title: Enhancement of the photodynamic activity of tri-cationic porphyrins towards proliferating keratinocytes by conjugation to poly-S-lysine.
abstract: A fast uptake of the tri-cationic 5-(4-carboxyphenyl)-10,15,20-tris(4-methylpyridinium-4-yl)porphyrin tri-iodide (P-H), independent of the presence or absence of proteins in the culture medium, occurs during incubation of NCTC 2544 human keratinocytes with this porphyrin. By contrast, the uptake of the poly-S-lysine conjugate (P-(Lys)(n)) is faster in serum-free medium than in the supplemented medium suggesting that P-(Lys)(n) interacts with serum proteins. The P-(Lys)(n) uptake is almost an order of magnitude greater than that of P-H in serum-free or supplemented culture medium. With histidine as a specific probe of type II photodynamic reactions, the relative photosensitizing effectiveness of the conjugate is only one fourth that of P-H. Nevertheless, the photocytotoxicity of the conjugate is strongly enhanced as compared to that of P-H as a result of its larger uptake. Thus, the doses achieving 50% of photocytotoxicity after incubation with 5 microM of the conjugate and its parent cationic porphyrin are about 20 min and 1 h, respectively. Similarly, the initial rate of the cell lipid peroxidation induced by photosensitization with P-(Lys)(n) is about 8 times higher than that obtained with P-H. Fluorescence microscopy reveals that P-H is more diffusely located in the cytoplasm than P-(Lys)(n) which seems to accumulate in lysosome-like structures. Little if any staining of the nucleus is observed with both photosensitizers.
authors.affiliation: Hospital de Santa Maria, Clinica Universitária de Dermatologia, 1600, Lisbon, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Nuno Silva
authors.forename: Josiane
authors.initials: J
authors.lastname: Haigle
authors.forename: João P C
authors.initials: JP
authors.lastname: Tomé
authors.forename: Maria G P M S
authors.initials: MG
authors.lastname: Neves
authors.forename: Augusto C
authors.initials: AC
authors.lastname: Tomé
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mazière
authors.forename: Cécile
authors.initials: C
authors.lastname: Mazière
authors.forename: René
authors.initials: R
authors.lastname: Santus
authors.forename: José A S
authors.initials: JA
authors.lastname: Cavaleiro
authors.forename: Paulo
authors.initials: P
authors.lastname: Filipe
authors.forename: Patrice
authors.initials: P
authors.lastname: Morlière
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry; D003592:Cytophotometry; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015603:Keratinocytes / Q000187:drug effects* / Q000528:radiation effects; D015394:Molecular Structure; D017319:Photosensitizing Agents / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects; D011107:Polylysine / Q000494:pharmacology*; D011166:Porphyrins / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects; D011726:Pyridinium Compounds / Q000737:chemistry / Q000494:pharmacology* / Q000528:radiation effects; D013329:Structure-Activity Relationship; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: C509722:5-(4-carboxyphenyl)-10,15,20-tris(4-methylpyridinium-4-yl)porphyrin; D003470:Culture Media; D017319:Photosensitizing Agents; D011166:Porphyrins; D011726:Pyridinium Compounds; D011107:Polylysine