The effect of 5-aminolevulinic acid-based photodynamic treatment (PDT) on nucleoli of leukemic granulocytic precursors represented by K562 blastic cells in vitro.
BACKGROUND
Since photodynamic treatment (PDT) induces apoptosis in individual HL-60 cells originating from early granulocytic precursors of acute myeloid leukemia, the present study was undertaken to provide information on such treatment of K562 cells, which originate from early granulocytic precursors of chronic myeloid leukemia (blastic phase) and carry the bcr/abl fusion gene with anti-apoptotic properties.


METHODS
PDT was based on the 5-aminolevulinic acid treatment of K562 cells, followed by blue light irradiation under conditions which in HL-60 cells induce an apoptotic process without previous terminal maturation. Nuclei and nucleoli were visualized by cytochemical procedures to demonstrate DNA, RNA and silver stained proteins of nucleolus organizer regions (AgNORs). TUNEL and propidium iodide assays were used for additional control of the incidence of apoptotic and necrotic cells.


RESULTS
In contrast to HL-60 cells, PDT did not induce apoptosis in K562 cells. However, after PDT some K562 cells exhibited major alterations, expressed by nuclear and cell swelling, reflecting a necrotic process, confirmed by propidium iodide. In addition, PDT produced a reduction of AgNORs, though smaller than that previously described in apoptotic HL-60 cells.


CONCLUSIONS
PDT produced only necrotic changes in some K562 cells under conditions which induced in apoptosis in HL-60 cells. Thus the induction of apoptosis, nuclear and nucleolar changes in individual cells does not depend on the inducer--PDT--but on the cell properties.
Smetana
Karel
K
Institute of Hematology and Blood Transfusion, Prague, Czech Republic. karel.smetana@uhkt.cz
Pluskalová
Michaela
M
Marinov
Yuri
Y
Hrkal
Zbynek
Z
D000622:Aminolevulinic Acid / Q000494:pharmacology*; D017209:Apoptosis; D002466:Cell Nucleolus / Q000187:drug effects* / Q000648:ultrastructure; D002467:Cell Nucleus / Q000187:drug effects / Q000648:ultrastructure; D002843:Chromatin / Q000648:ultrastructure; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000473:pathology*; D008938:Mitosis / Q000187:drug effects; D009336:Necrosis; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013234:Stem Cells / Q000187:drug effects
D002843:Chromatin; D017319:Photosensitizing Agents; D000622:Aminolevulinic Acid