| 1. |
- Hendrikse, Natalie, et al.
(author)
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Ancestral lysosomal enzymes with increased activity harbor therapeutic potential for treatment of Hunter syndrome
- 2021
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In: ISCIENCE. - : Elsevier BV. - 2589-0042. ; 24:3
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Journal article (peer-reviewed)abstract
- We show the successful application of ancestral sequence reconstruction to enhance the activity of iduronate-2-sulfatase (IDS), thereby increasing its therapeutic potential for the treatment of Hunter syndrome-a lysosomal storage disease caused by impaired function of IDS. Current treatment, enzyme replacement therapy with recombinant human IDS, does not alleviate all symptoms, and an unmet medical need remains. We reconstructed putative ancestral sequences of mammalian IDS and compared them with extant IDS. Some ancestral variants displayed up to 2-fold higher activity than human IDS in in vitro assays and cleared more substrate in ex vivo experiments in patient fibroblasts. This could potentially allow for lower dosage or enhanced therapeutic effect in enzyme replacement therapy, thereby improving treatment outcomes and cost efficiency, as well as reducing treatment burden. In summary, we showed that ancestral sequence reconstruction can be applied to lysosomal enzymes that function in concert with modern enzymes and receptors in cells.
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| 2. |
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| 3. |
- Larsson, Daniel H., et al.
(author)
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First application of liquid-metal-jet sources for small-animal imaging : High-resolution CT and phase-contrast tumor demarcation
- 2013
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In: Medical physics (Lancaster). - : Wiley. - 0094-2405 .- 2473-4209. ; 40:2, s. 021909-
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Journal article (peer-reviewed)abstract
- Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with similar to 7 mu m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 mu m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.
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| 4. |
- Lundström, Ulf, et al.
(author)
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X-ray phase contrast with injected gas for tumor microangiography
- 2014
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In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 59:11, s. 2801-2811
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Journal article (peer-reviewed)abstract
- We show that the microvasculature of mouse tumors can be visualized using propagation-based phase-contrast x-ray imaging with gas as the contrast agent. The large density difference over the gas-tissue interface provides high contrast, allowing the imaging of small-diameter blood vessels with relatively short exposure times and low dose using a compact liquid-metal-jet x-ray source. The method investigated is applied to tumors (E1A/Ras-transformed mouse embryonic fibroblasts) grown in mouse ears, demonstrating sub-15-mu m-diameter imaging of their blood vessels. The exposure time for a 2D projection image is a few seconds and a full tomographic 3D map takes some minutes. The method relies on the strength of the vasculature to withstand the gas pressure. Given that tumor vessels are known to be more fragile than normal vessels, we investigate the tolerance of the vasculature of 12 tumors to gas injection and find that a majority withstand 200 mbar pressures, enough to fill 12-mu m-diameter vessels with gas. A comparison of the elasticity of tumorous and non-tumorous vessels supports the assumption of tumor vessels being more fragile. Finally, we conclude that the method has the potential to be extended to the imaging of 15 mu m vessels in thick tissue, including mouse imaging, making it of interest for, e.g., angiogenesis research.
