to radiotherapy.4.Stability of the gut microbiotaIn this study,the first sampling of the patient’s gut microbiota was compared with the sampling of the patient’s gutmicrobiota under lung radiation therapy,dietary changes,and intervals of more than 20 days.Cluster analysis between samples using the Bray-Curtis distance matrix found that the similarity of microorganisms was the highest among the same samples.Conclusions: This study demonstrated that the diversity of gut microbiota in NSCLC patients was altered after chest radiotherapy.Moreover,results also indicated radiotherapy could significantly increase the species and abundance of harmful bacteria,while reduce beneficial bacteria.No obvious correlation between the diversity of gut microbiota diversity in NSCLC patients and smoking,age,clinical stage,pathological type,nutritional status,and inflammatory markers(NLR,PLR,LMR)was found.The diversity of gut microbiota after radiotherapy had no significant correlation with radiotherapy sensitivity.The strain structure and abundance of intestinal microorganisms have their own stability after the external environment changes.