ARTICLE ABSTRACT
Inhibitor of IκB kinases (IKK) are key regulators of NF-κB signaling. Three IKK isoforms—α, β, and ϵ—have been linked to oncogenesis, yet the precise components of NF-κB signaling in ovarian cancer have not yet been dissected. We surveyed 120 ovarian cancer specimens for IKK-ϵ expression. Notably, cytoplasmic expression was elevated in metastatic lesions relative to primary tumors (P = 0.03). Therefore, we hypothesized that IKK-ϵ drives ovarian cancer metastasis. IKK-ϵ was identified previously as a breast cancer oncogene and was associated with poor clinical outcome in ovarian cancer. We now define an ovarian cancer–specific IKK-ϵ–regulated gene expression signature using stably expressed short hairpin RNA targeting IKK-ϵ. Pathway analysis of the signature indicated that IKK-ϵ regulates expression of genes involved in cell motility and inflammation. We further showed that IKK-ϵ depletion in metastatic ovarian cancer cell lines decreased growth, adhesion, and invasion. Consistently, human xenografts depleted of IKK-ϵ in mice showed decreased aggressiveness, whereas overexpression of IKK-ϵ in a less invasive ovarian cancer cell line increased metastasis in vivo. Taken together, these data provide evidence that IKK-ϵ is a key coordinator of invasion and metastasis programs in ovarian cancer. Inhibition of IKK-ϵ signaling thus emerges as a viable therapeutic strategy in women whose ovarian cancer shows aberrant activation of this pathway. Cancer Res; 72(21); 5494–504. ©2012 AACR.
