[Subcellular distribution of daunorubicin in the P-glycoprotein-mediated multidrug-resistant cell line K562/ADR].
OBJECTIVE
To examine subcellular distribution of daunorubicin (DNR) in P-glycoprotein-mediated multidrug-resistant cell line K562/ADR and its relation to multidrug resistance.


METHODS
The subcellular distribution of DNR in K562/ADR was studied by confocal scanning laser microscopy (CSLM), fluorometry, RT-PCR. Rhodamine 123, NBD-ceramide and neutral red as fluorescent probes to stain the mitochondria, Golgi apparatus and lysosomes respectively were used to identify the subcellular compartments wherein DNR was sequestered. Effect of verapamil, chloroquine and brefeldin A on DNR distribution and accumulation was examined.


RESULTS
Compared with the drug-sensitive cell K562/S in which DNR fluorescence diffusely appeared in the nucleus and cytoplasm, DNR in K562/ADR cells was distributed to the perinuclear region and peripheral cytoplasm, It was scenty in the nucleus and other cytoplasmic regions, as suggested by the distribution of Rhodamine123. Only verapamil, but not chloroquine and brefeldin A, could markedly restore diffuse cytoplasmic and nuclear fluorescence distribution in the resistant cell line.


CONCLUSIONS
Altered subcellular distribution of DNR in drug resistant cell line may participate in the generation of multidrug resistance in which P-glycoprotein plays an important role.
Gong
Y
Y
Renji Hospital, Shanghai Second Medical University, Shanghai 200001, China.
Wang
Y
Y
Chen
F
F
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D003630:Daunorubicin / Q000378:metabolism*; D018432:Drug Resistance, Multiple / Q000502:physiology*; D005456:Fluorescent Dyes / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D004915:Leukemia, Erythroblastic, Acute; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D005456:Fluorescent Dyes; D003630:Daunorubicin