title: Genetic changes in the evolution of multidrug resistance for cultured human ovarian cancer cells.
abstract: The multidrug resistant (MDR) phenotype is often attributed to the activity of ATP-binding cassette (ABC) transporters such as P-glycoprotein (ABCB1). Previous work has suggested that modulation of MDR may not necessarily be a single gene trait. To identify factors that contribute to the emergence of MDR, we undertook integrative genomics analysis of the ovarian carcinoma cell line SKOV3 and a series of MDR derivatives of this line (SKVCRs). As resistance increased, comparative analysis of gene expression showed conspicuous activation of a network of genes in addition to ABCB1. Functional annotation and pathway analysis revealed that many of these genes were associated with the extracellular matrix and had previously been implicated in tumor invasion and cell proliferation. Further investigation by whole genome tiling-path array CGH suggested that changes in gene dosage were key to the activation of several of these overexpressed genes. Remarkably, alignment of whole genome profiles for SKVCR lines revealed the emergence and decline of specific segmental DNA alterations. The most prominent alteration was a novel amplicon residing at 16p13 that encompassed the ABC transporter genes ABCC1 and ABCC6. Loss of this amplicon in highly resistant SKVCR lines coincided with the emergence of a different amplicon at 7q21.12, which harbors ABCB1. Integrative analysis suggests that multiple genes are activated during escalation of drug resistance, including a succession of ABC transporter genes and genes that may act synergistically with ABCB1. These results suggest that evolution of the MDR phenotype is a dynamic, multi-genic process in the genomes of cancer cells.
authors.affiliation: British Columbia Cancer Research Centre, Vancouver, BC, Canada V5Z 1L3. tbuys@bccrc.ca
authors.forename: Timon P H
authors.initials: TP
authors.lastname: Buys
authors.forename: Raj
authors.initials: R
authors.lastname: Chari
authors.forename: Eric H L
authors.initials: EH
authors.lastname: Lee
authors.forename: May
authors.initials: M
authors.lastname: Zhang
authors.forename: Calum
authors.initials: C
authors.lastname: MacAulay
authors.forename: Stephen
authors.initials: S
authors.lastname: Lam
authors.forename: Wan L
authors.initials: WL
authors.lastname: Lam
authors.forename: Victor
authors.initials: V
authors.lastname: Ling
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D018432:Drug Resistance, Multiple / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D053263:Gene Regulatory Networks; D023281:Genomics; D006801:Humans; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C513055:ABCB1 protein, human