Effects of Pro-Inflammatory Cytokines on the Production of Soluble Fractalkine and ADAM17 by HepG2 Cells

Background and 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 ADAM 17 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-1 beta(p ≤ 0.005) and tumour necrosis factor-alpha (p ≤ 0.043), but not by interleukin-6 (p ≥ 0.316). This corresponded to minor increases in ADAM 17 protein, but not ADAM 17 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 ADAM 17 does not appear to be responsible for regulating this process.