Identification of targeting peptides to human prostate cancer cells (LNCAP) using phage display peptide libraries

Prostate cancer is one the most common causes of cancer-associated death in men. Studies have indicated that targeting peptides to prostate cancer cells represent potential to be used as valuable diagnostic and therapeutic tools. Over the recent years, phage display peptide libraries have been used for identifying targeting peptides to a variety of cancer cells. In the current study, we aim to isolate peptides targeting to LNCAP cells (human prostate adenocarcinoma cells). A heptapeptide phage display library was used through biopanning to isolate peptides binding specifically to LNCAP cells. Four rounds of positive panning on LNCAP (target cell) and 4 rounds of subtractive panning on control cells including 5637 (bladder), Huh-7 (liver) and SW480 (colon) and AGS (stomach) and human fibroblast normal cells were performed. Polyclonal phage ELISA was exploited to evaluate the process of enrichment during biopanning. Subsequently, phage clones were randomly picked out from titer plates, amplified by using plaque-PCR and their genomic DNA was sequenced. Bioinformatic analysis was conducted for further characterization of isolated peptides. Several rounds of panning resulted in the enrichment of peptides among which the peptide (NERALTL) was the most frequent. Also, in silico analysis showed the presence of several consensus amino acid motifs in peptides. The NERALTL peptide identified through biopanning can be considered as a potential specific binder to LNCAP cells. Further analysis of this peptides is required to show its capacity for targeted delivery of various gene and drug delivery vehicles into prostate cancer cells.