Factor inhibiting HIF (FIH) negatively regulates hypoxia inducible factor-1 (HIF-1) transcriptional activity, selectively controlling certain HIF-1 target genes, such as vascular endothelial growth factor (VEGF) and prolyl hydroxylase domain 3 (PHD3), but not others. PHD3 and VEGF are important for placental development and function and are overexpressed in preeclampsia (PE). The purpose of this study was to examine FIH in both normal and pathological human placentae. I hypothesized that FIH regulates VEGF and PHD3 in the placenta and that this rheostat is altered in PE. Results show that FIH suppresses PHD3 and VEGF in JEG-3 cells; this effect was abrogated by FIH gene silencing. Moreover, my data indicate that seven in absentia homologue-1 (Siah-1) targets FIH for degradation in the placenta; this degradation is enhanced in PE and likely contributes to aberrant VEGF and PHD3 expression. Overall, my data suggest an important role for FIH in the pathogenesis of PE.

Clear cell renal cell carcinoma (ccRCC) is an aggressive malignancy characterized by inactivation of the von Hippel-Lindau tumour suppressor gene, the protein product of which mediates degradation of the transcription factor hypoxia-inducible factor (HIF). GAL3ST1 is a sulfotransferase which catalyzes the production of sulfatide, a plasma membrane sulfolipid previously implicated in metastasis. We observed GAL3ST1 overexpression in primary ccRCC tumours relative to matched-normal tissue and subsequently asked if GAL3ST1 was a HIF-responsive gene that facilitates ccRCC metastasis. GAL3ST1 expression was suppressed in ccRCC cells by stable reconstitution of wild-type VHL and also siRNA-mediated knockdown of HIF1alpha and HIF2alpha. Dual luciferase assays and chromatin immunoprecipitation revealed a hypoxia-response element in the GAL3ST1 5’-UTR that appeared to be crucial for HIF-mediated upregulation. Finally, stable knockdown of GAL3ST1 significantly impeded ccRCC cell invasion through an in vitro basement membrane mimic. These results suggest GAL3ST1 is a HIF-responsive gene that promotes tumour cell invasion.

Activity of the hypoxia inducible HIF-alpha transcription factors drive the hypoxic response, resulting in enhancement of angiogenesis, tumour growth, invasion and metastasis. Seeking to uncover a role for Tid1 in control of HIF2-alpha, we used lentiviral shRNA to knock-down Tid1 in 786-0 RCC cells with and without pVHL. In 786-0 cells stably expressing pVHL30, Tid1 knock-down resulted in a dramatic reduction in HIF2-alpha levels relative to controls. Adenoviral-mediated overexpression of Tid1S rescued this decline in HIF2-alpha levels, while overexpression of Tid1L enhanced this decline. A protective role of Tid1S for HIF2-alpha was reproduced in a HEK293 cell model. Immunoprecipitations in HEK293 cells revealed a lack of direct binding between HIF2-alpha and Tid1 in vivo, while adenoviral-mediated overexpression of Tid1 in this model failed to alter in vitro binding between HIF2-alpha and pVHL30. We present a model in which Tid1 regulates HIF2-alpha stability through regulation of pVHL30 nuclear import.

