Role of endogenous type I Interferon in spontaneous, Her2/Neu oncogene-driven carcinogenesis

Type I Interferons (IFN-I) are anti-viral and immuno-modulating cytokines involved in many steps across tumor initiation and progression. IFN-I act directly on tumor cells inhibiting cell growth and indirectly by activating immune cells to mount antitumor response. To understand the role of endogenous IFN-I in spontaneous, oncogene-driven carcinogenesis, we characterized tumors arising in Her2/neu transgenic (neuT) mice carrying a non-functional mutation in the IFN-I receptor (IFNAR1), thus being unresponsive to this family of cytokines. Compared to parental neu+/-mice (neuT mice), IFNAR1-/- neu+/- mice (IFNAR-neuT mice) showed earlier onset and increased tumor multiplicity with marked vascularization. Of note, IFNAR-neuT tumors specifically exhibited deregulation of genes having adverse prognostic value in breast cancer patients, including breast cancer stem cells (BCSC) marker aldehyde dehydrogenase-1A1 (ALDH1A1). An increased amount of BCSC was observed in IFNAR-neuT tumors, as assessed by ALDH1A1 enzymatic activity, clonogenic assay and tumorigenic capacity. In vitro exposure of neuT+ mammospheres and cell lines to anti-IFN-I antibodies resulted in increased frequency of ALDH+ cells, suggesting that IFN-I control stemness in tumor cells. Altogether, these results reveal an essential role of IFN-I in NeuT-driven spontaneous carcinogenesis through intrinsic control of BCSC. 30 samples of mouse mammary glands, belonging to 4 groups: Wild-type, IFNAR1-/-, Her2/Neu+, and Her2/Neu+/IFNAR1-/-. Samples were cohybridized with Universal Reference Mouse RNA