ABSTRACT
The secondary bile acid lithocholic acid (LCA) induced expression of urokinase-type plasminogen activator receptor (uPAR) and enhanced cell invasiveness in colon cancer cells. A dominant negative mutant or a specific inhibitor of MEK-1 suppressed LCA-induced uPAR expression. Deletions and site-directed mutagenesis revealed that the AP-1 site was required for LCA-induced uPAR transcription. LCA-mediated enhanced cell invasiveness was partially abrogated by uPAR neutralizing antibody and inhibitors of both Erk-1/2 and AP-1. These results suggest that LCA induces uPAR expression via Erk-1/2 and AP-1 pathway and, in turn, stimulate invasiveness of human colon cancer cells.
Subject(s)
Lithocholic Acid/metabolism , Mitogen-Activated Protein Kinases/metabolism , Neoplasm Invasiveness/genetics , Receptors, Urokinase Plasminogen Activator/metabolism , Signal Transduction/physiology , Transcription Factor AP-1/metabolism , Blotting, Northern , Blotting, Western , Cell Line, Tumor , Colonic Neoplasms/genetics , Colonic Neoplasms/metabolism , Colonic Neoplasms/pathology , Electrophoretic Mobility Shift Assay , Gene Expression , Gene Expression Regulation, Neoplastic , Humans , Mitogen-Activated Protein Kinases/genetics , RNA, Messenger/analysis , Transcription Factor AP-1/genetics , Transfection , Up-RegulationABSTRACT
Resveratrol, a grape polyphenol, is thought to have anti-inflammatory, cardioprotective, and cancer preventive properties. However, the mechanisms by which resveratrol might produce these effects are not clearly defined. A study was performed on whether resveratrol could prevent tumor cells from adhering to endothelial cells, which is an essential step during tumor metastasis. Phorbol 12-myristate 13-acetate (PMA) induced human fibrosarcoma HT1080 cells to adhere to endothelial ECV304 cells. Resveratrol inhibited PMA-induced HT1080 cells adhesion in a dose-dependent manner. To further study the mechanisms of this resveratrol-mediated blockade of tumor cell adhesion, the expression of the cell adhesion molecules intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin were examined. PMA induced ICAM-1 expression in HT1080 cells. In contrast, the expression of VCAM-1 and E-selectin were not altered by PMA treatment. The increase in tumor cell adhesion to endothelial cells following PMA treatment was partially inhibited by ICAM-1 siRNA or neutralizing antibodies. Resveratrol reduced the PMA-induced ICAM-1 expression in HT1080 cells as determined by RT-PCR, flow cytometry and ELISA. As the induction of ICAM-1 requires activation of the transcription factor NF-kappaB, the effects of resveratrol on the activation of this factor in HT1080 cells was also investigated. Resveratrol inhibited the PMA-induced NF-kappaB activation and NF-kappaB-dependent luciferase activity. These results suggest that resveratrol may exert an antimetastatic effect by inhibiting NF-kappaB activation and ICAM-1 expression, leading to suppression of tumor cell adhesion to endothelial cells.
Subject(s)
Cell Adhesion/drug effects , Endothelial Cells/drug effects , Fibrosarcoma/pathology , Intercellular Adhesion Molecule-1/biosynthesis , Stilbenes/pharmacology , Dose-Response Relationship, Drug , Endothelial Cells/metabolism , Endothelial Cells/pathology , Fibrosarcoma/drug therapy , Fibrosarcoma/metabolism , Humans , Intercellular Adhesion Molecule-1/genetics , NF-kappa B/antagonists & inhibitors , NF-kappa B/metabolism , RNA, Small Interfering/genetics , Resveratrol , Tetradecanoylphorbol Acetate/pharmacology , TransfectionABSTRACT
There is a strong correlation between the overexpression of urokinase-type plasminogen activator receptor (uPAR) and gastric cancer invasion. This study examined the effect of phospholipid lysophosphatidic acid (LPA) on uPAR expression in human gastric cancer AGS cells and the underlying signal transduction pathways. Treating human gastric AGS cells with LPA induced the expression of uPAR mRNA and promoter activity in both a time- and dose-dependent manner. Small interfering RNA targeting for LPA receptors, dominant negative Rho-family GTPase (RhoA, Rac1, and Cdc42) and an expression vector encoding a mutated c-jun (TAM67) partially blocked the LPA-induced uPAR expression. Site-directed mutagenesis and electrophoretic mobility shift studies showed that the transcription factors activation protein-1 (AP-1) and nuclear factor (NF)-kappaB are essential for the LPA-induced uPAR transcription. In addition, AGS cells treated with LPA showed enhanced invasion, which was partially abrogated by the uPAR-neutralizing antibodies and inhibitors of Rho kinase, JNK, and NF-kappaB. This suggests that LPA induces uPAR expression through the LPA receptors, Rho-family GTPase, JNK, AP-1 and NF-kappaB signaling pathways, which in turn stimulates the cell invasiveness of human gastric cancer AGS cells.
Subject(s)
Gene Expression Regulation, Neoplastic , Lysophospholipids/pharmacology , Receptors, Cell Surface/metabolism , Stomach Neoplasms/metabolism , Up-Regulation , Cell Line, Tumor , Cell Movement , Cell Nucleus/metabolism , Collagen/metabolism , Drug Combinations , Humans , Laminin/metabolism , NF-kappa B/metabolism , Neoplasm Invasiveness , Promoter Regions, Genetic , Proteoglycans/metabolism , Receptors, Urokinase Plasminogen Activator , Transcription Factor AP-1/metabolismABSTRACT
Licochalcones have a variety of biological properties including anti-tumor, anti-parasitic and anti-bacterial activities. Recently, a new retrochalcone (licochalcone E, Lico-E) was isolated from the roots of Glycyrrhiza inflata (Chem. Pharm. Bull., 53, 2005, Yoon et al.) by cytotoxicity-guided fractionation. This study examined whether or not Lico-E-induced endothelial cell death occurs through apoptosis, and investigated molecular mechanisms involved in this process. Lico-E was found to suppress ECV304 cell growth and induce apoptosis. The induction of apoptosis by Lico-E was confirmed by the ladder-patterned DNA fragmentation, the presence of cleaved and condensed nuclear chromatin and the increased number of annexin V-positive cells. Lico-E could effectively inhibit the constitutive NF-kappaB activation, as revealed by the electrophoretic mobility shift assay and NF-kappaB-dependent luciferase reporter study. In addition, the Lico-E treatment caused a change in the Bax/Bcl-2 ratio that favored apoptosis. These results suggest that Lico-E induces endothelial cell apoptosis by modulating NF-kappaB and the Bcl-2 family.
