Functional and Phenotypic Characterisations of Common Syngeneic Tumour Cell Lines as Estrogen Receptor-Positive Breast Cancer Models.

Estrogen receptor-positive breast cancers (ER BCas) are the most common form of BCa and are increasing in incidence, largely due to changes in reproductive practices in recent decades. Tamoxifen is prescribed as a component of standard-of-care endocrine therapy for the treatment and prevention of ER BCa. However, it is poorly tolerated, leading to low uptake of the drug in the preventative setting.

Parity reduces mammary repopulating activity but does not affect mammary stem cells defined as CD24 + CD29/CD49fhi in mice.

Background: Breast cancer (BCa) mortality is decreasing with early detection and improvement in therapies. The incidence of BCa, however, continues to increase, particularly estrogen-receptor-positive (ER +) subtypes. One of the greatest modifiers of ER + BCa risk is childbearing (parity), with BCa risk halved in young multiparous mothers.

Estrogen receptor subtypes dictate the proliferative nature of the mammary gland.

Estrogen induces proliferation of breast epithelial cells and is responsible for breast development at puberty. This tightly regulated control is lost in estrogen-receptor-positive (ER+) breast cancers, which comprise over 70% of all breast cancers. Currently, breast cancer diagnosis and treatment considers only the α isoform of ER; however, there is a second ER, ERβ.

Histone deacetylase activity mediates acquired resistance towards structurally diverse HSP90 inhibitors.

Heat shock protein 90 (HSP90) regulates multiple signalling pathways critical for tumour growth. As such, HSP90 inhibitors have been shown to act as effective anticancer agents in preclinical studies but, for a number of reasons, the same effect has not been observed in the clinical trials to date. One potential reason for this may be the presence of de novo or acquired resistance within the tumours.

SCA-1 Labels a Subset of Estrogen-Responsive Bipotential Repopulating Cells within the CD24 CD49f Mammary Stem Cell-Enriched Compartment.

Estrogen stimulates breast development during puberty and mammary tumors in adulthood through estrogen receptor-α (ERα). These effects are proposed to occur via ERα luminal cells and not the mammary stem cells (MaSCs) that are ERα. Since ERα luminal cells express stem cell antigen-1 (SCA-1), we sought to determine if SCA-1 could define an ERα subset of EpCAM/CD24/CD49f MaSCs.