Decreased CP-1 (NF-Y) activity results in transcriptional down-regulation of topoisomerase IIalpha in a doxorubicin-resistant variant of human multiple myeloma RPMI 8226.
Biochem Biophys Res Commun
; 237(2): 217-24, 1997 Aug 18.
Article
de En
| MEDLINE
| ID: mdl-9268689
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 (Futscher B.W., Foley N., Gleason-Guzman M., Meltzer P.S., Sullivan D.M., and Dalton W.S., Int'l. J. Cancer, 66 520-5, 1996.). 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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Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Facteurs de transcription
/
Régulation négative
/
ADN topoisomérases de type II
/
Protéines de liaison à l'ADN
/
Isoenzymes
/
Myélome multiple
Type d'étude:
Prognostic_studies
Limites:
Humans
Langue:
En
Journal:
Biochem Biophys Res Commun
Année:
1997
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique