Cell-Penetrating Peptides. Discovery, Structure and Possible Usage in Cancer Treatment

Presentation (Handout) 2015 6 Pages

Chemistry - Organic Chemistry


Different Families of Cell-Penetrating Peptides (CPP‘s)


Short peptides (5 - 30 residues in length) with the ability to enter cells independently of a membrane receptor, and without cell-type specifity. They are either cationic or amphiphatic.

Can be distinguished by origin, cargo attachement, and mechanism of entry

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Types of Cargo and Cargo attachement

Covalent strategy

- chemical cross-linking or cloning followed by expression of a CPP fusion protein
- mainly disulfide or thioester linkages
- different transduction motifs are possible
- used for DNA, peptides, proteins
- procedure reproducible and controlled stoichiometry of the CPP-cargo
- might change the biological activity of the cargo
- CPPs: penetratin, pol-arg, VP22

Non-covalent strategy

- carriers need a hydrophillic and hydrophobic domain (primary or secondary)
- form complexes stable through electrosta- tic and hydrophobic interactions
- often associated with peptides favouring endosomal escape
- used for genes, peptides, proteins
- CPPs: MPG, Pep-1

Mechanism of Uptake

- internalization by energy-dependent vesicular mechanism (endocytosis) or translocating over the lipid bilayer
- depends on the celltype, the attached cargo and the CPP
- 3-step process: 1) membrane interaction, 2) membrane permeation, 3) release of CPP into the cytosol pathways differ from each other in step 2 and 3

Mechanisms of Uptake

Membrane interaction:

- heperan sulfate proteoglycans and syndecans are the major components of the extracellular matrix
- trigger reaction cascade for cellular uptake pathways
- CPPs bind electrostatically at surface proteoglycans glucosaminoglycan (GAG) platform leading to remodelling of the actin network and activation of GTPase Rho A or Rac1
- membrane fluidity is enhanced

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Potential Applications in Future Cancer Therapie

Cell Targeting Peptides

- molecules with the ability to recognize cancer cells selectively

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- conjugate of chlorambucil to pVEC-PEGA increases drug efficacy over four times
- transvascular delivery of siRNA to the CNS with a chimeric peptide consisting of rabies virus glycoprotein RVG and a polyarginine CPP at the carboxy terminus
- potential to target brain tumors
- CXC chemokine receptor 4 (CXCR4) over-expressed in 20 different types of cancer
- DV3-TAT-p53C’ (p-53-activating peptide) and DV3-TAT-RxL (cyclin-dependent kinase 2 antagonist) increase efficiency two times as unguided CPPs

Potential Applications in Future Cancer Therapie

Activatable CPP’s (ACCP)

- ACCP/DOX conjugate, sensitive to MMP-2/9 for tumor-targeting
- ACCP includes 3 units:
- polyargenine, R9
- cleavable enzyme-specific substrate domain of MMP-2/9, PLGLAG
- shielding peptide domain, DGGDGGDGGDG

- inactivated in cells lacking MMP-2/9

- after cleavage the CPP-cargo complex is able to penetrate the cell

- uptake and antiproliferative activity is observed

Potential Applications in Future Cancer Therapie

Transducible Agents of CPPs

- many tumors are dissimanated throughout the body
- intraperitoneal injection (IP) of TAT protein leeds to systemic distribution
- tumor cells create a hypoxic microenvironment due to their high metabolic demands
- proliferation is regulated by hypoxia inducible factor-1a (HIF-1a), containing oxygen-dependent degradation domains (ODD)
- wild-type caspase-3 fused to TAT-ODD leads to cell-death in cancer tissue


- existence of natural proteins with the capability to cross the cell membrane
- CPPs can be tailored and functionalized in order to increase their range of application
- nearly every kind of cargo can be attached, either covalent or by forming a complex
- different mechanism of uptake, endocytosis or direct translocation, do exist
- hard to predict and not fully understood
- various possibilities of potentially applications in cancer therapy or other diseases, but still most of the molecular mechanism is unrevealed


1. Green, M.; Loewenstein, P. M., Autonomous functional domains of chemically synthesized human immunodeficiency virus tat trans-activator protein. Cell 1988, 55 (6), 1179-1188.

2. Harada, H.; Hiraoka, M.; Kizaka-Kondoh, S., Antitumor Effect of TAT-Oxygen-dependent Degradation- Caspase-3 Fusion Protein Specifically Stabilized and Activated in Hypoxic Tumor Cells. Cancer Research 2002, 62 (7), 2013-2018.

3. Heitz, F. et al., Twenty years of cell-penetrating peptides: from molecular mechanisms to therapeutics. British Journal of Pharmacology 2009, 157, 195-206.

4. Patel, L. N.; Zaro, J. L.; Shen, W.-C., Cell Penetrating Peptides: Intracellular Pathways and Pharmaceutical Perspectives. Pharmaceutical Research 2007, 24 (11), 1977-1992.

5. Regberg, J. et al., Applications of Cell-Penetrating Peptides for Tumor Targeting and Future Cancer Therapies. Pharmaceuticals 2012, 5, 991-1007.

6. Sebbage, V., Cell-penetrating peptides and their therapeutic applications. Bioscience Horizons 2009, 2 (1), 64-72.

7. Snyder, E. L.; Dowdy, S. F., Cell Penetrating Peptides in Drug Delivery. Pharmaceutical Research 2004, 21 (3), 389-393.

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11 13.01.2015 Cell-Penetrating Peptides - Development, Molecular Mechanisms, and Therapeutic Applications Universität Konstanz



ISBN (eBook)
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University of Constance – Chemie
CPP penetration macropinozytose endozytose




Title: Cell-Penetrating Peptides. Discovery, Structure and Possible Usage in Cancer Treatment