Fig. 1.

Identification of a peptide that specifically binds with PSA^−/lo PCa cells. (A) Cells from LNCaP xenograft tumors were infected with PSAP-GFP lentiviral reporter for 72 h. Perform FACS to purify the top 10% GFP-bright (GFP⁺) and bottom 2%−6% GFP^−/lo cells. Representative images of GFP⁺ (PSA⁺) and GFP⁻ (PSA^−/lo) cells. Scale bars 25 μm. (B) Schematic diagram of phage display library screening. (C) Purified PSA^−/lo and PSA⁺ cells were incubated with biotinylated peptide TAP1 (5 μM) or biotinylated control peptide (5 μM) for 72 h. Biotinylated peptide TAP1 was stained with streptavidin-Alexafluor 594 (green) and cells nuclei were stained with Propidium Iodide (PI) (red).Scale bars 10 μm. (D) Cell subpopulations (PSA⁺ and PSA^−/lo cells, CD44⁺ and CD44⁻ cells, ALDH⁺CD44⁺α2β1⁺ and ALDH⁻CD44⁻α2β1⁻ cells, ALDH⁺CD44⁺CXCR4⁺CD24⁺ and ALDH⁻CD44⁻CXCR4⁻CD24⁻ cells) were incubated with biotinylated peptide TAP1 (5 μM) or biotinylated control peptide (5 μM) for 72 h. Biotinylated peptide TAP1 was stained with streptavidin-Alexafluor 594 (green) and cells nuclei were stained with Propidium Iodide (PI) (red). The percentage of peptide binding positivity was quantified in 10 randomly selected fields under an inverted light microscope. Data are presented as the mean ± SD. *p < 0.05. Experiments were performed in triplicate.