High-throughput surface marker screen on primary human breast tissues reveals further cellular heterogeneity

Siru Virtanen,Mona Shehata,John Stingl,Reiner Schulte,Carlos Caldas

doi:10.1186/s13058-021-01444-5

Abstract

BackgroundNormal human breast tissues are a heterogeneous mix of epithelial and stromal subtypes in different cell states. 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. Investigation of surface marker expression provides a valuable approach to resolve complex cell populations. However, the majority of cell surface maker expression of primary breast cells have not been investigated.MethodsTo 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.ResultsWe identified 35 surface marker proteins expressed on normal breast epithelial and/or stromal subpopulations that were previously unreported. We also show multiple markers were equally expressed in all cell populations (e.g. 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.ConclusionsOur dataset of CD marker expression in the normal breast provides better definition for breast cellular heterogeneity.

Highlights

Normal human breast tissues are a heterogeneous mix of epithelial and stromal subtypes in different cell states
To explore the heterogeneity of normal breast epithelial and stromal cells and to generate a dataset of surface protein expression, we subjected human reduction mammoplasty specimens to a panel of monoclonal antibodies specific for 242 human cell surface proteins using the BD Lyoplate system
The inclusion of the breast epithelial flow antibody strategy was imperative to eliminate the number of false positive surface markers irrelevant to the stromal/epithelial content of the normal human breast

Summary

Introduction

Normal human breast tissues are a heterogeneous mix of epithelial and stromal subtypes in different cell states. 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 receptorpositive populations. These populations are organised into a series of ductal networks, surrounded by stromal. 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. The cell surface proteome is central to many biological functions which reflect cell fate, yet expression patterns of many cell surface markers in the human breast cell subpopulations are poorly defined

Methods

Results

Discussion

Conclusion