P-glycoprotein (ABCB1) but not multidrug resistance-associated protein 1 (ABCC1) is induced by doxorubicin in primary cultures of rat astrocytes.
At least two drug efflux pumps involved in multidrug resistance, P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (Mrp1), are expressed in rat astrocyte primary cultures. The aim of this study was to compare the expression of P-gp and Mrp1 in primary cultures exposed to 50 or 500 ng/mL doxorubicin (DOX). Among the two P-gp genes expressed in rodents, mdr1a and mdr1b, a time- and dose-dependent increase in mdr1b mRNA levels was revealed by northern blot analysis. This up-regulation was inhibited by actinomycin D and occurred as early as 2 h after exposure to 50 or 500 ng/mL DOX, whereas mdr1a and mrp1 transcripts were not modified by the DOX exposure. In addition, DOX also strongly enhanced, in a time- and dose-dependent manner, P-gp but not Mrp1 expression. Moreover, DOX raised the cellular efflux of vincristine, a substrate for both P-gp and Mrp1. This efflux was inhibited by the P-gp modulators PSC833 and GW918, but not by the Mrp1 modulator MK571. On the other hand, a 24-h exposure to 500 ng/mL DOX, but not 50 ng/mL DOX, induced apoptosis in primary cultures of rat astrocytes. Fumonisin B1, a ceramide synthase inhibitor, reduced DOX-induced apoptosis, suggesting that de novo synthesis of the ceramide regulatory pathway might be involved in DOX-induced apoptosis. Moreover, western blot analysis showed that fumonisin B1 was not able to decrease the overexpression of P-gp induced by DOX. Our results provide evidence that DOX up-regulates a functional P-gp in primary cultures of rat astrocytes and might cause astrocyte apoptosis via the ceramide pathway.
Mercier
Claire
C
INSERM U26, Hôpital Fernand Widal, Paris, France. claire.mercier@fwidal.inserm.fr
Declèves
Xavier
X
Masseguin
Christophe
C
Fragner
Pascal
P
Tardy
Marcienne
M
Roux
Françoise
F
Gabrion
Jacqueline
J
Scherrmann
Jean-Michel
JM
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis / Q000235:genetics*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004317:Doxorubicin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000096:biosynthesis / Q000235:genetics*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014750:Vincristine / Q000493:pharmacokinetics
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000903:Antibiotics, Antineoplastic; D004317:Doxorubicin; D004791:Enzyme Inhibitors; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010088:Oxidoreductases; D012333:RNA, Messenger; D014750:Vincristine; C108138:dihydroceramide desaturase; C421109:multidrug resistance-associated protein 1