Abstract:
BACKGROUND : Inflammation is a hallmark of prostate cancer (PCa), yet no pathogenic
agent has been identified. Men from Africa are at increased risk for both aggressive
prostate disease and infection. We hypothesize that pathogenic microbes may be
contributing, at least in part, to high‐risk PCa presentation within Africa and in turn
the observed ethnic disparity.
METHODS : Here we reveal through metagenomic analysis of host‐derived wholegenome
sequencing data, the microbial content within prostate tumor tissue from 22
men. What is unique about this study is that patients were separated by ethnicity,
African vs European, and environments, Africa vs Australia.
RESULTS : We identified 23 common bacterial genera between the African, Australian,
and Chinese prostate tumor samples, while nonbacterial microbes were notably
absent. While the most abundant genera across all samples included: Escherichia,
Propionibacterium, and Pseudomonas, the core prostate tumor microbiota was enriched
for Proteobacteria. We observed a significant increase in the richness of the bacterial
communities within the African vs Australian samples (t = 4.6‐5.5; P = .0004‐.001),
largely driven by eight predominant genera. Considering core human gut microbiota,
African prostate tissue samples appear enriched for Escherichia and Acidovorax, with
an abundance of Eubacterium associated with host tumor hypermutation.
CONCLUSIONS : Our study provides suggestive evidence for the presence of a core,
bacteria‐rich, prostate microbiome. While unable to exclude for fecal contamination, the observed increased bacterial content and richness within the African vs non‐
African samples, together with elevated tumor mutational burden, suggests the
possibility that bacterially‐driven oncogenic transformation within the prostate
microenvironment may be contributing to aggressive disease presentation in Africa.
