The biology of hormone action in the normal breast and breast cancer


The ovarian hormone progesterone is essential for normal female reproductive function, including the development of the normal breast throughout life and in particular during pregnancy. However, exposure to progesterone analogues in hormone replacement therapy increases the risk of developing breast cancer, most likely through increasing the proliferation of existing lesions rather than initiating new lesions. The purpose of this project is to discover the changes in hormone signalling that occur in the normal breast as early breast cancer changes occur.


Professor Christine Clarke, Dr Dinny Graham

Research Location

Westmead - Westmead Institute for Medical Research

Program Type



Effect of carcinogenesis on endocrine signalling in the normal breast.
In order to understand the role of the ovarian hormones in breast cancer development it is important to study normal breast tissue. Our group has developed a 3D model of normal breast, which retains the features of normal breast tissue, including expression of hormone receptors. The aim of this project is to identify disruptions in hormone signalling once normal breast cells begin to accumulate the genetic alterations that are the earliest changes on the path to malignancy. We will use models of early malignancy, including activation of known oncogenes and introduction of breast cancer susceptibility gene mutations, to identify changed hormonal responsiveness acquired by the normal breast as it transitions to cancer. The effects and functional consequences of these transitions on ovarian hormone signalling will be measured by a range of methods, including flow cytometry and whole genome gene expression profiling. The project will employ high level molecular and cell biology approaches, which include gene transfection/transduction and live cell imaging of primary and continuous cell lines; gene expression analysis (including microarrays and RNA massively parallel sequencing); RNAi using lentivirus; cloning of expression and shRNA constructs; confocal imaging, FRET/FRAP; flow cytometry; high throughput viability/apoptosis/proliferation assays; digital image analysis; immunofluorescent protein expression analysis.

Influence of chromatin architecture on transcriptional function of hormone receptors.
Hormone receptors are members of a large family of ligand-activated nuclear transcription factors, which bind to target sites in DNA and activate transcription. We have previously shown that activity of the progesterone receptor requires its movement into discrete subnuclear aggregates that represent sites of active transcription. Malignant transformation alters the formation of these aggregates, and is also associated with altered progesterone receptor activity. We have evidence that chromatin architecture is a key determinant of progesterone receptor movement into subnuclear aggregates and that the differences in chromatin structure in normal and cancer cells are a key regulator of this process. This project aims, through genome-wide identification and analysis of the receptor binding sites on DNA coupled with the use of new informatic tools, to delineate the binding partners that are required for progesterone receptor movement into aggregates and to determine the mechanisms by which this process is disrupted in cancer cells. The project will involve the use of a range of high-level molecular and cell biology techniques, including transfection/transduction and live cell imaging of primary and continuous cell lines; confocal analysis of subnuclear localization; chromatin immunoprecipitation coupled to massively parallel sequencing (ChIP-seq); gene expression analysis, including whole genome microarray, RNA sequencing (RNA-seq) and global run-on sequencing (GRO-seq); and RNA and DNA fluorescence in situ hybridization.

Additional Information

The project is offered in the Breast Cancer Research Group of the Westmead Institute for Cancer Research, which is located in the Westmead Millennium Institute, one of Australia's largest medical research institutes, situated close to major medical facilities at Westmead Hospital and Children's Hospital Westmead, and the Western Clinical School of the University of Sydney. The Westmead Millennium Institute has over 450 staff conducting research into a wide range of important human disorders affecting both adults and children. WMI research spans infectious and immune diseases, cancer and leukaemia, liver and metabolic diseases, eye and brain-related disorders, heart and respiratory disorders. The Institute supports a range of innovative technologies and core facilities and offers a diverse and vibrant scientific and academic environment.
The overall motivation of the research being conducted in the Breast Cancer Research Group is to understand the role of the female hormones oestrogen and progesterone in the development of the normal breast, and in breast cancer. These hormones arise from the ovary and circulate in the female in a cyclical pattern throughout reproductive life. Ovarian hormones are fundamental regulators of normal cell growth and differentiation and are also crucial to the development and progression of breast cancer. This is underscored by the knowledge that women without ovaries have the same low risk of breast cancer as men. The underlying basis for the promoting role of ovarian hormones on breast cancer risk is unknown. The Breast Cancer Research Group is offering projects examining (i) the role of progesterone in regulating normal mammary gland development and identifying the underlying mechanisms through which progesterone increases breast cancer risk and (ii) the role of chromatin architecture in defining progesterone receptor localization and transcriptional fidelity in normal and malignant breast cells.

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breast, Breast Cancer, progesterone, progestins, progesterone receptors, nuclear receptors, normal breast, gene expression, mammary gland, endocrine signalling, Stem cells, female reproduction, breast neoplasms, transcriptional profiling, microarray, primary cell culture, next-generation sequencing, chromatin immunoprecipitation sequencing

Opportunity ID

The opportunity ID for this research opportunity is: 1640