Co-differences And Functional Analysis Of Breast Cancer Tissue And Intestinal Microbial Community Structure

Objective: The purpose of this study is to make use of published public data to bring together a number of studies to comprehensively and systematically analyze the changes in breast tissue and intestinal microbial structure of breast cancer patients,identify the differential microorganisms between breast cancer and non-cancer patients,and evaluate the accuracy of characteristic microorganisms for cancer diagnosis.In vitro cell experiments were conducted to study the effects of specific-metabolites of breast cancer-related biomarkers on breast cancer cells,revealing their role in the occurrence and development of breast cancer,and providing research basis for further research on the pathogenesis of breast cancer.Methods: Based on Pub Med database,16 s rRNA sequencing data available for analysis were collected after literature screening for re-analysis.The raw sequencing data was downloaded from the Bio Project number published by the National Center for Biotechnology’s Information Sequence Read Archive Database.QIIME 2.0 and R software(version 3.6.1)were used for consistency processing of downloaded FASTQ data to avoid bioinformatics analysis bias.Reads after quality control were annotated with RDP v16 database using Vsearch software.Microbial composition data were centralized logarithm ratio transformed to determine the difference between the groups and the biomarkers associated with breast cancer.R software "random Forest" package is used to construct a random forest model for cancer diagnosis.In addition,the effects of Clostridium specific-metabolite deoxycholic acid on proliferation,cycle and apoptosis of breast cancer cells were investigated in vitro cell experiments.Results:1.A total of 8 studies,768 breast tissue samples and 1311 stool samples were included in the study,including 660 healthy controls,165 benign tumors and 1254 breast cancer patients.2.Meta-analysis revealed significant differences in microbial structure among different disease types and sampling sites.At the phylum level, Proteobacteria were enriched in breast tissue and significantly increased in breast cancer tissue.The relative abundance of Halomonas and Shewanella in breast cancer tissues was significantly higher than that in non-cancerous tissues,while the abundance of Pelomonas was lower.In the intestinal environment,the abundance of Prevotella decreased gradually in healthy people,benign tumor patients,and breast cancer patients.3.In the analysis of differential bacteria between breast cancer samples and non-cancer samples,11 genera were enriched and 9 genera were depleted in breast cancer tissues compared with normal breast tissues,while 12 genera were enriched and 3 genera were depleted in fecal samples from breast cancer patients compared with fecal samples from health.4.The area under the curve(area under the cure,AUC)of the random forest model based on breast cancer tissue and intestinal microbes was 74.27% and 68.08%,respectively.The average AUC of the random forest model based on breast tissue microbes was 0.65 for cohort-to-cohort transfer verification and 0.66 for leave-one-cohort-out verification,which proved the effectiveness of the model.5.Clostridium＿Xl Va is the only overlapping biomarker in breast tissue and intestinal environment,and its specific-metabolite deoxycholic acid can promote the proliferation of HER2-positive breast cancer cells and stimulate G0/G1 phase cells to enter S phase,without affecting cell apoptosis.6.The results of proteomic analysis showed that the expression levels of cell cycle related proteins MAD1L1 and CDK7 increased significantly.Conclusion: The results of this study showed that the breast tissue and intestinal microbial community structure of breast cancer patients had significant changes.Random forest model based on microbial community of breast tissue and intestinal environment is helpful for early diagnosis of breast cancer.In vitro cell experiments also confirmed that deoxycholic acid,a specific metabolite of breast cancer-related biomarkers,can promote the proliferation of HER2-positive breast cancer cells.In addition,this study believes that the use of intestinal fecal microorganisms to assist cancer diagnosis as a non-invasive and convenient method is more easily accepted in clinic.