title: From amplification to function: the case of the MDR1 gene.
abstract: This review describes the features of gene amplification associated with the selection of multidrug-resistant cell lines. Some of these lines carry multiple copies of the MDR1 gene that encodes P-glycoprotein, a broad specificity efflux pump. The MDR1 gene was initially identified as the common component of the amplicons found in multidrug-resistant cell lines selected with different drugs. Subsequent studies have established that increased MDR1 expression is sufficient for the multidrug-resistant phenotype. MDR1-containing amplicons may include a number of additional transcribed genes that do not appear to contribute to multidrug resistance. MDR1 amplification is associated with specific chromosomal changes and apparently non-random recombinational events. Increased expression of the MDR1 gene, however, does not necessarily require gene amplification. Although amplification of the MDR1 gene has not been found in clinical tumor samples, increased expression of this gene is commonly observed in different types of cancer and appears to be a significant marker of clinical drug resistance.
authors.affiliation: Department of Genetics, University of Illinois, Chicago 60612.
authors.forename: I B
authors.initials: IB
authors.lastname: Roninson
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000818:Animals; D004351:Drug Resistance; D005784:Gene Amplification; D006801:Humans; D008562:Membrane Glycoproteins; D012641:Selection, Genetic
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D008562:Membrane Glycoproteins