| 1. |
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| 2. |
- Cutts, Briony, 1976, et al.
(författare)
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Nf1 deficiency cooperates with oncogenic K-RAS to induce acute myeloid leukemia in mice.
- 2009
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 114:17, s. 3629-32
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Tidskriftsartikel (refereegranskat)abstract
- Hyperactive RAS signaling is caused by mutations in RAS genes or a deficiency of the neurofibromatosis gene (NF1) and is common in myeloid malignancies. In mice, expression of oncogenic K-RAS or inactivation of Nf1 in hematopoietic cells results in myeloproliferative disorders (MPDs) that do not progress to acute myeloid leukemia (AML). Because NF1 is a RAS-GTPase-activating protein it has been proposed that NF1 deficiency is functionally equivalent to an oncogenic RAS. It is not clear, however, whether Nf1 deficiency would be redundant in K-RAS-induced MPD development or whether the 2 mutations would cooperate in leukemogenesis. Here, we show that the simultaneous inactivation of Nf1 and expression of K-RAS(G12D) in mouse hematopoietic cells results in AML that was fatal in primary mice within 4 weeks and transplantable to sublethally irradiated secondary recipients. The data point to a strong cooperation between Nf1 deficiency and oncogenic K-RAS.
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| 3. |
- Khan, Omar M., 1980, et al.
(författare)
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Geranylgeranyltransferase type I (GGTase-I) deficiency hyperactivates macrophages and induces erosive arthritis in mice.
- 2011
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Ingår i: The Journal of clinical investigation. - 1558-8238. ; 121:2, s. 628-39
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Tidskriftsartikel (refereegranskat)abstract
- RHO family proteins are important for the function of inflammatory cells. They are modified with a 20-carbon geranylgeranyl lipid in a process catalyzed by protein geranylgeranyltransferase type I (GGTase-I). Geranylgeranylation is viewed as essential for the membrane targeting and activity of RHO proteins. Consequently, inhibiting GGTase-I to interfere with RHO protein activity has been proposed as a strategy to treat inflammatory disorders. However, here we show that mice lacking GGTase-I in macrophages develop severe joint inflammation resembling erosive rheumatoid arthritis. The disease was initiated by the GGTase-I-deficient macrophages and was transplantable and reversible in bone marrow transplantation experiments. The cells accumulated high levels of active GTP-bound RAC1, CDC42, and RHOA, and RAC1 remained associated with the plasma membrane. Moreover, GGTase-I deficiency activated p38 and NF-κB and increased the production of proinflammatory cytokines. The results challenge the view that geranylgeranylation is essential for the activity and localization of RHO family proteins and suggest that reduced geranylgeranylation in macrophages can initiate erosive arthritis.
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| 4. |
- Liu, Meng, 1976, et al.
(författare)
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Targeting the protein prenyltransferases efficiently reduces tumor development in mice with K-RAS-induced lung cancer
- 2010
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 107:14, s. 6471-6476
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Tidskriftsartikel (refereegranskat)abstract
- RAS and RHO proteins, which contribute to tumorigenesis and metastasis, undergo posttranslational modification with an isoprenyl lipid by protein farnesyltransferase (FTase) or protein geranylgeranyltransferase-I (GGTase-I). Inhibitors of FTase and GGTase-I were developed to block RAS-induced malignancies, but their utility has been difficult to evaluate because of off-target effects, drug resistance, and toxicity. Moreover, the impact of FTase deficiency and combined FTase/GGTase-I deficiency has not been evaluated with genetic approaches. We found that inactivation of FTase eliminated farnesylation of HDJ2 and H-RAS, prevented H-RAS targeting to the plasma membrane, and blocked proliferation of primary and K-RAS(G12D)-expressing fibroblasts. FTase inactivation in mice with K-RAS-induced lung cancer reduced tumor growth and improved survival, similar to results obtained previously with inactivation of GGTase-I. Simultaneous inactivation of FTase and GGTase-I markedly reduced lung tumors and improved survival without apparent pulmonary toxicity. These data shed light on the biochemical and therapeutic importance of FTase and suggest that simultaneous inhibition of FTase and GGTase-I could be useful in cancer therapeutics.
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| 5. |
- Sjögren, Anna-Karin, 1980, et al.
