bcl-2 over-expression enhances NF-kappaB activity and induces mmp-9 transcription in human MCF7(ADR) breast-cancer cells

Int J Cancer. 2000 Apr 15;86(2):188-96. doi: 10.1002/(sici)1097-0215(20000415)86:2<188::aid-ijc7>3.0.co;2-w.


bcl-2 expression is often associated with poor prognosis in several types of tumors; however, the role of this molecule in breast cancer is still controversial. We found earlier that over-expression of bcl-2 in a human breast-cancer cell line (MCF7(ADR)) enhances its tumorigenicity and metastatic potential by inducing metastasis-associated properties such as increased secretion of the matrix metalloproteinase-9 (mmp-9). In the present study, we investigated the effect of bcl-2 over-expression on the activity of the transcription factor NF-kappaB, an important regulator of genes involved in tumor progression and invasion. Transient transfection experiments indicate that over-expression of bcl-2 in the MCF7(ADR) cell line, enhances NF-kappaB-dependent transcriptional activity. Mobility-shift analysis revealed an increase of NF-kappaB DNA-binding in bcl-2-over-expressing clones that correlated with lower levels of the NF-kappaB cytoplasmic inhibitor IkappaBalpha. Moreover, point mutations of 2 highly conserved residues within the BH1 and BH2 domains that abrogate the interaction of bcl-2 with bax, or deletion of the N-terminal BH4 domain, completely eliminate the ability of this molecule to up-regulate NF-kappaB-dependent transactivation. Since mmp-9 is a NF-kappaB-regulated gene, we also investigated whether bcl-2 over-expression up-regulated mmp-9 transcription. We found that induction of mmp-9 mRNA correlates with the activation of an mmp-9-promoter-reporter-gene construct in transient transfection assay, and a mutation of the (-600)mmp-9-NF-kappaB binding element abolishes this effect. The overall data indicate that bcl-2-mediated regulation of NF-kappaB-transcription-factor activity may represent an important mechanism for the promotion of malignant behavior in MCF-7(ADR) cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • DNA / metabolism
  • DNA-Binding Proteins / metabolism
  • Gene Expression*
  • Genes, bcl-2*
  • Humans
  • I-kappa B Proteins*
  • Matrix Metalloproteinase 9 / genetics*
  • NF-KappaB Inhibitor alpha
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism*
  • Point Mutation
  • Proto-Oncogene Proteins c-bcl-2 / physiology
  • RNA, Messenger / biosynthesis
  • Transcription, Genetic*
  • Transfection
  • Tumor Cells, Cultured


  • DNA-Binding Proteins
  • I-kappa B Proteins
  • NF-kappa B
  • NFKBIA protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • NF-KappaB Inhibitor alpha
  • DNA
  • Matrix Metalloproteinase 9