Primary research

Functional and structural characteristics of anticancer peptide Pep27 analogues

Dong Gun Lee¹ , Kyung-Soo Hahm² , Yoonkyung Park² , Hai-Young Kim³ , Weontae Lee³ , Sung-Chul Lim⁴ , Youn-Kyung Seo⁵ and Cheol-Hee Choi⁵

¹  School of Life Science and Biotechnology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuk-dong, Puk-ku, Taegu 702-701, Korea

²  Research Center for Proteinous Materials, Chosun University, Gwangju 501–759, Korea

³  Departement of Biochemistry and HTSD-NMR National Research Laboratory, Yonsei University, Seoul, South Korea

⁴  Department of Pathology, College of Medicine, Chosun University, Gwangju 501–759, Korea

⁵  Research Center for Resistant Cells and Department of Pharmacology, College of Medicine, Chosun University, Gwangju 501–759, Korea

author email corresponding author email

Cancer Cell International 2005, 5:21doi:10.1186/1475-2867-5-21

Published:	11 July 2005

Abstract

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 μM 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 α-helical conformations in solutions.

Conclusion

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.