| 51. |
- Jögi, Annika
(författare)
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Transcriptional regulation in neuroblastoma cells under normoxic and hypoxic conditions
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The childhood malignancy neuroblastoma develops from early cells of the sympathetic nervous system (SNS), and the tumors often produce catecholamines. Neuroblastoma cells retain several characteristics of immature sympathetic cells including the expression of a number of transcription factors normally expressed during embryogenesis. The genesis of the SNS requires the correct expression pattern of several transcription factors of the basic helix-loop-helix (bHLH) family, such as HASH-1 a pro-neuronal gene. HASH-1 expression is negatively regulated by another bHLH factor, HES-1. In these studies, we show that HASH-1 form transcription activating dimers with the ubiquitously expressed bHLH factor E2-2 in neuroblastoma cells. Furthermore, we establish that the Id proteins, which lack the basic DNA-binding domain and act as dominant negative inhibitors in the bHLH network, bind to HES-1. By dimerization with HES-1 the Id proteins may act to repress the HES-1 mediated transcriptional repression. In addition, HES-1 can alleviate the negative effect of Id proteins on bHLH factor induced transcription, by sequestration of Id. These findings reveal a novel regulatory level of the bHLH network. Solid tumors most often contain regions with impaired circulation and hypoxia. Two transcription factors of the bHLH/PAS subgroup, the hypoxia inducible factors HIF-1a and HIF-2a, are key regulators of the cellular response to oxygen deprivation. Interestingly, HIF-2a is also expressed in the developing SNS and required for catecholamine production, and HIF-2a deficient mice die with bradycardia before birth. The dual implications of HIF-2a in neuroblastoma tumors, involvement in SNS development as well as in adaptation to the tumor microenvironment , prompted us to investigate how neuroblastoma cells respond to growth under hypoxic conditions. Unexpectedly, we found that hypoxia (1% oxygen) drive the neuroblastoma cells toward an immature and neural crest-like phenotype. Several neuronal and neuroendocrine marker genes, such as chromogranin A/B, NPY, and HASH-1, were down-regulated in response to oxygen deprivation, whereas a number of genes expressed during early neural crest development were up-regulated, examplified by c-kit, Notch-1, and Id2. To further delineate the the hypoxic phenotype of human neuroblastoma cells, we have analyzed their gene expression after 72 h exposure to hypoxia employing microarray analysis harboring 35 000 clones. Almost one percent of the represented transcripts were up-regulated more than three-fold and about 0.5 % were down-regulated more than three-fold in response to hypoxia. The microarray results strenghten our view of hypoxic neuroblastoma cells as less mature. To test whether hypoxia-induced dedifferentiation is a neuroblastoma specific event or may occur also in other solid tumors, we have analyzed a panel of ductal breast carcinoma in situ. Also in these tumors, were hypoxia associated with a less mature phenotype of the tumor cells. We propose hypoxia-induced dedifferentiation as one means by which intra-tumor hypoxia drives tumor propagation.
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| 52. |
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| 53. |
- Kinhult, Sara
(författare)
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Endothelial and cardiac effects of 5-fluorouracil. An experimental and clinical study.
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The cytostatic drug 5-fluorouracil (5-FU) has been shown to affect both morphology and function of vascular endothelium. These effects could be part of the pathophysiology for 5-FU induced cardiotoxicity. The present thesis explores the mechanisms of this endothelial toxicity. In an animal model, treatment with thromboprophylactic doses of the low-molecular weight heparin (LMWH) dalteparin could not protect the endothelium from damage caused by 5-FU, although the secondary thrombosis was prevented. A subsequent study with three different LMWH (dalteparin, enoxaparin and tinzaparin) showed a moderate endothelial injury after treatment with LMWH alone for up to 60 days. Probucol, a lipid-lowering drug with strong antioxidant properties, was given as prophylaxis for two weeks before 5-FU treatment. With this drug, the endothelium was protected from the negative effects of 5-FU and had a normal morphology. Patients receiving 5-days infusion of 5-FU, combined with cisplatin, were studied for endothelial and cardiac effects. There was a significant increase in markers for endothelial injury (von Willebrand factor and soluble thrombomodulin) and in malondialdehyde, a marker for increased lipoperoxidation and possibly free radical production. Myocardial and echocardiographic parameters were not changed. Human umbilical vein endothelial cells (HUVEC) were incubated with 5-FU. A dose-dependant increase in secretion of endothelin-1 (a potent vasoconstrictor) was shown. No influence of apoptosis was seen. The results indicate increased oxidative stress caused by 5-FU, followed by endothelial damage and secretion of a vasoactive peptide. This could be part of the pathophysiological mechanisms of 5-FU induced cardiotoxicity.
