Reactive oxygen species regulate urokinase plasminogen activator expression and cell invasion via mitogen-activated protein kinase pathways after treatment with hepatocyte growth factor in stomach cancer cells.
BACKGROUND
Reactive oxygen species (ROS) are closely associated with the intracellular signal cascade, thus strongly implicating involvement in tumor progression. However, the mechanism by which ROS are generated and how ROS target downstream molecules to trigger tumor metastasis is unclear. In this study, we investigated the underlying signal pathways in ROS-induced urokinase plasminogen activator (uPA) expression in the human gastric cancer cells, NUGC-3 and MKN-28.


RESULTS
Intracellular ROS, as determined using the fluorescent probe, 2'-7' dichlorofluorescein diacetate, decreased after treatment with hepatocyte growth factor (HGF). We confirmed that Rac-1 regulated ROS production after activation of the AKT pathway with HGF. Exogenously added H2O2 promoted the expression of HGF, but not in a dose-dependent manner and also showed negative expression of HGF after co-treatment with H2O2 and HGF. Treatment with NAC, an intracellular free radical scavenger, decreased the enhancement of uPA production and tumor invasion in both cells. We clarified the downstream pathways regulated by ROS after treatment with H2O2, which showed negative control between FRK and p38 kinase activities for uPA regulation.


CONCLUSIONS
HGF regulates Rac-1-induced ROS production through the Akt pathway and ROS regulates uPA production and invasion via MAP kinase, which provides novel insight into the mechanisms underlying the progression of gastric cancer.
Lee
Kyung Hee
KH
Biochemistry and Molecular Biology, College of Medicine, Yeungnam University, Daegu, Korea. lkhee@med.yu.ac.kr
Kim
Sang Woon
SW
Kim
Jae-Ryong
JR
D015153:Blotting, Western; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D016877:Oxidants / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics* / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
D016877:Oxidants; C107953:RAC1 protein, human; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D017228:Hepatocyte Growth Factor; D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D014568:Urokinase-Type Plasminogen Activator; D020830:rac1 GTP-Binding Protein