Validating these novel cell states is problematic due to technical difficulties in isolating viable live cells based on their transcriptomic profile. The different cell states are essential to predicting a cellular trajectory hierarchy.
Single cell transcriptome analysis of primary human breast tissue confirmed the three main epithelial cell types and has highlighted that there are additional cell states within each cell population. Investigating breast cellular heterogeneity has taken a leap forward with the enhancement of single cell omic studies. Currently, the combination of two key cell surface markers, EpCAM and CD49f, are widely used as differentiation markers to identify the basal, luminal progenitor (LP), mature luminal (ML) and stromal compartments of the normal breast. Subsequently, different cell isolation protocols and cell surface marker combinations were utilised to identify dissimilar subpopulations adding to the complexity with minimal overlap between studies. One of the earliest studies used a combination of cell surface markers including EpCAM (ESA), CD10, CD49f (Integrin α6) and MUC1 (CD227) to identify the basal and luminal populations via flow cytometry. Many studies have relied on in vitro and in vivo assays to understand the hierarchical organisation and the progenitor/stem capacities of breast epithelial cells. A better understanding of the cellular heterogeneity existing in the breast epithelium and different cell states provides useful clues to how these cell types transform into the distinct breast cancer subtypes. K5 and K14 are often referred to as basal keratins based on their expression in the mouse mammary gland, specifically within the basal layer of the ducts, yet they were also expressed within the luminal layer of TDLUs of human breast tissues, therefore making cell identity difficult to interpret using these markers. Reliance on immunostaining for specific keratin (K) markers classifying breast cell types has led to discrepancy. Historically mammographic and histology analyses were limited in defining the exact cell compartment responsible for neoplastic transformation.
The origins and development of breast cancer revealed that most breast cancers originate from a single TDLUs. This breast network is structured via a main stem or primary duct ending in a cluster of sac-like lobules termed terminal ductal lobular units (TDLUs).
SCREEN MARKER SERIES
These populations are organised into a series of ductal networks, surrounded by stromal cells and adipocytes.
The breast epithelium is composed of two known cell types, an outer layer of myoepithelial/basal cells and an inner luminal layer composed of separate secretory and hormone receptor-positive populations. The human breast is a complex steroid-responsive organ which undergoes morphological and structural changes depending on the reproductive stage. Our dataset of CD marker expression in the normal breast provides better definition for breast cellular heterogeneity. CD9, CD59, CD164) while other surface markers were confirmed to be enriched in different cell lineages: CD24, CD227 and CD340 in the luminal compartment, CD10 and CD90 in the basal population, and CD34 and CD140b on stromal cells. We also show multiple markers were equally expressed in all cell populations (e.g. We identified 35 surface marker proteins expressed on normal breast epithelial and/or stromal subpopulations that were previously unreported. To determine the differences in expression of a range of uninvestigated cell surface markers between the normal breast cell subpopulations, primary human breast cells were analysed using high-throughput flow cytometry for the expression of 242 cell surface proteins in conjunction with EpCAM/CD49f staining. However, the majority of cell surface maker expression of primary breast cells have not been investigated. Investigation of surface marker expression provides a valuable approach to resolve complex cell populations. Delineating the spectrum of cellular heterogeneity will provide new insights into normal cellular properties within the breast tissue that might become dysregulated in the initial stages of cancer.
Normal human breast tissues are a heterogeneous mix of epithelial and stromal subtypes in different cell states.
0 kommentar(er)
