Photodynamic therapy (PDT) is a treatment against various diseases whose basic principle is based on the use of a photosensitizer molecule and visible light. The main objective of our research project is to identify specific mechanisms of induction of photoinduced cell death. One possibility aiming to increase the specificity of PDT is to damage multidrug transport proteins, which could disfavor resistance in classic tumor treatments. We will compare the photosensitizer activity of phenothiazines on models expressing multidrug transporters in different levels. We will characterize the effect of the PDT at different levels: at the cellular level, by characterizing cellular viability, efflux of rhodamine-123, efficiency and mechanism of cell death; at the level of the transporter proteins, by using biochemical techniques (western blot and mass spectrometry); and at the level of the generation of reactive intermediates, which will be identified and quantified by time-resolved fluorescence microscopy. The comprehension of the relationship between the intracellular localization of the photosensitizer and the cell death efficiency is critical to increase the efficiency of PDT and we intend to extend the understanding of this relationship by using Time resolved fluorescence confocal microscopy techniques (FLIM, FRET, FRAP).
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