Molecular and cellular characterization of ABCG2 in the prostate

Abstract

Abstract Background Identification and characterization of the prostate stem cell is important for understanding normal prostate development and carcinogenesis. The flow cytometry-based side population (SP) technique has been developed to isolate putative adult stem cells in several human tissue types including the prostate. This phenotype is mainly mediated by the ATP-binding cassette membrane transporter ABCG2. Methods Immunolocalization of ABCG2 was performed on normal prostate tissue obtained from radical prostatectomies. Normal human prostate SP cells and ABCG2+ cells were isolated and gene expression was determined with DNA array analysis and RT-PCR. Endothelial cells were removed by pre-sorting with CD31. Results ABCG2 positive cells were localized to the prostate basal epithelium and endothelium. ABCG2+ cells in the basal epithelium constituted less than 1% of the total basal cell population. SP cells constituted 0.5–3% of the total epithelial fraction. The SP transcriptome was essentially the same as ABCG2+ and both populations expressed genes indicative of a stem cell phenotype, however, the cells also expressed many genes in common with endothelial cells. Conclusion These results provide gene expression profiles for the prostate SP and ABCG2+ cells that will be critical for studying normal development and carcinogenesis, in particular as related to the cancer stem cell concept.