Aminolevulinic acid derivatives-based photodynamic therapy in human intra- and extrahepatic cholangiocarcinoma cells.

Hexyl-aminolevulinic acid (HALA) was compared with aminolevulinic acid (ALA) in terms of improving ALA-based photodynamic therapy (PDT) for human intra- and extrahepatic cholangiocarcinoma (CCA) HuCC-T1 and SNU1196 cells. Because of the different uptake mechanisms of HALA, a relatively higher amount of protoporphyrin IX (PpIX) was induced in the both CCA cell types at low concentrations of HALA. Furthermore, higher expression of porphobilinogen deaminase, coproporphyrinogen III oxidase, and protoporphyrinogen oxidase, the key enzymes for synthesizing PpIX in the heme biosynthetic pathway, facilitated the exuberant generation of PpIX in HuCC-T1 cells. PpIX accumulation with ALA was markedly different between the two CCA cell types. Even at lower concentrations of ALA, SNU1196 cell successfully synthesized PpIX, due to the higher expression of the ALA transporter, mammalian H (+)/peptide co-transporter PEPT1. Considering the difference of PEPT1 or key enzyme expression, HALA could be a very effective substitute for ALA in doing PDT for cure of CCA.