The membrane bound receptor tyrosine kinase Her2 is overexpressed in approximately 30% of human breast cancers which correlates with poor prognosis. Her2-induced signaling pathways include MAPK and PI3K/Akt, of which the latter has been shown to be critical for Her2+ breast cancer cell growth and survival. Additionally, the NF-κB pathway has been shown to be activated downstream of Her2 overexpression, however the mechanisms leading to this activation are not currently clear. Using Her2+/ER- breast cancer cells, we show that Her2 activates NF-κB through the canonical pathway which, surprisingly, involves IKKα. Knockdown of IKKα led to a significant decrease in transcription levels of multiple NF-κB-regulated cytokine and chemokine genes. siRNA-mediated knockdown of IKKα resulted in a decrease in cancer cell invasion, but had no effect on cell proliferation. Inhibition of the PI3K/Akt pathway had no effect on NF-κB activation, but significantly inhibited cell proliferation. Our study suggests different roles for the NF-κB and PI3K pathways downstream of Her2, leading to changes in invasion and proliferation of breast cancer cells. Additionally this work indicates the importance of IKKα as a mediator of Her2-induced tumor progression
