Nitric oxide-dependent osteopontin expression induces metastatic behavior in HepG2 cells.
Our objective was to delineate the role of nitric oxide (NO) in osteopontin (OPN)-associated metastatic properties in HepG2 cells. OPN is the major phosphoprotein secreted by malignant cells in patients with advanced metastatic cancer, is frequently overexpressed in human tumors, and has been implicated as a key mediator of tumor cell metastasis. OPN is significantly overexpressed in hepatocellular cancer (HCC) and correlates with capsular infiltration and behavior. In addition, significantly increased inducible nitric oxide synthase (iNOS) and NO expression are found in HCC. In archived human samples of normal, cirrhotic, and HCC livers, we demonstrate that iNOS and OPN protein are strongly coexpressed in hepatoma cells. In the setting of cirrhosis, hepatocytes express iNOS, but not OPN. Further in vitro studies performed with HepG2 hepatocellular cancer cells demonstrate that exogenous NO transcriptionally upregulates OPN expression. Enhanced expression of OPN in this setting is associated with increased in vitro cell adhesion and invasion. These data suggest that NO enhances HCC expression of OPN and, as a result, conveys a metastatic phenotype.
Guo
Hongtao
H
Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
Marroquin
Carlos E
CE
Wai
Philip Y
PY
Kuo
Paul C
PC
D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000503:physiopathology / Q000556:secondary*; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002465:Cell Movement; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology* / Q000503:physiopathology; D009361:Neoplasm Invasiveness; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D053495:Osteopontin; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012333:RNA, Messenger; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II