A Basal Stem Cell Signature Identifies Aggressive Prostate Cancer Phenotypes

Aggressive cancers and normal stem cells often share similar molecular and functional traits. It is unclear if aggressive phenotypes of prostate cancer molecularly resemble normal stem cells residing within the human prostate. We performed high-throughput RNA sequencing on uncultured, highly purified epithelial populations from human prostates obtained after radical prostatectomy. We found the basal population to be defined by genes associated with developmental programs, epigenetic remodeling, and invasiveness. We further generated a 91-gene basal signature and applied it to gene expression datasets from patients with organ-confined or castration-resistant, metastatic prostate cancer. Metastatic prostate cancer was more enriched for the basal stem cell signature than organ-confined prostate cancer. Moreover, histological subtypes within prostate cancer metastases varied in their enrichment of the stem cell signature with small cell neuroendocrine carcinoma being the most stem cell-like. Bioinformatic analysis of the basal cell and two human small cell gene signatures identified a set of E2F target genes common to all three signatures. These results suggest that the most aggressive variants of prostate cancer share a core transcriptional program with normal prostate basal stem cells.