Impact Of Progesterone Receptor Subnuclear Localisation On Progesterone Action In Endocrine Target Cells
Funder
National Health and Medical Research Council
Funding Amount
$459,514.00
Summary
Breast cancer affects 10,000 Australian women annually and is a major cause of cancer death. The hormone progesterone, which is produced by the ovaries in women, is responsible for some aspects of the development of the normal breast in women and is also implicated in the development and response of breast and endometrial cancers. In normal cells progesterone acts via a specific protein (or receptor) in the nucleus, and we have shown that this protein accumulates into foci when it is active. We ....Breast cancer affects 10,000 Australian women annually and is a major cause of cancer death. The hormone progesterone, which is produced by the ovaries in women, is responsible for some aspects of the development of the normal breast in women and is also implicated in the development and response of breast and endometrial cancers. In normal cells progesterone acts via a specific protein (or receptor) in the nucleus, and we have shown that this protein accumulates into foci when it is active. We have noticed that in cancers, this accumulation is disrupted, and this is a bad sign for the cancer. As breast cancer develops, it causes many dramatic changes in the structure of cells of the breast, and particularly in the nucleus, which carries the genetic information that programs cancer cell behaviour. The nucleus normally is highly organised into compartments, which carry out different functions of the cell, such as duplication of the DNA, repair of DNA after damage, and switching on and off of particular genes important to the function of the cell. This organisation is altered dramatically in cancer cells, and it seems that this altered organisation is responsible for altered function. In this project we aim to work out what makes the receptor for progesterone form foci, how these foci are involved in the action of progesterone, and how the changed structure of the nucleus changes this process. This project will link the structure of the cell nucleus with the ability of progesterone to switch on or off particular genes, and this will provide the first signposts of how changes seen in cancer cell nuclei are reflected in changed hormonal signalling. Healthy women are regularly exposed to progestins in oral contraceptives and hormone replacement therapy. The known increased risk of breast cancer as a result of exposure to progestins creates an imperative to understand how progesterone may have aberrant effects. This project will address this important health issue.Read moreRead less
Alpha-2-Macroglobulin And The Transport And Uptake Of The Hormone, Hepcidin
Funder
National Health and Medical Research Council
Funding Amount
$533,541.00
Summary
Hepcidin is a peptide hormone that is a major regulator of iron metabolism. It has been suggested that hepcidin is free in the blood. However, we recently identified that hepcidin binds with alpha-2-macroglobulin (a2-M) in the plasma and this increases the efficacy of this peptide. The demonstration that a2-M plays a role in hepcidin biology will lead to a better understanding of hepcidin physiology, the development of methods for its measurement and improved treatment of iron related diseases.
Validating A New Model For Growth Hormone Receptor Activation
Funder
National Health and Medical Research Council
Funding Amount
$472,500.00
Summary
Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflam ....Growth hormone is an important hormone therapeutic for treating dwarfism. Recently, many new therapeutic applications for growth hormone have been discovered, particularly in relation to its anabolic actions. These include post surgery recovery, enhanced bone fracture healing, Crohns disease, dilated cardiomyopathy, infertility and ageing. The hormone exerts these actions through its receptor, which is a class1 cytokine receptor, similar to many receptors important in regulating immunity, inflammation, metabolism and cancers. In principle, if we can find out how the GH receptor works, this information would help in designing drugs to treat many immune and inflammatory disorders. With current NHMRC support we have developed a model which describes how GH activates the receptor at a molecular level. The model involves two pre-associated receptors at the cell surface binding to the hormone, with the result that the receptors are rotated relative to each other, and this brings the two JAK2 signalling units attached tothe receptor inside the cell into alignment, so they can activate each other. We can activate the receptor without hormone by artificially rotating it. This model is a prediction based on several techniques, but lacks proof of rotation. There are also a number of issues relating to the need for rigidity in the receptors, so the torque can be transmitted into the cell, since many believe there is no rigidity just above the membrane. We predict there is , but need to prove this. This information is vital for designing small orally active mimics of growth hormone, and for developing GH antagonists, likely to be useful for breast and colon cancer. Finally, we have evidence that the specificity of receptor signalling can be changed by mutating the outer part of the receptor (novel). We believe this can be used to change the activity spectrum of GH, hence decrease side effects, by developing analogs which activate one pathway or the other.Read moreRead less
