| 1. |
- Delgado Verdugo, Alberto
(författare)
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Genetic Aspects of Endocrine Tumorigenesis : A Hunt for the Endocrine Neoplasia Gene
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Endocrine tumors arise from endocrine glands. Most endocrine tumors are benign but malignant variants exist. Several endocrine neoplasms display loss of parts of chromosome 11 or 18, produce hormones and responds poorly to conventional chemotherapeutics. The multiple endocrine neoplasia syndromes are mainly confined to endocrine tumors. This opens the question if there exists a single or several endocrine tumor genes.The aim of the study was to describe genetic derangements in endocrine tumors.Paper I: Investigation of mutational status of SDHAF2 in parathyroid tumors. SDHAF2 is located in the proximity of 11q13, a region that frequently displays loss in parathyroid tumors. We established that mutations in SDHAF2 are infrequent in parathyroid tumors.Paper II: Study of SDHAF2 gene expression in a cohort of benign pheochromocytomas (PCC) (n=40) and malignant PCC (n=10). We discovered a subset of benign PCC (28/40) and all malignant PCC (10/10) with significantly lower SDHAF2 expression. Benign PCC with low SDHAF2 expression and malignant tumors consistently expressing low levels of SDHAF2 were methylated in the promoter region. SDHAF2 expression was restored in vitro after treatment with 5- aza-2-deoxycytidine.Paper III: HumanMethylation27 array (Illumina) covering 27578 CpG sites spanning over 14495 genes were analyzed in a discovery cohort of 10 primary small neuroendocrine tumors (SI-NETs) with matched metastases. 2697 genes showed different methylation pattern between the primary tumor and its metastasis. We identified several hypermethylated genes in key regions. Unsupervised clustering of the tumors identified three distinct clusters, one with a highly malignant behavior.Paper IV: Loss of chromosome 18 is the most frequent genetic aberration in SI-NETs. DNA from SI-NETs were subjected to whole exome capture sequencing and high resolution SNP array. Genomic profiling revealed loss of chromosome 18 in 5 out of 7 SI-NETs. No tumor-specific somatic mutation on chromosome 18 was identified which suggests involvement of other mechanisms than point mutations in SI-NET tumorigenesis.Paper V: The cost for diagnostic genetic screening of common susceptibility genes in PCC is expensive and labor intensive. Three PCC from three patients with no known family history were chosen for exome capture sequencing. We identified three variants in known candidate genes. We suggest that exome-capture sequencing is a quick and cost-effective tool.
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| 2. |
- Farnebo, Filip
(författare)
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Molecular mechanisms of tumor development in hyperparathyroidism
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Loss of heterozygosity (LOH) analysis and comparative genomic hybridization (CGH) were used in an attempt to identify recurrent chromosomal alterations in different types of parathyroid tumors. These included familial and sporadic, benign and malignant, as well as primary, irradiation associated and secondary tumors. Hitherto unidentified tumor suppressor genes were implicated on chromosomes 1p, 6q, 9p, 11p, 11q, 13q, 15q, 18q and X, as well as a putative oncogene locus represented by a gain of DNA copy number on chromosome 19 (Papers I and V). Since many genes responsible for familial cancer syndromes also are mutated in their sporadic counterparts, another approach was to search for deletions of chromosomal regions to which familial syndromes are mapped. The 11q13 region, which harbors the multiple endocrine neoplasia type 1 (MEN 1) tumor suppressor gene, is deleted in the majority of parathyroid tumors from MEN 1 patients. Similarly, a third of tumors from patients with sporadic primary HPT showed LOH at 11q13 (Papers 1 and II) and in half of these cases a somatic MEN1 mutation could be demonstrated (Paper II). The sporadic adenomas with MEN1 involvement also displayed a significantly higher number of CGH aberrations as compared with the non-MEN1 associated group (p< 0.05) (Paper V). The genetic profile obtained for the radiation associated adenomas closely resembled that of the ordinary adenomas with involvement of the MEN1 gene, i.e. multiple CGH alterations and frequent losses of 11q. Indeed, inactivating mutations of the MEN1 gene were identified in four of the eight irradiation associated tumors analyzed (Paper V). Changes in the calcium receptor (CaR) have been proposed to be responsible for the increase in set-point of parathyroid hormone secretion seen in primary HPT. The level of CaR mRNA in the adenomas was in the range of 41-98 % (median of 64 %) of the expression level in the normal parathyroid tissue (Paper VI). The mRNA level was not found to correlate with serum calcium, parathyroid hormone or adenoma weight. It seems likely that the reduced levels of receptor mRNAs and protein is a secondary phenomenon, rather than a primary event. Two families