The induction of protoporphyrin (PP) synthesis in B16 melanoma cells and their subsequent photodestruction was investigated. Chemical induction of the porphyrin biosynthesis pathway was achieved by pretreatment of the cells with dimethyl-sulfoxide (DMSO), a differentiation-inducer and the porphyrogenic agent allyl-isopropyl-acetamide (AIA) followed by 5-aminolevulinic acid (5-ALA) supplementation to the cultures. A phenomenal increase in cellular PP from 8 (control melanoma cells) up to 22000 pmol/mg protein was revealed by the use of this triple induction protocol. The porphyrins produced consisted of PP when analyzed by high pressure liquid chromatography (HPLC). Transmission electron microscopy depicted an initial damage located exclusively in mitochondria. This was revealed as an immediate expansion of mitochondrial volume subsequent to irradiation, presumably a consequence of water influx. Photosensitized cells gradually disintegrated following prolonged irradiation. The photosensitized cells showed an immediate potassium loss compensated only partially by influx of Na and other ions. The dominant characteristics of these cells were potassium efflux, water influx and ultrastructural damage in subcellular compartments. In conclusion, a highly efficient system for killing B16 melanoma cells was achieved by photosensitization of endogenous PP produced subsequent to chemical induction.
|Number of pages
|Proceedings of SPIE - The International Society for Optical Engineering
|Published - 1 Mar 1994
|Photodynamic Therapy of Cancer 1993 - Budapest, Hungary
Duration: 29 Aug 1993 → 3 Sep 1993
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