(författare)
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GGTase-I deficiency reduces tumor formation and improves survival in mice with K-RAS-induced lung cancer
- 2007
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Ingår i: J Clin Invest. - 0021-9738. ; 117:5, s. 1294-304
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Tidskriftsartikel (refereegranskat)abstract
- Protein geranylgeranyltransferase type I (GGTase-I) is responsible for the posttranslational lipidation of CAAX proteins such as RHOA, RAC1, and cell division cycle 42 (CDC42). Inhibition of GGTase-I has been suggested as a strategy to treat cancer and a host of other diseases. Although several GGTase-I inhibitors (GGTIs) have been synthesized, they have very different properties, and the effects of GGTIs and GGTase-I deficiency are unclear. One concern is that inhibiting GGTase-I might lead to severe toxicity. In this study, we determined the effects of GGTase-I deficiency on cell viability and K-RAS-induced cancer development in mice. Inactivating the gene for the critical beta subunit of GGTase-I eliminated GGTase-I activity, disrupted the actin cytoskeleton, reduced cell migration, and blocked the proliferation of fibroblasts expressing oncogenic K-RAS. Moreover, the absence of GGTase-I activity reduced lung tumor formation, eliminated myeloproliferative phenotypes, and increased survival of mice in which expression of oncogenic K-RAS was switched on in lung cells and myeloid cells. Interestingly, several cell types remained viable in the absence of GGTase-I, and myelopoiesis appeared to function normally. These findings suggest that inhibiting GGTase-I may be a useful strategy to treat K-RAS-induced malignancies.
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| 6. |
- Wahlström, Annika, 1975, et al.
(författare)
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Inactivating Icmt ameliorates K-RAS-induced myeloproliferative disease.
- 2008
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 112:4, s. 1357-65
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Tidskriftsartikel (refereegranskat)abstract
- Hyperactive signaling through the RAS proteins is involved in the pathogenesis of many forms of cancer. The RAS proteins and many other intracellular signaling proteins are either farnesylated or geranylgeranylated at a carboxyl-terminal cysteine. That isoprenylcysteine is then carboxyl methylated by isoprenylcysteine carboxyl methyltransferase (ICMT). We previously showed that inactivation of Icmt mislocalizes the RAS proteins away from the plasma membrane and blocks RAS transformation of mouse fibroblasts, suggesting that ICMT could be a therapeutic target. However, nothing is known about the impact of inhibiting ICMT on the development of malignancies in vivo. In the current study, we tested the hypothesis that inactivation of Icmt would inhibit the development or progression of a K-RAS-induced myeloproliferative disease in mice. We found that inactivating Icmt reduced splenomegaly, the number of immature myeloid cells in peripheral blood, and tissue infiltration by myeloid cells. Moreover, in the absence of Icmt, the ability of K-RAS-expressing hematopoietic cells to form colonies in methylcellulose without exogenous growth factors was reduced dramatically. Finally, inactivating Icmt reduced lung tumor development and myeloproliferation phenotypes in a mouse model of K-RAS-induced cancer. We conclude that inactivation of Icmt ameliorates phenotypes of K-RAS-induced malignancies in vivo.
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| 7. |
- Wahlström, Annika, 1975, et al.
(författare)
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Rce1 deficiency accelerates the development of K-RAS-induced myeloproliferative disease
- 2007
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Ingår i: Blood. ; 109:2, s. 763-768
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Tidskriftsartikel (refereegranskat)abstract
- The RAS proteins undergo farnesylation of a carboxyl-terminal cysteine (the "C" of the carboxyl-terminal CaaX motif). After farnesylation, the 3 amino acids downstream from the farnesyl cysteine (the -aaX of the CaaX motif) are released by RAS-converting enzyme 1 (RCE1). We previously showed that inactivation of Rce1 in mouse fibroblasts mislocalizes RAS proteins away from the plasma membrane and inhibits RAS transformation. Therefore, we hypothesized that the inactivation of Rce1 might inhibit RAS transformation in vivo. To test this hypothesis, we used Cre/loxP recombination techniques to simultaneously inactivate Rce1 and activate a latent oncogenic K-RAS allele in hematopoietic cells in mice. Normally, activation of the oncogenic K-RAS allele in hematopoietic cells leads to rapidly progressing and lethal myeloproliferative disease. Contrary to our hypothesis, the inactivation of Rce1 actually increased peripheral leukocytosis, increased the release of immature hematopoietic cells into the circulation and the infiltration of cells into liver and spleen, and caused mice to die more rapidly. Moreover, in the absence of Rce1, splenocytes and bone marrow cells expressing oncogenic K-RAS yielded more and larger colonies when grown in methylcellulose. We conclude that the inactivation of Rce1 worsens the myeloproliferative disease caused by oncogenic K-RAS.
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| 8. |
- Holmgren, Gustav, et al.
(författare)
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Long-Term Chronic Toxicity Testing Using Human Pluripotent Stem Cell-Derived Hepatocytes
- 2014
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Ingår i: Drug Metabolism and Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:9, s. 1401-1406
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cells (hPSC) have the potential to become important tools for the establishment of new models for in vitro drug testing of, for example, toxicity and pharmacological effects. Late-stage attrition in the pharmaceutical industry is to a large extent caused by selection of drug candidates using nonpredictive preclinical models that are not clinically relevant. The current hepatic in vivo and in vitro models show clear limitations, especially for studies of chronic hepatotoxicity. For these reasons, we evaluated the potential of using hPSC-derived hepatocytes for long-term exposure to toxic drugs. The differentiated hepatocytes were incubated with hepatotoxic compounds for up to 14 days, using a repeated-dose approach. The hPSC-derived hepatocytes became more sensitive to the toxic compounds after extended exposures and, in addition to conventional cytotoxicity, evidence of phospholipidosis and steatosis was also observed in the cells. This is, to the best of our knowledge, the first report of a long-term toxicity study using hPSC-derived hepatocytes, and the observations support further development and validation of hPSC-based toxicity models for evaluating novel drugs, chemicals, and cosmetics.
