Characterization Of Lung Microbiota In Non-small Cell Lung Cancer And The Molecular Mechanism Of Growth Promotion Of Lung Adenocarcinoma By Veillonella Parvula

BackgroundAlthough the overall incidence of lung cancer has slowed down,the incidence and mortality rate of lung adenocarcinoma,the main type of non-small cell lung cancer,are increasing year by year,posing a serious threat to human life and health.Smoking is an important causative factor in the development of lung cancer,but only a minority of the population smokes in lung adenocarcinoma,suggesting that there are influential factors other than smoking.The mechanism of lung adenocarcinoma and the identification of effective diagnostic markers are still difficult clinical and scientific problems.The "diversity of microorganisms" is a new cancer marker,and the flora is closely related to cancer progression.The research on lung flora and lung cancer is still in its initial stage,so it is important to understand the characteristics of lung flora,find the key differential genera,and reveal the role and mechanism of specific genera in lung cancer,in order to discover the predictive markers for diagnosis and targets for therapeutic intervention.In this study,we intend to analyze the characteristics and functions of the flora in non-small cell lung cancer,explore and identify the role of important differential genera in lung adenocarcinoma,and conduct a preliminary exploration of their molecular mechanisms.Methods.We collected alveolar lavage fluid samples from 48 patients with primary non-small cell lung cancer and 23 patients with benign lung disease,characterized the lung flora of non-small cell lung cancer by 16s rRNA sequencing combined with bioinformatics,including flora diversity and species composition,constructed a diagnostic prediction model and assessed the function of predicted flora,and identified key differential genera of non-small cell lung cancer using LefSe and significant difference tests We also constructed a mouse tumor model and a bacterial cell co-culture model to determine the role of different genera on the progression of non-small cell lung cancer in vitro and in vivo.Further,through transcriptome sequencing and TCGA public database,we will search and validate the role and molecular mechanism of differential genera on non-small cell lung cancer.ResultsFirmicutes and Veillonella were the predominant differential phylum(genus),where Veillonella combined with Rhodococcus and Lineage_Ⅳ had a good predictive diagnostic value with an AUC value of 0.85 for predicting non-small cell lung cancer.Veillonella abundance correlated with lung cancer pathology type and was significantly higher in lung adenocarcinoma The abundance of Veillonella was significantly higher in lung adenocarcinoma.In in vivo experiments,Veillonella parvula promoted the growth of lung adenocarcinoma in mice and induced lung flora disorders,reduced tumor-infiltrating T lymphocytes and suppressed T lymphocyte expression in peripheral immunity.In vitro experiments showed that Veillonella parvula had the ability to adhere to and invade lung adenocarcinoma cells,and promoted the proliferation and clonogenesis of lung adenocarcinoma cells.The molecular mechanism may be related to the activation of NF-κB signaling pathway by Veillonella parvula via Nod2/CCN4 signaling.ConclusionsVeillonella is a key differential genus for non-small cell lung adenocarcinoma and promotes lung adenocarcinoma growth both in vivo and ex vivo.Abnormal enrichment of Veillonella parvula in vivo could disrupt lung flora balance,reduce tumor infiltration and peripheral T lymphocyte colonization;Veillonella has a strong affinity for lung adenocarcinoma cells and activates the Nod2/CCN4/NF-κB signaling pathway to promote the growth of lung adenocarcinoma cells.These findings provide a basis for the diagnosis and treatment of non-small cell lung adenocarcinoma.