title: Expression of the MDR1 and MDR3 gene products in acute and chronic leukemias.
abstract: We performed immunocytochemistry to detect mdr1 and mdr3 P-glycoproteins (P-gps) in 81 patients with acute and chronic leukemia, using the mdr1 P-gp-specific monoclonal antibody (MoAb) MRK16, and the mdr3 P-gp-specific MDR3M. Immunoreactivity for the mdr1 gene product was positive in 27 out of 81 (33%) patients. Immunoreactivity with the anti-mdr3 P-gp MoAb was positive in 20 out of 81 (25%) patients. Of 54 patients with acute leukemia, 17 (31%) were positive for mdr1 P-gp and 8 (15%) for mdr3 P-gp. A high proportion (60%) of patients with chronic lymphocytic leukemia (CLL) were mdr3 P-gp positive. Of the patients with granular-lymphocyte proliferative disorder (GLPD), a chronic T-cell or natural killer cell leukemia, 8/17 (47%) were positive for mdr1 P-gp and 6/17 (35%) for mdr3 P-gp. Of 23 patients with chronic leukemia (CLL and GLPD), 10 (37%) were positive for mdr1 P-gp and 12 (44%) for mdr3 P-gp. To clarify the function of the mdr3 P-gp, we examined the intracellular rhodamine123 (Rh123) levels of mdr1 P-gp-negative and mdr3 P-gp-positive leukemic cells from patients with acute lymphocytic leukaemia, on the addition of 10 microM cyclosporin A (CyA). The addition of CyA led to significant increases in intracellular Rh123 levels in mdr1 P-gp-negative and mdr3 P-gp-positive leukemic cells. Results of the assay for dye efflux suggested that the mdr3 P-gp has a role in drug resistance, and functional drug-efflux capacity. In 31 acute leukemia patients at initial diagnosis, mdr1 or mdr3 P-gp expression correlated significantly to an outcome of complete remission (CR). In 54 acute leukemia patients, exposure to precytotoxic agents correlated significantly to expression, with a significant higher number of patients mdr1 or mdr3 P-gp positive than negative. In the 54 patients with acute leukemia, mdr1 P-gp expression correlated to mdr3 P-gp expression significantly (p=0.0007). In the 27 patients with chronic leukemia (CLL and GLPD), mdr1 and mdr3 P-gp expression did not correlate to exposure to precytotoxic agents, nor did mdr1 P-gp expression correlate to mdr3 P-gp expression. It may be speculated that precytotoxic agents induced mdr1 and mdr3 P-gp expression in acute leukemia; however, in chronic leukemia, both P-gps were expressed independently of exposure to precytotoxic agents.
authors.affiliation: Department of Hematology, Tokyo Women's Medical College, Shinjuku-ku, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Arai
authors.forename: M
authors.initials: M
authors.lastname: Masuda
authors.forename: I
authors.initials: I
authors.lastname: Sugawara
authors.forename: T
authors.initials: T
authors.lastname: Arai
authors.forename: T
authors.initials: T
authors.lastname: Motoji
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo
authors.forename: K
authors.initials: K
authors.lastname: Oshimi
authors.forename: H
authors.initials: H
authors.lastname: Mizoguchi
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000235:genetics; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis* / Q000235:genetics; D000208:Acute Disease; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D014408:Biomarkers, Tumor; D002908:Chronic Disease; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D007938:Leukemia / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018528:ATP-Binding Cassette Transporters; D014408:Biomarkers, Tumor; C095122:multidrug resistance protein 3