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| 54. |
- Massoumi, Ramin
(författare)
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Regulation of the cytoskeleton and the adhesiveness of intestinal epithelial cells by leukotriene D4
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Leukotrienes belong to a family of biologically active conjugated trienes that are formed from arachidonic acid via the 5-lipoxygenase pathway and are important mediators of inflammatory reactions. The CysLT1 receptor that specifically serves as receptor for leukotriene D4 (LTD4) has been identified as a G-protein coupled receptor. Cell-cell and cell-matrix complexes of epithelial cells are interconnected through cytoskeletal filaments and proteins, and they influence the activities and outcome of various cellular processes. This thesis is focused primarily on the effect that LTD4 has on reorganisation of the actin cytoskeleton and on cell-cell and cell-matrix adhesion properties. We found that LTD4 caused dramatic changes in the actin cytoskeleton in intestinal epithelial cells, and an important factor in this context was the impact of this leukotriene on the actin-binding protein vinculin, which included inducing translocation of vinculin from a cell-cell to a cell-matrix complex. In general, cell adhesion favours cell survival signalling, and integrins are the main receptors responsible for mediating the attachment of different types of cells to matrix proteins. We have unequivocally established that direct signalling occurs between the LTD4 receptor and the collagen integrins in two different cell lines respectively derived from human colon carcinoma and intestinal epithelial cells. Increased adhesion of the cancer cells depended on activation of cyclooxygenase-2, an enzyme that is involved in progression of colon cancers, whereas adhesion of the intestinal epithelial cells was augmented by LTD4-induced translocation of protein kinase C to areas where integrins bind to matrix proteins (focal adhesions). In conclusion, inflammatory mediators such as LTD4 can affect cell survival through their impact on specific integrins.
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| 55. |
- Nilsson, Jonas, et al.
(författare)
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Cloning, characterization and expression of human LIG1
- 2001
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 284:5, s. 1155-1161
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Tidskriftsartikel (refereegranskat)abstract
- Growth factor receptors are frequently amplified and over-expressed in various human cancers. Recently, a Drosophila cell surface protein, Kekkon-1, was found to participate in an epidermal growth factor (EGF) driven negative feedback loop. Kekkon-1 is induced by EGF, binds to the EGF-receptor, and inhibits receptor-mediated signaling. Here, we have searched for human genes with homologies to Kekkon-1 and identified human LIG1. The gene is the human homologue of mouse Lig-1 and is located on chromosome band 3p14, a region frequently deleted in various human cancers. It is predicted to encode a transmembrane cell-surface protein with extracellular leucine-rich repeats and immunoglobulin-like domains. LIG1 mRNA was detected in all tissues analyzed. The highest and lowest relative expression levels were found in brain and spleen, respectively, and differed by more than 200-fold. Taken together, our data are compatible with a role for LIG1 as a growth and tumor suppressor in human tissues.
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| 56. |
- Persson, Christina, 1946-
(författare)
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Improved Nutritional Support in Cancer Patients
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Weight loss and other nutritional problems are common in cancer patients. The problems are of importance for response to treatment and survival and the well-being of the patients.Nutritional support can be carried out in different ways. The efforts considered in this thesis are; assessment of nutritional status to find the patients who are at risk to become or already are malnourished, assessment of dietary intake, dietary advice, information and support to the families, information and education to the caregivers, and supplementation with drugs that possibly could influence the weight development. The Swedish version of the Patient Generated Subjective Global assessment of nutritional status, PG-SGA, is useful in assessment of nutritional status in cancer patients. Dietary advice and support to patients and their families combined with information and education to the staff, at the hospital and in the home care, turned out to have a positive influence at the weight development and other parameters related to nutrition. The effects were seen in consecutive patients with small cell lung cancer in comparison with a historical control group, and in patients in a randomised trial. Fish oil and melatonin could stabilise weight development in patients with advanced gastrointestinal cancer, but had no marked influence on factors reflecting cachexia. Problems with nutrition in cancer patients are possible to recognise and various interventions may be beneficial.
