Quantitative Analysis of Pc 4 Localization in Mouse Lymphoma (LY-R) Cells via Double-label Confocal Fluorescence Microscopy

Abstract

Photodynamic therapy (PDT) is a novel cancer therapy that uses light‐activated drugs (photosensitizers) to destroy tumor tissue. Reactive oxygen species produced during PDT are thought to cause the destruction of tumor tissue. However, the precise mechanism of PDT is not completely understood. To provide insight into the in vitro mechanisms of PDT, we studied the subcellular localization of the photosensitizer HOSiPcOSi(CH3)2‐(CH2)3N(CH3)2 (Pc 4) in mouse lymphoma (LY‐R) cells using double‐label confocal fluorescence microscopy. This technique allowed us to observe the relative distributions of Pc 4 and an organelle‐specific dye within the same cell via two, spectrally distinct, fluorescence images. To quantify the localization of Pc 4 within different organelles, linear correlation coefficients from the fluorescence data of Pc 4 and the organelle‐specific dyes were calculated. Using this measurement, the subcellular spatial distributions of Pc 4 could be successfully monitored over an 18 h period. At early times (0–1 h) after introduction of Pc 4 to LY‐R cells, the dye was found in the mitochondria, lysosomes and Golgi apparatus, as well as other cytoplasmic membranes, but not in the plasma membrane or the nucleus. Over the next 2 h, there was some loss of Pc 4 from the lysosomes as shown by the correlation coefficients. After an additional incubation period of 2 h Pc 4 slowly increased its accumulation in the lysosomes. The highest correlation coefficient (0.65) was for Pc 4 and BODIPY‐FL C5 ceramide, which targets the Golgi apparatus, and also binds to other cytoplasmic membranes. The correlation coefficient was also high (0.60) for Pc 4 and a mitochondria‐targeting dye (Mitotracker Green FM). Both of these correlation coefficients were higher than that for Pc 4 with the lysosome‐targeting dye (Lysotracker Green DND‐26). The results suggest that Pc 4 binds preferentially and strongly to mitochondria and Golgi complexes.

Silicon Phthalocyanine 4 Phototoxicity in Trichophyton rubrum

“…In addition, the Pc 4 fluorescence appears to be site specific, which is consistent with previous studies which showed that Pc 4 preferentially binds to intracellular organelles once the cellular uptake has occurred (31,39). To examine whether the mitochondrion is one of the organelles to which Pc 4 binds, we coloaded the Pc 4-treated microconidia and hyphae with a commercially available mitochondrion-specific probe.…”

A carboxylated Zn‐phthalocyanine inhibits fibril formation of Alzheimer's amyloid β peptide

“…Finally, we examined the effect of ZnPc on neuronal viability. In agreement with previous studies [38], our preliminary experiments showed that ZnPc(COONa) 8 accumulated inside the cells in a neuronal cell culture system (data not shown). Nevertheless, ZnPc(COONa) 8 alone did not decrease the cell viability; rather it provided at least some protection against Abinduced neurotoxicity.…”

Peripheral and Axial Substitution of Phthalocyanines with Solketal Groups: Synthesis and In Vitro Evaluation for Photodynamic Therapy

“…Localization of PSs in membranes of organelles like lysosomes or mitochondria have been reported to be most effective. 9,42 Pc4 mainly localizes in mitochondrial membranes, 43 which is one of the main factors contributing to its high photodynamic efficacy. Si(sol) 2 Pc was found to be localized in lipid droplets.…”