Unique Gut microbiome signature with expression of microbial oncogenes among Indian breast cancer patients

Breast cancer has evolved as one of the leading cancer-related mortality particularly in low and middle-income countries including India. Studies revealed the changes in gut microbiota during breast cancer in different populations and in parallel, the Indian gut microbiome has unique features attributed to the different life style and dietary habits. This study is aimed at unravelling the taxonomic and functional gut microbiota changes in breast cancer patients of India. Faecal samples were collected from breast cancer patients (n = 22), benign (n = 08) and healthy controls (n = 30). The total metagenomic DNA was isolated and 16S rDNA sequencing was performed. The taxonomic data were correlated with clinical features of the breast cancer. The expression of microbial oncogenes was studied by qPCR. The microbiota reflects the unique feature of Indian gut microbiome including dominance of Segatella (formerly Prevotella ), Faecalibacterium and lactic acid bacteria. Among breast cancer patients, the increase in genera ( Bacteroides and Escherichia/Shigella ) associated with inflammation and toxin production and decrease in beneficial bacteria associated with short chain fatty acid production was observed. The qPCR analysis revealed the increased expression of microbial oncogenes associated with colibactin and cadaverine in breast cancer patients. Altogether this study showcases the uniqueness of gut microbiome in Indian breast cancer patients with expression of microbial oncogenes. Further studies on mechanistic details and association with longitudinal outcomes will lead to novel microbiota-based, geographic-specific strategies for early diagnosis and treatment of breast cancer.