Barcoding reveals complex clonal dynamics of de novo transformed human mammary cells

Abstract

Most human breast cancers have diversified genomically and biologically by the time they become clinically evident. Early events involved in their genesis and the cellular context in which these events occur have thus been difficult to characterize. Here we present the first formal evidence of the shared and independent ability of basal cells and luminal progenitors, isolated from normal human mammary tissue and transduced with a single oncogene (KRAS(G12D)), to produce serially transplantable, polyclonal, invasive ductal carcinomas within 8 weeks of being introduced either subrenally or subcutaneously into immunodeficient mice. DNA barcoding of the initial cells revealed a dramatic change in the numbers and sizes of clones generated from them within 2 weeks, and the first appearance of many 'new' clones in tumours passaged into secondary recipients. Both primary and secondary tumours were phenotypically heterogeneous and primary tumours were categorized transcriptionally as 'normal-like'. This system challenges previous concepts that carcinogenesis in normal human epithelia is necessarily a slow process requiring the acquisition of multiple driver mutations. It also presents the first description of initial events that accompany the genesis and evolution of malignant human mammary cell populations, thereby contributing new understanding of the rapidity with which heterogeneity in their properties can develop.

Digital image analysis outperforms manual biomarker assessment in breast cancer

“…Here, it is worth noting that when PAM50 subtyping is applied to a whole tumor, intratumor heterogeneity is not taken into consideration and as such is unlikely to represent each and every subset of clones within the tumor. [37][38][39] …”

Basal-like Breast Cancers: From Pathology to Biology and Back Again

“…The use of normal human cells as the initial targets also bypasses the caveats of species differences inherent in mouse models. The advent of lentiviral vectors that can deliver multiple genetic payloads at high efficiency into primary human mammary cell types has now made this approach feasible, although the number of successful models remains very limited (Keller et al., 2012, Morel et al., 2017, Nguyen et al., 2015, Proia et al., 2011). …”

“…Underscoring the promise of this approach is the recent discovery of the speed, reproducibility, and efficiency with which serially transplantable human breast cancers can now be produced from normal human mammary cells transduced with KRAS G12D (Nguyen et al., 2015). Interestingly, the initial tumors obtained are polyclonal and morphologically highly heterogeneous with no dominant basal, basal-like, or luminal features evident from IHC analyses.…”

Distinct Effects of Adipose-Derived Stem Cells and Adipocytes on Normal and Cancer Cell Hierarchy

“…Thus, there may be interindividual variation in the effect of ASCs on stem/progenitor composition of breast epithelial cells. CD44 þ /CD24 À cells are considered breast cancer stem cells and CD44 expression alone is linked to undifferentiated status of breast epithelial cells (27,30). We used these two markers to characterize the mammospheres for undifferentiated cells.…”

“…surface marker profile, respectively (26,27). We used these two marker combinations to determine the effects of ASCs on phenotype of cells in the mammospheres.…”