Up-regulation of the kinase gene by progesterone activates the AP-1-NDRG1 axis in both PR-positive and -negative breast cancer cells.

Preoperative progesterone intervention has been shown to confer a survival benefit to breast cancer patients independently of their progesterone receptor (PR) status. This observation raises the question how progesterone affects the outcome of PR-negative cancer. Here, using microarray and RNA-Seq-based gene expression profiling and ChIP-Seq analyses of breast cancer cells, we observed that the serum- and glucocorticoid-regulated kinase gene () and the tumor metastasis-suppressor gene N-Myc downstream regulated gene 1 () are up-regulated and that the microRNAs and targeting the 3'-UTR of are down-regulated in response to progesterone. We further demonstrate a dual-phase transcriptional and post-transcriptional regulation of in response to progesterone, leading to an up-regulation of that is mediated by a set of genes regulated by the transcription factor AP-1. We found that , in turn, inactivates a set of kinases, impeding the invasion and migration of breast cancer cells. In summary, we propose a model for the mode of action of progesterone in breast cancer. This model helps decipher the molecular basis of observations in a randomized clinical trial of the effect of progesterone on breast cancer and has therefore the potential to improve the prognosis of breast cancer patients receiving preoperative progesterone treatment.