Effects of Pro-Inflammatory Cytokines on the Production of Soluble Fractalkine and ADAM17 by HepG2 Cells
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Sharon L. Turner1, David Mangnall2, Nigel C. Bird2, Maria E. Blair-Zajdel1, Rowena A.D. Bunning1
1) Biomedical Research Centre, Sheffield Hallam University, Sheffield;
2) Liver Research Group, Royal Hallamshire Hospital, University of Sheffield, Sheffield, UK
Background & Aims: Soluble fractalkine is increased in the liver during times of injury; however the effect of pro-inflammatory cytokines in this process is currently unknown. The aim of this study was to determine whether pro-inflammatory cytokines elevated in patients with hepatocellular carcinoma influence fractalkine shedding from HepG2 cells and whether ADAM17 was involved in this process.
Methods: In vitro experiments were performed in the human hepatocellular carcinoma cell line HepG2. Soluble fractalkine was detected using an ELISA. ADAM17 expression was investigated using quantitative real time (reverse transcription)-polymerase chain reaction and flow cytometry. Short interfering RNA transfection was used to down-regulate ADAM17 expression.
Results: Soluble fractalkine was present in supernatants of HepG2 cells, and was significantly increased by interleukin-1β (p≤0.005) and tumour necrosis factor-α (p≤0.043), but not by interleukin-6 (p≥0.316). This corresponded to minor increases in ADAM17 protein, but not ADAM17 mRNA, following the same treatments. However, the down-regulation of ADAM17 protein did not affect fractalkine shedding.
Conclusions: This study showed that soluble fractalkine is up-regulated under inflammatory conditions associated with hepatocellular carcinoma development, but ADAM17 does not appear to be responsible for regulating this process.
Fractalkine - ADAM17 - cytokines - cancer - hepatocellular carcinoma - HepG2.