Metagenomic Analysis Unveils the Microbial Landscape of Pancreatic Tumors
Introduction
The composition of resident microbes in the human body is linked to various diseases and their treatment outcomes. Studies have identified bacterial communities associated with pancreatic ductal adenocarcinoma (PDAC), mainly in oral and gut samples. However, the prevalence of microbiota in pancreatic tumor tissues compared to their adjacent normal appearing tissues from the same patient can provide meaningful insights to develop newer diagnostic/prognostic molecular signatures.
Methods
In this study we performed a comparative profiling for bacterial inhabitance in pancreatic tumors and their respective adjacent normal tissues using 16S rRNA based metagenomics analysis.
Results
This study reveals the abundance of Cloacibacterium, Delftia, Stenotrophomonas, Pseudomonas, Pelomonas, Methylobacterium, Achromobacter, Micrococcus, Enhydrobacter, and Corynebacterium genera in cancer lesions. Whereas Acholeplasma, Mycoplasma, Novosphingobium, Thermus, and Sphingomonas genera were found in abundance in adjacent normal tissues, Propionibacterium was the most prevalent bacterial species that showed presence both in tumor and normal tissues. The Random Forest model identified Delftia and Micrococcus as the most predominant contributors in tumor tissues. The PCoA plot for Beta diversity indicates the microbiota of cancer specimens is distinct from normal adjacent tissues. Additionally, our data suggests an association of the microbial species with a PDL-1 expression and warrants further investigation to identify interindividual variations.
Conclusion
Collectively, these findings demonstrate that PDAC lesions harbor relatively different microbiota as compared to its normal tumor adjacent tissues. Additionally, our study suggests that the tissue-associated microbiota can serve as novel diagnostic/prognostic markers and could influence the expression of immune check point markers in PDAC patients.