title: Restoration of retinoid sensitivity by MDR1 ribozymes in retinoic acid-resistant myeloid leukemic cells.
abstract: Complete remission is achieved in a high proportion of patients with acute promyelocytic leukemia (APL) after all-trans retinoic acid (RA) treatment, but most patients relapse and develop RA-resistant APL. We have previously reported that both RA-resistant HL-60 (HL-60R) and APL cells express P-glycoprotein and MDR1 transcripts; and these cells differentiate to mature granulocytes after culture with RA and P-glycoprotein antagonist. Ribozymes have been shown to be able to intercept a target RNA by catalytic activity. To address the role of MDR1 in overcoming RA-resistance in APL cells, we investigated the biologic effects of ribozymes against the MDR1 transcript in HL-60R cells. These ribozymes efficiently cleaved MDR1 mRNA at a specific site in vitro. The 196 MDR1 ribozyme was cloned into an expression vector, and stably transfected (HL-60R/196Rz) cells were obtained. Expression of MDR1 transcripts was decreased in HL-60R/196Rz cells compared with parental HL-60R and empty vector-transfected (HL-60R/neo) cells. Interestingly, RA inhibited cellular proliferation and induced differentiation of HL-60R/196Rz cells in a dose-dependent manner, suggesting reversal of drug resistance in HL-60R cells by the MDR1 ribozyme. These data are direct evidence that P-glycoprotein/MDR1 is responsible in part for acquired resistance to RA in myeloid leukemic cells. The MDR1 ribozyme may be a useful tool for investigating the biology of retinoid resistance and may have therapeutic potential for patients with RA-resistant APL.
authors.affiliation: Division of Hematology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Matsushita
authors.forename: M
authors.initials: M
authors.lastname: Kizaki
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: H
authors.initials: H
authors.lastname: Ueno
authors.forename: A
authors.initials: A
authors.lastname: Muto
authors.forename: N
authors.initials: N
authors.lastname: Takayama
authors.forename: N
authors.initials: N
authors.lastname: Awaya
authors.forename: K
authors.initials: K
authors.lastname: Kinjo
authors.forename: Y
authors.initials: Y
authors.lastname: Hattori
authors.forename: Y
authors.initials: Y
authors.lastname: Ikeda
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D018014:Gene Transfer Techniques; D019450:Genes, MDR; D018922:HL-60 Cells; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy / Q000235:genetics*; D016337:RNA, Catalytic / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D014212:Tretinoin / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000970:Antineoplastic Agents; D016337:RNA, Catalytic; D012333:RNA, Messenger; D014212:Tretinoin