Examination Of The Molecular Pharmacology Of Anthracyclines Induced Via Their Interaction With Iron
Funder
National Health and Medical Research Council
Funding Amount
$618,401.00
Summary
Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and ....Anthracyclines are highly effective anti-cancer drugs, but their use is limited by toxic effects on the heart. This is thought to be due to these drugs directly binding iron (Fe). Indeed, we showed that anthracyclines induced marked changes in the way heart cells utilise Fe (DR1-3, 38; Mol. Pharmacol. 2002, 2003, 2004, 2005). We were the first to show that anthracyclines prevent Fe release from the criticial Fe storage protein ferritin. This prevents the use of Fe for vital processes eg. DNA and haem synthesis. Hence, this effect probably contributes to the cytotoxic activity of anthracyclines on the heart. We showed that novel drugs developed in my lab that bind Fe called chelators show high activity in animals (DR4) and prevent anthracycline-mediated Fe accumulation in ferritin. Importantly, Fe chelators have been shown to inhibit anthracycline-mediated cardiotoxicity. Indeed, the clinically used cardioprotective agent, ICRF-187, is actually an Fe chelator (5, DR6). However, ICRF-187 is not totally successful in terms of its cardioprotective effects and can cause myelosuppression (5, DR6). While the clinically used chelator, desferrioxamine (DFO), can prevent anthracycline-mediated cardiotoxicity, its poor membrane permeability limits its effectiveness. Our chelators are highly permeable and overcome the disadvantages of DFO (DR4). Thus, they are vital to examine for preventing anthracycline-mediated cardiotoxicity. In this proposal we will examine the changes in Fe metabolism induced by anthracyclines and test the hypothesis that novel Fe chelators may prevent the cardiotoxicity of these agents. We also aim to be the first to assess if preparation of anthracyclines which cannot bind iron prevents their cardiotoxicity. This will be done by preparing metal complexes of these drugs which prevent Fe-binding eg. anthracycline-zinc complexes. These studies are important for the development of less cardiotoxic forms of these very useful anti-tumour agents.Read moreRead less
Novel Approaches To The Prevention And Treatment Of Chronic Heart Disease And Its Co-morbid Complications
Funder
National Health and Medical Research Council
Funding Amount
$5,793,580.00
Summary
Cardiovascular disease (CVD) and its associated additional disorders constitute major public health problems, especially given the rapidly ageing population which is increasingly affected by obesity and diabetes. This Program will explore novel therapies for the treatment of CVD and associated diseases, particularly focussing on chronic kidney disease, translating preliminary laboratory-based findings into clinical trials and then clinical and epidemiological findings into practice and policy.
Pharmacology Of Potential Anti-Tumour Agents: Iron Chelators Of The BpT Class
Funder
National Health and Medical Research Council
Funding Amount
$585,455.00
Summary
Pharmacology of Potential Anti-Tumour Agents: Iron Chelators of the BpT Class Cancer cells have a high iron requirement for DNA synthesis and many clinical trials showed Fe chelators are effective anti-cancer drugs. Their potential to act as anti-tumour agents has been confirmed by the entrance of Triapine into widespread NCI clinical trials. In this NHMRC Renewal, we will perform pharmacological and preclinical studies to promote the development of BpT chelators as novel anti-tumour agents.
Mitochondrial Iron Overload And Friedreich's Ataxia: The Role Of Frataxin In Iron And Haem Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$285,990.00
Summary
Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. Recent studies using Baker's yeast have shown that the deletion of frataxin results in the accumulation of toxic iron in the mitochondrion. More recently, a variety of studies have shown that FA patients have iron loading within their cells. The iron build-up may cause severe damage. At present, the role of frataxin in mammalian mitochondrial iron metabolism is unknown. Our preliminary studies demonstrate that frataxin i ....Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. Recent studies using Baker's yeast have shown that the deletion of frataxin results in the accumulation of toxic iron in the mitochondrion. More recently, a variety of studies have shown that FA patients have iron loading within their cells. The iron build-up may cause severe damage. At present, the role of frataxin in mammalian mitochondrial iron metabolism is unknown. Our preliminary studies demonstrate that frataxin is down-regulated by either erythroid differentiation or the haem precursor protoporphyrin IX (Becker and Richardson, submitted). These data strongly suggest a role for frataxin in iron metabolism. In the present study we will continue to assess if frataxin plays a role in the way cells handle iron. Using a unique model of mitochondrial iron overload developed in my lab (Richardson et al. (1996) BLOOD 87:3477), we will extensively investigate the iron metabolism of the mitochondrion in order to determine the function of frataxin and its role in Friedreich's ataxia. In addition, we have developed a series of new drugs known as iron chelators that can enter the mitochondrion due to their high lipid solubility (Becker and Richardson 1999 J. Lab. Clin. Med. 134:510). These latter drugs are far more effective than the chelator currently used to treat iron overload, desferrioxamine (DFO). Indeed, our chelators have been designed to result in high iron chelation efficacy but low toxicity (see Becker and Richardson, 1999). This exciting research may be crucial in understanding the development of FA and in creating new therapies such as the use of iron chelators.Read moreRead less