<p>Malignant gliomas are highly lethal cancers characterized by florid angiogenesis. Glioma stem cells (GSCs), enriched through CD133 (Prominin1) selection, are highly tumorigenic and therapy resistance. However, the mechanism through which GSCs promote tumor growth was largely unknown. As we noticed that tumors derived from GSCs contain widespread tumor angiogenesis, necrosis, and hemorrhage, we examined thepotential of GSCs to support tumor angiogenesis. We measured the expression of a panel of angiogenic factors secreted by GSCs. In comparison with matched non-GSC populations, GSCs consistently secreted markedly elevated levels of vascular endothelial growth factor (VEGF), which were further induced by hypoxia. In an in vitro model of angiogenesis, GSC-conditioned medium significantly increased endothelial cell migration and tube formation compared with non-GSC glioma cell-conditioned medium. The proangiogenic effects of GSCs on endothelial cells were specifically abolished by the anti-VEGF neutralizing antibody bevacizumab, which is in clinical use for cancer therapy. Furthermore, bevacizumab displayed potent antiangiogenic efficacy in vivo and suppressed growth of xenografts derived from GSCs but limited efficacy against xenografts derived from a matched non-GSC population. As hypoxia is a key regulator of angiogenesis, I further examined hypoxic responses in GSCs to determine the molecular mechanisms underlying their angiogenic drive. I demonstrated that multiple hypoxia response genes, including the hypoxia-inducible factors (HIFs)-1a and -2a(EPAS-1) were differentially expressed in GSCs in comparison to non-stem glioma cells and normal neural progenitors. GSCs preferentially induced HIF2a; and HIF2a-regulated genes under hypoxia in comparison to non-stem glioma cells. In contrast, neural progenitor/stem cells did not induce HIF2a in response to hypoxia suggesting that the HIF2a hypoxic response is not a general stem cell response. Targeting HIF1a or HIF2a in GSCs using short hairpin RNA (shRNA) inhibited neurosphere formation efficiency, indicating a requirement for HIFs in cancer stem cell self-renewal. HIF1a and HIF2a were also necessary for VEGF expression in GSCs, but HIF2a was not required in matched non-stem glioma cells. In vivo experiments determined that knockdown of HIFs significantly attenuated the tumorigenic capacity of GSCs and increased survival of immunocompromised mice. Together, our work provides the first evidence that that GSCs can be a crucial source of key angiogenic factors in cancers due to their differential hypoxia responses. It also suggests that anti-angiogenic therapies can be designed to target GSC-specific molecular mechanisms of neoangiogenesis, including the expression and/or activity of HIF2a.</p> / Dissertation

<p>Imbalance between oxygen consumption and supply often makes tumors hypoxic (Bristow and Hill 2008). Tumor hypoxia is significantly correlated with aggressive tumor growth, ineffective response to radiation and chemotherapy, and as a result, poor patient prognosis. Hyperthermia (HT) is a strong adjuvant treatment to overcome these challenges of tumor hypoxia because it causes tumor reoxygenation at temperatures lower than 43ºC (Song, Park, and Griffin 2001). However, the detailed molecular mechanisms of how HT enhances tumor oxygenation have not been elucidated. Here we determine that 1 hour HT activates hypoxia-inducible factor-1 (HIF-1) and its downstream targets, vascular endothelial growth factor (VEGF), lactate dehydrogenase A (LDHA), and pyruvate dehydrogenase kinase 1 (PDK1) in tumors. Consistent with HIF-1 activation and upregulation of its downstream genes, HT also enhances tumor perfusion/vascularization and decreases oxygen consumption rates. As a result, tumor hypoxia is reduced after HT suggesting that these physiological changes contribute to HT-induced tumor reoxygenation. Since HIF-1 is a potent regulator of tumor vascularization and metabolism, our findings suggest that HIF-1 plays a role in HT-induced tumor reoxygenation by transactivating its downstream targets. Mechanistically, we demonstrate that NADPH oxidase-mediated reactive oxygen species (ROS) production upregulates HIF-1 after HT. Further, we determine that this pathway is initiated by increased transcription of NADPH oxidase-1 (NOX1) through the ERK pathway.</p><p>A major research effort at Duke focuses on combinations of HT and doxorubicin in the treatment of locally advanced breast and other cancers. Thus, we investigated whether there are HIF-1 responses to doxorubicin treatment. We reveal that doxorubicin also activates HIF-1. Unlike HT, doxorubicin-induced HIF-1 promotes persistent tumor angiogenesis. We also reveal that the signal transducer and activator of transcription 1 (STAT1)/inducible nitric oxide synthase (iNOS) pathway causes HIF-1&#945; accumulation in an oxygen-independent manner. We show that activated STAT1 upregulates iNOS expression and promotes nitric oxide (NO) production in tumor cells resulting in HIF-1&#945; stabilization. We further determine that both iNOS inhibitor, 1400W and STAT1 inhibitor, epigallocatechin-3-gallate (EGCG) significantly decrease intracellular NO production and suppress doxorubicin-induced normoxic HIF-1&#945; accumulation.</p><p>HIF-1 is often considered a promising therapeutic target because of its role in tumor progression (Semenza 2003) and therapy resistance (Moeller et al. 2004). However, our findings suggest that HIF-1 plays a pleiotropic role in response to HT and chemotherapy. Therefore, to preferentially take advantage of HT-induced HIF-1 activation and also to suppress its deleterious effects induced by chemotherapy or as we have previously reported, by radiation (Moeller et al. 2004), HIF-1 inhibition needs to be carefully regulated in a time-sensitive manner to achieve optimal therapeutic effects.</p> / Dissertation

