ABSTRACT
BACKGROUND: Up-regulation of the hepatocyte growth factor (HGF), its transmembrane tyrosine kinase receptor (c-Met), and urokinase type plasminogen activator (uPA), is associated with the development and metastasis of various types of cancers. However, the mechanisms by which HGF/c-Met signaling mediates cancer progression and metastasis are unclear. METHODS: We investigated the roles of HGF/c-Met in tumor progression and metastasis in NUGC-3 and MKN-28 stomach cancer cell lines. RESULTS: Treatment with HGF increased c-Met phosphorylation in a dose-dependent manner, as well as increasing cell proliferation. HGF treatment also increased the protein level and the activity of uPA in NUGC-3 and MKN-28 cells. A monoclonal antibody against human uPA receptor (uPAR), mAb 3936, inhibited HGF-mediated tumor cell invasion in a dose-dependent manner. Down-regulation of uPA using uPA-shRNA induced a decrease in in vitro cell invasion in NUGC-3 cells. CONCLUSIONS: These results suggest that NUGC-3 and MKN-28 cells express functional c-Met, which may provide a therapeutic target for interfering with metastases of cancer cells by inhibiting uPA and uPAR-mediated proteolysis.
Subject(s)
Humans , Urokinase-Type Plasminogen Activator/antagonists & inhibitors , Stomach Neoplasms/drug therapy , Signal Transduction/drug effects , Receptors, Growth Factor/drug effects , Receptor Protein-Tyrosine Kinases/drug effects , Proto-Oncogene Proteins c-met/drug effects , Neoplasm Metastasis , Hepatocyte Growth Factor/metabolism , Disease Progression , Adenocarcinoma/drug therapyABSTRACT
PURPOSE: Increased expression of the hepatocytes growth factor (HGF) receptor (c-Met) and urokinase type plasminogen activator (uPA) correlate with the development and metastasis of cancers. However, the mechanisms by which HGF/c-Met signaling mediate cancer progression and metastasis are unclear. Therefore, we investigated the roles of HGF/c-Met in tumor progression and metastasis in pancreatic cancer cell lines, L3.6PL and IMIN-PC2. MATERIALS AND METHODS: To see the functional c-Met protein, we were performed immunoprecipitation for functional c-Met protein. And also performed western bolot analysis and gel zymography for the functional uPA protein. To see the inhibition effects of uPAR monoclonal antibody on invasiveness of two pancreatic cancer cell lines, we were carried out standard two chamber invasion assay. RESULTS: At first, we observed the HGF-mediated c-Met phosphorylation and cell growth. c-Met phosphorylation was increased in the HGF-treated cells in a dose dependent manner. HGF resulted in increments of cell growth and ERK phosphorylation. HGF treatment increased the uPA expression and the uPA activity. A monoclonal antibody 3936, specific to uPAR receptor, inhibited HGF- mediated tumor cell invasion in a dose dependent manner. CONCLUSION: These results suggest that functional c- Met and HGF/c-Met signaling up-regulate the activity of uPA and result in increments of invasion-metastasis in the pancreatic cancer cells.