Apoptosis Inducing, Conformationally Constrained, Dimeric Peptide Analogs of KLA with Submicromolar Cell Penetrating Abilities

• Published in: Biomacromolecules Vol. 15; no. 10; pp. 3746 - 3752
• Main Authors: Hyun, Soonsil, Lee, Seonju, Kim, Seoyeon, Jang, Sangmok, Yu, Jaehoon, Lee, Yan
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.10.2014
• Subjects: Antineoplastic agents; Apoptosis - physiology; Biological and medical sciences; Cell Line, Tumor; Cell-Penetrating Peptides - metabolism; Chemistry; Chemotherapy; Dimerization; Exact sciences and technology; HeLa Cells; Humans; Medical sciences; Mitochondria - metabolism; Mitochondria - physiology; Molecular Conformation; Organic chemistry; Peptides; Peptides - metabolism; Pharmacology. Drug treatments; Preparations and properties; Antineoplastic agent; Peptides; Experimental study; Oxidative coupling; In vitro; Hela cell line; Biological activity; Mechanism; Organic disulfide; Internalization; Dimer; Helical structure; Peptide synthesis; Apoptosis
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm501026e

The apoptosis inducing KLA peptide, (KLAKLAK)2, possesses an ability to disrupt mitochondrial membranes. However, this peptide has a poor eukaryotic cell penetrating potential and, as a result, it requires the assistance of other cell penetrating peptides for effective translocation in micromolar concentrations. In an effort to improve the cell penetrating potential of KLA, we have created a library in which pairs of residues on its hydrophobic face are replaced by Cys. The double Cys mutants were then transformed to bundle dimers by oxidatively generating two intermolecular disulfide bonds. We envisioned that once transported into cells, the disulfide bonds would undergo reductive cleavage to generate the monomeric peptides. The results of these studies showed that one of the mutant peptides, dimer B, has a high cell penetrating ability that corresponds to 100% of fluorescence positive cells at 250 nM. Even though dimer B induces disruption of the mitochondrial potential and cytochrome c release followed by caspase activation at submicromolar concentrations, it displays an LD50 of 1.6 μM under serum conditions using HeLa cells. Taken together, the results demonstrate that the strategy involving formation of bundle dimeric peptides is viable for the design of apoptosis inducing KLA peptide that translocate into cells at submicromolar concentrations.