Photodynamic therapy with 5-aminolevulinic acid hydrochloride for canine urinary bladder transitional cell carcinoma

We investigated the uptake and metabolism of 5-aminolevulinic acid hydrochloride (5-ALA) and the cytotoxic effects of 5-ALA-photodynamic therapy (5-ALA-PDT) in eight types of primary cultured canine transitional cell carcinoma (bTCC) cells established by the present author. The aim was to evaluate the potential of 5-ALA-PDT as a treatment for bTCC. We compared the intracellular and extracellular protoporphyrin IX (PpIX) concentrations with cell viability following 5-ALA-PDT. Additionally, we analyzed the expression levels of various genes, including those encoding 5-ALA uptake transporters, and their correlation with cell viability after 5-ALA-PDT. A significant negative correlation was observed between intracellular PpIX concentration and cell viability. Intracellular PpIX concentration was positively correlated with the gene expression level of the 5-ALA uptake transporter PEPT2 and negatively correlated, though weakly, with the expression level of the FECH gene. 5-ALA-PDT may exert cytotoxicity effects against bTCC, particularly in cells where PpIX has accumulated.