Mammals are well adapted to respond to changes in ambient oxygen concentration (O2) by activating homeostatic physiological and cellular responses which maintain cell function and survival. Although anemia has been associated with increased mortality in a number of clinical settings, surprisingly little is known about how anemia affects tissue PO2 and hypoxia signaling. Because nitric oxide synthases (NOSs) figure prominently in the cellular response to acute hypoxia, we define the effects of NOS deficiency in acute anemia. Unlike wildtype (WT), endothelial NOS (eNOS) and inducible NOS (iNOS) deficient mice, only neuronal NOS (nNOS) deficient mice (nNOS-/-) demonstrated increased mortality during acute anemia. With respect to global tissue O2 delivery, anemia did not increase cardiac output (CO) or reduce systemic vascular resistance (SVR) in nNOS -/- mice. At the cellular level, anemia increased expression of HIF-1α and HIF-responsive mRNA levels (EPO, VEGF, GLUT1, PDK) in the brain of WT, but not nNOS-/- mice. These date suggest that nNOS contributed to cardiovascular and cellular mechanisms which maintain oxygen homeostasis in anemia. To confirm the physiological relevance of these findings in a whole animal model of anemia, we utilized transgenic animals which express a reporter HIF-α(ODD)-luciferase chimeric protein. Using this model, we confirmed that nNOS is essential for anemia-induced increases in HIF-α protein stability in vivo in real-time whole animal images and brain tissue. With respect to the mechanism, nNOS-derived NO is known to affect S-nitrosylation of specific proteins, which may interfere with HIF-α and von Hippal Lindau protein (pVHL) interaction. Utilizing the biotin switch assay, we demonstrated that anemia caused a time-dependent increase in S-nitrosylation of pVHL in brain tissue from WT but not nNOS-/- mice. In addition, anemia also leads to a decrease in S-nitrosoglutathione (GSNO) reductase protein expression, an important enzyme responsible for de-nitrosylation of proteins. The combination of increased nNOS expression and decreased GSNO reductase expression would favor prolonged S-nitrosylation of proteins during anemia. These findings identify nNOS effects on the HIF/pVHL signaling pathway as critically important in the physiological responses to anemia in vivo. By contrast, after exposure to acute hypoxia, nNOS-/- mice survived longer, retained the ability to regulate CO and SVR, and increased brain HIF-α protein levels and HIF-responsive mRNA transcripts. This comparative assessment provided essential mechanistic insight into the unexpected and striking difference between anemia and hypoxia. Understanding the adaptive responses to acute anemia will help to define novel therapeutic strategies for anemic patients.

Mammals are well adapted to respond to changes in ambient oxygen concentration (O2) by activating homeostatic physiological and cellular responses which maintain cell function and survival. Although anemia has been associated with increased mortality in a number of clinical settings, surprisingly little is known about how anemia affects tissue PO2 and hypoxia signaling. Because nitric oxide synthases (NOSs) figure prominently in the cellular response to acute hypoxia, we define the effects of NOS deficiency in acute anemia. Unlike wildtype (WT), endothelial NOS (eNOS) and inducible NOS (iNOS) deficient mice, only neuronal NOS (nNOS) deficient mice (nNOS-/-) demonstrated increased mortality during acute anemia. With respect to global tissue O2 delivery, anemia did not increase cardiac output (CO) or reduce systemic vascular resistance (SVR) in nNOS -/- mice. At the cellular level, anemia increased expression of HIF-1α and HIF-responsive mRNA levels (EPO, VEGF, GLUT1, PDK) in the brain of WT, but not nNOS-/- mice. These date suggest that nNOS contributed to cardiovascular and cellular mechanisms which maintain oxygen homeostasis in anemia. To confirm the physiological relevance of these findings in a whole animal model of anemia, we utilized transgenic animals which express a reporter HIF-α(ODD)-luciferase chimeric protein. Using this model, we confirmed that nNOS is essential for anemia-induced increases in HIF-α protein stability in vivo in real-time whole animal images and brain tissue. With respect to the mechanism, nNOS-derived NO is known to affect S-nitrosylation of specific proteins, which may interfere with HIF-α and von Hippal Lindau protein (pVHL) interaction. Utilizing the biotin switch assay, we demonstrated that anemia caused a time-dependent increase in S-nitrosylation of pVHL in brain tissue from WT but not nNOS-/- mice. In addition, anemia also leads to a decrease in S-nitrosoglutathione (GSNO) reductase protein expression, an important enzyme responsible for de-nitrosylation of proteins. The combination of increased nNOS expression and decreased GSNO reductase expression would favor prolonged S-nitrosylation of proteins during anemia. These findings identify nNOS effects on the HIF/pVHL signaling pathway as critically important in the physiological responses to anemia in vivo. By contrast, after exposure to acute hypoxia, nNOS-/- mice survived longer, retained the ability to regulate CO and SVR, and increased brain HIF-α protein levels and HIF-responsive mRNA transcripts. This comparative assessment provided essential mechanistic insight into the unexpected and striking difference between anemia and hypoxia. Understanding the adaptive responses to acute anemia will help to define novel therapeutic strategies for anemic patients.

