The Role Of Ghrelin And Growth Hormone Releasing Hormone In The Autocrine Regulation Of Prostate Cancer Cell Growth
Funder
National Health and Medical Research Council
Funding Amount
$240,990.00
Summary
Insulin-like growth factor-I (IGF-I) is an important growth factor with a major role in the growth and development of many normal and tumour cells. Its production is controlled by growth hormone (GH), released from the pituitary gland at the base of the brain. GH releasing hormone (GHRH), a hormone released from higher centres in the brain, regulates the production of GH itself and now it is recognised that a second pathway, the ghrelin-GH secretagogue receptor (GHS-R) axis is also important in ....Insulin-like growth factor-I (IGF-I) is an important growth factor with a major role in the growth and development of many normal and tumour cells. Its production is controlled by growth hormone (GH), released from the pituitary gland at the base of the brain. GH releasing hormone (GHRH), a hormone released from higher centres in the brain, regulates the production of GH itself and now it is recognised that a second pathway, the ghrelin-GH secretagogue receptor (GHS-R) axis is also important in regulating GH release. There is growing evidence that the GHRH-GH-IGF axis has a significant role in prostate cancer, but little is known about how this happens. We also have evidence that the ghrelin-GHS-R axis is involved in prostate cancer, as prostate cancer cell lines produce both ghrelin and the receptor through which it acts. Our preliminary studies show that ghrelin enhances cell growth in these cells. GHRH blocking agents (antagonists) are potential treatments for prostate cancer, as they slow the growth of prostate tumours. How they act is unclear, but they might interfere with a locally active GHRH pathway in the prostate. This study aims to explore the role of ghrelin and GHRH in prostate cancer. Since there is an increase in the use of GHRH, GH and-or IGF-I and potentially ghrelin for the treatment of a variety of medical conditions, including some in the aging male, the need for a fuller understanding of the role of this axis in prostate cancer is increasingly important. Such information will lead to a deeper understanding of the actions of ghrelin and GHRH and provide potential opportunities for design of new therapies for prostate and other GH-IGF-responsive tumours.Read moreRead less
Regulation Of Growth Hormone Action By Oestrogen And Selective Oestrogen Receptor Modulators
Funder
National Health and Medical Research Council
Funding Amount
$474,750.00
Summary
Growth hormone (GH) is essential for body growth and development. In adult life, it plays a key role in regulating the ratio of body fat to muscle, thus influencing health. Disruption of GH action decreases muscle mass and increases body fat. These changes lead to reduced muscle strength and fitness, and increase the risk of diabetes, hypertension and cardiovascular mortality. Our laboratory has reported that oestrogens taken orally blunt GH action and cause unfavourable changes in body fat and ....Growth hormone (GH) is essential for body growth and development. In adult life, it plays a key role in regulating the ratio of body fat to muscle, thus influencing health. Disruption of GH action decreases muscle mass and increases body fat. These changes lead to reduced muscle strength and fitness, and increase the risk of diabetes, hypertension and cardiovascular mortality. Our laboratory has reported that oestrogens taken orally blunt GH action and cause unfavourable changes in body fat and muscle. How this happens is not known. As oral oestrogens are widely used in our society, it is important to understand the basis of their impact on GH action. SERMs, or selective oestrogen receptor modulators, are a group of drugs used in the treatment of breast cancer and osteoporosis. These substances mimic oestrogen action in some tissues, and block oestrogen action in others. Whether SERMs interfere with GH action as oestrogens do have not been studied, but such knowledge would have therapeutic significance because of their widespread and long-term use. GH action is mediated by a protein, called the GH receptor, located on the surface of target tissues. We propose that oestrogens and SERMs alter the production and function of this protein to control GH action. Thereby, this project is designed to test, in cultured cells of human origin, how oestrogens and SERMs modulate abundance of the GH receptor and its ability to mediate GH action. This work is anticipated to gain novel insights into the interaction of GH with oestrogens and SERMs. This information may also be useful for the design of new drugs devoid of adverse effects on GH action, and hence would have potentially significant implications in women s health and disease.Read moreRead less
Biomarkers For The Treatment And Prognosis Of Sight-threatening Diabetic Retinopathy
Funder
National Health and Medical Research Council
Funding Amount
$598,305.00
Summary
Diabetic retinopathy (DR) is a highly specific vascular complication of both type 1 and type 2 diabetes, with prevalence strongly related to the duration of diabetes. Clinic biomarkers of DR have become the basis for preventive medicine. In this project, we aim to evaluate possible biomarkers in both Chinese and Australian diabetic populations at different stages of DR. We will also investigate pathological mechanisms and novel drugs to treat DR in animal models.
Functional Modulation Of Ovine And Human Somatotropes By In Vitro Application Of Leptin
Funder
National Health and Medical Research Council
Funding Amount
$227,036.00
Summary
Obesity is a common disorder in developed countries and a prevalent condition which is often stigmatized. Actuarial data indicate that life expectancy is reduced when body-mass index (body mass in kg-square of the height in metres) is 20% or more above the ideal (obesity is >28% above ideal). Growth hormone (GH) from pituitary gland is the major anabolic hormone to increase muscle and reduce fat. A significant reduction in GH is found in obesity. Indeed, visceral fat mass is primary negative ....Obesity is a common disorder in developed countries and a prevalent condition which is often stigmatized. Actuarial data indicate that life expectancy is reduced when body-mass index (body mass in kg-square of the height in metres) is 20% or more above the ideal (obesity is >28% above ideal). Growth hormone (GH) from pituitary gland is the major anabolic hormone to increase muscle and reduce fat. A significant reduction in GH is found in obesity. Indeed, visceral fat mass is primary negative statistical determinant of GH secretion in middle age men and women. It is clear that the reduction in GH is due to a low sensitivity of GH cells to GH-releasing hormone (GHRH) from brain. It is therefore necessary to understand the change of pituitary GH cells in obesity. A recently identified, fat cell secreted, polypeptide (leptin) is demonstrated to reduce food intake and increase energy expenditure. Receptors for leptin have been found in pituitary gland, mainly in GH secreting cells. In our preliminary experiments, leptin reduces GH secretion by decreasing GHRH receptor synthesis. Meanwhile, this leptin treatment increased the receptors for GH-releasing peptide (GHRP), a synthetic peptide stimulating GH secretion. We aim to investigate the effect of leptin on cultured ovine and human GH cells by studying important cell functions including hormone and receptors synthesis, intracellular signaling molecules, membrane ion channels and cellular secreting machinery. The results will clarify the mechanism underlying GH deficiency in obese patients. We will also test the effect of synthetic GHRP in combination with leptin in vitro. The relationship between GHRP and leptin on the functional modification of GH cells will also be studied. It is likely to see that GHRP reduces the inhibitory effect of leptin on GH cells. This may end up an effective therapeutical use of GHRP (oral available) in the treatment of obesity.Read moreRead less
The Mechanism Of Growth Hormone Receptor Activation
Funder
National Health and Medical Research Council
Funding Amount
$679,500.00
Summary
Growth hormone GH excess or deficit results in considerably shortened lifespan. While cardiovascular disease is a major element in this mortality, GH status has also been linked to kidney disease and diabetic retinopathy. Importantly, GH produced locally in breast cells and prostate cells transform s these cells, creating cancers. We aim to define how GH activates its receptor, to facilitate a GH antagonist which results from understanding how GH activates its cell surface receptor.
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