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| 5. |
- Westermark, Ulrica
(author)
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DNA repair by HDR in experimental tumorigenesis
- 2008
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Doctoral thesis (other academic/artistic)abstract
- The aim of this thesis was to further understand how defects in the homology-directed repair (HDR) pathway affect tumor formation and development. To study proteins involved in HDR is challenging since most of its members are required for cell viability. For our studies we have therefore taken a dominant-negative approach to address the importance of the BRCA1 interacting protein BARD1 in HDR (paper I) and investigate the role of HDR in PDGFB-induced gliomagenesis by interfering with a key protein, RAD51 (paper II). In addition we have also investigated how Platelet-derived growth factor A receptor (PDGFRA) is transcriptionally regulated by interleukin-1b (IL-1b) (paper III). The breast cancer susceptibility gene BRCA1 is frequently mutated in hereditary breast and ovarian cancers. BRCA1 has been implicated in many different cellular processes, among them DNA repair by HDR. In Paper I we investigated if BARD1 was involved in HDR through its interaction with BRCA1. We could show that expression of a truncated BARD1 decreased HDR of an induced double-strand break and that this decrease was even more pronounced in Brca1-deficient cells expressing a splice variant of Brca1 that still are able to bind BARD1. We could also show that the role of BARD1 in HDR was dependent on binding to BRCA1 and that the HDR defect resulting from the truncated BARD1 was caused by lack of regulatory elements in the C-terminal end of BARD1 and not caused by improper cellular localization of either the BARD1 construct or the endogenous Brca1 protein. We conclude that BARD1 is important for HDR and that the repair function of BARD1 is dependent on its interaction with BRCA1. The expression of PDGFRa is strictly regulated during embryogenesis and aberrant PDGFRa expression can lead to malignant transformation, in brain tumors for example. Highly malignant gliomas are the most frequent primary tumor of the central nervous system in adults. To study the effect of different genetic changes in gliomagenesis, glioma-like tumors can be induced by intracerebral injections of oncogene carrying retroviruses. The RCAS/tv-a model system provides the possibility to study combinations of different genetic alterations in a specific cell type. In paper II we have used wild type and Arf-/- nestin tv-a (Ntv-a) transgenic mice, where expression of the RCAS constructs were directed to neural progenitor cells. It has previously been shown that expression of PDGFB can induce glioma-like tumors in these mice. To investigate the role of HDR in tumorigenesis we co-expressed RAD51 or a DNA repair deficient RAD51 (RAD51KR) contruct with PDGFB in either wild type or Arf-/- Ntv-a mice. We could show that co-expression of RAD51 or RAD51KR can suppress PDGFB-induced tumorigenesis in wild type mice. However, only RAD51 was able to suppress tumor formation in the Arf-null background. We could also show that all the PDGFB-induced tumors were aneuploid, independent of genotype, tumor grade or tumor size. Interestingly, expression of RAD51 or RAD51KR reduced aneuploidy in the PDGFB-induced tumors.
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| 6. |
- Westermark, Ulrica K, et al.
(author)
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RAD51 can inhibit PDGFB-induced gliomagenesis and genomic instability
- 2011
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In: Neuro-Oncology. - : Oxford University Press (OUP). - 1522-8517 .- 1523-5866. ; 13:12, s. 1277-1287
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Journal article (peer-reviewed)abstract
- Faithful replication and DNA repair are vital for maintenance of genome integrity. RAD51 is a central protein in homologous recombination repair and during replication, when it protects and restarts stalled replication forks. Aberrant RAD51 expression occurs in glioma, and high expression has been shown to correlate with prolonged survival. Furthermore, genes involved in DNA damage response (DDR) are mutated or deleted in human glioblastomas, corroborating the importance of proper DNA repair to suppress gliomagenesis. We have analyzed DDR and genomic instability in PDGF-B-induced gliomas and investigated the role of RAD51 in glioma development. We show that PDGF-B-induced gliomas display genomic instability and that co-expression of RAD51 can suppress PDGF-B-induced tumorigenesis and prolong survival. Expression of RAD51 inhibited proliferation and genomic instability of tumor cells independent of Arf status. Our results demonstrate that the RAD51 pathway can prevent glioma initiation and maintain genome integrity of induced tumors, suggesting reactivation of the RAD51 pathway as a potential therapeutic avenue.
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| 7. |
- Zirath, Hanna, et al.
(author)
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MYC inhibition induces metabolic changes leading to accumulation of lipid droplets in tumor cells
- 2013
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In: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 110:25, s. 10258-10263
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Journal article (peer-reviewed)abstract
- The MYC genes are the most frequently activated oncogenes in human tumors and are hence attractive therapeutic targets. MYCN amplification leads to poor clinical outcome in childhood neuroblastoma, yet strategies to modulate the function of MYCN do not exist. Here we show that 10058-F4, a characterized c-MYC/Max inhibitor, also targets the MYCN/Max interaction, leading to cell cycle arrest, apoptosis, and neuronal differentiation in MYCN-amplified neuroblastoma cells and to increased survival of MYCN transgenic mice. We also report the discovery that inhibition of MYC is accompanied by accumulation of intracellular lipid droplets in tumor cells as a direct consequence of mitochondrial dysfunction. This study expands on the current knowledge of how MYC proteins control the metabolic reprogramming of cancer cells, especially highlighting lipid metabolism and the respiratory chain as important pathways involved in neuroblastoma pathogenesis. Together our data support direct MYC inhibition as a promising strategy for the treatment of MYC-driven tumors.
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