Sequential gene expression of P-glycoprotein (P-gp), multidrug resistance-associated protein (MRP) and lung resistance protein: functional activity of P-gp and MRP present in the doxorubicin-resistant human K562 cell lines.
Previous studies have reported that P-glycoprotein (P-gp), a transmembrane efflux pump involved in multidrug resistance (MDR), was overexpressed in the doxorubicin (Dox)-resistant human erythroleukemia cell line K562. Nevertheless, several results suggested that P-gp was not the only mechanism involved in these resistant cells. Sequential co-expression of other MDR-associated proteins was sometimes reported, as MDR-associated protein (MRP) and lung resistance protein (LRP), in different MDR cell lines. Thus, mRNA expression and stability of P-gp, MRP and LRP were analyzed, while their corresponding protein levels were quantified in correlation with functional assay, in the K562 cell line and two Dox-resistant variants (K562/R). Their P-gp content was in accordance with their degree of resistance, but not as much in the level of mRNA expression, suggesting a post-transcriptional regulation. On the other hand, MRP could play a minor role in MDR because of an unchanged expression in K562/R sublines. A surprising progressive disappearance of LRP in both resistant cells suggested that the original mechanism of drug redistribution may be operative, involving a negative role for LRP.
Grandjean
F
F
Groupe Physiologie Moléculaire Mitochondriale et Immunitaire, UMR 6101, CNRS, Faculté de Médecine, 87025 Limoges Cedex, France.
Brémaud
L
L
Verdier
M
M
Robert
J
J
Ratinaud
M H
MH
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000633:toxicity*; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D017931:DNA Primers / Q000737:chemistry; D004317:Doxorubicin / Q000494:pharmacology*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm; D004795:Enzyme Stability / Q000502:physiology*; D005434:Flow Cytometry; D015870:Gene Expression; D019450:Genes, MDR / Q000502:physiology; D006801:Humans; D020014:K562 Cells / Q000187:drug effects* / Q000378:metabolism; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D020394:Vault Ribonucleoprotein Particles / Q000235:genetics* / Q000378:metabolism; D000099187:Major Vault Protein
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D017931:DNA Primers; D004317:Doxorubicin; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein