IL-13 regulates cancer invasion and metastasis through IL-13Rα2 via ERK/AP-1 pathway in mouse model of human ovarian cancer.

Previously, we have demonstrated that a variety of human cancers including the ovarian cancer express IL-13Rα2, a high affinity receptor for IL-13. Herein, we have examined if IL-13 regulates invasion and metastasis of ovarian cancer through IL-13Rα2 in vitro and in vivo in animal models of human ovarian cancer. We tested cell invasion and protease activity in IL-13Rα2-overexpressing and IL-13Rα2-negative ovarian tumor cell lines. IL-13 treatment significantly augmented both cell invasion and enzyme activities in only IL-13Rα2-positive cells but not in IL-13Rα2-negative cells in vitro. Mechanistically, IL-13 enhanced ERK1/2, AP-1 and MMP activities only in IL-13Rα2-positive cells but not in IL-13Rα2-negative cells. In contrast, other signaling pathways such as IRS1/2, PI3K and AKT do not seem to be involved in IL-13 induced signaling in ovarian cancer cell lines. Highly specific inhibitors for MMP and AP-1 efficiently inhibited both invasion and protease activities without impacting the basal level invasion and protease activities in vitro. In orthotopic animal model of human ovarian cancer, IL-13Rα2-positive tumors metastasized to lymph nodes and peritoneum earlier than IL-13Rα2-negative tumors. Interestingly, the IL-13Rα2-positive tumor bearing mice died earlier than mice with IL-13Rα2-negative tumor. Intraperitoneal injection of IL-13 further shortened survival of IL-13Rα2-positive tumor bearing mice compared to IL-13Rα2-negative tumor mice. IL-13Rα2-positive tumors and lymph node metastasis expressed higher levels of MMPs and higher ERK1/2 activation compared to IL-13Rα2-negative tumors. Taken together, IL-13Rα2 is involved in cancer metastasis through activation of ERK/AP-1 and that targeting IL-13Rα2 might not only directly kill primary tumors but also prevent cancer metastasis.