ATAC-seq of mouse luminal progenitors isolated from wild-type or Blg-Cre;Brca1f/f;p53+/- mouse models

One of the major hurdles for the early detection of cancer is our poor understanding of tumour initiating events. Historically, cancer research has focused on histological and molecular characterisation of established tumours which has led to the identification of hundreds of putative driver mutations. It is currently unclear how these genetic aberrations impact the cell state of nascent tumour cells and their microenvironment. BRCA1 driven triple negative breast cancer (TNBC) for example has been shown to arise from luminal progenitor cells yet little is known about how BRCA1 loss-of-function (LOF) and concomitant mutations affect the luminal progenitor cell state. This repository contains ATAC-sequencing dataset of luminal progenitors isolated from 6-months old Brca1/p53 and wild-type mice. This data was used to show that the perturbation of Brca1/p53in luminal progenitors induces an aberrant alveolar differentiation pre-malignancy. Unlike alveolar differentiation occurring during gestation, this process is cell autonomous and characterised by the dysregulation of transcription factors driving alveologenesis. The ATAC-sequencing data supports a model where transcriptional and epigenetic changes driven by Brca1/p53 inadvertently promote a differentiation program hardwired in luminal progenitors, highlighting the deterministic role of the cell of origin and offering a potential explanation for the tissue specificity of BRCA1 tumours.