with HPT-JT syndrome were investigated and in both families renal hamartomas or cystic kidney disease were prominent associated features, possibly representing a new phenotypic variant of the HPT-JT syndrome. A sex dependent penetrance of HPT was seen, resulting in mainly male affected cases (Paper III). Three large previously unreported FIHP families in whom the disease was linked to the chromosome 1q21-q32 region were analyzed and two of these families were considered to be true FIHP families, i.e. there was no evidence of jaw or renal lesions despite careful radiological investigations. In the third family, a parathyroid cancer and two cases of polycystic kidney disease were found and that family was therefore considered as being affected by the classical HPT-JT syndrome. The same sex-dependent penetrance of HPT was seen in the FIHP families as in the HPT-JT families reported in paper III. LOH analysis showed loss in the l q region of the wild type allele in the renal hamartomas and in some of the parathyroid tumors, including the parathyroid cancer, suggesting that this gene is a tumor suppressor gene. Parathyroid cancer is a rare cause of primary HPT. Nevertheless this group creates diagnostic and therapeutic problems, since in the absence of invasion of adjacent organs or structures and/or metastases, the diagnosis of parathyroid cancer cannot be definitely established based on histopathology. The expression of Ki-67, RB and Gelatinase A were investigated as possible tumor markers in parathyroid cancers. However, none of these markers was suitable for reliable differentiation between benign and malignant parathyroid tumors (Papers VII and VIII).
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| 3. |
- Hägerkvist, Robert, et al.
(författare)
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Consequences of Shb and c-Abl interactions for cell death in response to various stress stimuli
- 2007
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Ingår i: Experimental Cell Research. - : Elsevier BV. - 0014-4827 .- 1090-2422. ; 313:2, s. 284-291
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Tidskriftsartikel (refereegranskat)abstract
- The adaptor protein Shb has previously been shown to regulate apoptosis in response to cytokines and inhibitors of angiogenesis although the mechanisms governing these effects have remained obscure. We currently demonstrate interactions between Shb and c-Abl and that Shb regulates c-Abl kinase activity. The data suggest that c-Abl binds to tyrosine phosphorylated Shb via a concerted effort involving both the c-Abl SH3 and SH2 domains. The biological significance of the Shb/c-Abl interaction was presently tested in overexpression experiments and was found to promote hydrogen peroxide-induced cell death. We also show by Shb knockdown experiments that Shb regulates c-Abl activity and modulates cell death in response to the genotoxic agent cisplatin and the endoplasmic reticulum stress-inducer tunicamycin. The findings are in agreement with the notion of Shb playing a pivotal role in modulating c-Abl pro-apoptotic signaling in response to various stress stimuli.
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| 4. |
- Jin, Shaobo, et al.
(författare)
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Notch signaling regulates platelet-derived growth factor receptor-beta expression in vascular smooth muscle cells
- 2008
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Ingår i: Circulation Research. - 0009-7330 .- 1524-4571. ; 102:12, s. 1483-1491
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Tidskriftsartikel (refereegranskat)abstract
- Notch signaling is critically important for proper architecture of the vascular system, and mutations in NOTCH3 are associated with CADASIL, a stroke and dementia syndrome with vascular smooth muscle cell (VSMC) dysfunction. In this report, we link Notch signaling to platelet-derived growth factor (PDGF) signaling, a key determinant of VSMC biology, and show that PDGF receptor (PDGFR)-beta is a novel immediate Notch target gene. PDGFR-beta expression was upregulated by Notch ligand induction or by activated forms of the Notch receptor. Moreover, upregulation of PDGFR-beta expression in response to Notch activation critically required the Notch signal integrator CSL. In primary VSMCs, PDGFR-beta expression was robustly upregulated by Notch signaling, leading to an augmented intracellular response to PDGF stimulation. In newborn Notch3-deficient mice, PDGFR-beta expression was strongly reduced in the VSMCs that later develop an aberrant morphology. In keeping with this, PDGFR-beta upregulation in response to Notch activation was reduced also in Notch3-deficient embryonic stem cells. Finally, in VSMCs from a CADASIL patient carrying a NOTCH3 missense mutation, upregulation of PDGFR-beta mRNA and protein in response to ligand-induced Notch activation was significantly reduced. In sum, these data reveal a hierarchy for 2 important signaling systems, Notch and PDGF, in the vasculature and provide insights into how dysregulated Notch signaling perturbs VSMC differentiation and function.
