nsforming Growth Factor-β1–Mediated Activation of κB Contributes to Enhanced ADAM-12 Expression

ownload isintegrin and metalloproteinase-12 (ADAM-12), a member of multifunctional family of proteins, is lated in many cancers, including breast, lung, liver, prostate, gastric, and bladder. The multidomain re, composed of a prodomain, a metalloproteinase, disintegrin-like, epidermal growth factor–like, cysteined transmembrane domains, and a cytoplasmic tail, allows ADAM-12 to promote matrix degradation, ll adhesion, and intracellular signaling capacities and thereby to play a critical role in cancer growth etastasis. Despite ample evidence linking increased ADAM-12 expression with cancer, the mechanisms lling its upregulation are still unknown. In the present study, transforming growth factor-β1 (TGF-β1) is to increase ADAM-12 mRNA expression in MDA-MB-231 breast carcinoma cells. We have identified a ter element responsible for TGF-β1–mediated ADAM-12 induction. We show interaction of NF-κB DAM-12 promoter and that high level of NF-κB activity in breast carcinoma cells results in the upren of ADAM-12 expression. Site-directed mutagenesis of the NF-κB element in ADAM-12 promoter and tion of NF-κB activity by Bay-11-7085 and MG-132 significantly reduced TGF-β1–mediated increase of -12 promoter-driven gene expression. Transfection of cells with a dominant-negative mutant form of (IκBαΔN), which inhibits activation of NF-κB, significantly reduced transcription from ADAM-12 ter-reporter in TGF-β1–stimulated MDA-MB-231 cancer cells. In correlation, overexpression of induced ADAM-12 expression in a dose-dependent manner. DNA-binding and ChIP assays indicated 65 subunit of NF-κB binds to ADAM-12 promoter. Together, our study identified a cellular mechanism that p for induction of ADAM-12, which involves NF-κB and its activation by TGF-β1. Mol Cancer Res; 8(9); 1261–70. ©2010 AACR.