title: Rhodamine dyes as potential agents for photochemotherapy of cancer in human bladder carcinoma cells.
abstract: The phototoxicity in vitro of rhodamine 123 and tetrabromo rhodamine 123 (TBR) was compared, in order to assess their photochemotherapeutic potential. Exposure to 514.5-nm radiation from an argon ion laser caused phototoxicity in MGH-U1 bladder carcinoma cells previously treated with either dye at 10 microM for 30 min. As assessed by colony formation and cellular morphology, TBR was markedly more phototoxic than rhodamine 123, reflecting increased intersystem crossing of TBR to the triplet manifold via spin-orbital coupling induced by the heavy bromine atoms. Photoreactions of TBR very efficiently generated singlet oxygen (1O2) in solution; furthermore, irradiation of TBR-treated cells was significantly more toxic when performed in the presence of deuterium oxide, an enhancer of damage caused by 1O2. Retention of fluorescence in TBR-treated cells was enhanced by irradiation, indicating that a stable photoproduct may be formed in reaction with cellular components.
authors.affiliation: Wellman Laboratories of Photomedicine, Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston 02114.
authors.forename: C R
authors.initials: CR
authors.lastname: Shea
authors.forename: N
authors.initials: N
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Wimberly
authors.forename: T
authors.initials: T
authors.lastname: Hasan
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002295:Carcinoma, Transitional Cell / Q000188:drug therapy*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D007834:Lasers; D010778:Photochemotherapy; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D020112:Rhodamine 123; D012235:Rhodamines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000528:radiation effects; D014410:Tumor Stem Cell Assay; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy*; D014966:Xanthenes / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D011838:Radiation-Sensitizing Agents; D012235:Rhodamines; D014966:Xanthenes; D020112:Rhodamine 123; C060140:tetrabromorhodamine 123