Dataset Information

Immortalized, pre-malignant epithelial cell populations contain long-lived, label-retaining cells that asymmetrically divide and retain their template DNA.

ABSTRACT:

Introduction

During selective segregation of DNA, a cell asymmetrically divides and retains its template DNA. Asymmetric division yields daughter cells whose genome reflects that of the parents', simultaneously protecting the parental cell from genetic errors that may occur during DNA replication. We hypothesized that long-lived epithelial cells are present in immortal, premalignant cell populations, undergo asymmetric division, retain their template DNA strands, and cycle both during allometric growth and during pregnancy.

Methods

The glands of 3-week old immune competent Balb/C female mice were utilized intact or cleared of host epithelium and implanted with ductal-limited, lobule-limited, or alveolar-ductal progenitor cells derived from COMMA-D1 pre-malignant epithelial cells. 5-bromo-2-deoxyuridine (5-BrdU) was administered to identify those cells which retain their template DNA. Nulliparous mice were then either injected with [(3)H]-thymidine ((3)H-TdR) to distinguish 5-BrdU-label retaining cells that enter the cell cycle and euthanized, or mated, injected with (3)H-TdR, and euthanized at various days post-coitus. Sections were stained for estrogen receptor-α(ER-α) or progesterone receptor (PR) via immunohistochemistry. Cells labelled with both 5-BrdU and (3)H-TdR were indicative of label-retaining epithelial cells (LREC).

Results

Cells that retained a 5-BrdU label and cells labelled with [(3)H]-thymidine were found in all mice and were typically detected along the branching epithelium of mature mouse mammary glands. Cells containing double-labelled nuclei (LREC) were found in the intact mammary gland of both pregnant and nulliparous mice, and in mammary glands implanted with pre-malignant cells. Double-labelled cells ((3)H-TdR/5-BrdU) represent a small portion of cells in the mammary gland that cycle and retain their template DNA (5-BrdU). Some label-retaining cells were also ER-α or PR positive. LRECs distributed their second label ((3)H-TdR) to daughter cells; and this effect persisted during pregnancy. LRECs, and small focal hyperplasia, were found in all immortalized premalignant mammary implant groups.

Conclusions

The results indicate that a subpopulation of long-lived, label-retaining epithelial cells (LRECs) is present in immortal premalignant cell populations. These LRECs persist during pregnancy, retain their original DNA, and a small percentage express ER-α and PR. We speculate that LRECs in premalignant hyperplasia represent the long-lived (memory) cells that maintain these populations indefinitely.

SUBMITTER: Bussard KM

PROVIDER: S-EPMC3096979 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:The epithelial lining of the small intestine is continuously renewed from a small number of stem cells including Lgr5 expressing crypt base cells that have been shown to be a rapidly cycling stem cell population in homeostasis. Alternative markers of intestinal stem cells have variously identified populations as rapidly cycling or quiescent with proposed roles for the latter as a parallel or reserve stem cell population. However, the exact nature of quiescent crypt cells remains unknown. Here by applying novel mouse models that permit their isolation and characterisation as label-retaining cells (LRCs), and for the first time performing lineage tracing from them, we show quiescent cells to be committed secretory precursors that are capable of recall to the stem cell state. We reveal LRCs to be a small subset of the rapidly cycling Lgr5 expressing population committed along the Paneth-enteroendocrine lineage. Significantly, after injury and subsequent regeneration they are clonogenic, as shown by both lineage tracing and organoid growth demonstrating that they can be recalled to the stem cell pool. These findings in establishing quiescent cells as an effective clonogenic reserve during injury provides a motivation for investigating their role in the maintenance of cancer growth following adjuvant treatment. Six age and sex (female) matched Cyp1a1-H2B-YFP mice ten days post βNF induction were used comparing three cell populations from each. Following epithelial isolation, single cell preparation and staining with anti-CD24 anitbody and UEA-1 lectin, 30,000 cells were flow sorted for each population: Paneth cells (Paneth) were defined as CD24+/UEA+, YFP-LRCs (YFPpos) as CD24+/UEA-/YFP+ and LCCs (YFPneg) as CD24+/UEA-/YFP-. Microarray expression comparison was then performed to identify unique markers of each population. RNA amplification and hybridisation was performed at the Paterson Institute, Manchester, UK, Microarray Facility using Nugen Ovation Pico WTA System for amplification and then hybridisation to a Mouse Exon 1.0 ST Array. Arrays were scanned using an Affymetrix GeneChip scanner 3000 running GCOS software.