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| 2. |
- Broom, Oliver, et al.
(författare)
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CD47 regulates collagen I-induced cyclooxygenase-2 expression and intestinal epithelial cell migration.
- 2009
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:7, s. e6371-
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Tidskriftsartikel (refereegranskat)abstract
- Increased epithelial cell expression of the cyclooxygenase-2 (COX-2) enzyme is a characteristic event of both inflammatory bowel disease and colon cancer. We here report the novel findings that collagen I-induced de novo synthesis of COX-2 in intestinal epithelial cells is inhibited by pertussis toxin (PTX) and by an inhibitory peptide selective for the heterotrimeric G alpha(i3)-protein. These findings could be explained by a regulatory involvement of the G-protein-dependent integrin-associated protein CD47. In support of this notion, we observed a collagen I-induced association between CD47 and alpha2 integrins. This association was reduced by a blocking anti-CD47 antibody but not by PTX or a control anti-beta2 antibody. Furthermore, a blocking antibody against CD47, dominant negative CD47 or specific siRNA knock down of CD47, significantly reduced collagen I-induced COX-2 expression. COX-2 has previously been shown to regulate intestinal epithelial cell adhesion and migration. Morphological analysis of intestinal cells adhering to collagen I revealed a co-localisation of CD47 and alpha2 integrins to non-apoptotic membrane blebs enriched in Rho A and F-actin. The blocking CD47 antibody, PTX and a selective COX-2 inhibitor, dramatically inhibited the formation of these blebs. In accordance, migration of these cells on a collagen I-coated surface or through a collagen I gel were significantly reduced by the CD47 blocking antibody, siRNA knock down of CD47 and the COX-2 inhibitor NS-398. In conclusion, we present novel data that identifies the G-protein-dependent CD47 protein as a key regulator of collagen I-induced COX-2 expression and a promoter of intestinal epithelial cell migration.
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| 3. |
- Broom, Oliver
(författare)
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Involvement of eicosanoid signalling in epithelial cell migration
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of inflammatory bowel diseases (IBD) and colon cancer (CC) has been shown to involve the up-regulation of inflammatory mediators and the machinery producing them such as the eicosanoids. Changes in the expression of extracellular matrix proteins and their related integrin receptors have also been shown to be important in the advancement IBD and CC. In light of this, we have investigated the role of eicosanoids in cell migration a key process in IBD and CC. This was through direct stimulation, with the eicosanoid leukotriene D4 (LTD4) or indirectly through inducing cyclooxygenase-2 (COX-2; an enzyme involved in the production of various eicosanoids) expression, by activating integrin collagen receptors. We observed that direct stimulation with LT D4, induced intestinal epithelial cell migration, through activation of the CysLT1 receptor, phosphotidylinositol-3 kinase, Vav2 and Rac localisation to membrane ruffles. Indirect stimulation, by activating COX-2 expression in a _2_1 integrin dependent manner was able to elicit a migratory response. The integrin dependent COX-2 expression was shown to be mediated through the activation of CD47 and its associated G_i3 protein, which in turn lead to protein kinase C_, the Ras GTPase and NF_B activation. COX-2 expression is synonymous with activation of the protein. Inhibition of COX-2 expression or specifically inhibiting COX-2 activity, resulted in cell adhesion being favoured over cell migration in a CD47 dependent manner. Thus understanding cellular mechanisms leading to cell migration may reveal novel targets and lead to new therapeutic strategies in treating IBD and CC.
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| 4. |
- Meisgen, Florian, et al.
(författare)
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MiR-21 is up-regulated in psoriasis and suppresses T cell apoptosis.
- 2012
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Ingår i: Experimental dermatology. - : Wiley. - 0906-6705 .- 1600-0625. ; 21:4, s. 312-4
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Tidskriftsartikel (refereegranskat)abstract
- MicroRNAs are short non-coding RNAs that regulate gene expression. Previously, in a genome-wide screen, we found deregulation of microRNA expression in psoriasis skin. MicroRNA-21 (miR-21) is one of the microRNAs significantly up-regulated in psoriasis skin lesions. To identify the cell type responsible for the increased miR-21 level, we compared expression of miR-21 in epidermal cells and dermal T cells between psoriasis and healthy skin and found elevated levels of miR-21 in psoriasis in both cell types. In cultured T cells, expression of miR-21 increased markedly upon activation. To explore the function of miR-21 in primary human T helper cells, we inhibited miR-21 using a tiny seed-targeting LNA-anti-miR. Specific inhibition of miR-21 increased the apoptosis rate of activated T cells. Our results suggest that miR-21 suppresses apoptosis in activated T cells, and thus, overexpression of miR-21 may contribute to T cell-derived psoriatic skin inflammation.