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| 5. |
- Kiwanuka, Elizabeth, 1983-
(författare)
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CCN2 – Keratinocyte Interactions In Vitro and In Vivo
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cutaneous wound healing is a complex process involving the migration of inflammatory cells to the wound site, deposition of extracellular matrix, and the reestablishment of an intact epithelial barrier. Re-epithelialization depends on the proliferation and directional migration of keratinocytes from the wound edges. Initially, keratinocytes migrate over a provisional wound matrix that is rich in fibronectin, and as the wound heals the provisional matrix becomes replaced by one consisting of collagen and proteoglycans. Re-epithelialization is tightly regulated by a variety of peptides such as growth factors, cytokines and proteases, and abnormalities may result in chronic non-healing wounds or hypertrophic scars. CCN2 (Connective Tissue Growth Factor) is a multifunctional protein with effects on cells and their interactions with the connective tissue. CCN2 is expressed in a variety of cell types and regulates numerous cell functions including proliferation, differentiation, adhesion, migration and stimulation of collagen production. While the importance of CCN2 for the fibrotic response has been well studied, its involvement in keratinocyte function has not yet been fully explored. Using an in vivo wound model, the expression of CCN2 was captured at the leading keratinocyte edge during re-epithelialization. In vitro, exogenous addition of CCN2 to human keratinocyte cultures promoted keratinocyte migration. Subsequently, integrin a5b1 was identified as an important mediator of CCN2 enhancement of keratinocyte adhesion to fibronectin. CCN2 activated the FAK-MAPK signaling pathway, and pretreatment with MEK1 specific inhibitor PD98059 markedly reduced CCN2-promoted keratinocyte migration. In vitro, CCN2 expression was induced by TGF-β1. Compared with inhibiting the SMAD pathway, blocking MAPK was more effective in reducing TGF-β1-induced CCN2 mRNA and protein expression. In addition, CCN2-induced keratinocyte spreading required FAK. Treatment with CCN2 led to actin disassembly and altered the activity of the Rho proteins and p190RhoGAP in keratinocytes. Furthermore, Cdc42 mediated CCN2-induced cell polarity. In conclusion, using in vivo and in vitro models, CCN2 was shown to regulate keratinocyte function by promoting keratinocyte adhesion, spreading and migration. A complete understanding of CCN2 expression in keratinocytes is crucial in order to develop novel therapies for wound healing.
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| 6. |
- Lanner, Fredrik, et al.
(författare)
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Heparan Sulfation-Dependent Fibroblast Growth Factor Signaling Maintains Embryonic Stem Cells Primed for Differentiation in a Heterogeneous State
- 2010
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 28:2, s. 191-200
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Tidskriftsartikel (refereegranskat)abstract
- Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous leukemia inhibitory factor and BMP4 perpetuate a pluripotent state, less is known about the factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical coreceptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and NDST2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild-type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine fibroblast growth factor 4 (FGF4) signaling. Microarray analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3, and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5, and Brachyury were induced by sulfation-dependent FGF receptor (FGFR) signaling. We show that several of these genes are heterogeneously expressed in ES cells, and that targeting of heparan sulfation or FGFR-signaling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signaling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6-positive primitive endoderm progenitors generating a homogenous Nanog-positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signaling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naive ground state.
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| 7. |
- Lanner, Fredrik, et al.
