IL-33-induced JNK pathway activation confers gastric cancer chemotherapy resistance

Inflammation is regarded as one of the major hallmarks of tumors, and has a very close relationship with gastric cancer. Interleukin-33 (IL-33), a new member of the IL-1 family, plays an important role in both inflammatory disease and tumors. The present study was designed to explore the effects of IL-33 on the proliferation, drug sensitivity, and the invasiveness of gastric cancer cells in vitro. IL-33 at concentrations lower than 100 pg/ml did not alter the inhibitory rate of gastric cancer cells. Moreover, IL-33 at these low concentrations protected against platinum-induced apoptosis in various gastric cancer cell lines, yet not in normal gastric epithelial cells. We also found that IL-33 increased the activation of the JNK pathway, and enhanced the expression of ST2. Furthermore, SP600125, a selective inhibitor of the JNK pathway, significantly blocked the protective effects of IL-33 in gastric cancer cells. In addition, Matrigel invasion assay showed that IL-33 markedly promoted gastric cancer cell invasion. In conclusion, the present study demonstrated that IL-33 protected against platinum-induced apoptosis and promoted cell invasion via activation of the JNK pathway in gastric cancer cells. In light of the prevalence of platinum-based chemotherapeutics in the treatment of gastric cancer, our results suggest that the level of IL-33 should be monitored during the treatment of gastric cancer, particularly when using platinum-based chemotherapeutics.