Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2021 Mar 2:26:100966.
doi: 10.1016/j.bbrep.2021.100966. eCollection 2021 Jul.

Screening for new peptide substrates for the development of albumin binding anticancer pro-drugs that are cleaved by prostate-specific antigen (PSA) to improve the anti tumor efficacy

Bakheet E M Elsadek  1 , Mohammed H Hassan  2
Affiliations

Screening for new peptide substrates for the development of albumin binding anticancer pro-drugs that are cleaved by prostate-specific antigen (PSA) to improve the anti tumor efficacy

Bakheet E M Elsadek et al. Biochem Biophys Rep. .

Abstract

Several attempts have been made over the past decade to explore the concept of prodrug strategies that exploit PSA as a molecular target for the release of anticancer drugs in prostate tumors using various prostate specific antigen (PSA)-cleavable peptide linkers, but the desired antitumor and antimetastatic efficacy has not yet been fully achieved. We set out to look for new PSA-cleavable peptide substrates that could be cleaved more rapidly and efficiently than the previously used peptides. To look for the most susceptible PSA-cleavable peptide substrates, we used the so-called spot technology. With the following general formula, we designed 25 different fluorogenic heptapeptides; Cellulose-P5-P4-P3-P2-P1-P1'-P2' (Fluorophore). The increase of the fluorescence in the supernatant of the reaction mixture was monitored using a 96-well fluorometric plate reader with excitation of λ ex 485 nm and λ em 535 nm. Three sequences showed a high fluorogenic liberation after incubation with PSA, i.e., Arg-Arg-Leu-His-Tyr-Ser-Leu (7), Arg-Arg-Leu-Asn-Tyr-Ser-Leu (8) and Arg-Ser-Ser-Tyr-Arg-Ser-Leu (23). Future incorporation of these optimized substrates in the PSA-cleavable prodrug formulations could further optimize the cleavage pattern and so the release characteristics of these prodrugs to rapidly and efficiently liberate the free cytotoxic agents inside the tumor tissues.

Keywords: Peptide substrate; Prodrug; Prostate cancer; Prostate-specific antigen (PSA); Spot assay.

PubMed Disclaimer

Conflict of interest statement

The authors declare that they have no known competing financialinterestsor personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Diagrammatic illustration for the principle of assay and monitoring the fluorescence increase in the reaction supernatant after PSA cleavage of the fluorogenic heptapeptides substrates.
Fig. 2
Fig. 2
The mean fluorescence change per hour (ΔF/h) of each individual fluorogenic heptapeptide substrates afterPSA cleavage. Data are presented as the mean ± SEM (n = 3).
See this image and copyright information in PMC

References

    1. Denmeade S.R., Nagy A., Gao J., Lilja H., Schally A.V., Isaacs J.T. Enzymatic activation of a doxorubicin-peptide prodrug by prostate-specific antigen. Canc. Res. 1998;58:2537–2540. - PubMed
    1. Robert M., Gibbs B.F., Jacobson E., Gagnon C. Characterization of prostate-specific antigen proteolytic activity on its major physiological substrate, the sperm motility inhibitor precursor/semenogelin I. Biochemistry. 1997;36:3811–3819. - PubMed
    1. Hassan M.I., Kumar V., Singh T.P., Yadav S. Structural model of human PSA: a target for prostate cancer therapy. Chem. Biol. Drug Des. 2007;70:261–267. - PubMed
    1. Yang C.F., Porter E.S., Boths J., Kanyi D., Hsieh M., Cooperman B.S. Design of synthetic hexapeptide substrates for prostate-specific antigen using single-position minilibraries. J. Pept. Res. 1999;54:444–448. - PubMed
    1. Lilja H. A kallikrein-like serine protease in prostatic fluid cleaves the predominant seminal vesicle protein. J. Clin. Invest. 1985;76:1899–1903. - PMC - PubMed