title: In vitro photodynamic therapy of nasopharyngeal carcinoma using 5-aminolevulinic acid.
abstract: The purpose of this study was to investigate the potential use of 5-aminolevulinic acid (5-ALA, 5-amino-4-oxovaleric acid) induced protoporphyrin IX (PPIX) for photodynamic therapy (PDT) of nasopharyngeal carcinoma (NPC) and its related mechanisms of inducing cell death. PPIX biosynthesis at I to 8 h after incubation of a cultured NPC cell line (HNE1) with 5-ALA (10-5,000 microg ml(-1)) was determined via fluorescence analysis HNEI cells were irradiated at 4 h after incubation with 5-ALA (10-200 microg ml(-1)) by diode laser (lambda = 630 nm) at various energy levels (1-50 J cm(-2)). The survival rates at 6, 12, 24 and 48 h after PDT were determined by MTT assay. Mechanisms of PDT-induced cell death were investigated via Anncxin-V/propidium iodide staining and DNA electrophoresis After incubation with 5-ALA, a time- and dose-dependent increase of cellular PPIX-fluorescence was recorded up to a threshold concentration of 1,000 microg ml(-1) 5-ALA, above which a decline of fluorescence intensities occurred. Similar values of PPIX-fluorescence were found at 100-1,000 microg ml(-1) of 5-ALA. Unlike sole incubation with 5-ALA or sole laser irradiation, the combination of both factors lead to a significant, concentration-, energy- and time-dependent increase of cell death (p < 0.01). At 100 microg ml(-1) ALA and 10 J cm 2 laser irradiation, cellular survival was <5% after 48 h. More than 80% of induced cell deaths thereby occurred via apoptosis within the first 12 h following irradiation; necrosis was accountable for less than 20%. High level induction of apoptosis by 5-ALA-PDT was confirmed by DNA electrophoresis. Our investigations show promising results of 5-ALA based PDT of nasopharyngeal carcinoma in vitro and set the basis for future studies in tumor models or humans, respectively.
authors.affiliation: Department of Otorhinolaryngology/Head and Neck Surgery, University of Munich, Marchioninistrasse 15, 81377 Munich, Germany. cbetz@life.med.uni-muenchen.de
authors.forename: Christian S
authors.initials: CS
authors.lastname: Betz
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Lai
authors.forename: Wei
authors.initials: W
authors.lastname: Xiang
authors.forename: Philip
authors.initials: P
authors.lastname: Janda
authors.forename: Peter
authors.initials: P
authors.lastname: Heinrich
authors.forename: Herbert
authors.initials: H
authors.lastname: Stepp
authors.forename: Reinhold
authors.initials: R
authors.lastname: Baumgartner
authors.forename: Andreas
authors.initials: A
authors.lastname: Leunig
mesh_terms: D000622:Aminolevulinic Acid / Q000378:metabolism / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002277:Carcinoma / Q000188:drug therapy* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D007700:Kinetics; D007834:Lasers; D008856:Microscopy, Fluorescence; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D009336:Necrosis; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000378:metabolism / Q000494:pharmacology*; D011524:Protoporphyrins / Q000096:biosynthesis; D014407:Tumor Cells, Cultured
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX