| 1. |
- Agarwal, Shruti, et al.
(författare)
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The activation loop tyrosine 823 is essential for the transforming capacity of the c-Kit oncogenic mutant D816V.
- 2015
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 1476-5594 .- 0950-9232. ; 34:35, s. 4581-4590
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Tidskriftsartikel (refereegranskat)abstract
- Oncogenic c-Kit mutations have been shown to display ligand-independent receptor activation and cell proliferation. A substitution of aspartate to valine at amino acid 816 (D816V) is one of the most commonly found oncogenic c-Kit mutations and is found in >90% of cases of mastocytosis and less commonly in germ-cell tumors, core-binding factor acute myeloid leukemia and mucosal melanomas. The mechanisms by which this mutation leads to constitutive activation and transformation are not fully understood. Previous studies have shown that the D816V mutation causes a structural change in the activation loop (A-loop), resulting in weaker binding of the A-loop to the juxtamembrane domain. In this paper, we have investigated the role of Y823, the only tyrosine residue in the A-loop, and its role in oncogenic transformation by c-Kit/D816V by introducing the Y823F mutation. Although dispensable for the kinase activity of c-Kit/D816V, the presence of Y823 was crucial for cell proliferation and survival. Furthermore, mutation of Y823 selectively downregulates the Ras/Erk and Akt pathways as well as the phosphorylation of STAT5 and reduces the transforming capacity of the D816V/c-Kit in vitro. We further show that mice injected with cells expressing c-Kit/D816V/Y823F display significantly reduced tumor size as well as tumor weight compared with controls. Finally, microarray analysis, comparing Y823F/D816V cells with cells expressing c-Kit/D816V, demonstrate that mutation of Y823 causes upregulation of proapoptotic genes, whereas genes of survival pathways are downregulated. Thus, phosphorylation of Y823 is not necessary for kinase activation, but essential for the transforming ability of the c-Kit/D816V mutant.Oncogene advance online publication, 1 December 2014; doi:10.1038/onc.2014.383.
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| 2. |
- Arts, F. A., et al.
(författare)
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PDGFRB mutants found in patients with familial infantile myofibromatosis or overgrowth syndrome are oncogenic and sensitive to imatinib
- 2016
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 35:25, s. 3239-3248
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Tidskriftsartikel (refereegranskat)abstract
- Recently, germline and somatic heterozygous mutations in the platelet-derived growth factor receptor beta (PDGFRB) have been associated with familial infantile myofibromatosis (IM), which is characterized by soft tissue tumors, and overgrowth syndrome, a disease that predisposes to cancer. These mutations have not been functionally characterized. In the present study, the activity of three PDGFRB mutants associated with familial IM (R561C, P660T and N666K) and one PDGFRB mutant found in patients with overgrowth syndrome (P584R) was tested in various models. The P660T mutant showed no difference with the wild-type receptor, suggesting that it might represent a polymorphic variant unrelated to the disease. By contrast, the three other mutants were constitutively active and able to transform NIH3T3 and Ba/F3 cells to different extents. In particular, the germline mutant identified in overgrowth syndrome, P584R, was a stronger oncogene than the germline R561C mutant associated with myofibromatosis. The distinct phenotypes associated with these two mutations could be related to this difference of potency. Importantly, all activated mutants were sensitive to tyrosine kinase inhibitors such as imatinib, nilotinib and ponatinib. In conclusion, the PDGFRB mutations previously identified in familial IM and overgrowth syndrome activate the receptor in the absence of ligand, supporting the hypothesis that these mutations cause the diseases. Moreover, imatinib seems to be a promising treatment for patients carrying these mutations. To our knowledge, these are the first confirmed gain-of-function point mutations of PDGFRB in human cancer.
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| 3. |
- Aydin, Ebru, et al.
(författare)
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NOX2 inhibition reduces oxidative stress and prolongs survival in murine KRAS-induced myeloproliferative disease
- 2019
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 38:9, s. 1534-1543
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Tidskriftsartikel (refereegranskat)abstract
- Mutations leading to constitutive RAS activation contribute in myeloid leukemogenesis. RAS mutations in myeloid cells are accompanied by excessive formation of reactive oxygen species (ROS), but the source of ROS and their role for the initiation and progression of leukemia have not been clearly defined. To determine the role of NOX2-derived ROS in RAS-driven leukemia, double transgenic LSL-Kras(G12D) x Mx1-Cre mice expressing oncogenic KRAS in hematopoietic cells (M-Kras(G12D)) were treated with N-alpha-methyl-histamine (NMH) that targeted the production of NOX2-derived ROS in leukemic cells by agonist activity at histamine H-2 receptors. M-Kras(G12D) mice developed myeloid leukemia comprising mature CD11b(+)Gr1(+) myeloid cells that produced NOX2-derived ROS. Treatment of M-Kras(G12D) mice with NMH delayed the development of myeloproliferative disease and prolonged survival. In addition, NMH-treated M-Kras(G12D) mice showed reduction of intracellular ROS along with reduced DNA oxidation and reduced occurence of double-stranded DNA breaks in myeloid cells. The in vivo expansion of leukemia was markedly reduced in triple transgenic mice where KRAS was expressed in hematopoietic cells of animals with genetic NOX2 deficiency (Nox2(-/-) x LSL-Kras(G12D) x Mx1-Cre). Treatment with NMH did not alter in vivo expansion of leukemia in these NOX2-deficient transgenic mice. We propose that NOX2-derived ROS may contribute to the progression of KRAS-induced leukemia and that strategies to target NOX2 merit further evaluation in RAS-mutated hematopoietic cancer.
