Comparative photodynamic effects of three photosensitisers in a human carcinoma cells

BATLLE, ALCIRA; ALVAREZ, GABRIELA; RIVAROLA, VIVIANA; FUKUDA, HAYDÉE

Bath, Inglaterra

Congreso; 12th Congress European Society for Photobiology – ESP 2007; 2007

European Society for Photobiology

Introduction: All living cells form Haem from Aminolevulinic acid (ALA). After exogenous administration, ALA is converted into the photosensitiser (PS) Protoporphyrin IX (PPIX). PPIX is preferentially accumulated in malignant cells. After exposure to light, activated PPIX generates reactive oxygen species (ROS) leading to cell death, the so-called Photodynamic Therapy (PDT). The aim of this work have been to evaluate the photokilling activity of three PSs in Hep-2 cells. Materials and Methods: The Hep-2 human larynx carcinoma cell line and the following PSs were used: molecular dyad porphyrinC-(60) (P-C(60)); the monocationic porphyrin derivative 5-(4-trimethyl ammoniumphenyl)-10,15,20-tris (2,4,6-trimethoxyphenyl) porphyrin (CP) and PPIX synthesized in situ from ALA. The mechanism of cell death was analyzed by Hoechst -33258 and toluidine blue staining, TUNEL assay and DNA fragmentation. Results: No dark cytotoxicity was observed  with  1 mμM PC (60 ), 5 μM CP or 1 mM ALA along the 24 h incubation. Cell survival after irradiation with visible light was dependent on incubation time. Cells treated 24 h with P-C(60) and irradiated with 54 J/cm2  showed 58 % of apoptosis. Instead, under these conditions, CP induced a 58 % of necrosis. PPIX accumulated after incubation with 1 mM ALA for 45 h induced 40 % of apoptosis. Upon irradiation in anaerobiosis of cells incubated with P-C(60), necrosis predominated over apoptosis. Microscopy under violet-blue light, revealed that fluorescence of CP was localized in mitochondria, while ALA-induced PPIX was localized in lysosomes. Conclusion: Photodamage in PDT is dependent on the PS, the light dose and the atmosphere conditions.