Cellular localization of selected porphyrins and their effect on the In Vitro motility of human colon tumors and normal cells

Abstract

Standard therapies for colorectal cancer cannot eliminate or sufficiently reduce the metasta-sis process. Photodynamic therapy (PDT) may be an alternative to minimizing this problem. Here, we examined the cellular localization of selected porphyrins and determined whether free-baseand manganese (III) metallated porphyrins may limit colon cancer cells’ (HT29) or normal colonepithelial cells’ (CCD 841 CoTr) motility in vitro. White light irradiation was used to initiate the photodynamic effect. Porphyrin uptake by the cells was determined by porphyrin fluorescence measurements through the use of confocal microscopy. Free-base porphyrin was found in cells, where it initially localized at the edge of the cytoplasm and later in the perinuclear area. The concentrations of porphyrins had no effect on cancer cell migration but had a significant effect on normal cell motility. Due to the low concentrations of porphyrins used, no changes in F-actin filaments of the cellular cytoskeleton were detected. Signal transmission via connexons between neighbouring cells was limited to a maximum of 40 μm for HT29 and 30 μm for CCD 841 CoTr cells. The tested porphyrins differed in their activity against the tumor and normal cells’ migration capacity. Depending on the porphyrin used and the type of cells, their migration changed in relation to the control sample. The use of white light may change the activity of the porphyrins relative to the migratory capacity of the cells. The aim of the present study was to analyse the intracellular localization of tested porphyrins and their influence on the mobility of cells after irradiation with harmless white light.