Evidence for linear extrachromosomal elements mediating gene amplification in the multidrug-resistant J774.2 murine cell line

Eckart U. Meese, Susan Band Horwitz, Jeffrey M. Trent

Research output: Contribution to journalArticle

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Abstract

Previous studies from our laboratory have demonstrated specific cytogenetic alterations accompanying development of colchicine resistance in the J774.2 murine cell line and in two sublines (J7.Cl-30 and J7.Cl-100) [1]. Although gene amplification is not observed in the parental J774.2 cell line, a ∼35-fold amplification of the gene for p-glycoprotein (mdr) was noted in the J7.Cl-30 subline (770-fold CLCR) and a ∼70-fold amplification in the J7.Cl-100 subline (2500-fold CLCR). In this study, we analyzed the localization and organization of the mdr gene. In the colchicine-resistant (CLCR) J7.Cl-30 subline, the p-glycoprotein domain was observed to reside on differently sized extrachromosomal elements. Our results indicate not only circular extrachromosomal elements but also linear extrachromosomal elements. By means of pulsed-field gel electrophoresis (PFGE), the sizes of the extrachromosomal elements were shown to be >2,500 kilobasepairs (kb), 800 kb, and 400 kb. In contrast, the J7.Cl-100 subline was characterized by the presence of homogeneously staining regions (HSRs). We have noted that with increasing colchicine resistance the extrachromosomal elements are replaced by HSRs. Our findings of linear elements that appear to be precursors of HSRs may offer a new way to interpret different theories of extrachromosomal gene amplification. The J7.Cl-30 cell line presents a unique system to analyze further the formation and structure of extrachromosomal elements.

Original languageEnglish (US)
Pages (from-to)20-25
Number of pages6
JournalCancer Genetics and Cytogenetics
Volume59
Issue number1
DOIs
StatePublished - 1992
Externally publishedYes

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Gene Amplification
Colchicine
Cell Line
Staining and Labeling
Glycoproteins
Pulsed Field Gel Electrophoresis
Cytogenetics
Genes

ASJC Scopus subject areas

  • Cancer Research
  • Genetics
  • Molecular Biology

Cite this

Evidence for linear extrachromosomal elements mediating gene amplification in the multidrug-resistant J774.2 murine cell line. / Meese, Eckart U.; Band Horwitz, Susan; Trent, Jeffrey M.

In: Cancer Genetics and Cytogenetics, Vol. 59, No. 1, 1992, p. 20-25.

Research output: Contribution to journalArticle

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