(författare)
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Hypoxia-Induced Arterial Differentiation Requires Adrenomedullin and Notch Signaling
- 2013
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Ingår i: Stem Cells and Development. - : Mary Ann Liebert Inc. - 1547-3287 .- 1557-8534. ; 22:9, s. 1360-1369
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia (low oxygen) and Notch signaling are 2 important regulators of vascular development, but how they interact in controlling the choice between arterial and venous fates for endothelial cells during vasculogenesis is less well understood. In this report, we show that hypoxia and Notch signaling intersect in promotion of arterial differentiation. Hypoxia upregulated expression of the Notch ligand Dll4 and increased Notch signaling in a process requiring the vasoactive hormone adrenomedullin. Notch signaling also upregulated Dll4 expression, leading to a positive feedback loop sustaining Dll4 expression and Notch signaling. In addition, hypoxia-mediated upregulation of the arterial marker genes Depp, connexin40 (Gja5), Cxcr4, and Hey1 required Notch signaling. In conclusion, the data reveal an intricate interaction between hypoxia and Notch signaling in the control of endothelial cell differentiation, including a hypoxia/adrenomedullin/Dll4 axis that initiates Notch signaling and a requirement for Notch signaling to effectuate hypoxia-mediated induction of the arterial differentiation program.
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| 8. |
- Li, Xiujuan, et al.
(författare)
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Lentiviral rescue of vascular endothelial growth factor receptor-2 expression in flk1-/- embryonic stem cells shows early priming of endothelial precursors
- 2007
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Ingår i: Stem Cells. - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 25:12, s. 2987-2995
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Tidskriftsartikel (refereegranskat)abstract
- The vascular endothelial growth factor ( VEGF) family and its receptors are important for vascular development and maintenance of blood vessels, as well as for angiogenesis, the formation of new vessels. Loss of VEGF receptor-2 (VEGFR-2; designated Flk-1 in mouse) results in arrest of vascular and hematopoietic development in vivo. We used lentiviral transduction to reconstitute VEGFR-2 expression in flk1-/- embryonic stem (ES) cells. VEGF-induced vasculogenesis and sprouting angiogenesis were rescued in transduced ES cultures differentiating in vitro as EBs. Although the transgene was expressed in the pluripotent stem cells and lacked linage restriction during differentiation, the extent of endothelial recruitment was similar to that in wild-type EBs. Reconstitution of VEGFR-2 in flk1-/- ES cells allowed only precommitted precursors to differentiate into functional endothelial cells able to organize into vascular structures. Chimeric EB cultures composed of wild-type ES cells mixed with flk1-/- ES cells or reconstituted VEGFR-2expressing ES cells were created. In the chimeric cultures, flk1-/- endothelial precursors were excluded from wild-type vessel structures, whereas reconstituted VEGFR-2-expressing precursors became integrated together with wild-type endothelial cells to form chimeric vessels. We conclude that maturation of endothelial precursors, as well as organization into vascular structures, requires expression of VEGFR-2.
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| 9. |
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| 10. |
- Neovius, Erik, et al.
(författare)
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Long-term sensory disturbances after orbitozygomatic fractures
- 2017
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Ingår i: Journal of Plastic, Reconstructive & Aesthetic Surgery. - : Elsevier. - 1748-6815 .- 1878-0539. ; 70, s. 120-126
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Tidskriftsartikel (refereegranskat)abstract
- Background: Orbitozygomatic fractures often lead to infraorbital nerve (ION) injury, and affected sensibility is a common long-term complaint within this patient group. We present a long-term follow-up study where the validated von Frey filament system was used for testing ION sensibility. Furthermore, we examined the incidence of persistent nerve injury and whether more complex fractures led to more pronounced ION sensibility disturbances. Methods: Patients treated for facial fractures involving the orbitozygomatic complex were included and the follow-up time was 3 years or more. Depending on the location and severity of the fractures, the patients were divided into 4 groups. The patients answered a questionnaire before ION sensibility testing with von Frey filaments. Results: Eighty-one patients were examined: 65 males (80%) and 16 females (20%). Examinations were conducted between 3.0 and 7.6 years (mean 4.9 years) after injury. Sixteen patients (20%) had affected and 6 patients (7.4%) had severely affected ION sensibility according to von Frey testing. No statistically significant differences were found in terms of questionnaire score between the groups. There was also no statistically significant correlation between questionnaire results and log von Frey values. Although the effect of groups could not be statistically verified using the log von Frey values, a larger proportion of patients with complex fractures had higher log von Frey values than the other groups
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