Fig. 1

Isolation, immortalization and characterization of luminal progenitors. A FACS diagrams showing the gating strategy for sorting of luminal progenitors. Uncultured single cells were harvested from freshly thawed collagenase digests and further submitted to a TROP2/CD271/CD117/CD166 FACS protocol to separate luminal, myoepithelial and stromal cells (left) and further separate luminal progenitor (LP) from mature luminal (ML) cells (middle). Candidate TROP2⁺/CD271⁻/CD117⁺/CD166⁻ progenitors were gated as illustrated with squares and plated in culture for sequential transduction with hTERT, shp16, shp53 and PIK3CA^H1047R (right). The resulting cell line is referred to as PIK3CA^H1047R-iHBEC^CD117. B scRNA sequenced basal and luminal cells were resolved by UMAP dimensionality reduction and clustering of uncultured cells from three reduction mammoplasty samples (left, n = 3) and compared with data from the PIK3CA^H1047R-iHBEC^CD117 cell line (right). Clusters with related expression profiles were annotated with identical colors as shown on the left (red for ML, yellow for LP, and green for Basal). PIK3CA^H1047R-iHBEC^CD117 clusters with no equivalent among uncultured cells were colored gray and cluster 4 with a stem like profile was colored blue. C Examples of genes enriched in ML (ANKRD30A, AGR2, ESR1 and PGR), LP (KRT15 and SLPI) and Basal (POSTN and MME) clusters, respectively