Background: Prostate Stem Cell Antigen (PSCA) is a small cell surface protein, overexpressed
in 90% of prostate cancers. Determination of epitopes that elicit an appropriate response to
the antibody generation is vital for diagnostic and immunotherapeutic purposes for prostate cancer
treatment. Presently, bioinformatics B-cell prediction tools can predict the location of epitopes,
which is uncomplicated, faster, and more cost-effective than experimental methods.
Objective: We aimed to predict a novel linear peptide for Prostate Stem Cell Antigen (PSCA) protein
in order to generate anti-PSCA-peptide (p) antibody and to investigate its effect on prostate
Methods: In the current study, a novel linear peptide for PSCA was predicted using in silico methods
that utilize a set of linear B-cell epitope prediction tools. Polyclonal antibody (anti-PSCA-p
antibody “Patent No. 99318”) against PSCA peptide was generated. The antibody reactivity was determined
by the Enzyme-Linked Immunosorbent Assay (ELISA) and its specificity by immunocytochemistry
(ICC), immunohistochemistry (IHC), and Western Blotting (WB) assays. The effect of
the anti-PSCA-p antibody on PSCA-expressing prostate cancer cell line was assessed by Methylthiazolyldiphenyl-
Tetrazolium bromide (MTT) assay.
Results: New peptide-fragment of PSCA sequence as “N-CVDDSQDYYVGKKN-C” (PSCA-p)
was selected and synthesized. The anti-PSCA-p antibody against the PSCA-p showed immunoreactivity
with PSCA-p specifically bound to PC-3 cells. Also, the anti-PSCA-p antibody strongly
stained the prostate cancer tissues as compared to Benign Prostatic Hyperplasia (BPH) and normal
tissues (P < 0.001). As the degree of malignancy increased, the staining intensity was also elevated
in prostate cancer tissue (P < 0.001). Interestingly, the anti-PSCA-p antibody showed anti-proliferative
effects on PC-3 cells (31%) with no growth inhibition effect on PSCA-negative cells.
Conclusion: In this study, we developed a new peptide sequence (PSCA-p) of PSCA. The PSCA-p
targeting by anti-PSCA-p antibody inhibited the proliferation of prostate cancer cells, suggesting
the potential of PSCA-p immunotherapy for future prostate cancer studies.