Comparative analysis of racial differences in breast tumor microbiome

Srikantha Thyagarajan,Nicole Phillips,Yan Zhang,Santosh Thapa,Jamboor K Vishwanatha,Meghana V Kashyap,Pankaj Chaudhary,Michael S Allen

doi:10.1038/s41598-020-71102-x

Abstract

Studies have demonstrated that environmental, host genetic, and socioeconomic factors influence the breast cancer prevalence landscape with a far-reaching influence on racial disparity to subtypes of breast cancer. To understand whether breast tissue harbors race-specific microbiota, we performed 16S rRNA gene-based sequencing of retrospective tumor and matched normal tissue adjacent to tumor (NAT) samples collected from Black non-Hispanic (BNH) and White non-Hispanic (WNH) women. Analysis of Triple Negative Breast cancer (TNBC) and Triple Positive Breast Cancer (TPBC) tissues for microbiota composition revealed significant differences in relative abundance of specific taxa at both phylum and genus levels between WNH and BNH women cohorts. Our main findings are that microbial diversity as measured by Shannon index was significantly lower in BNH TNBC tumor tissue as compared to matched NAT zone. In contrast, the WNH cohort had an inverse pattern for the Shannon index, when TNBC tumor tissue was compared to the matched NAT. Unweighted Principle Coordinates Analysis (PCoA) revealed a distinct clustering of tumor and NAT microbiota in both BNH and WNH cohorts.

Highlights

Studies have demonstrated that environmental, host genetic, and socioeconomic factors influence the breast cancer prevalence landscape with a far-reaching influence on racial disparity to subtypes of breast cancer
White non-Hispanic (WNH) tumor showed the opposite scenario, with a higher evenness/Shannon index in tumor tissue compared to normal tissue
The reason for reverse pattern in diversity could be due to the compositional differences of beneficial vs pathogenic species as demonstrated in a previous study between native African and migrated African American populations on microbiota profiles with beneficial vs CRC carcinogenic inducing m etabolites[31]

Summary

Introduction

Studies have demonstrated that environmental, host genetic, and socioeconomic factors influence the breast cancer prevalence landscape with a far-reaching influence on racial disparity to subtypes of breast cancer. The intent of this study was two-fold: first, to address whether racial differences in microbiota are associated with archived retrospective breast tissue of tumor and adjacent normal tissue among BNH and WNH women population cohorts representing New England, USA; second, to determine if racial ancestry is strongly associated with microbiome profiles irrespective of cancer subtypes. This information will lay the crucial foundation to understand the extent of influence of geography, race, and ancestry/genetic background on microbiota profiles and increased incidence of aggressive TNBC subtypes within African American (BNH) populations

Objectives

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Conclusion