Nuclear transport of photosensitizers during photosensitization and oxidative stress

Abstract

The nuclear transport pathways of the photosensitizers meso-tetra(4-sulfonatophenyl)porphyrin (TPPS4) and meso-tetra(4-N-methylpyridyl)porphyrin (TMPyP) during photosensitization and oxidative stress were characterized in CT-26 murine colon carcinoma cells using fluorescence microscopy and multi-pixel spectral imaging. Prior to irradiation, TPPS4 and TMPyP localized mainly in the lysosomes, while irradiation or H2O2 treatment induced a relocalization into the nucleus and nucleoli. Flow cytometry analysis of isolated nuclei from the treated cells showed an increase in nuclear fluorescence accompanying the relocalization. Isolation and separation of the nuclear proteins according to molecular weight was performed using a sephadex G-100 column. The protein fractions exhibiting high fluorescence were separated by high performance liquid chromatography. Five major classes of proteins with a retention time of 1, 7, 11, 12 and 15 min were obtained. Each photosensitizer was associated with a distinct class of proteins. While TPPS4 fluorescence was detected in the protein fraction with a retention time of 11 min, TMPyP fluorescence was associated with a protein fraction having a retention time of 7 min. We conclude that although oxidative stress triggers entry into the nucleus of both TPPS4 and TMPyP, each sensitizer uses a distinct transport mechanism based on its chemical properties.

Anti-infective photodynamic biomaterials for the prevention of intraocular lens-associated infectious endophthalmitis

“…Furthermore, all porphyrin-impregnated materials, irrespective of their composition, had similar contact angles, and the contact angles were not significantly different for materials dipped in a 1 mg/mL or 100 mg/mL TMPyP solution. TMPyP is a hydrophilic photosensitizer [42], its hydrophilicity due to the presence of hydrophilic pyridinium groups at pH 7.4. As these groups are attracted to the negatively charged carboxylate groups of the MAA in the p(HEMAco-MAA) copolymers, which in the hydrated state are likely to be orientated at the surface of these materials, these hydrophilic groups are therefore present on the surface.…”

Singlet Oxygen in a Cell: Spatially Dependent Lifetimes and Quenching Rate Constants

“…16 Upon initial incorporation, TMPyP is first localized in lysosomes. 37,38 However, the dye eventually localizes in the nucleus (Figure 3a). 22,39 Under our cell handling conditions, experiments were invariably initiated with an intracellular TMPyP distribution such as that shown in Figure 3a.…”

Evaluating the antitumor activity of combined photochemotherapy mediated by a meso-substituted tetracationic porphyrin and adriamycin

“…However, such weak interaction did not inhibit the dark toxicity of the co-mixture against HepG2 cells, compared with the toxicity of ADM or TMPyP alone. Under culture conditions, the two sensitizers disengage as each is attracted to its specific target in cells, where TMPyP binds readily with the negative sites of the cell membrane and localizes preferentially in lysosomes by endocytosis [13,26], although ADM localizes mainly in the groove of DNA double helix via an intercalative process employing the hydroquinone portion of the drug and also through an electrostatic interaction involving the protonated amino group on the drug and the negatively charged phosphate groups on the DNA backbone [27]. The enhanced dark toxicity of TMPyP/ADM co-mixture could be attributed to a probable weakening of cellular defense mechanisms due to free radical generation by ADM [28] and by ADM induced increase in the electronegative, hydrophilic glycoproteins on the cell surface [24], thus, increasing the uptake of the hydrophilic cationic TMPyP rendering the cells more sensitive to the same concentration that initially has minimum impact when administered alone.…”