Targeting IL-6 signaling by monoclonal antibody siltuximab attenuates cholangiocarcinoma growth.

Background and aim Cholangiocarcinoma has an unimproved prognosis. Interleukin 6 (IL-6) has an oncogenic potential in some cancer diseases. However, the role of IL-6 in cholangiocarcinoma carcinogenesis is not well understood. The current study investigated the role of IL-6 signaling in cholangiocarcinoma carcinogenesis and efficacy of siltuximab treatment on Cholangiocarcinoma in vitro and in vivo. Methods The expression of IL-6 was analyzed on human cholangiocarcinoma cell lines, murine and human cholangiocarcinoma tissues, using reverse transcription real time PCR and immunohistochemistry. In addition, the effect of anti-IL-6 chimeric monoclonal antibody, siltuximab, were investigated in vitro by proliferation, migration, two-dimensional and three-dimensional invasion assays and in vivo by xenograft mouse model. Western blot was applied to study the molecular alteration. Results Our result shows high expression of IL-6 in human cholangiocarcinoma cells, and IL-6 stimulants enhance cholangiocarcinoma cell proliferation. In addition, murine and human cholangiocarcinoma tissues express significantly higher levels of IL-6, compared to adjacent non-tumor tissues. On the cholangiocarcinoma engineered mouse model, IL-6 level is associated with tumor volume. Taken together, our data indicate an oncogenic potential of IL-6 in cholangiocarcinoma carcinogenesis. Siltuximab sufficiently abrogates IL-6 signaling and inhibits cholangiocarcinoma progression in vitro and in vivo. The results additionally indicate a relative alteration of IL-6 signaling and its molecular targets, such as STAT3, Wnt/β-catenin and mesenchymal markers. Conclusions IL-6 plays an essential role in cholangiocarcinoma carcinogenesis, and siltuximab has the potential to be considered as a new treatment option for cholangiocarcinoma patients.