Stabilization of Angiotensin-(1–7) by key substitution with a cyclic non-natural amino acid
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Angiotensin-(1–7) [Ang-(1–7)], a heptapeptide hormone of the renin–angiotensin–aldosterone system, is a promising candidate as a treatment for cancer that reflects its anti-proliferative and anti-angiogenic properties. However, the peptide’s therapeutic potential is limited by the short half-life and low bioavailability resulting from rapid enzymatic metabolism by peptidases including angiotensin-converting enzyme (ACE) and dipeptidyl peptidase 3 (DPP 3). We report the facile assembly of three novel Ang-(1–7) analogues by solid-phase peptide synthesis which incorporates the cyclic non-natural δ-amino acid ACCA. The analogues containing the ACCA substitution at the site of ACE cleavage exhibit complete resistance to human ACE, while substitution at the DDP 3 cleavage site provided stability against DPP 3 hydrolysis. Furthermore, the analogues retain the anti-proliferative properties of Ang-(1–7) against the 4T1 and HT-1080 cancer cell lines. These results suggest that ACCA-substituted Ang-(1–7) analogues which show resistance against proteolytic degradation by peptidases known to hydrolyze the native heptapeptide may be novel therapeutics in the treatment of cancer.
KeywordsPeptidomimetic Non-natural amino acid Angiotensin-(1–7) Angiotensin-converting enzyme Dipeptidyl peptidase 3 ACCA
N-[(Dimethylamino)-1H-1,2,3-triazolo-[4,5-b]pyridin-1-ylmethylene]-N-methylmethanaminium hexafluorophosphate N-oxide
High-performance liquid chromatography
High-resolution mass spectrometry
- 2CT resin
- DPP 3
Dipeptidyl peptidase 3
Solid-phase peptide synthesis
We would like to thank the National University of Ireland for funding this research. We would like to acknowledge the facilities in the Centre for Synthesis and Chemical Biology (CSCB), funded by the Higher Education Authority’s Programme for Research in Third Level Institutions (PRTLIs). We are grateful to Dr. Helge Müller-Bunz for his work on the X-ray crystal structure. We would also like to acknowledge the Science Foundation Ireland Equipment Grant 06/RFP/CHO024/EC07, the National Institutes of Health (NIH) HD084227, the American Heart Association Grants AHA-151521 and AHA-355741, the Randi B. Weiss Cancer Research Fund (Winston-Salem, NC), and the Farley-Hudson Foundation (Jacksonville, NC). Finally, we acknowledge the technical expertise of Nancy T. Pirro for the peptide metabolism studies and L. Tenille Howard for cell proliferation studies.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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