Work

Estrogen Up-Regulation of p53 Gene Expression in MCF-7 Breast Cancer Cells Is Mediated by Calmodulin Kinase IV-Dependent Activation of a Nuclear Factor κB/CCAAT-Binding Transcription Factor-1 Complex

Year: 2002

Type: article

Abstract: This study investigates the mechanism of hormonal regulation of p53 gene expression in MCF-7 human breast cancer cells. 17beta-Estradiol (E2) induced a 2-fold increase in p53 mRNA levels and a 2- to 3-fold increase in p53 protein. Analysis of the p53 gene promoter has identified a minimal E2-responsive region at -106 to -40, and mutation/deletion analysis of the promoter showed that motifs that bind CCAAT-binding transcription factor-1 (CTF-1) and nuclear factor kappaB (NFkappaB) proteins are required for hormone responsiveness. The p65 subunit of NFkappaB was identified in both nuclear and cytosolic fractions of untreated MCF-7 cells; however, formation of the nuclear NFkappaB complex was E2 independent. Hormonal activation of constructs containing p53 promoter inserts (-106 to -40) and the GAL4-p65 fusion proteins was inhibited by the intracellular Ca2+ ion chelator EGTA-AM and Ca2+/calmodulin-dependent protein kinase (CaMK) inhibitor KN-93. Constitutively active CaMKIV but not CaMKI activated p65, and treatment of MCF-7 cells with E2 induced phosphorylation of CaMKIV but not CaMKI. The results indicate that hormonal activation of p53 though nongenomic pathways was CaMKIV-dependent and involved cooperative p65-CTF-1 interactions.

Source: Molecular Endocrinology

DOI: 10.1210/me.2002-0006

Authors: Chunhua Qin, Thu Nguyen, Jessica Stewart, Ismael Samudio, Robert Burghardt, Stephen Safe

Institution: Texas A&M University

Language: English

Topic: Estrogen and related hormone effects

Subfield: Genetics

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: Texas AgriLife Research, National Institutes of Health, National Institute of Environmental Health Sciences