title: Modulation of multidrug resistance gene (mdr-1) with antisense oligodeoxynucleotides.
abstract: 1. Multidrug resistance is the major obstacle to successful cancer chemotherapy. Circumventing multidrug resistance therefore represents a high priority for clinical anti-cancer treatment. Among many reversal strategies, antisense oligodeoxynucleotides may offer a molecular targeting tool for overcoming cellular multidrug resistance. 2. Two 17-mer phosphorothioate antisense oligomers, complementary to the 5' end of the ATG initiator codon-containing region and loop-forming site (located at nucleotides 991-1007 from the first ATG codon) in mdr-1 cDNA sequence, were synthesized. The purpose was to study their effects on the function and expression of P-glycoprotein and mdr-1 gene. 3. The results showed that 10 mumol/l antisense oligomers could significantly inhibit the growth of multidrug resistant K562/Adm cells cultured in adriamycin-containing medium. No such effect was observed for parental (sensitive) K562/S cells. Intracellular daunorubicin accumulation increased greatly in the K562/Adm cells after they were treated with oligomers for 48 h and P-glycoprotein synthesis was strikingly reduced. 4. Further investigation with [alpha-32P]dCTP incorporation by the reverse transcriptase-polymerase chain reaction method revealed that antisense oligomers could result in a reduction in the level of mdr-1 mRNA, probably through hindering mdr-1 gene transcription. 5. The high reversal efficiency and specificity of antisense oligomers in regulating mdr-1 gene expression suggest a potential clinical application in gene therapy for drug resistant malignancies.
authors.affiliation: Research Unit of Haematology, Huashan Hospital, Shanghai Medical University, People's Republic of China.
authors.forename: C
authors.initials: C
authors.lastname: Liu
authors.forename: I A
authors.initials: IA
authors.lastname: Qureshi
authors.forename: X
authors.initials: X
authors.lastname: Ding
authors.forename: Y
authors.initials: Y
authors.lastname: Shan
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.forename: Y
authors.initials: Y
authors.lastname: Xie
authors.forename: M
authors.initials: M
authors.lastname: Ji
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D001483:Base Sequence; D002455:Cell Division / Q000187:drug effects; D003630:Daunorubicin / Q000493:pharmacokinetics; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D007942:Leukemia, Experimental / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D003630:Daunorubicin