title: Endogenous and exogenous porphyrins as photosensitizers in the Hep-2 human carcinoma cell line.
abstract: The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivative 5-(4-trimethylammoniumphenyl)-10, 5, 20-tris (2,4,6- trimethoxyphenyl) porphyrin (CP) and the molecular dyad porphyrin-C(60) (P-C(60)), the last two incorporated into liposomal vesicles, was evaluated on Hep-2 human larynx carcinoma cell line. ALA-induced accumulation of the endogenous PS PPIX, reached saturation values between 5 and 24 h incubation time; the maximal PPIX content was 5.7 nmol/106 cells. The same intracellular level was accumulated when the cationic porphyrin CP was used, while the amount of P-C(60) attained was 1.5 nmol/106 cells. Under violet-blue exciting light, the fluorescence of PPIX and P-C(60) was found in the cytoplasm showing a granular appearance indicating lysosomal localization. CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. No dark cytotoxicity was observed using 1mM ALA, 5 microM CP and 1 microM P-C(60) after 24 h incubation. Cell morphology was analyzed using Hoechst-33258, toluidine blue staining, TUNEL assay and DNA fragmentation, 24 h after irradiation with 54 J/cm2. When photosensitized with ALA and P-C(60), chromatine condensation characteristic of apoptotic cell death was found; instead, 58 % of necrotic cells were observed with CP. The results show that in the Hep-2 cells, of the three PS analyzed, the molecular dyad P-C(60) was more efficient than CP and PPIX, and confirm that PDT can induce different mechanisms of cell death depending on the PS and the irradiation dose.
authors: Departamento de Biologia Molecular, Universidad Nacional de Rio Cuarto, Argentina.
authors: M G
authors: MG
authors: Alvarez
authors: M
authors: M
authors: Milanesio
authors: V
authors: V
authors: Rivarola
authors: E
authors: E
authors: Durantini
authors: A
authors: A
authors: Batlle
authors: H
authors: H
authors: Fukuda
mesh_terms: D000622:Aminolevulinic Acid / Q000737:chemistry; D002277:Carcinoma / Q000188:drug therapy; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D037741:Fullerenes / Q000737:chemistry; D006801:Humans; D007822:Laryngeal Neoplasms / Q000188:drug therapy; D008027:Light; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000378:metabolism* / Q000627:therapeutic use / Q000633:toxicity; D011166:Porphyrins / Q000737:chemistry* / Q000627:therapeutic use / Q000633:toxicity; D011524:Protoporphyrins / Q000737:chemistry
chemical_list: D037741:Fullerenes; D008081:Liposomes; D017319:Photosensitizing Agents; D011166:Porphyrins; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; C069837:fullerene C60