Identification of novel prostate-specific antigen-binding peptides modulating its enzyme activity

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Prostate-specific antigen (PSA) is a crucial biomarker for prostate cancer diagnosis and monitoring.
• PSA's role in prostate cancer progression, including metastasis and angiogenesis, is complex and not fully understood.
• Developing specific tools to interact with PSA is essential for advancing prostate cancer research and therapy.

Purpose of the Study:

• To identify and characterize peptides that specifically bind to prostate-specific antigen (PSA).
• To investigate the effect of these peptides on PSA enzyme activity.
• To explore the potential applications of PSA-binding peptides in prostate cancer diagnostics and therapeutics.

Main Methods:

• Screening of cyclic phage display peptide libraries to isolate PSA-specific peptides.
• Production of PSA-binding peptides as glutathione S-transferase (GST) fusion proteins.
• Characterization of peptide binding specificity using various serine proteases and monoclonal antibodies (mAbs).
• Assessment of peptide influence on PSA enzyme activity using chromogenic substrates.

Main Results:

• Identification of several PSA-specific peptides, with a tetra-cysteine peptide exhibiting the highest affinity.
• Peptide binding was confirmed to be specific for PSA, not other serine proteases.
• Peptides bind to a region near the active site of free PSA, as indicated by cross-inhibition studies.
• The identified peptides enhanced PSA enzyme activity.

Conclusions:

• Phage display is an effective technique for developing peptides that bind to and modulate PSA activity.
• These novel PSA-binding peptides show promise for identifying PSA variants.
• Potential applications include imaging and targeted therapy for prostate tumors.