Mitochondrial Iron Overload And Friedreich's Ataxia: The Role Of Frataxin In Iron And Haem Metabolism
Funder
National Health and Medical Research Council
Funding Amount
$606,000.00
Summary
Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. A variety of studies using Baker's yeast and conditional frataxin knockout (KO) mice have shown that deletion of frataxin leads to the accumulation of toxic iron in their mitochondrion. More recently, a variety of studies have shown that FA patients have iron-loading within their mitochondrion. Iron in the highly redox active environment of the mitochondrion could contribute to the generation of cytotoxic radicals that c ....Friedreich's ataxia (FA) is due to the lack of a protein known as frataxin. A variety of studies using Baker's yeast and conditional frataxin knockout (KO) mice have shown that deletion of frataxin leads to the accumulation of toxic iron in their mitochondrion. More recently, a variety of studies have shown that FA patients have iron-loading within their mitochondrion. Iron in the highly redox active environment of the mitochondrion could contribute to the generation of cytotoxic radicals that cause severe damage. Further, cells deficient in frataxin are sensitive to oxidant stress and Fe chelators rescue oxidant-mediated death of cells from FA patients. Indeed, free radical scavengers have shown to be of use in the treatment of this disease. Studies in DR's lab during this NHMRC grant have shown that frataxin is down-regulated by erythroid differentiation or the haem precursor, protoporphyrin IX (BLOOD 2002;99:3813-22). These data indicate a role for frataxin in Fe metabolism and the pathogenesis of FA. In this study we will continue to examine the role of frataxin in the way cells handle Fe using experimental models developed under the current NHMRC grant. These include transfected cell lines with low frataxin expression generated using an expression vector containing anti-sense frataxin cDNA. Further we obtained the frataxin conditional KO mouse and generated a breeding colony. These animals display many of the pathological features of FA and are the best current model of the disease. Indeed, they will be critical for assessing the role of frataxin in Fe metabolism and as a model to test the ability of Fe-binding drugs to prevent the pathology observed. We designed lipid-soluble chelators that can enter the mitochondrion to bind Fe (Biochim Biophys Acta 2001;1536:133-140) and these ligands will be tested to prevent disease progression in the KO mice. This exciting research is crucial for understanding the pathogenesis of FA and in creating new therapies.Read moreRead less
Platelet Glycoprotein Proteolysis: Novel Mechanisms And Risk Factors
Funder
National Health and Medical Research Council
Funding Amount
$441,473.00
Summary
Platelets are the richest source of amyloid precursor protein (APP) in the body. Platelet ADAM10 regulates both the expression and function of the major platelet collagen receptor GPVI, and protective APP processing. Coagulation protein Factor X has a role in activation of ADAM10. This activation is disrupted in blood that has been treated with direct oral anticoagulant (DOAC) rivaroxaban. This grant will investigate the implications for people taking rivaroxaban on regulation of APP and GPVI.
The Role Of A Presenilin 2 Truncation (PS2V) In Alzheimer's Disease
Funder
National Health and Medical Research Council
Funding Amount
$552,741.00
Summary
The Presenilin and APP proteins are centrally important in inherited, early onset Alzheimer's disease. We have discovered that a shortened form of Presenilin protein, "PS2V", appears to increase specifically the rate at which the APP protein is cleaved to produce the "Amyloid beta" protein fragment that is found in Alzheimer's disease brains. This occurs when brain cells are under oxidative stress. Understanding this process will facilitate development of appropriate therapeutic strategies for t ....The Presenilin and APP proteins are centrally important in inherited, early onset Alzheimer's disease. We have discovered that a shortened form of Presenilin protein, "PS2V", appears to increase specifically the rate at which the APP protein is cleaved to produce the "Amyloid beta" protein fragment that is found in Alzheimer's disease brains. This occurs when brain cells are under oxidative stress. Understanding this process will facilitate development of appropriate therapeutic strategies for the disease.Read moreRead less
The Role Of Gonadotropins In Regulating The Production Of Alzheimer's Beta Amyloid
Funder
National Health and Medical Research Council
Funding Amount
$400,278.00
Summary