Impaired implantation and placental development have been implicated in several disorders of pregnancy such as unexplained miscarriage, preeclampsia, and intrauterine growth retardation. Insulin-Like Growth Factor (IGF)-II has previously been shown to promote blastocyst development and placental growth and function. We were interested in how IGF-II interacts with other factors throughout blastocyst development, implantation and placentation in the mouse to improve pregnancy outcome. In vitro embryo culture increases the risk of pregnancy complications associated with poor placentation. Recent research has focussed on optimising the culture conditions to more resemble that of the in vivo environment. IGF-II, Urokinase Plasminogen Activator (uPA) and Plasminogen individually have all been shown to be important for embryo development. However, it is likely that a combination of factors is required to counteract the negative effects of in vitro culture. Here we show that IGF-II, uPA and Plasminogen, in combination, significantly improve mouse blastocyst hatching rates and implantation rates on day 8 and doubles the number of mothers that are pregnant after embryo transfer. Following implantation, IGF-II is suggested to play a role in promoting placental development and function. We demonstrate that IGF-II is co-localised with both IGF receptors throughout early pregnancy in trophoblasts and in the developing blood vessels and adjacent stromal cells in the mesometrial decidua. This suggests that IGF-II may play a role in both decidual angiogenesis and placentation. We suggest that perhaps murine trophoblasts secrete molecules such as IGF-II to promote angiogenesis in the decidua early in pregnancy to compensate for their shallow invasion and allow for adequate trophoblast remodelling later in pregnancy. The first trimester human placenta experiences a low oxygen environment. The Hypoxia-Inducible Factors (HIFs) mediate the response to low oxygen, inducing genes such as IGF-II. Currently, the role of oxygen in mouse placentation, the mechanisms by which HIFs promote placentation or their interaction with IGF-II in the placenta is unknown. Here, we demonstrate that the early mouse implantation site is exposed to low oxygen levels similar to those seen in humans and expresses HIF-1 protein. We were interested then in the interaction between IGF-II, oxygen and HIFs in trophoblasts in vitro. Prolonged exposure to low oxygen reduced trophoblast outgrowth, and increased Tpbp mRNA levels, suggesting commitment to the spongiotrophoblast lineage. Interestingly, we found that antisense (as) Hif-1 may mediate the response to prolonged hypoxia in murine trophoblasts. Importantly, Hif-1 and Hif-2 were differentially regulated by oxygen and IGF-II in cultured trophoblast cells suggesting a novel interaction between IGF-II and oxygen. In conclusion, it appears that IGF-II is a central growth factor which interacts with other molecules to regulate a wide variety of process in early pregnancy to promote blastocyst development, implantation and placentation. The results outlined in this thesis demonstrate a novel interaction between IGF-II, uPA and Plasminogen in promoting blastocyst development and implantation which may be used to improve pregnancy outcome following ART. In addition, we have also identified a novel interaction between IGF-II, oxygen and the HIF system which may regulate trophoblast function. This has important implications not only for placental research, but also for cancer research. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1326731 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

