Epithelial-mesenchymal transition: NF-kappaB takes center stage.

Activation of the transcription factor NF-kappaB occurs in many human tumors, and studies have shown that NF-kappaB can promote cell proliferation and oncogenesis, possibly by protecting cells from apoptosis. Little is known, however, about whether NF-kappaB is involved in tumor progression including epithelial-mesenchymal transition (EMT), a central process governing both morphogenesis and carcinoma progression in multicellular organisms. In a combined in vitro/in vivo model of mammary carcinogenesis, NF-kappaB was essential both for the induction and maintenance of EMT and for in vivo metastasis. NF-kappaB and the signaling pathways that are involved in its activation should therefore receive attention as potential targets for the development of novel anti-metastatic cancer treatments.