Intratumoral microbiota is associated with prognosis in patients with adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare but aggressive malignancy. Recent studies have discovered a pivotal role of the intratumoral microbiota in various cancers, yet it remains elusive in ACC. Here, we explored the intratumoral microbiome data derived from in silico identification, further validated in an in-house cohort by bacterial 16S rRNA fluorescence in situ hybridization and lipopolysaccharide staining. Unsupervised clustering determined two naturally distinct clusters of the intratumoral microbiome in ACC, which was associated with overall survival. The incorporation of microbial signatures enhanced the prognostic performance of the clinical stage in an immunity-dependent manner. Genetic and transcriptomic association analyses identified significant upregulation of the cell cycle and p53 signaling pathways associated with microbial signatures for worsened prognosis. Our study not only supports the presence of intratumoral bacteria but also implies a prognostic and biological role of intratumoral microbiota in ACC, which can advance a better understanding of the biology of ACC. The Cancer Genome Atlas primary tumors were subject to whole-genome sequencing and RNA-Seq, in which microbial abundance (comprising virus, archaea, and bacteria) was identified and normalized by Poore et al. (left panel). To confirm the presence of intratumor bacteria, 37 adrenocortical carcinoma tissue microarray chips from the in-house cohort were stained for fluorescence in situ hybridization and immunohistochemistry examination. Unsupervised clustering was performed on microbiome data to explore natural clusters of patients with distinct microbiomes, thereby influencing prognoses. The microbial signatures associated with prognosis were further determined (middle panel). Defined microbial signatures were tested to improve prognosis prediction. The intratumoral microbiome was found to be associated with immune status, genetic events, and molecular pathways (right panel).Highlightsimage Adrenocortical carcinoma (ACC) harbors intratumoral microbes.The intratumoral microbiome is associated with prognosis in ACC.The intratumoral microbiota might correlate with genomic events, immune status and specific carcinogenic pathways.