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| 9. |
- Sjögren, Anna-Karin, 1980, et al.
(författare)
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Monozygotic twins discordant for intermittent allergic rhinitis differ in mRNA and protein levels
- 2012
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Ingår i: Allergy. European Journal of Allergy and Clinical Immunology. - : John Wiley and Sons. - 0105-4538 .- 1398-9995. ; 67:6, s. 831-833
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Tidskriftsartikel (refereegranskat)abstract
- Monozygotic (MZ) twins discordant for complex diseases may help to find disease mechanisms that are not due to genetic variants. Intermittent allergic rhinitis (IAR) is an optimal disease model because it occurs at defined time points each year, owing to known external antigens. We hypothesized that MZ twins discordant for IAR could help to find gene expression differences that are not dependent on genetic variants. We collected blood outside of the season from MZ twins discordant for IAR, challenged their peripheral blood mononuclear cells (PBMC) with pollen allergen in vitro, collected supernatants and isolated CD4+ T cells. We identified disease-relevant mRNAs and proteins that differed between the discordant MZ twins. By contrast, no differences in microRNA expression were found. Our results indicate that MZ twins discordant for IAR is an optimal model to identify disease mechanisms that are not due to genetic variants.
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| 10. |
- Sjögren, Anna-Karin, 1980
(författare)
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The Importance of Isoprenylation and Nf1 Deficiency in K-RAS-induced Cancer
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The RAS and RHO family proteins contribute to tumorigenesis and metastasis and belong to a family of so called CAAX proteins. The membrane targeting and proper function of CAAX proteins are dependent on posttranslational isoprenylation by farnesyltransferase (FTase) or geranylgeranyltransferase type I (GGTase-I). Inhibitors of FTase and GGTase-I have been developed to block RAS-induced cancer, but their utility has been difficult to evaluate because of off-target effects, drug resistance, and toxicity. One aim of this thesis was to use genetic strategies in mice to define the physiologic importance of CAAX protein isoprenylation and to evaluate FTase and GGTase-I as potential anti-cancer drug targets. Oncogenic mutations in RAS are common in cancer and result in hyperactive RAS signaling. However, a RAS mutation alone is not sufficient for cancer development in humans. Rather, cancer arises as a consequence of cooperation between several mutational events. The tumor suppressor gene neurofibromatosis type I (NF1) is a RAS-inactivating protein. Thus, loss of NF1 also results in hyperactive RAS signaling and this occurs in some types of cancer. It has been proposed that NF1 deficiency is functionally equivalent to an oncogenic RAS; but NF1 may operate in other pathways. It is not clear if NF1 deficiency would be redundant in RAS-induced cancer development or if the two mutations would cooperate. A second aim of this thesis was to define the impact of Nf1 deficiency on the development of K-RAS–induced cancer in mice. To approach these aims, Cre/loxP gene targeting techniques in mice were used, to simultaneously activate an oncogenic K-RAS allele, to induce lung cancer or myeloid leukemia, and inactivate the genes encoding FTase and GGTase-I, or Nf1. Inactivating the gene encoding the b-subunit of GGTase-I eliminated enzyme activity, blocked proliferation and reduced motility of fibroblasts. Moreover, inactivation of GGTase-I reduced tumor formation and increased survival of mice with K-RAS–induced lung cancer. Finally, several cell types, including lung tumor cells and macrophages remained viable in the absence of GGTase-I. Inactivating the gene encoding the b-subunit of FTase eliminated farnesylation of HDJ2 and H-RAS, prevented H-RAS targeting to the plasma membrane, and blocked proliferation of fibroblasts. FTase inactivation reduced tumor formation and increased survival of mice with K-RAS–induced cancer to a similar extent as the inactivation of GGTase-I. The simultaneous inactivation of FTase and GGTase-I markedly reduced lung tumors and improved survival. These data suggest that inhibition of FTase and/or GGTase-I could be useful in the treatment of K-RAS–induced cancer. In mice, expression of oncogenic K-RAS or inactivation of Nf1 in hematopoietic cells results in myeloproliferative disorders (MPDs) that do not progress to acute myeloid leukemia (AML). However, the simultaneous inactivation of Nf1 and activation of oncogenic K-RAS in hematopoietic cells induced AML in mice. The levels of active RAS were not increased in mice with AML, raising the possibility that Nf1 deficiency may contribute to AML by non-RAS pathways. This result points to a strong cooperation between Nf1 deficiency and oncogenic K-RAS and sheds new light on mechanisms of RAS-induced leukemia development.
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