Dynamic patterns of DNA methylation in the normal prostate epithelial differentiation program are targets of aberrant methylation in prostate cancer

Understanding the epigenetic control of normal differentiation programs might yield principal information about critical regulatory states that are disturbed in cancer. We utilized the established non-malignant HPr1-AR prostate epithelial cell model that upon androgen exposure commits to a luminal cell differentiation trajectory from that of a basal-like state. We profile the dynamic transcriptome associated with this transition at multiple time points (0 h, 1 h, 24 h, 96 h), and confirm that expression patterns are strongly indicative of a progressive basal to luminal cell differentiation program based on human expression signatures. Furthermore, we establish dynamic patterns of DNA methylation associated with this program by use of whole genome bisulfite sequencing (WGBS). Expression patterns associated with androgen induced luminal cell differentiation were found to have significantly elevated DNA methylation dynamics. Shifts in methylation profiles were strongly associated with Polycomb repressed regions and to promoters associated with bivalency, and strongly enriched for binding motifs of AR and MYC. Importantly, we found that dynamic DNA methylation patterns observed in the normal luminal cell differentiation program were significant targets of aberrant methylation in prostate cancer. These findings suggest that the normal dynamics of DNA methylation in luminal differentiation contribute to the aberrant methylation patterns in prostate cancer.

Transcriptional changes in the mammary gland during lactation revealed by single cell sequencing of cells from human milk

Findings from epidemiological studies suggest that breast cancer risk is influenced by parity in an age-dependent manner. However, human mammary tissue remodelling that takes place during pregnancy and lactation remain little understood due to the challenge of acquiring samples. Here, we present an approach to overcome this using single-cell RNA sequencing to examine viable primary mammary epithelial cells isolated from human milk compared to resting, non-lactating breast tissue. Thereby, we determined that separate to breast tissue, human milk largely contains epithelial cells belonging to the luminal lineage, as well as immune cells. Our data reveal the presence of two distinct secretory luminal cell clusters in milk which highly express luminal progenitor signatures akin to non-lactating breast tissue luminal cells. Taking advantage of the fact that both the resting and lactating mammary gland contain a luminal compartment, we focussed on comparing these transcriptomes and identified differences in mammary cell function and metabolism between these maturation states. These findings provide the basis to dissect human luminal differentiation and milk biosynthesis pathways that in the future, may be interrogated to determine how parity influences luminal cell metabolism and breast cancer risk.

TET2 directs mammary luminal cell differentiation and endocrine response

Epigenetic regulation plays an important role in governing stem cell fate and tumorigenesis. Lost expression of a key DNA demethylation enzyme TET2 is associated with human cancers and has been linked to stem cell traits in vitro; however, whether and how TET2 regulates mammary stem cell fate and mammary tumorigenesis in vivo remains to be determined. Here, using our recently established mammary specific Tet2 deletion mouse model, the data reveals that TET2 plays a pivotal role in mammary gland development and luminal lineage commitment. We show that TET2 and FOXP1 form a chromatin complex that mediates demethylation of ESR1, GATA3, and FOXA1, three key genes that are known to coordinately orchestrate mammary luminal lineage specification and endocrine response, and also are often silenced by DNA methylation in aggressive breast cancers. Furthermore, Tet2 deletion-PyMT breast cancer mouse model exhibits enhanced mammary tumor development with deficient ERα expression that confers tamoxifen resistance in vivo. As a result, this study elucidates a role for TET2 in governing luminal cell differentiation and endocrine response that underlies breast cancer resistance to anti-estrogen treatments.

P-cadherin and CD10 Expression to Distinguish between Ductal Carcinoma in Situ and Invasive Ductal Carcinoma of the Breast

Objective: To use placental cadherin (P-cadherin) and cluster of differentiation 10 (CD10) immunohisto chemical staining, to separate ductal carcinoma in situ (DCIS) from invasive ductal carcinoma (IDC).Material and Methods: DCIS (n=48), equivocal (n=18), and IDC grade 1 (n=17) cases were evaluated by using immunohisto chemical staining, with P-cadherin and CD10 for identifying the myoepithelial cells.Results: P-cadherin is positive in myoepithelial cells in almost all cases of DCIS (79.0%), and equivocal groups (61.0%). CD10 also shows a positive result in most cases of DCIS (98.0%) along with equivocal groups (72.0%). Both, P-cadherin and CD10 are negative in all cases of IDC grade 1. P-cadherin shows a high percentage of positivity in luminal cell in DCIS (83.0%), equivocal group (100.0%) and IDC grade 1 (88.0%). CD10 shows a low positive in the luminal cell of most cases of DCIS (13.0%), equivocal group (6.0%) and IDC grade 1 (0.0%). CD10 is positive in myofibroblastic cells in approximately 30.0% of all cases, but P-cadherin shows all negative staining.Conclusion: P-cadherin and CD10 show high sensitivity for detecting the myoepithelial cells, but P-cadherin has a lower specificity, due to it having more luminal cells expression. Therefore, P-cadherin may be helpful for diagnosis in some cases that have a high expression of CD10 in myofibroblastic cells.