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| 4. |
- Berbegall, A. P., et al.
(författare)
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Comparative genetic study of intratumoral heterogenous MYCN amplified neuroblastoma versus aggressive genetic profile neuroblastic tumors
- 2016
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 35:11, s. 1423-1432
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Tidskriftsartikel (refereegranskat)abstract
- Intratumoral heterogeneous MYCN amplification (hetMNA) is an unusual event in neuroblastoma with unascertained biological and clinical implications. Diagnosis is based on the detection of MYCN amplification surrounded by non-amplified tumor cells by fluorescence in situ hybridization (FISH). To better define the genetic features of hetMNA tumors, we studied the Spanish cohort of neuroblastic tumors by FISH and single nucleotide polymorphism arrays. We compared hetMNA tumors with homogeneous MNA (homMNA) and nonMNA tumors with 11q deletion (nonMNA w11q-). Of 1091 primary tumors, 28 were hetMNA by FISH. Intratumoral heterogeneity of 1p, 2p, 11q and 17q was closely associated with hetMNA tumors when analyzing different pieces for each case. For chromosome 2, 16 cases showed 2p intact, 4 focal gain at 2p24.3 and 8 MNA. The lengths of the smallest regions of overlap (SROs) for 2p gains and 1p deletions were between the SRO lengths observed in homMNA and nonMNA w11q- tumors. Co-occurrence of 11q- and +17q was frequently found with the largest SROs for both aberrations. The evidence for and frequency of different genetic subpopulations representing a hallmark of the hetMNA subgroup of NB indicates, on one hand, the presence of a considerable genetic instability with different SRO of either gains and losses compared with those of the other NB groups and highlights and, on the other hand, the need for multiple sampling from distant and macroscopically and microscopically distinct tumor areas. Narrowing down the different SRO for both deletions and gains in NB groups would be crucial to pinpointing the candidate gene(s) and the critical gene dosage with prognostic and therapeutic significance. This complexity of segmental chromosomal aberration patterns reinforces the necessity for a larger cohort study using FISH and pangenomic techniques to develop a suitable therapeutic strategy for these patients.
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| 5. |
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| 6. |
- Bolin, Sara, 1988-, et al.
(författare)
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Combined BET bromodomain and CDK2 inhibition in MYC-driven medulloblastoma
- 2018
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Ingår i: Oncogene. - : Nature Publishing Group. - 0950-9232 .- 1476-5594. ; 37:21, s. 2850-2862
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Tidskriftsartikel (refereegranskat)abstract
- Medulloblastoma (MB) is the most common malignant brain tumor in children. MYC genes are frequently amplified and correlate with poor prognosis in MB. BET bromodomains recognize acetylated lysine residues and often promote and maintain MYC transcription. Certain cyclin-dependent kinases (CDKs) are further known to support MYC stabilization in tumor cells. In this report, MB cells were suppressed by combined targeting of MYC expression and MYC stabilization using BET bromodomain inhibition and CDK2 inhibition, respectively. Such combination treatment worked synergistically and caused cell cycle arrest as well as massive apoptosis. Immediate transcriptional changes from this combined MYC blockade were found using RNA-Seq profiling and showed remarkable similarities to changes in MYC target gene expression when MYCN was turned off with doxycycline in our MYCN-inducible animal model for Group 3 MB. In addition, the combination treatment significantly prolonged survival as compared to single-agent therapy in orthotopically transplanted human Group 3 MB with MYC amplifications. Our data suggest that dual inhibition of CDK2 and BET bromodomains can be a novel treatment approach for suppressing MYC-driven cancer.
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| 7. |
- Brix, Ditte Marie, et al.
