Transcriptional activation of insulin-like growth factor-binding protein-4 by 17β-estradiol in MCF-7 cells: Role of estrogen receptor-sp1 complexes

Chunhua Qin, Pomila Singh, Stephen Safe

Research output: Contribution to journalArticle

101 Citations (Scopus)

Abstract

Insulin-like growth factor-binding protein-4 (IGFBP-4) is expressed in MCF-7 human breast cancer cells, and treatment of these cells with 17β-estradiol (E2) resulted in induction of IGFBP-4 gene expression (>3-fold) and protein secretion (>6-fold). To identify genomic sequences associated with E2 responsiveness, the 5′-promoter region (-1214 to +18) of the IGFBP-4 gene was cloned into a vector upstream from the firefly luciferase reporter gene, and E2 induced a 10-fold increase in luciferase activity in MCF-7 cells transiently transfected with this construct. Deletion analysis of this region of the IGFBP-4 gene promoter identified two GC-rich sequences at -559 to -553 and -72 to -64 that were important for E2-induced trans-activation. Gel mobility shift assays using 32P-labeled -569 to -540 and -83 to -54 oligonucleotides from the IGFBP-4 gene promoter showed that Sp1 protein bound these oligonucleotides to form a retarded band, and the intensity of the band was competitively decreased after coincubation with unlabeled IGFBP-4-derived and consensus Sp1 oligonucleotides. Mutation of the GC-rich sites within these sequences resulted in loss of the retarded band formation. Wild-type human estrogen receptor did not bind directly to the IGFBP-4 oligonucleotides; however, human estrogen receptor enhanced Sp1-DNA binding in a concentration-dependent manner. The results of this study demonstrate that at least two GC-rich sequences at -559 to -553 and -72 to -64 are required for induction of IGFBP-4 gene expression by E2 in MCF-7 cells.

Original languageEnglish (US)
Pages (from-to)2501-2508
Number of pages8
JournalEndocrinology
Volume140
Issue number6
DOIs
StatePublished - 1999

Fingerprint

Insulin-Like Growth Factor Binding Protein 4
MCF-7 Cells
Estrogen Receptors
Transcriptional Activation
Estradiol
Oligonucleotides
GC Rich Sequence
Genes
Firefly Luciferases
Gene Expression
Electrophoretic Mobility Shift Assay
Luciferases
Reporter Genes
Genetic Promoter Regions
Proteins
Gels
Breast Neoplasms
Mutation

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Transcriptional activation of insulin-like growth factor-binding protein-4 by 17β-estradiol in MCF-7 cells : Role of estrogen receptor-sp1 complexes. / Qin, Chunhua; Singh, Pomila; Safe, Stephen.

In: Endocrinology, Vol. 140, No. 6, 1999, p. 2501-2508.

Research output: Contribution to journalArticle

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