Decreased CP-1 (NF-Y) activity results in transcriptional down-regulation of topoisomerase IIα in a doxorubicin-resistant variant of human multiple myeloma RPMI 8226

Hong Wang, Zhi Gang Jiang, Yee W. Wong, William S. Dalton, Bernard W Futscher, Victor T W Chan

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Decreased topoisomerase II (Topo II) activity results in resistance to antineoplastic agents targeting this enzyme. Dox1V derived from human multiple myeloma RPMI 8226 demonstrated a 4-fold resistance to doxorubicin in the absence of MDR1 overexpression or topo II mutations. Consistent with its drug resistant phenotype, a 2- to 3-fold decrease in topo II expression was identified. To investigate the molecular basis for decreased topo II expression in Dox1V, a semi-quantitative analysis of Topo II activity, protein level and mRNA transcript were performed. The results demonstrated that reduced Topo II activity is due to a decreased mRNA level. Southern blot and sequencing experiments revealed wild-type sequence of the topo II promoter in the drug resistant cells. Transient gene expression assays demonstrated that topo II is transcriptionally down-regulated in Dox1V independent of the promoter sequence of the endogenous alleles. Instead, the activity of a ubiquitous transcription factor CP-1 (NF-Y) interacting with the topo II promoter is decreased. The decrease in CP-1/NF-Y activity in Dox1V is correlated well with the decrease in topo II transcriptional activity, transcript level, Topo II protein and enzyme activity. Therefore, transcriptional down-regulation resulted from a reduced CP-1/NF-Y activity is responsible for decreased topo II expression in Dox1V cells.

Original languageEnglish (US)
Pages (from-to)217-224
Number of pages8
JournalBiochemical and Biophysical Research Communications
Volume237
Issue number2
DOIs
StatePublished - Aug 18 1997

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Type II DNA Topoisomerase
Multiple Myeloma
Doxorubicin
Down-Regulation
Neoplasm Drug Resistance
Messenger RNA
Enzyme activity
Enzymes
Southern Blotting
Gene expression
Pharmaceutical Preparations
Antineoplastic Agents
Assays
Proteins
Transcription Factors
Alleles
Phenotype
Gene Expression
Mutation
Chemical analysis

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Decreased CP-1 (NF-Y) activity results in transcriptional down-regulation of topoisomerase IIα in a doxorubicin-resistant variant of human multiple myeloma RPMI 8226. / Wang, Hong; Jiang, Zhi Gang; Wong, Yee W.; Dalton, William S.; Futscher, Bernard W; Chan, Victor T W.

In: Biochemical and Biophysical Research Communications, Vol. 237, No. 2, 18.08.1997, p. 217-224.

Research output: Contribution to journalArticle

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abstract = "Decreased topoisomerase II (Topo II) activity results in resistance to antineoplastic agents targeting this enzyme. Dox1V derived from human multiple myeloma RPMI 8226 demonstrated a 4-fold resistance to doxorubicin in the absence of MDR1 overexpression or topo II mutations. Consistent with its drug resistant phenotype, a 2- to 3-fold decrease in topo II expression was identified. To investigate the molecular basis for decreased topo II expression in Dox1V, a semi-quantitative analysis of Topo II activity, protein level and mRNA transcript were performed. The results demonstrated that reduced Topo II activity is due to a decreased mRNA level. Southern blot and sequencing experiments revealed wild-type sequence of the topo II promoter in the drug resistant cells. Transient gene expression assays demonstrated that topo II is transcriptionally down-regulated in Dox1V independent of the promoter sequence of the endogenous alleles. Instead, the activity of a ubiquitous transcription factor CP-1 (NF-Y) interacting with the topo II promoter is decreased. The decrease in CP-1/NF-Y activity in Dox1V is correlated well with the decrease in topo II transcriptional activity, transcript level, Topo II protein and enzyme activity. Therefore, transcriptional down-regulation resulted from a reduced CP-1/NF-Y activity is responsible for decreased topo II expression in Dox1V cells.",
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