TY - JOUR
T1 - Regulation of 5-aminolevulinic acid-mediated protoporphyrin IX accumulation in human urothelial carcinomas
AU - Inoue, Keiji
AU - Karashima, Takashi
AU - Kamada, Masayuki
AU - Shuin, Taro
AU - Kurabayashi, Atsushi
AU - Furihata, Mutsuo
AU - Fujita, Hirofumi
AU - Utsumi, Kozo
AU - Sasaki, Junzo
N1 - Copyright:
Copyright 2010 Elsevier B.V., All rights reserved.
PY - 2009/12
Y1 - 2009/12
N2 - Purpose: The purpose of this study was to clarify the regulatory mechanism of protoporphyrin IX (PpIX) synthesis mediated by 5-aminolevulinic acid (ALA) in human urothelial carcinoma (UC), leading to improved accuracy in photodynamic diagnosis and therapy using ALA. Experimental Design: PpIX accumulation in cultured UC cells after incubation for 1-5 h with 0.5-5 mM ALA was analyzed by fluorescence analysis using fluorescence microscopy and flow cytometry technique. Results: PpIX fluorescence mediated by ALA was increased, and the intensity of PpIX fluorescence was time-dependently increased in UC cells compared to noncancerous cells. The distribution of endogenous PpIX fluorescence primarily coincided with mitochondria, and then increased at a specific perinuclear region in the cells during the time of incubation. The ALA-mediated PpIX synthesis in UC cells was suppressed by β-alanine, an inhibitor of β-transporters of cell membrane, and carbonylcyanide p- trifluoromethoxyphenyl hydrazone, an uncoupler of mitochondrial oxidative phosphorylation. In contrast, the ALA-mediated PpIX accumulation was increased by deferoxamine, an iron chelator, manganese and nitric oxide, which is contributed to PpIX metabolism by inhibiting ferrochelatase activity, generated by a nitric oxide-generating reagent NOC-18. As observed above, ALA-mediated PpIX synthesis in human UC cells was regulated by the process of ALA uptake, ALA conversion to PpIX and metabolism of accumulated PpIX to heme. Conclusions: This shows that the suppression of ferrochelatase increased PpIX accumulation in UC cells using small amount of ALA, thus leading to an improved clinical practicability of photodynamic diagnosis and therapy.
AB - Purpose: The purpose of this study was to clarify the regulatory mechanism of protoporphyrin IX (PpIX) synthesis mediated by 5-aminolevulinic acid (ALA) in human urothelial carcinoma (UC), leading to improved accuracy in photodynamic diagnosis and therapy using ALA. Experimental Design: PpIX accumulation in cultured UC cells after incubation for 1-5 h with 0.5-5 mM ALA was analyzed by fluorescence analysis using fluorescence microscopy and flow cytometry technique. Results: PpIX fluorescence mediated by ALA was increased, and the intensity of PpIX fluorescence was time-dependently increased in UC cells compared to noncancerous cells. The distribution of endogenous PpIX fluorescence primarily coincided with mitochondria, and then increased at a specific perinuclear region in the cells during the time of incubation. The ALA-mediated PpIX synthesis in UC cells was suppressed by β-alanine, an inhibitor of β-transporters of cell membrane, and carbonylcyanide p- trifluoromethoxyphenyl hydrazone, an uncoupler of mitochondrial oxidative phosphorylation. In contrast, the ALA-mediated PpIX accumulation was increased by deferoxamine, an iron chelator, manganese and nitric oxide, which is contributed to PpIX metabolism by inhibiting ferrochelatase activity, generated by a nitric oxide-generating reagent NOC-18. As observed above, ALA-mediated PpIX synthesis in human UC cells was regulated by the process of ALA uptake, ALA conversion to PpIX and metabolism of accumulated PpIX to heme. Conclusions: This shows that the suppression of ferrochelatase increased PpIX accumulation in UC cells using small amount of ALA, thus leading to an improved clinical practicability of photodynamic diagnosis and therapy.
KW - 5-aminolevulinic acid
KW - Cancer
KW - Flow cytometry
KW - Photodynamic diagnosis
KW - Protoporphyrin IX
KW - Urothelial lesions
UR - http://www.scopus.com/inward/record.url?scp=72449163576&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=72449163576&partnerID=8YFLogxK
U2 - 10.1159/000245896
DO - 10.1159/000245896
M3 - Article
C2 - 19955842
AN - SCOPUS:72449163576
VL - 76
SP - 303
EP - 314
JO - Pathobiology
JF - Pathobiology
SN - 1015-2008
IS - 6
ER -