title: Expression level of MDR1 message in peripheral blood leukocytes from healthy adults: a competitive nucleic acid sequence-based amplification assay for its determination.
abstract: Accurate quantification of multidrug resistance-1 gene (MDR1) expression in target cells would be of important therapeutic value in predicting cellular response to anticancer drugs. Because certain normal cells in peripheral blood physiologically express MDR1, increasing the sensitivity of the detection methods might result in confounding low-degree expression in tumor cells with physiologic expression in normal cells. The purpose of this study was to determine MDR1 mRNA expression levels in peripheral blood leukocytes obtained from healthy adult volunteers using a competitive nucleic acid sequence-based amplification (NASBA) assay. We determined the reference intervals of MDR1 mRNA expression in peripheral blood obtained from 98 healthy adults by measuring its expression with the quantitative NASBA assay between 5.50 x 10(4) copies/microg RNA and 6.76 x 10(5) copies/microg RNA. The new reference intervals were evaluated using a number of sensitive or resistant cell lines as control; positive or negative MDR1 expression was clearly demonstrated. We also reevaluated MDR1 expression levels in leukemia cells obtained from patient peripheral blood; 18 of 31 samples (58%) exceeded the newly established upper reference limit. The cutoff value established could be used to distinguish significant MDR1 expression in tumor cells from physiologic expression in certain normal cells coexistent in peripheral blood.
authors.affiliation: Department of Pharmacology, Tokai University School of Medicine, Isehara, Japan. hkobayas@is.icc.u-tokai.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Takemura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Hayashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ujiiye
authors.forename: Masako
authors.initials: M
authors.lastname: Kawase
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Niino
authors.forename: Hayato
authors.initials: H
authors.lastname: Miyachi
authors.forename: Toshio
authors.initials: T
authors.lastname: Ohshima
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Hotta
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism*; D000328:Adult; D016022:Case-Control Studies; D015870:Gene Expression; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D021161:Self-Sustained Sequence Replication / Q000379:methods; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D012333:RNA, Messenger