With increased participation of women in the military there is an increased need to effectively diagnose, manage and cure breast cancer in the veteran population. The invasive and metastatic nature of this cancer poses a formidable challenge. Our long term goal is to identify therapeutic avenues to effectively treat metastasis of breast cancer. The objective of the proposed work is to understand the mechanistic and functional consequences of the loss of a gatekeeper protein NMI, on breast cancer metastasis. We hypothesize that loss of NMI unleashes unwarranted activation of Hh signaling and enhances the propensity of breast cancer cells to metastasize. As our first Aim, we will employ thorough investigation using innovative experimental approach to elucidate the mechanistic and functional consequences of NMI loss on Hh driven metastatic progression of breast cancer. We will use a unique reagent created by us, to determine whether the modulation of Hh signaling is via classical Hh ligand-dependent or non-classical Hh ligand-independent mechanisms. We will characterize the molecular events that lead to activated Hh signaling and interrogate the outcomes on cancer cell attributes of stemness, drug resistance and mesenchymal phenotype. We also will employ in vivo assays that encompass xenograft studies and investigations with genetically engineered mouse models that will enable us to specifically query activation of Hh signaling in situations of NMI loss. In the second Aim, we will develop an understanding of the correlative expression between NMI and molecular signatures of metastasis in tumor specimens derived from Stage IV breast cancer patients. We will follow upon our findings that NMI expression is compromised in hypoxic conditions, a finding with profound implications for metastasis; and test an innovative pre-clinical pharmacological inhibition strategy to reduce metastasis of breast cancer that is devoid of NMI. Collectively, this Aim will allow us to strengthen the clinical (translational) applicability of our observations and lay the foundation to move towards a future clinical trial.