Transforming growth factor-beta1-mediated activation of NF-kappaB contributes to enhanced ADAM-12 expression in mammary carcinoma cells.
A disintegrin and metalloproteinase-12 (ADAM-12), a member of multifunctional family of proteins, is upregulated in many cancers, including breast, lung, liver, prostate, gastric, and bladder. The multidomain structure, composed of a prodomain, a metalloproteinase, disintegrin-like, epidermal growth factor-like, cysteine-rich and transmembrane domains, and a cytoplasmic tail, allows ADAM-12 to promote matrix degradation, cell-cell adhesion, and intracellular signaling capacities and thereby to play a critical role in cancer growth and metastasis. Despite ample evidence linking increased ADAM-12 expression with cancer, the mechanisms controlling its upregulation are still unknown. In the present study, transforming growth factor-β1 (TGF-β1) is shown to increase ADAM-12 mRNA expression in MDA-MB-231 breast carcinoma cells. We have identified a promoter element responsible for TGF-β1-mediated ADAM-12 induction. We show interaction of NF-κB with ADAM-12 promoter and that high level of NF-κB activity in breast carcinoma cells results in the upregulation of ADAM-12 expression. Site-directed mutagenesis of the NF-κB element in ADAM-12 promoter and inhibition of NF-κB activity by Bay-11-7085 and MG-132 significantly reduced TGF-β1-mediated increase of ADAM-12 promoter-driven gene expression. Transfection of cells with a dominant-negative mutant form of IκBα (IκBαΔN), which inhibits activation of NF-κB, significantly reduced transcription from ADAM-12 promoter-reporter in TGF-β1-stimulated MDA-MB-231 cancer cells. In correlation, overexpression of NF-κB induced ADAM-12 expression in a dose-dependent manner. DNA-binding and ChIP assays indicated that p65 subunit of NF-κB binds to ADAM-12 promoter. Together, our study identified a cellular mechanism for induction of ADAM-12, which involves NF-κB and its activation by TGF-β1.
Ray
Alpana
A
Department of Veterinary Pathobiology, University of Missouri, 124 Connaway Hall, Columbia, MO 65211, USA.
Dhar
Srijita
S
Ray
Bimal K
BK
D051722:ADAM Proteins / Q000235:genetics* / Q000378:metabolism; D000072199:ADAM12 Protein; D001483:Base Sequence; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005799:Genes, Dominant; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
D020672:I-kappa B Proteins; D008565:Membrane Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D053773:Transforming Growth Factor beta1; D000072000:NF-KappaB Inhibitor alpha; D051722:ADAM Proteins; D000072199:ADAM12 Protein; C000606480:ADAM12 protein, human