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| 6. |
- Stäubert, Claudia, et al.
(författare)
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Hydroxycarboxylic acid receptors are essential for breast cancer cells to control their lipid/fatty acid metabolism
- 2015
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 6:23, s. 19706-19720
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Tidskriftsartikel (refereegranskat)abstract
- Cancer cells exhibit characteristic changes in their metabolism with efforts being made to address them therapeutically. However, targeting metabolic enzymes as such is a major challenge due to their essentiality for normal proliferating cells. The most successful pharmaceutical targets are G protein-coupled receptors (GPCRs), with more than 40% of all currently available drugs acting through them. We show that, a family of metabolite-sensing GPCRs, the Hydroxycarboxylic acid receptor family (HCAs), is crucial for breast cancer cells to control their metabolism and proliferation. We found HCA(1) and HCA(3) mRNA expression were significantly increased in breast cancer patient samples and detectable in primary human breast cancer patient cells. Furthermore, siRNA mediated knock-down of HCA3 induced considerable breast cancer cell death as did knock-down of HCA1, although to a lesser extent. Liquid Chromatography Mass Spectrometry based analyses of breast cancer cell medium revealed a role for HCA3 in controlling intracellular lipid/fatty acid metabolism. The presence of etomoxir or perhexiline, both inhibitors of fatty acid beta-oxidation rescues breast cancer cells with knocked-down HCA3 from cell death. Our data encourages the development of drugs acting on cancer-specific metabolite-sensing GPCRs as novel anti-proliferative agents for cancer therapy.
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| 7. |
- Stäubert, Claudia, et al.
(författare)
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Increased lanosterol turnover : a metabolic burden for daunorubicin-resistant leukemia cells
- 2016
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Ingår i: Medical Oncology. - : Springer-Verlag New York. - 1357-0560 .- 1559-131X. ; 33:1
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Tidskriftsartikel (refereegranskat)abstract
- The cholesterol metabolism is essential for cancer cell proliferation. We found the expression of genes involved in the cholesterol biosynthesis pathway up-regulated in the daunorubicin-resistant leukemia cell line CEM/R2, which is a daughter cell line to the leukemia cell line CCRF-CEM (CEM). Cellular (H2O)-H-2 labelling, mass spectrometry, and isotopomer analysis revealed an increase in lanosterol synthesis which was not accompanied by an increase in cholesterol flux or pool size in CEM/R2 cells. Exogenous addition of lanosterol had a negative effect on CEM/R2 and a positive effect on sensitive CEM cell viability. Treatment of CEM and CEM/R2 cells with cholesterol biosynthesis inhibitors acting on the enzymes squalene epoxidase and lanosterol synthase, both also involved in the 24,25-epoxycholesterol shunt pathway, revealed a connection of this pathway to lanosterol turnover. Our data highlight that an increased lanosterol flux poses a metabolic weakness of resistant cells that potentially could be therapeutically exploited.
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| 8. |
- Stäubert, Claudia, et al.
(författare)
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Rewired metabolism in drug-resistant leukemia cells : a metabolic switch hallmarked by reduced dependence on exogenous glutamine
- 2015
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 290:13, s. 8348-8359
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Tidskriftsartikel (refereegranskat)abstract
- Cancer cells that escape induction therapy are a major cause of relapse. Understanding metabolic alterations associated with drug resistance opens up unexplored opportunities for the development of new therapeutic strategies. Here, we applied a broad spectrum of technologies including RNA sequencing, global untargeted metabolomics, and stable isotope labeling mass spectrometry to identify metabolic changes in P-glycoprotein overexpressing T-cell acute lymphoblastic leukemia (ALL) cells, which escaped a therapeutically relevant daunorubicin treatment. We show that compared with sensitive ALL cells, resistant leukemia cells possess a fundamentally rewired central metabolism characterized by reduced dependence on glutamine despite a lack of expression of glutamate-ammonia ligase (GLUL), a higher demand for glucose and an altered rate of fatty acid beta-xidation, accompanied by a decreased pantothenic acid uptake capacity. We experimentally validate our findings by selectively targeting components of this metabolic switch, using approved drugs and starvation approaches followed by cell viability analyses in both the ALL cells and in an acute myeloid leukemia (AML) sensitive/resistant cell line pair. We demonstrate how comparative metabolomics andRNAexpression profiling of drug-sensitive and -resistant cells expose targetable metabolic changes and potential resistance markers. Our results show that drug resistance is associated with significant metabolic costs in cancer cells, which could be exploited using new therapeutic strategies.
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