title: Electrophoretic analysis of 248 clinical breast cancer specimens for P-glycoprotein overexpression or gene amplification.
abstract: Multiple drug resistance (MDR), consisting of acquired cross resistance to anthracyclines, vinca alkyloids, and other antineoplastic antibiotics, has been described in a variety of cell lines. This MDR phenotype is associated with overexpression and sometimes amplification of a gene coding for a 170 kDa glycoprotein, termed P-glycoprotein. To understand the role of this mechanism in clinical breast cancer, 248 breast cancer specimens representing both untreated primary and refractory relapsing disease were probed for evidence of P-glycoprotein gene amplification or overexpression using Southern, Northern, or Western blot techniques. In no case was an increase in P-glycoprotein gene copy number or expression detected. Though these findings do not necessarily rule out a role for P-glycoprotein in mediating drug resistance in breast cancer, electrophoretic analysis of clinical specimens is unlikely to provide useful predictive information. More sensitive assays must be developed to overcome the difficulties inherent in analyzing heterogenous tissue samples.
authors.affiliation: Department of Medicine/Oncology, University of Texas Health Science Center, San Antonio.
authors.forename: D E
authors.initials: DE
authors.lastname: Merkel
authors.forename: S A
authors.initials: SA
authors.lastname: Fuqua
authors.forename: A K
authors.initials: AK
authors.lastname: Tandon
authors.forename: S M
authors.initials: SM
authors.lastname: Hill
authors.forename: A U
authors.initials: AU
authors.lastname: Buzdar
authors.forename: W L
authors.initials: WL
authors.lastname: McGuire
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000818:Animals; D001798:Blood Proteins / Q000032:analysis* / Q000235:genetics; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000032:analysis* / Q000235:genetics; D002460:Cell Line; D006224:Cricetinae; D004273:DNA, Neoplasm / Q000032:analysis; D004351:Drug Resistance; D004586:Electrophoresis; D005260:Female; D005784:Gene Amplification; D006801:Humans; D008562:Membrane Glycoproteins / Q000032:analysis* / Q000235:genetics; D009693:Nucleic Acid Hybridization; D012334:RNA, Neoplasm / Q000032:analysis* / Q000235:genetics
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001798:Blood Proteins; D004273:DNA, Neoplasm; D008562:Membrane Glycoproteins; D012334:RNA, Neoplasm