transportan and Melanoma

Cell-penetrating peptides (CPPs) are promising vectors for the intracellular delivery of a variety of membrane-impermeable bioactive compounds. The mechanisms by which CPPs cross the cell membrane, and the effects that CPPs may have on cell function, still remain to be fully clarified. In this work, we employed confocal Raman microscopy (CRM) and atomic force microscopy (AFM) to study the infiltration and physiological effects of the amphipathic CPP transportan (Tp) on the metastatic melanoma cell line SK-Mel-2. CRM enabled the detection of label-free Tp within the cells. Raman maps of live cells revealed rapid entry (within 5 min) and widespread distribution of the peptide throughout the cytoplasm and the presence of the peptide within the nucleus after ∼20 min. Principal component analysis of the CRM data collected from Tp-treated and untreated cells showed that Tp Raman bands were not positively correlated with lipid Raman bands, indicating that Tp entered the cells via a nonendocytic mechanism. Analysis of intracellularly recovered Tp by mass spectrometry showed that Tp remained intact in SK-Mel-2 cells for up to 24 h. The Raman spectroscopic data also showed that, although Tp was predominantly unstructured (random coil) in aqueous solution, it accumulated to high densities within the cells with mostly β-sheet and α-helical structures. AFM was employed to measure the effect of Tp treatment on cell stiffness. These data showed that Tp induced a significant increase in cell stiffness within the first hour of treatment, which was partially abated after 2 h. It is hypothesized that the increase in cell stiffness was the result of cytoskeletal changes triggered by Tp.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Membrane; Cell Membrane Permeability; Cell-Penetrating Peptides; Cytoskeleton; Drug Carriers; Galanin; Humans; Intravital Microscopy; Melanoma; Microscopy, Atomic Force; Microscopy, Confocal; Principal Component Analysis; Recombinant Fusion Proteins; Spectrum Analysis, Raman; Wasp Venoms

Transportan is a 27 amino acid-long peptide containing 12 functional amino acids from the amino terminus of the neuropeptide galanin and mastoparan in the carboxyl terminus, connected via a lysine. Transportan is a cell-penetrating peptide as judged by indirect immunofluorescence using N epsilon13-biotinyl-transportan. The internalization of biotinyl-transportan is energy independent and takes place efficiently at 37 degrees, 4 degrees, and 0 degrees C. Cellular uptake of transportan is probably not mediated by endocytosis, since it cannot be blocked by treating the cells with phenylarsine oxide or hyperosmolar sucrose solution and is nonsaturable. The kinetics of internalization was studied with the aid of the 125I-labeled peptide. At 37 degrees C, the maximal intracellular concentration is reached in about 20 min. The internalized transportan is protected from trypsin. The cell-penetrating ability of transportan is not restricted by cell type, but seems to be a general feature of this peptide. In Bowes' melanoma cells, transportan first localizes in the outer membrane and cytoplasmatic membrane structures. This is followed by a redistribution into the nuclear membrane and uptake into the nuclei where transportan concentrates in distinct substructures, probably the nucleoli.

Topics: 1-Octanol; Amino Acid Sequence; Biotin; Endocytosis; Galanin; GTP Phosphohydrolases; Hydrolysis; Intercellular Signaling Peptides and Proteins; Iodine Radioisotopes; Kinetics; Melanoma; Models, Biological; Molecular Sequence Data; Peptides; Recombinant Fusion Proteins; Tumor Cells, Cultured; Wasp Venoms; Water

Peptide nucleic acids (PNAs) form stable and tight complexes with complementary DNA and/or RNA and would be promising antisense reagents if their cellular delivery could be improved. We show that a 21-mer PNA, complementary to the human galanin receptor type 1 mRNA, coupled to the cellular transporter peptides, transportan or pAntennapedia(43-58), is efficiently taken up into Bowes cells where they block the expression of galanin receptors. In rat, the intrathecal administration of the peptide-PNA construct results in a decrease in galanin binding in the dorsal horn. The decrease in binding results in the inability of galanin to inhibit the C fibers stimulation-induced facilitation of the rat flexor reflex, demonstrating that peptide-PNA constructs act in vivo to suppress expression of functional galanin receptors.

Topics: Amino Acid Sequence; Animals; Antennapedia Homeodomain Protein; Base Sequence; Down-Regulation; Female; Galanin; Homeodomain Proteins; Humans; Melanoma; Molecular Sequence Data; Nuclear Proteins; Pain; Peptide Fragments; Peptide Nucleic Acids; Rats; Rats, Sprague-Dawley; Receptor, Galanin, Type 1; Receptors, Galanin; Receptors, Neuropeptide; Recombinant Fusion Proteins; RNA, Messenger; Signal Transduction; Spinal Cord; Transcription Factors; Tumor Cells, Cultured; Wasp Venoms