Currently, about 160,000 Australians suffer from dementia; of which 50-70% are Alzheimer's disease (AD) cases. AD is characterised clinically by memory and personality changes and pathologically by deposition of amyloid. Of particular importance in the disease pathogenesis, is a small molecule called beta amyloid, of which the overproduction is thought to be central to the development of AD. Changes in the levels of the reproductive hormones, particularly low levels of oestrogen during menopause ....Currently, about 160,000 Australians suffer from dementia; of which 50-70% are Alzheimer's disease (AD) cases. AD is characterised clinically by memory and personality changes and pathologically by deposition of amyloid. Of particular importance in the disease pathogenesis, is a small molecule called beta amyloid, of which the overproduction is thought to be central to the development of AD. Changes in the levels of the reproductive hormones, particularly low levels of oestrogen during menopause or testosterone during andropuase, has been associated with the increased risk of developing AD and in altering the levels of beta amyloid. Furthermore, menopause and andropause are also characterised by changes in other reproductive hormones such as the gonadotropins. High levels of the gonadotropins have also been associated with the increased risk of developing AD. Therefore it is important to identify how these changes modify the risk of developing AD. This study examines the role of the gonadotropins in regulating beta amyloid levels in cell culture and in an animal model for AD. Furthermore, this study will assess, in the animal model, the use of gonadotropin lowering agents to reduce levels of beta amyloid. The results from this study will provide important data on how reproductive hormones regulate beta amyloid. Further insight into these mechanisms will provide therapeutic or preventative strategies for AD.Read moreRead less
Developing Novel Molecules To Down-Regulate Src Family Tyrosine Kinases
Funder
National Health and Medical Research Council
Funding Amount
$201,261.00
Summary
Leukaemia and cancer cells have altered biochemical properties resulting in their high rate of growth compared to normal cells. One of the common biochemical characteristics of cancer-leukaemia cells is augmented activity levels of enzymes called tyrosine kinases. A major group of tyrosine kinase involved in several cancer-leukaemia types is called the Src family of tyrosine kinases. One member of this family called Lyn has been our focus of study for several years, investigating the signalling ....Leukaemia and cancer cells have altered biochemical properties resulting in their high rate of growth compared to normal cells. One of the common biochemical characteristics of cancer-leukaemia cells is augmented activity levels of enzymes called tyrosine kinases. A major group of tyrosine kinase involved in several cancer-leukaemia types is called the Src family of tyrosine kinases. One member of this family called Lyn has been our focus of study for several years, investigating the signalling pathways that it is involved in. This molecule has also been implicated in several specific leukaemia (Chronic Myeloid Leukaemia and Acute Myeloid Leukaemia) as well as cancer (Prostate, Colon, Breast) in recent years. We have identified a novel mechanism of down-regulation of this enzyme mediated by an adapter molecule called Cbp, which recruits the Lyn inactivating molecules Csk-Ctk as well as SOCS-1; together they inhibit the activity of Lyn and degrade the enzyme. Using our knowledge of the essential interaction elements of Cbp we will design and test various mini-Cbp molecules for their ability to inactivate and degrade Lyn in leukemic and cancer cells. These molecules may allow us to develop novel therapeutics capable of inactivating-degrading specific tyrosine kinases in cancer and leukaemia.Read moreRead less
Characterization Of Novel Regulators Of Erythropoiesis
Funder
National Health and Medical Research Council
Funding Amount
$437,545.00
Summary
Mature red and white blood cells develop from hemopoietic stem cells in the adult bone marrow. The production of red blood cells is primarily controlled by the hormone erythropoietin (epo). The availability of this hormone in a recombinant form has aided in the treatment of numerous forms of anaemia resulting from kidney failure, malignancies, and AIDS. Previously we had identified that the protein Lyn must be present inside primitive red blood cells for epo to stimulate them to become mature fu ....Mature red and white blood cells develop from hemopoietic stem cells in the adult bone marrow. The production of red blood cells is primarily controlled by the hormone erythropoietin (epo). The availability of this hormone in a recombinant form has aided in the treatment of numerous forms of anaemia resulting from kidney failure, malignancies, and AIDS. Previously we had identified that the protein Lyn must be present inside primitive red blood cells for epo to stimulate them to become mature functional cells. We have identified six molecules which interact with Lyn in red blood cells. We have shown that amolecule called HS1 is important for epo function in individual red blood cells and now we plan to investigate its functions in whole animals, including mice that lack the HS1 gene. We have also shown that a molecule called Trip1 is important for red blood cell development. Interestingly, this molecule also interacts with the thyroid hormone receptor and can influence the effects of epo and thyroid hormone on red blood cell development. The interplay between these two hormones will be looked at in more detail both at the cell and whole animal levels in normal mice and those lacking the thyroid hormone receptor gene. The third Lyn binding molecule we isolated is a novel gene-we have named it ankyrin repeat protein in line with the molecules it is related to. This gene is expressed in red blood cells and we aim to investigate what role it plays in the development of these cells. The fourth gene is also novel and is closely related to another called AFAP-110, which can exert effects on the structure of a cell. Its role in red blood cell structure will also be investigated. Finally, the last two molecule we have identified are both novel and are unrelated to any other known proteins. As above, the effects of these two molecules on red blood cell development will be investigated.Read moreRead less