title: Drug-induced changes in the expression of MDR-associated genes: investigations on cultured cell lines and chemotherapeutically treated leukemias.
abstract: The induced expression of multiple drug resistance (MDR)-associated genes as a direct response of tumor cells to antineoplastic drugs could be an important factor influencing the success of cancer chemotherapy. We investigated the effects of such compounds on mdr1/P-glycoprotein (P-gp) gene expression and drug sensitivities in the T-lymphoblastoid human cell line CCRF-CEM and MDR sublines. Thereby, we observed that actinomycin D or adriamycin administered at sublethal concentrations induced increases of mdr1 mRNA levels and resistance within 72 h. Furthermore, on leukemia cell samples collected before and after chemotherapy we checked by a complementary DNA polymerase chain reaction (cDNA-PCR) approach for similar alterations in the relative expression levels of the MDR-associated genes (a) mdr1/P-gp (b) mrp (MDR related protein), and (c) the topoisomerase II isoforms alpha and beta. We found a concomitant increase in mdr1 and mrp gene expression combined with a decreased expression of topoisomerase II alpha in the course of the second relapse of an acute lymphoblastic leukemia (ALL). This points to the emergence of at least three different MDR mechanisms in this type of leukemia unresponsive to chemotherapy. A chronic myeloid leukemia (CML) in blast crisis, however, showed combined increases in mdr1 (about 20-fold) and mrp (about four fold) gene expression after intense but unsuccessful chemotherapy over a 6-month period. Our results indicate the occurrence of induced resistance in vitro and in vivo and suggest a contribution of the newly identified ATP-binding cassette (ABC) transporter MRP in MDR.
authors.affiliation: Abteilung FP3, Byk Gulden GmbH, Konstanz, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Gekeler
authors.forename: J
authors.initials: J
authors.lastname: Beck
authors.forename: A
authors.initials: A
authors.lastname: Noller
authors.forename: A
authors.initials: A
authors.lastname: Wilisch
authors.forename: G
authors.initials: G
authors.lastname: Frese
authors.forename: M
authors.initials: M
authors.lastname: Neumann
authors.forename: R
authors.initials: R
authors.lastname: Handgretinger
authors.forename: G
authors.initials: G
authors.lastname: Ehninger
authors.forename: H
authors.initials: H
authors.lastname: Probst
authors.forename: D
authors.initials: D
authors.lastname: Niethammer
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001483:Base Sequence; D001752:Blast Crisis; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D003609:Dactinomycin / Q000494:pharmacology; D004351:Drug Resistance / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D007938:Leukemia / Q000188:drug therapy / Q000235:genetics*; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D003609:Dactinomycin; D004250:DNA Topoisomerases, Type II