Antiestrogenic and anticancer activities of peptides derived from the active site of alpha-fetoprotein

• Published in: Journal of peptide science Vol. 15; no. 4; pp. 319 - 325
• Main Authors: Joseph, Leroy C., Bennett, James A., Kirschner, Karl N., Shields, George C., Hughes, John, Lostritto, Nicole, Jacobson, Herbert I., Andersen, Thomas T.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-04-2009
• Subjects: alpha-fetoprotein; alpha-Fetoproteins - chemical synthesis; alpha-Fetoproteins - chemistry; alpha-Fetoproteins - pharmacology; Amino Acid Sequence; Animals; anticancer; Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Binding Sites; breast cancer; Breast Neoplasms - drug therapy; Cell Line, Tumor; dose range; Estrogen Receptor Modulators - chemical synthesis; Estrogen Receptor Modulators - chemistry; Estrogen Receptor Modulators - pharmacology; Female; Humans; linear peptides; Mice; Peptide Fragments - chemical synthesis; Peptide Fragments - chemistry; Peptide Fragments - pharmacology; Transplantation, Heterologous; Uterus - drug effects; Uterus - growth & development
• ISSN: 1075-2617; 1099-1387
• DOI: 10.1002/psc.1119

Cyclo[EKTOVNOGN] (AFPep), a cyclic 9‐amino acid peptide derived from the active site of alpha‐fetoprotein, has been shown to prevent carcinogen‐induced mammary cancer in rats and inhibit the growth of ER+ human breast cancer xenografts in mice. Recently, studies using replica exchange molecular dynamics predicted that the TOVN region of AFPep might form a dynamically stable putative Type I beta‐turn, and thus be biologically active without additional amino acids. The studies presented in this paper were performed to determine whether TOVN and other small analogs of AFPep would inhibit estrogen‐stimulated cancer growth and exhibit a broad effective‐dose range. These peptides contained nine or fewer amino acids, and were designed to bracket or include the putative pharmacophoric region (TOVN) of AFPep. Biological activities of these peptides were evaluated using an immature mouse uterine growth inhibition assay, a T47D breast cancer cell proliferation assay, and an MCF‐7 breast cancer xenograft assay. TOVN had very weak antiestrogenic activity in comparison to AFPep's activity, whereas TOVNO had antiestrogenic and anticancer activities similar to AFPep. OVNO, which does not form a putative Type I beta‐turn, had virtually no antiestrogenic and anticancer activities. A putative proteolytic cleavage product of AFPep, TOVNOGNEK, significantly inhibited E2‐stimulated growth in vivo and in vitro over a wider dose range than AFPep or TOVNO. We conclude that TOVNO has anticancer potential, that TOVNOGNEK is as effective as AFPep in suppressing growth of human breast cancer cells, and that it does so over a broader effective‐dose range. Copyright © 2009 European Peptide Society and John Wiley & Sons, Ltd.