Transforming Growth Factor-β1–Mediated Activation of NF-κB Contributes to Enhanced ADAM-12 Expression in Mammary Carcinoma Cells

Abstract

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, cysteinerich 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.

RETRACTED: Minocycline Targets the NF-κB Nexus through Suppression of TGF-β1-TAK1-IκB Signaling in Ovarian Cancer

“…On the basis of these data, it has been suggested that in the context of ovarian cancer, mutations and/or alterations of the key nodes along canonical TGF-b pathway shift TGF-b to noncanonical pathways such as activation of NF-kB which describes the pro-oncogenic role of TGF-b in advanced ovarian cancer (38,39). In fact, activation of TGF-b/NFkB pathway has been defined as the underlying mechanism in the phenomenon of conversion of TGF-b from a tumor suppressor to a tumor promoter during tumorigenesis (28,40,41). In our study, it was found that minocycline downregulates the endogenous levels of TGF-b1.…”

Metalloprotease-Disintegrin ADAM12 Expression Is Regulated by Notch Signaling via MicroRNA-29

“…We and others have recently demonstrated that ADAM12 expression is induced by transforming growth factor ␤ (TGF␤) via Smad-dependent and Smad-independent signaling pathways (35)(36)(37)(38)(39). Consistently, ADAM12 induction by TGF␤ is significantly attenuated in Smad2 Ϫ/Ϫ or Smad3 Ϫ/Ϫ MEFs (37).…”

“…Several studies demonstrated that ADAM12 expression is induced by TGF␤, via both Smad-dependent and Smad-independent pathways (35)(36)(37)(38)(39). Interestingly, ADAM12 induction by TGF␤, similar to the induction by Notch, is completely abolished by MG132 (37,39).…”

“…It has been reported recently that NF-B interacts with certain regions of the human ADAM12 promoter (39). Thus, it seemed feasible that Notch might activate transcription of the Adam12 gene, either through stimulation of the NF-B pathway or via direct binding of CSL to Adam12 promoter.…”

Perivascular Cells in Diffuse Cutaneous Systemic Sclerosis Overexpress Activated ADAM12 and Are Involved in Myofibroblast Transdifferentiation and Development of Fibrosis

“…ADAM12 plays a direct profibrotic role, regulating TGF-β signaling 23,42,43 . After TGF-β binds with specific receptors, the signal is transduced to the nucleus by members of the Sma-and Mad-related (Smad) family.…”