(författare)
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Release of transcriptional repression via ErbB2-induced, SUMO-directed phosphorylation of myeloid zinc finger-1 serine 27 activates lysosome redistribution and invasion
- 2019
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 38:17, s. 3170-3184
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Tidskriftsartikel (refereegranskat)abstract
- HER2/ErbB2 activation turns on transcriptional processes that induce local invasion and lead to systemic metastasis. The early transcriptional changes needed for ErbB2-induced invasion are poorly understood. Here, we link ErbB2 activation to invasion via ErbB2-induced, SUMO-directed phosphorylation of a single serine residue, S27, of the transcription factor myeloid zinc finger-1 (MZF1). Utilizing an antibody against MZF1-pS27, we show that the phosphorylation of S27 correlates significantly (p < 0.0001) with high-level expression of ErbB2 in primary invasive breast tumors. Phosphorylation of MZF1-S27 is an early response to ErbB2 activation and results in increased transcriptional activity of MZF1. It is needed for the ErbB2-induced expression of MZF1 target genes CTSB and PRKCA, and invasion of single-cells from ErbB2-expressing breast cancer spheroids. The phosphorylation of MZF1-S27 is preceded by poly-SUMOylation of K23, which can make S27 accessible to efficient phosphorylation by PAK4. Based on our results, we suggest for an activation mechanism where phosphorylation of MZF1-S27 triggers MZF1 dissociation from its transcriptional repressors such as the CCCTC-binding factor (CTCF). Our findings increase understanding of the regulation of invasive signaling in breast cancer by uncovering a detailed biological mechanism of how ErbB2 activation can rapidly lead to its invasion-promoting target gene expression and invasion.
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| 8. |
- Busch, Susann, et al.
(författare)
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TGF-beta receptor type-2 expression in cancer-associated fibroblasts regulates breast cancer cell growth and survival and is a prognostic marker in pre-menopausal breast cancer
- 2015
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 34:1, s. 27-38
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Tidskriftsartikel (refereegranskat)abstract
- Transforming growth factor-beta (TGF-beta) is a pleiotropic cytokine with the capability to act as tumour suppressor or tumour promoter depending on the cellular context. TGF-beta receptor type-2 (TGFBR2) is the ligand-binding receptor for all members of the TGF-beta family. Data from mouse model experiments demonstrated that loss of Tgfbr2 expression in mammary fibroblasts was linked to tumour initiation and metastasis. Using a randomised tamoxifen trial cohort including in total 564 invasive breast carcinomas, we examined TGFBR2 expression (n = 252) and phosphorylation level of downstream target SMAD2 (pSMAD2) (n = 319) in cancer-associated fibroblasts (CAFs) and assessed links to clinicopathological markers, prognostic and treatment-predictive values. The study revealed that CAF-specific TGFBR2 expression correlated with improved recurrence-free survival. Multivariate analysis confirmed CAF-TGFBR2 to be an independent prognostic marker (multivariate Cox regression, hazard ratio: 0.534, 95% (CI): 0.360-0.793, P = 0.002). CAF-specific pSMAD2 levels, however, did not associate with survival outcome. Experimentally, TGF-beta signalling in fibroblasts was modulated using a TGF-beta ligand and inhibitor or through lentiviral short hairpin RNA-mediated TGFBR2-specific knockdown. To determine the role of fibroblastic TGF-beta pathway on breast cancer cells, we used cell contact-dependent cell growth and clonogenicity assays, which showed that knockdown of TGFBR2 in CAFs resulted in increased cell growth, proliferation and clonogenic survival. Further, in a mouse model transfected CAFs were co-injected with MCF7 and tumour weight and proportion was monitored. We found that mouse xenograft tumours comprising TGFBR2 knockdown fibroblasts were slightly bigger and displayed increased tumour cell capacity. Overall, our data demonstrate that fibroblast-related biomarkers possess clinically relevant information and that fibroblasts confer effects on breast cancer cell growth and survival. Regulation of tumour-stromal cross-talk through fibroblastic TGF-beta pathway may depend on fibroblast phenotype, emphasising the importance to characterise tumour microenvironment subtypes.
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| 9. |
- Caja, Laia, et al.
(författare)
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Snail regulates BMP and TGF beta pathways to control the differentiation status of glioma-initiating cells
- 2018
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 37:19, s. 2515-2531
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma multiforme is a brain malignancy characterized by high heterogeneity, invasiveness, and resistance to current therapies, attributes related to the occurrence of glioma stem cells (GSCs). Transforming growth factor beta (TGF beta) promotes self-renewal and bone morphogenetic protein (BMP) induces differentiation of GSCs. BMP7 induces the transcription factor Snail to promote astrocytic differentiation in GSCs and suppress tumor growth in vivo. We demonstrate that Snail represses stemness in GSCs. Snail interacts with SMAD signaling mediators, generates a positive feedback loop of BMP signaling and transcriptionally represses the TGFB1 gene, decreasing TGF beta 1 signaling activity. Exogenous TGF beta 1 counteracts Snail function in vitro, and in vivo promotes proliferation and re-expression of Nestin, confirming the importance of TGFB1 gene repression by Snail. In conclusion, novel insight highlights mechanisms whereby Snail differentially regulates the activity of the opposing BMP and TGF beta pathways, thus promoting an astrocytic fate switch and repressing stemness in GSCs.
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| 10. |
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