<title>Differential accumulation and organ-specific metabolism of 5-aminolevulinic acid between cancer cells and normal epithelial and stromal cells</title>

Abstract

To optimize conditions of photodynamic therapy (PDT) with ALA induced protoporphyrin IX (PPIX), topography of accumulation and metabolism of PPIX were analyzed in vitro. Adenocarcinoma cell lines, urothelial carcinoma cell lines, and a normal fibroblast cell line were cultured in plateau phase. ALA-induced PPIX accumulation, porphobilinogendeaminase-, ferrochelatase- activity, intracellular iron content, transferrin receptor expression and PPIX localization were determined using standard techniques. PBG activity as well as PPIX content were found higher in adenocarcinoma cells than in urothelial cells. Urothelial cell lines showed significant alterations in FC values in contrast to similar levels of FC in adenocarcinoma cell lines overall. Well differentiated cells showed higher iron content than lower differentiated cells. Transferrin receptor expression was found independent of PPIX content and intracellular iron content. In HT29, PPIX localizes mostly in the cell membrane, in SW480 and CaCo2 in mitochondria, and in urothelial cells mainly in cytosol. Data presented encourage the systematic and organ- related analysis of PPIX metabolism, since significant differences have been found between urothelial tumor cells and adenocarcinoma cells which may demand different strategies of therapy optimization and combination therapy regimens.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.