Comparison of uptake mechanisms for anthracyclines in human leukemic cells.
OBJECTIVE
The mechanisms behind cellular anthracycline uptake are not completely understood. Knowledge about uptake mechanisms could be used to increase the selectivity of the drugs. We compared the uptake patterns of, daunorubicin (DNR), doxorubicin (DOX), epirubicin (EPI), idarubicin (IDA), and pirarubicin (PIRA) by cultured leukemic cells and investigated possible involvement of specific carriers.


METHODS
HL-60 cells were incubated with anthracyclines for 1 hour in the absence or presence of transport inhibitors, suramin, or nucleosides and cellular drug uptake was determined. Cell survival was also determined. MCF-7 breast cancer cells were used as a negative control for concentrative nucleoside transporters (CNTs). Anthracycline concentration was determined with HPLC and fluorometric detection and apoptosis was determined with propidium iodide and flow cytometry.


RESULTS
DNR, IDA, and PIRA had higher uptake than DOX and EPI with a prominent increase in uptake at concentrations > 1 µM. Uptake of all anthracyclines was greatly reduced at 0°C. Suramin, a purinergic-2-receptor inhibitor, strongly inhibited the uptake of all anthracyclines except PIRA and increased cell survival. Dipyridamole, an equilibrative NT (ENT) inhibitor, significantly inhibited the uptake of DNR only. The addition of nucleosides significantly inhibited the uptake of DNR, IDA, and PIRA but not in MCF-7 cells lacking functional CNTs.


CONCLUSIONS
Our results suggest different uptake mechanisms for the anthracyclines studied. We found evidence for carrier mediated uptake mechanisms, supporting involvement of NTs in transmembrane transport of DNR, IDA, and PIRA. The results also showed a strong inhibition of suramin on anthracycline uptake by so far unknown mechanisms.
Division of Clinical Pharmacology, Department of Medicine, L7:03, Karolinska University Hospital, Solna, SE-171 76 Stockholm, Sweden. sigurd.vitols@karolinska.se
Hazhar
H
Karim
Alex
A
Bogason
Hasanuzzaman
H
Bhuiyan
Alan K
AK
Fotoohi
Pierre
P
Lafolie
Sigurd
S
Vitols
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors; D018943:Anthracyclines / Q000494:pharmacology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001692:Biological Transport; D004176:Dipyridamole / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000378:metabolism; D061986:MCF-7 Cells; D033703:Nucleoside Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009705:Nucleosides / Q000494:pharmacology; D058914:Purinergic Antagonists / Q000494:pharmacology; D013498:Suramin / Q000494:pharmacology; D013696:Temperature; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018943:Anthracyclines; D000903:Antibiotics, Antineoplastic; D033703:Nucleoside Transport Proteins; D009705:Nucleosides; D058914:Purinergic Antagonists; D013868:Thioinosine; D013498:Suramin; D004176:Dipyridamole; D014700:Verapamil; C001789:4-nitrobenzylthioinosine