Steroid hormones, such as estrogen and androgens, act in the body by locking onto a family of proteins (nuclear receptors) that bind directly to the DNA to regulate genes. The mechanisms underlying this process are complex and involve recruitment of additional molecules or coactivators to improve efficiency. Recently a novel coactivator was identified, termed SRA, which exerts its effects as an RNA, rather than as a protein. SRA is aberrantly expressed in breast cancer, raising the possibility t ....Steroid hormones, such as estrogen and androgens, act in the body by locking onto a family of proteins (nuclear receptors) that bind directly to the DNA to regulate genes. The mechanisms underlying this process are complex and involve recruitment of additional molecules or coactivators to improve efficiency. Recently a novel coactivator was identified, termed SRA, which exerts its effects as an RNA, rather than as a protein. SRA is aberrantly expressed in breast cancer, raising the possibility that it plays an important role in breast cancer cell proliferation. To better understand how estrogen signals in breast cancer and identify proteins that bind to SRA in cancer cells, we established a collaboration with the O'Malley group at Baylor College of Medicine in Texas (who discovered SRA). We have identified several novel SRA-binding proteins, each of which plays an important role to regulate estrogen and androgen action. Up to this point, we have used a model that has enabled proof of principle studies in the same cancer cells from which SRA was discovered (non-breast or prostate cancer). However, we now need to carefully study the role of these proteins in cancer cells relevant to breast and prostate cancer. Thus, we plan to investigate how these proteins interact with SRA, how they influence nuclear receptor activity and breast and prostate cancer cell proliferation, examine their role in activating other pathways of cell growth in cancer cells, assay the levels of each protein in a series of human breast cancer specimens and solve the physcial 3-D structure of these proteins complexed to the SRA RNA. This work will provide novel insight into several key areas of hormone action in breast and prostate cancer. We hope to identify new markers that can be used for improved diagnosis and for prognosis, and provide structural information for the development of novel therapeutics.Read moreRead less
CHAPERONES IN BREAST CANCER AND ESTROGEN RECEPTOR FUNCTION
Funder
National Health and Medical Research Council
Funding Amount
$256,573.00
Summary
Resistance to hormone therapy in breast cancer is due to adaptations of estrogen signalling mechanisms that result in ERa activation causing growth. So, in the search for new treatments, we are looking for ways to remove ERa from the breast cancer cell. Our study addresses this major issue by focussing on Hsp90 molecular chaperone machinery that is essential for ERa function and in particular immunophilin 'helper' cochaperones that form part of receptor-Hsp90 complexes and fine-tune receptor res ....Resistance to hormone therapy in breast cancer is due to adaptations of estrogen signalling mechanisms that result in ERa activation causing growth. So, in the search for new treatments, we are looking for ways to remove ERa from the breast cancer cell. Our study addresses this major issue by focussing on Hsp90 molecular chaperone machinery that is essential for ERa function and in particular immunophilin 'helper' cochaperones that form part of receptor-Hsp90 complexes and fine-tune receptor responses to hormone. Through a novel mode of action, coumarin-based Hsp90 inhibitors disrupt Hsp90 dimerization causing receptor release and subsequent depletion. We will confirm this novel mechanism for new, high affinity Hsp90 inhibitors and determine which can best interfere with estrogen signalling, either alone or in combination with antiestrogen therapies in the treatment of hormone-dependent cancers. Our study has the potential to pin point the site of action of the immunophilins in ERa to a proline in a region critical for ligand-induced receptoractivation. We will determine the role of the immunophilins and this active-site proline residue in modulating receptor stability and function. Aberrant expression of receptor-associated immunophilins appears linked to endocrine resistance and metastasis in breast cancer. Our study will profile the expression of these chaperones in well defined breast cancer tissue microarrays, and has the potential to identify them as informative biomarkers in the treatment of the disease.Read moreRead less
Kallikrein Gene Variants In Prostate Cancer: Analysis Of Gene Regulation And Diagnostic/Prognostic Use
Funder
National Health and Medical Research Council
Funding Amount
$486,801.00
Summary
Prostate cancer is the most common male cancer in Australia. However, early detection through screening programs has proven challenging, and about 30% of the 10,000 new cases diagnosed annually already have advanced disease. Hence, there is a fundamental need for increased basic research in prostate cancer etiology (cause) and tumour biology, and a critical requirement for methods that will assist in earlier detection of the disease and predict progression. A family of proteins called kallikrein ....Prostate cancer is the most common male cancer in Australia. However, early detection through screening programs has proven challenging, and about 30% of the 10,000 new cases diagnosed annually already have advanced disease. Hence, there is a fundamental need for increased basic research in prostate cancer etiology (cause) and tumour biology, and a critical requirement for methods that will assist in earlier detection of the disease and predict progression. A family of proteins called kallikreins (including prostate specific antigen, PSA) are often associated with clinical features of prostate cancer. We will characterise genetic variants (polymorphisms) in kallikrein genes that are consistently over-produced in prostate cancer, and determine whether they cause more protein to be produced in cells grown in the laboratory and in tumour tissue, and-or give rise to different expression products or splice variants. We will use bioinformatics (computer programs) to characterise published kallikrein gene sequences and to examine them for genetic variants that might be related to changes in gene expression or to splice variants. We will then use a case-control study, involving 1200 men with prostate cancer and 1200 healthy men, to determine whether these gene variants are associated with an increased risk of prostate cancer or with clinical aspects of the disease. Finally, we will examine the functional significance of the gene variants. This project represents an important and novel combination of molecular biology with the study of clinical disease at the population level, in the relatively new field of molecular epidemiology. It will clarify the role of kallikrein gene variants in prostate cancer risk and progression. The technologies may ultimately prove useful clinically for diagnosis of prostate cancer or for monitoring of treatment and prognosis, and hopefully will assist in clinical decision-making.Read moreRead less