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Mol Cell Biol. 2009 Jul;29(14):3832-44. doi: 10.1128/MCB.00032-09. Epub 2009 May 11.

RelB NF-kappaB represses estrogen receptor alpha expression via induction of the zinc finger protein Blimp1.

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1
Department of Biochemistry K615, Boston University School of Medicine, 72 E. Concord Street, Boston, MA 02118, USA.

Abstract

Aberrant constitutive expression of NF-kappaB subunits, reported in more than 90% of breast cancers and multiple other malignancies, plays pivotal roles in tumorigenesis. Higher RelB subunit expression was demonstrated in estrogen receptor alpha (ERalpha)-negative breast cancers versus ERalpha-positive ones, due in part to repression of RelB synthesis by ERalpha signaling. Notably, RelB promoted a more invasive phenotype in ERalpha-negative cancers via induction of the BCL2 gene. We report here that RelB reciprocally inhibits ERalpha synthesis in breast cancer cells, which contributes to a more migratory phenotype. Specifically, RelB is shown for the first time to induce expression of the zinc finger repressor protein Blimp1 (B-lymphocyte-induced maturation protein), the critical mediator of B- and T-cell development, which is transcribed from the PRDM1 gene. Blimp1 protein repressed ERalpha (ESR1) gene transcription. Commensurately higher Blimp1/PRDM1 expression was detected in ERalpha-negative breast cancer cells and primary breast tumors. Induction of PRDM1 gene expression was mediated by interaction of Bcl-2, localized in the mitochondria, with Ras. Thus, the induction of Blimp1 represents a novel mechanism whereby the RelB NF-kappaB subunit mediates repression, specifically of ERalpha, thereby promoting a more migratory phenotype.

PMID:
19433448
PMCID:
PMC2704748
DOI:
10.1128/MCB.00032-09
[Indexed for MEDLINE]
Free PMC Article
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