Abstract
Elevated serum interleukin-6 (IL-6) levels correlates with tumor grade and poor prognosis in cancer patients. IL-6 has been shown to promote tumor lymphangiogenesis through vascular endothelial growth factor-C (VEGF-C) induction in tumor cells. We recently showed that IL-6 also induced VEGF-C expression in lymphatic endothelial cells (LECs). However, the signaling mechanisms involved in IL-6-induces VEGF-C induction in LECs remain incompletely understood. In this study, we explored the causal role of focal adhesion kinase (FAK) in inducing VEGF-C expression in IL-6-stimulated murine LECs (SV-LECs). FAK signaling blockade by NSC 667249 (a FAK inhibitor) attenuated IL-6-induced VEGF-C expression and VEGF-C promoter-luciferase activities. IL-6's enhancing effects of increasing FAK, ERK1/2, p38MAPK, C/EBPβ, p65 and STAT3 phosphorylation as well as C/EBPβ-, κB- and STAT3-luciferase activities were reduced in the presence of NSC 667249. STAT3 knockdown by STAT3 siRNA abrogated IL-6's actions in elevating VEGF-C mRNA and protein levels. Moreover, Src-FAK signaling blockade reduced IL-6's enhancing effects of increasing STAT3 binding to the VEGF-C promoter region, cell migration and endothelial tube formation of SV-LECs. Together these results suggest that IL-6 increases VEGF-C induction and lymphangiogenesis may involve, at least in part, Src-FAK-STAT3 cascade in LECs.
MeSH terms
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Animals
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Cell Line
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Cell Movement / drug effects
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Endothelial Cells / drug effects*
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Endothelial Cells / metabolism
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Extracellular Signal-Regulated MAP Kinases / metabolism
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Focal Adhesion Protein-Tyrosine Kinases / metabolism*
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Gene Expression / drug effects
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Immunoblotting
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Interleukin-6 / pharmacology*
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Lymphangiogenesis / drug effects
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Mice
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Phosphorylation / drug effects
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Promoter Regions, Genetic / genetics
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Protein Binding / drug effects
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RNA Interference
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Reverse Transcriptase Polymerase Chain Reaction
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STAT3 Transcription Factor / genetics
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STAT3 Transcription Factor / metabolism*
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Signal Transduction / drug effects
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Signal Transduction / genetics
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Vascular Endothelial Growth Factor C / genetics
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Vascular Endothelial Growth Factor C / metabolism*
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p38 Mitogen-Activated Protein Kinases / metabolism
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src-Family Kinases / metabolism*
Substances
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Interleukin-6
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STAT3 Transcription Factor
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Vascular Endothelial Growth Factor C
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Focal Adhesion Protein-Tyrosine Kinases
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src-Family Kinases
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Extracellular Signal-Regulated MAP Kinases
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p38 Mitogen-Activated Protein Kinases
Grants and funding
This work was supported by grants (MOST 102-2314-B-706-001, 103-2314-B-706-001) from the Ministry of Science and Technology of Taiwan (
https://www.most.gov.tw/), Y.F.H; grant (102TMU-WFH-02-4) from the Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan (
http://wfh.tmu.edu.tw/), M.J.H; and grant (LSH-2013-01) from the Landseed Hospital, Taoyuan, Taiwan (
http://www.landseedhospital.com.tw), Y.F.H. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.