Effects of pro-inflammatory cytokines on the production of soluble fractalkine and ADAM17 by HepG2 cells.

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.