Retro-inversion of certain cell-penetrating peptides causes severe cellular toxicity.
Cell-penetrating peptides (CPPs) are a promising group of delivery vectors for various therapeutic agents but their application is often hampered by poor stability in the presence of serum. Different strategies to improve peptide stability have been exploited, one of them being "retro-inversion" (RI) of natural peptides. With this approach the stability of CPPs has been increased, thereby making them more efficient transporters. Several RI-CPPs were here assessed and compared to the corresponding parent peptides in different cell-lines. Surprisingly, treatment of cells with these peptides induced trypsin insensitivity and rapid severe toxicity in contrast to L-peptides. This was measured as reduced metabolic activity and condensed cell nuclei, in parity with the apoptosis inducing agent staurosporine. Furthermore, effects on mitochondrial network, focal adhesions, actin cytoskeleton and caspase-3 activation were analyzed and adverse effects were evident at 20 μM peptide concentration within 4 h while parent L-peptides had negligible effects. To our knowledge this is the first time RI peptides are reported to cause cellular toxicity, displayed by decreased metabolic activity, morphological changes and induction of apoptosis. Considering the wide range of research areas that involves the use of RI-peptides, this finding is of major importance and needs to be taken under consideration in applications of RI-peptides.
Department of Neurochemistry, Stockholm University, SE-106 91 Stockholm, Sweden. tina@neurochem.su.se
Tina
T
Holm
Helin
H
Räägel
Samir E L
SE
Andaloussi
Margot
M
Hein
Maarja
M
Mäe
Margus
M
Pooga
Ülo
Ü
Langel
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000737:chemistry / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D057846:Cell-Penetrating Peptides; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects*; D005452:Fluoresceins / Q000737:chemistry; D015696:Gene Products, tat / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*
D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D005452:Fluoresceins; D015696:Gene Products, tat; D010455:Peptides; C414409:penetratin; D053148:Caspase 3