title: TNF-α induces expression of urokinase-type plasminogen activator and β-catenin activation through generation of ROS in human breast epithelial cells.
abstract: Malignant tumors have a capability to degrade the extracellular matrix (ECM) by controlled proteolysis. One of the important components of the proteolysis system involved in such process is urokinase-type plasminogen activator (uPA). Tumor necrosis factor (TNF)-α was found to stimulate uPA. TNF-α impaired the ability of cells to aggregate and to attain compaction. Dyscohesion (cell-cell dissociation) induced by TNF-α was associated with the disordered expression of cadherin/β-catenin at the sites of cell-cell contact. We observed that human breast epithelial (MCF-10A) cells treated with TNF-α transiently up-regulated expression of uPA and its mRNA transcript. In addition, TNF-α induced activation of β-catenin in MCF-10A cells. Based on these findings, we attempted to examine the role of β-catenin and its partner, Tcf-4 in upregulation of uPA. siRNA knock down of β-catenin abrogated TNF-α-induced uPA expression as well as Tcf-4/β-catenin DNA binding. TNF-α-stimulated MCF-10A cells exhibited increased intracellular accumulation of reactive oxygen species (ROS). TNF-α-induced expression of uPA and activation of β-catenin signaling appear to be mediated by ROS in MCF-10A cells, as both events were blocked by the antioxidant N-acetylcysteine. Eupatilin (5,7-dihydroxy-3',4',6-tri-methoxy-flavone), a pharmacologically active flavone derived from Artemisia asiatica, has been shown to possess strong antioxidative activity. Eupatilin inhibited TNF-α-induced intracellular ROS accumulation, expression of uPA and β-catenin activation. Moreover, eupatilin inhibited the TNF-α-induced invasion of MCF-10A cells. Taken together, the above results suggest that eupatilin has chemopreventive effects on mammary tumorigenesis by targeting the β-catenin-uPA axis stimulated by TNF-α.
authors.affiliation: College of Pharmacy, Seoul National University, Seoul, South Korea.
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Do-Hee
authors.initials: DH
authors.lastname: Kim
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Na
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Surh
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology; D002460:Cell Line; D002465:Cell Movement; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D042361:Mammary Glands, Human / Q000187:drug effects / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis*; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D016588:Anticarcinogenic Agents; D005419:Flavonoids; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D051176:beta Catenin; C045325:eupatilin; D014568:Urokinase-Type Plasminogen Activator