Impaired implantation and placental development have been implicated in several disorders of pregnancy such as unexplained miscarriage, preeclampsia, and intrauterine growth retardation. Insulin-Like Growth Factor (IGF)-II has previously been shown to promote blastocyst development and placental growth and function. We were interested in how IGF-II interacts with other factors throughout blastocyst development, implantation and placentation in the mouse to improve pregnancy outcome. In vitro embryo culture increases the risk of pregnancy complications associated with poor placentation. Recent research has focussed on optimising the culture conditions to more resemble that of the in vivo environment. IGF-II, Urokinase Plasminogen Activator (uPA) and Plasminogen individually have all been shown to be important for embryo development. However, it is likely that a combination of factors is required to counteract the negative effects of in vitro culture. Here we show that IGF-II, uPA and Plasminogen, in combination, significantly improve mouse blastocyst hatching rates and implantation rates on day 8 and doubles the number of mothers that are pregnant after embryo transfer. Following implantation, IGF-II is suggested to play a role in promoting placental development and function. We demonstrate that IGF-II is co-localised with both IGF receptors throughout early pregnancy in trophoblasts and in the developing blood vessels and adjacent stromal cells in the mesometrial decidua. This suggests that IGF-II may play a role in both decidual angiogenesis and placentation. We suggest that perhaps murine trophoblasts secrete molecules such as IGF-II to promote angiogenesis in the decidua early in pregnancy to compensate for their shallow invasion and allow for adequate trophoblast remodelling later in pregnancy. The first trimester human placenta experiences a low oxygen environment. The Hypoxia-Inducible Factors (HIFs) mediate the response to low oxygen, inducing genes such as IGF-II. Currently, the role of oxygen in mouse placentation, the mechanisms by which HIFs promote placentation or their interaction with IGF-II in the placenta is unknown. Here, we demonstrate that the early mouse implantation site is exposed to low oxygen levels similar to those seen in humans and expresses HIF-1 protein. We were interested then in the interaction between IGF-II, oxygen and HIFs in trophoblasts in vitro. Prolonged exposure to low oxygen reduced trophoblast outgrowth, and increased Tpbp mRNA levels, suggesting commitment to the spongiotrophoblast lineage. Interestingly, we found that antisense (as) Hif-1 may mediate the response to prolonged hypoxia in murine trophoblasts. Importantly, Hif-1 and Hif-2 were differentially regulated by oxygen and IGF-II in cultured trophoblast cells suggesting a novel interaction between IGF-II and oxygen. In conclusion, it appears that IGF-II is a central growth factor which interacts with other molecules to regulate a wide variety of process in early pregnancy to promote blastocyst development, implantation and placentation. The results outlined in this thesis demonstrate a novel interaction between IGF-II, uPA and Plasminogen in promoting blastocyst development and implantation which may be used to improve pregnancy outcome following ART. In addition, we have also identified a novel interaction between IGF-II, oxygen and the HIF system which may regulate trophoblast function. This has important implications not only for placental research, but also for cancer research. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1326731 / Thesis (Ph.D.) -- University of Adelaide, School of Paediatrics and Reproductive Health, 2008

This thesis sought to improve our understanding of how kidneys become injured as a consequence of organ donation, with the aim of improving the outcomes of transplantation. Every year, hundreds of patients on the waiting list die whilst awaiting a kidney transplant. With an ever-increasing demand for suitable organs, supply cannot keep up with the pressures on the transplant waiting list. As a consequence the transplant community are forced to use organs that previously would not have been considered suitable for transplant, including from older donors with additional comorbidities. This thesis aimed to develop an understanding as to how the kidney becomes injured during the donation process, identifying which key cellular homeostatic processes are disturbed as a consequence of donation. The thesis outlines the experimental development of rodent models of organ donation replicating the donation process for donation after brain death (DBD) and donation after circulatory death (DCD) donors and also the development of a kidney ischaemia reperfusion injury (IRI) model. Proteomics was subsequently used to identifying global protein alterations in the kidney as a consequence of brain death and ischemia reperfusion injury using bioinformatics tools to identify involvement of cellular pathways. The results indicated alterations in mitochondrial function and metabolic homeostasis occurring following brain death. Alterations in cellular metabolism and mitochondrial function were then confirmed using metabolomics and mitochondrial functional assays. I subsequently evaluated how alterations in cellular hypoxia and the hypoxia inducible factor system is altered in the brain dead organ donor kidney and aimed to target this system as a means of conditioning the brain dead organ donor to prevent mitochondrial and metabolic mediated injury to kidney cells following brain death. This involved exploring the role of prolyl hydroxylase inhibitors, including dimethyloxalylglycine, on mitochondrial function and whether this could be a therapeutic target in organ donation. This thesis provides important insights into the mechanism of injury of kidneys following brain death, providing evidence that even before procurement and preservation in the DBD donor alterations in mitochondrial function and metabolic homeostasis occur. I provide preliminary data on the use of prolyl hydroxylase inhibitors in altering mitochondrial function. I also outline my involvement in other ongoing projects in organ donation and machine perfusion that also aim to improve the outcomes of deceased donor kidney and liver transplantation.