title: Cytogenetic characterization and gene expression profiling of the trastuzumab-resistant breast cancer cell line JIMT-1.
abstract: Resistance to the HER-2 targeting drug trastuzumab can be observed clinically, but the lack of suitable experimental models hampers studies of resistance mechanisms. We characterized a HER-2-positive carcinoma cell line (JIMT-1) derived from a 62-year-old breast cancer patient which was clinically resistant to trastuzumab. Multicolor fluorescence in situ hybridization revealed a complex hyperdiploid karyotype with numerous marker chromosomes and unbalanced translocations. Comparative genomic hybridization (CGH) revealed numerous regions of copy number aberration (CNA). Further analysis by array CGH identified 27 regions of CNA (16 amplified, 11 deleted). Thirty-eight percent of the genes in the amplified regions were overexpressed, compared to only 9% in regions of normal copy number ratios (CNR). Accordingly, 26% of the genes in the deleted regions were underexpressed, compared to 10% in regions of normal CNR. Most amplified and overexpressed genes were located on chromosome 1 as well as on 8q, 12q14.1, 17q11 approximately q21, and 20q13. In 17q11 approximately q21, we identified two separate amplicons, the HER-2 amplicon and a previously unreported amplicon at 17q21.31. Several aberrant genes are implicated in cancer development (e.g., JUN, CDK4, and SLUG protooncogenes, as well as the drug/hormone-metabolizing genes GSTM1 and CYP24). We conclude that cytogenetic and expression profiling of JIMT-1 revealed several new features that need further characterization and may shed light on trastuzumab resistance.
authors.affiliation: Department of Oncology, Clinical Sciences, Lund University, Barngatan 2:1, SE-221 85 Lund, Sweden. Karin.Rennstam@med.lu.se
authors.forename: Karin
authors.initials: K
authors.lastname: Rennstam
authors.forename: Göran
authors.initials: G
authors.lastname: Jönsson
authors.forename: Minna
authors.initials: M
authors.lastname: Tanner
authors.forename: Pär-Ola
authors.initials: PO
authors.lastname: Bendahl
authors.forename: Johan
authors.initials: J
authors.lastname: Staaf
authors.forename: Anita I
authors.initials: AI
authors.lastname: Kapanen
authors.forename: Ritva
authors.initials: R
authors.lastname: Karhu
authors.forename: Bo
authors.initials: B
authors.lastname: Baldetorp
authors.forename: Ake
authors.initials: A
authors.lastname: Borg
authors.forename: Jorma
authors.initials: J
authors.lastname: Isola
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002869:Chromosome Aberrations / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D008819:Mice, Nude; D008875:Middle Aged; D009693:Nucleic Acid Hybridization / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D014183:Transplantation, Heterologous; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000068878:Trastuzumab