title: Preferential cytotoxicity for multidrug-resistant K562 cells using the combination of a photosensitizer and a cyanine dye.
abstract: The cyanine dye 1,1',3,3,3',3'-hexamethylindodicarbocyanine iodide (HIDC) protects K562 leukemia cells from photodynamic membrane damage caused by cis-di(4-sulfonatophenyl)diphenylporphine (TPPS2) and 420 nm light. This wavelength of light is chosen because it is absorbed by TPPS2, but not by HIDC. The photodynamic system studied may be useful as a model for antineoplastic therapy. A subline of K562 leukemia (K562/DOX), expressing the multidrug-resistance (MDR) phenotype, is found to accumulate smaller amounts of HIDC than the parent cell line and thus has less photoprotection. In the absence of added HIDC, the K562/DOX cell line is more resistant to photodynamic cytotoxicity than the K562 cell line. The resistance of the K562/DOX cell line is not due to a smaller accumulation of TPPS2 than the K562 cell line. However, when both cell lines are incubated with HIDC and TPPS2, and then exposed to light, the K562/DOX cell line becomes more sensitive to photodynamic cell damage than the K562 cell line. The combination of a photosensitizer with a cationic or lysomorphotropic photoprotector represents a novel strategy for the eradication of malignant cells expressing the MDR phenotype.
authors.affiliation: Medical Service, Edward Hines, Jr., Department of Veterans Affairs Hospital, Hines, IL 60641, USA. jeff.kanofsky@med.va.gov
authors.forename: J R
authors.initials: JR
authors.lastname: Kanofsky
authors.forename: P D
authors.initials: PD
authors.lastname: Sima
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000473:pathology; D004396:Coloring Agents / Q000494:pharmacology*; D003486:Cyanides / Q000378:metabolism / Q000494:pharmacology*; D004351:Drug Resistance; D006801:Humans; D020014:K562 Cells; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011166:Porphyrins / Q000494:pharmacology*
chemical_list: D004396:Coloring Agents; D003486:Cyanides; D017319:Photosensitizing Agents; D011166:Porphyrins; C016136:tetraphenylporphine sulfonate