title: NGAL knockdown by siRNA in human cholangiocarcinoma cells suppressed invasion by reducing NGAL/MMP-9 complex formation.
abstract: We studied the role of Neutrophil Gelatinase-associated Lipocalin (NGAL, lipocalin 2) in regulating the invasiveness of a cholangiocarcinoma cell line, RMCCA-1. RMCCA-1 cells expressed multiple forms of 25, 40, 75 and 115/135 kDa NGAL which were detected in the conditioned medium, whereas only the 25 kDa form was detected in the cell lysates. NGAL expression was induced by serum deprivation. NGAL downregulation by siRNA suppressed NGAL mRNA and protein expression by about 70-80%, concommittant with a significant reduction of in vitro invasiveness, migration and pro-MMP-9 activity, but not cell proliferation. Suppression of pro-MMP-9 activity paralleled a reduction of NGAL/MMP-9 complex in the conditioned medium, although MMP-9 mRNA expression was unaffected. Our data suggest that NGAL promotes the invasiveness of the cholangiocarcinoma cells by forming complex with MMP-9, stabilizing its activity and rendering the cancer cells to be more invasive.
authors.affiliation: Department of Biochemistry, Faculty of Science, Mahidol University, Rama 6 Road, Rajthevi, Bangkok, 10400, Thailand.
authors.forename: Chalinee
authors.initials: C
authors.lastname: Nuntagowat
authors.forename: Kawin
authors.initials: K
authors.lastname: Leelawat
authors.forename: Rutaiwan
authors.initials: R
authors.lastname: Tohtong
mesh_terms: D000209:Acute-Phase Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000235:genetics* / Q000473:pathology; D017931:DNA Primers; D055785:Gene Knockdown Techniques; D006801:Humans; D007150:Immunohistochemistry; D000071068:Lipocalin-2; D054834:Lipocalins / Q000235:genetics* / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000209:Acute-Phase Proteins; D017931:DNA Primers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D020780:Matrix Metalloproteinase 9