Functional and structural characteristics of anticancer peptide Pep27 analogues.
BACKGROUND
A secreted peptide Pep27 initiates the cell death program in S. pneumoniae through signal transduction. This study was undertaken to evaluate the relation between the structure and cytotoxic activity of Pep27 and its analogues on cancer cells.


RESULTS
Pep27anal2 characterized substituting (2R-->W), (4E-->W), (11S-->W) and (13Q-->W) in native Pep27, exhibited greater hydrophobicity and anticancer activity than Pep27 and other analogues. The IC50 values of Pep27anal2 were approximately 10 - 30 microM in a number of cell lines (AML-2, HL-60, Jurkat, MCF-7 and SNU-601). Confocal microscopy showed that Pep27anal2-FITC was localized in the plasma membrane, and then moving from the membrane to subcellular compartments with the initiation of membrane blebbing. Flow cytometric analysis using propidium iodide and Annexin V also revealed that Pep27anal2 induced apoptosis with minor membrane damage. Electron microscopy revealed that Pep27 induced apoptosis in Jurkat cells. The anticancer activity of Pep27anal2 was neither abrogated by pan-caspase inhibitor (Z-VAD-fmk) nor related to cytochrome c release from mitochondria. The 3D solution structures of these two Pep27 peptides revealed that both form a random coil conformation in water; however, they adopted stable alpha-helical conformations in solutions.


CONCLUSIONS
The results indicate that Pep27anal2 can penetrate the plasma membrane, and then induce apoptosis in both caspase-and cytochrome c-independent manner. The hydrophobicity of Pep27anal2 appears to play an important role in membrane permeabilization and/or anticancer properties. The structure-functional relationships of these peptides are also discussed. It is proposed that Pep27anal2 is a potential candidate for anticancer therapeutic agents.
Lee
Dong Gun
DG
School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, Taegu 702-701, Korea. dglee222@knu.ac.kr
Hahm
Kyung-Soo
KS
Park
Yoonkyung
Y
Kim
Hai-Young
HY
Lee
Weontae
W
Lim
Sung-Chul
SC
Seo
Youn-Kyung
YK
Choi
Cheol-Hee
CH