Transcription profiling by array of hepatocellular carcinoma cell lines following treatment with STAT3 shRNA and IL-6, IL-27 or IFN-gamma

Interleukin-27 (IL27) is a type-I-cytokine of the IL6/IL12 family predominantly secreted by activated macrophages and dendritic cells. Best understood are the effects of IL27 on immune cells where it has been described to have pro- or anti-inflammatory properties, either promoting TH1 responses or suppressing TH1 and TH2 responses. The action on other cell types is less well studied. In the liver, IL27 expression was observed to be upregulated in patients with hepatitis B, and sera of hepatocellular carcinoma (HCC) patients contain significantly elevated levels of IL27 compared to healthy controls or patients with hepatitis and/or liver cirrhosis. We previously reported interferon-gamma-like antiviral activity of IL27 in hepatic cells. Here we further studied the effects of IL27 on HCC cells in comparison to other cytokines. We were especially interested in the relevance of the IL27-induced STAT3 activation. Thus we compared its response with those induced by IFNg (STAT1-dominated response) or IL6-type cytokines (IL6, Hyper-IL6 or OSM) (STAT3-dominated response). We find that in hepatocytes, IL27 induces an IFNg-like, STAT1-dependent transcriptional response, but we do not find an effective STAT3-dependent response. The availability of STAT1 seems critical in the shaping of the IL27 response, as the siRNA knock-down of STAT1 revealed its ability to induce the acute-phase protein gamma-fibrinogen, a typical IL6 family characteristic. Moreover, we describe a crosstalk between the signaling of IL6-type cytokines and IL27: responses to the gp130-engaging cytokine IL27 (but not those to IFNs) can be inhibited by IL6-type cytokine pre-stimulation, likely by a SOCS3-mediated mechanism. This experiment represents microarray analysis of three hepatocellular carcinoma cell lines treated with IL-27, IFNg, hyper-IL6 or OSM in combination with shRNA knockdown of STAT3.