Single cell transcriptomics reveals involution mimicry during the specification of the basal breast cancer subtype

Here, we use spatially and time controlled induction of Elf5 within the mammary epithelium in the context of the luminal MMTV-PyMT mouse mammary cancer to study tumour progression mechanisms associated to the specification of the basal breast cancer subtype at single-cell resolution. In this study we used two mouse models, the well-established MMTV-PYMT mouse mammary tumour model (PyMT/WT) and a mammary restricted (MMTV) doxycycline-inducible (rtTA) Elf5 expression model crossed with the PyMT/WT model (PyMT/Elf5) . Consistent with previous reports, the specific induction of Elf5 in the mammary gland epithelium results in a significant increase of lung metastases and a dramatic leaky vasculature phenotype in the PyMT model. A total of fifteen mouse mammary tumours at metastatic stage (14 weeks old FBVn background) from the MMTV-PyMT/WT and /ELF5 model were harvested and analysed using Drop-seq[24].