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| 57. |
- Persson, Paula
(författare)
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Regulation and functions of basic helix-loop-helix transcription factors in neuroblastoma cells
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Neuroblastoma is a childhood tumor derived from primordial neural crest cells. The tumor cells exhibit a phenotype similar to that of developing neuroblasts, which indicates that the tumor arises due to perturbed differentiation of the sympathetic nervous system. It is well established that transcription factors control the steps leading to neuronal differentiation, and a number of basic helix-loop-helix (bHLH) proteins have been implicated in this process. To understand the genesis of neuroblastoma, it is essential to elucidate the transcriptional cascades involved in regulating neuronal differentiation. The present studies focused mainly on the role and function of the bHLH transcription factor human achaete-scute homologue 1 (HASH-1) in neuroblastoma cells. Two novel HASH-1-interacting proteins were isolated: the broadly expressed E2-2 and the ubiquitin-related ubiquilin-1. We found that the bHLH protein E2-2 associates with HASH-1 to form a functional, transactivating complex that may be involved in neurogenesis. It has been suggested that ubiquilin-1 participates in protein turnover, which agrees with our finding that ubiquilin-1 promotes accumulation of HASH-1. Our results also establish that Id proteins (i.e., HLH proteins lacking the basic domain) are expressed in neuroblastoma cells and are down-regulated during induced differentiation of these cells, and they interact with HES-1, but not with HASH-1 or dHAND. Furthermore, we discovered that neuroblastoma cells express O/E-1 and O/E-2, and that the DNA-binding activity of these proteins are increased during induced differentiation of neuroblastoma cells. In addition, we identified CgA and SCG10, as novel neuronal target genes of O/E-1. Much remains to be learned about how the bHLH proteins act in synergy with other transcriptional regulators and in this thesis novel interactions and connections are described.
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| 58. |
- Ruuth, Kristina, et al.
(författare)
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Interferon-alpha promotes survival of human primary B-lymphocytes via phoshatidylinositol 3-kinase
- 2001
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Academic Press. - 0006-291X .- 1090-2104. ; 284:3, s. 583-586
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Tidskriftsartikel (refereegranskat)abstract
- Signaling pathways for the antiviral and antiproliferative biological effects of type I interferons (IFN) are well established. In this report we demonstrate a novel signaling pathway for IFN-α, as it induced rapid phosphorylation of both PKB/Akt and its substrate forkhead. The PI3-kinase inhibitor LY294002 abolished these phosphorylations. PI3-kinase has been implicated in cell survival mediating its effect through the second messenger PIP3 and the subsequent activation of PKB/Akt. We could show that IFN-α inhibited spontaneous apoptosis of primary B-lymphocytes, in the absence of a mitogenic stimulus. This effect was inhibited by LY294002. Thus, our data suggests that IFN-α promotes survival of peripheral B-lymphocytes via the PI3-kinase-PKB/Akt pathway. In addition, IFN-α stimulation of anti-IgM activated cells resulted in downregulated expression of the cell cycle inhibitor p27/Kip1.
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| 59. |
- Thulesius, Hans, et al.
(författare)
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Balancing : a basic process in end-of-life cancer care.
- 2003
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Ingår i: Qualitative Health Research. - : Sage Publications. - 1049-7323 .- 1552-7557. ; 13:10, s. 1353-1377
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Tidskriftsartikel (refereegranskat)abstract
- In this grounded theory study, the authors interviewed caregivers and patients in end-of-life cancer care and found Balancing to be a fundamental process explaining the problem-solving strategies of most participants and offering a comprehensive perspective on both health care in general and end-of-life cancer care in particular. Balancing stages were Weighing--sensing needs and wishes signaled by patients, gauging them against caregiver resources in diagnosing and care planning; Shifting--breaking bad news, changing care places, and treatments; and Compensating--controlling symptoms, educating and team-working, prioritizing and "stretching" time, innovating care methods, improvising, and maintaining the homeostasis of hope. The Balancing outcome is characterized by Compromising, or "Walking a fine line," at best an optimized situation, at worst a deceit.
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| 60. |
- Falkenberg, Cecilia, et al.
(författare)
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Expression of a functional proteinase inhibitor capable of accepting xylose: bikunin
- 2001
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Ingår i: Archives of Biochemistry and Biophysics. - : Elsevier BV. - 0003-9861. ; 387:1, s. 99-106
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Tidskriftsartikel (refereegranskat)abstract
- Bikunin is a Kunitz-type proteinase inhibitor, which is cross-linked to heavy chains via a chondroitin sulfate chain, forming inter-alpha-inhibitor and related molecules. Rat bikunin was produced by baculovirus-infected insect cells. The protein could be purified with a total yield of 20 mg/liter medium. Unlike naturally occuring bikunin the recombinant protein had no galactosaminoglycan chain. Endoglycosidase digestion also suggested that the recombinant form lacked N-linked oligosaccharides. Bikunin is translated as a part of a precursor, alpha1-microglobulin/bikunin, but the functional significance of the cotranslation is unknown. Our results indicate that the proteinase inhibitory function of bikunin is not regulated by the alpha1-microglobulin-part of the alpha1-microglobulin/bikunin precursor since recombinant bikunin had the same trypsin inhibitory activity as the recombinant precursor. Both free bikunin and the precursor were also functional as a substrate in an in vitro xylosylation system. This demonstrates that the alpha1-microglobulin-part is not necessary for the first step of galactosaminoglycan assembly.
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