title: Integrin-linked kinase regulates melanoma angiogenesis by activating NF-κB/interleukin-6 signaling pathway.
abstract: Integrin-linked kinase (ILK) is a highly conserved serine-threonine protein kinase involved in cell-extracellular matrix interactions, cytoskeletal organization and cell signaling. Overexpression of ILK in epithelial cells leads to anchorage-independent growth with increased cell cycle progression. Previously, we have shown that ILK upregulation strongly correlates with melanoma progression, invasion and inversely correlates with 5-year survival of melanoma patients. However, the molecular mechanism by which ILK enhances melanoma progression is currently unknown. In the present study, we found that proangiogenic molecule interleukin-6 (IL-6) is the downstream target of ILK in melanoma cells. ILK overexpression increased IL-6, whereas silencing of ILK suppressed IL-6 expression at both messenger RNA and protein levels. ILK also altered the activity and subcellular localization of nuclear factor-kappaB (NF-κB) subunit p65. We further found that ILK enhanced the IL-6 gene transcription by promoting the binding of NF-κB p65 to IL-6 promoter. Moreover, ILK overexpression in melanoma cells enhanced the tube-forming ability of endothelial cells in vitro and microvessel formation in vivo. ILK-induced tube and blood vessel formation of endothelial cells was significantly reduced upon IL-6 inhibition in ILK-overexpressing melanoma cells. To delineate the mechanism by which ILK-induced IL-6 production can enhance angiogenesis, further analysis of the downstream targets of IL-6 signaling showed an increased activity of the signal transducer and activator of transcription 3 (STAT3) in ILK-overexpressing cells. As STAT3 binds to vascular endothelial growth factor (VEGF) promoter, we found that VEGF levels were elevated in ILK-overexpressing cells and declined upon transfection of IL-6 small interfering RNA, suggesting that ILK may regulate VEGF expression through IL-6 pathway by activating STAT3.
authors.affiliation: Department of Dermatology and Skin Science, Jack Bell Research Centre, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: A A
authors.initials: AA
authors.lastname: Wani
authors.forename: S M
authors.initials: SM
authors.lastname: Jafarnejad
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: G
authors.initials: G
authors.lastname: Li
mesh_terms: D021581:Active Transport, Cell Nucleus; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000502:physiology*; D008545:Melanoma / Q000098:blood supply* / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000209:etiology*; D018919:Neovascularization, Physiologic; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D051996:Transcription Factor RelA / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics; D000099200:Scaffold Protein ILK
chemical_list: D015850:Interleukin-6; D017346:Protein Serine-Threonine Kinases; D050796:STAT3 Transcription Factor; D051996:Transcription Factor RelA; D042461:Vascular Endothelial Growth Factor A; D000099200:Scaffold Protein ILK; C498143:RELA protein, human; C494086:STAT3 protein, human