| 1. |
- Guo, Min, et al.
(författare)
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Identification of functionally distinct and interacting cancer cell subpopulations from glioblastoma with intratumoral genetic heterogeneity
- 2020
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Ingår i: Neuro-Oncology Advances. - : Oxford University Press. - 2632-2498. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundGlioblastomas display a high level of intratumoral heterogeneity with regard to both genetic and histological features. Within single tumors, subclones have been shown to communicate with each other to affect overall tumor growth. The aim of this study was to broaden the understanding of interclonal communication in glioblastoma.MethodsWe have used the U-343 model, consisting of U-343 MG, U-343 MGa, U-343 MGa 31L, and U-343 MGa Cl2:6, a set of distinct glioblastoma cell lines that have been derived from the same tumor. We characterized these with regard to temozolomide sensitivity, protein secretome, gene expression, DNA copy number, and cancer cell phenotypic traits. Furthermore, we performed coculture and conditioned media-based experiments to model cell-to-cell signaling in a setting of intratumoral heterogeneity.ResultsTemozolomide treatment of a coculture composed of all 4 U-343 cell lines presents a tumor relapse model where the least sensitive population, U-343 MGa 31L, outlives the others. Interestingly, the U-343 cell lines were shown to have distinct gene expression signatures and phenotypes although they were derived from a single tumor. The DNA copy number analysis revealed both common and unique alterations, indicating the evolutionary relationship between the cells. Moreover, these cells were found to communicate and affect each other’s proliferation, both via contact-dependent and -independent interactions, where NOTCH1, TGFBI, and ADAMTS1 signaling effects were involved, respectively.ConclusionsThese results provide insight into how complex the signaling events may prove to be in a setting of intratumoral heterogeneity in glioblastoma and provide a map for future studies.
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| 2. |
- Guo, Min, et al.
(författare)
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SFRP2 induces a mesenchymal subtype transition by suppression of SOX2 in glioblastoma
- 2021
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Ingår i: Oncogene. - : Springer Nature. - 0950-9232 .- 1476-5594. ; 40:32, s. 5066-5080
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Tidskriftsartikel (refereegranskat)abstract
- Intratumoral heterogeneity is a characteristic of glioblastomas that contain an intermixture of cell populations displaying different glioblastoma subtype gene expression signatures. Proportions of these populations change during tumor evolution, but the occurrence and regulation of glioblastoma subtype transition is not well described. To identify regulators of glioblastoma subtypes we utilized a combination of in vitro experiments and in silico analyses, using experimentally generated as well as publicly available data. Through this combined approach SOX2 was identified to confer a proneural glioblastoma subtype gene expression signature. SFRP2 was subsequently identified as a SOX2-antagonist, able to induce a mesenchymal glioblastoma subtype signature. A subset of patient glioblastoma samples with high SFRP2 and low SOX2 expression was particularly enriched with mesenchymal subtype samples. Phenotypically, SFRP2 decreased tumor sphere formation, stemness as assessed by limiting dilution assay, and overall cell proliferation but increased cell motility, whereas SOX2 induced the opposite effects. Furthermore, an SFRP2/non-canonical-WNT/KLF4/PDGFR/phospho-AKT/SOX2 signaling axis was found to be involved in the mesenchymal transition. Analysis of human tumor tissue spatial gene expression patterns showed distinct expression of SFRP2- and SOX2-correlated genes in vascular and cellular areas, respectively. Finally, conditioned media from SFRP2 overexpressing cells increased CD206 on macrophages. Together, these findings present SFRP2 as a SOX2-antagonist with the capacity to induce a mesenchymal subtype transition in glioma cells located in vascular tumor areas, highlighting its role in glioblastoma tumor evolution and intratumoral heterogeneity.
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| 3. |
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| 4. |
- Hägerstrand, Daniel, et al.
(författare)
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Characterization of an imatinib-sensitive subset of high-grade human glioma cultures
- 2006
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 25:35, s. 4913-4922
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Tidskriftsartikel (refereegranskat)abstract
- High-grade gliomas, including glioblastomas, are malignant brain tumors for which improved treatment is urgently needed. Genetic studies have demonstrated the existence of biologically distinct subsets. Preliminary studies have indicated that platelet-derived growth factor (PDGF) receptor signaling contributes to the growth of some of these tumors. In this study, human high-grade glioma primary cultures were analysed for sensitivity to treatment with the PDGF receptor inhibitor imatinib/Glivec/Gleevec/STI571. Six out of 15 cultures displayed more than 40% growth inhibition after imatinib treatment, whereas seven cultures showed less than 20% growth inhibition. In the sensitive cultures, apoptosis contributed to growth inhibition. Platelet-derived growth factor receptor status correlated with imatinib sensitivity. Supervised analyses of gene expression profiles and real-time PCR analyses identified expression of the chemokine CXCL12/SDF-1 (stromal cell-derived factor 1) as a predictor of imatinib sensitivity. Exogenous addition of CXCL12 to imatinib-insensitive cultures conferred some imatinib sensitivity. Finally, coregulation of CXCL12 and PDGF alpha-receptor was observed in glioblastoma biopsies. We have thus defined the characteristics of a novel imatinib-sensitive subset of glioma cultures, and provided evidence for a functional relationship between imatinib sensitivity and chemokine signaling. These findings will assist in the design and evaluation of clinical trials exploring therapeutic effects of imatinib on malignant brain tumors.
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| 5. |
- Hägerstrand, Daniel, et al.
(författare)
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Gene expression analyses of grade II gliomas and identification of rPTPbeta/ as a candidate oligodendroglioma marker
- 2008
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Ingår i: Neuro-Oncology. - : Oxford University Press (OUP). - 1522-8517 .- 1523-5866. ; 10:1, s. 2-9
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Tidskriftsartikel (refereegranskat)abstract
- Grade 11 gliomas are morphologically and clinically heterogeneous tumors for which histopathological typing remains the major tool for clinical classification. To what extent the major histological subtypes-astrocytomas, oligodendrogliomas, and oligoastrocytomas-constitute true biological entities is largely unresolved. Furthermore, morphological classification is often ambiguous and would be facilitated by specific subtype markers. In this study, 23 grade II gliomas were expression-profiled and subjected to hierarchical clustering. All six oligodendrogliomas were grouped together in one of two major clusters; a significant correlation was thus observed between gene expression and histopathological subtype. Supervised analyses were performed to identify genes differentiating oligodendrogliomas from other grade II tumors. In a leave-one-out test using 10 features for classification, 20 out of 23 tumors were correctly classified. Among the most differentially expressed genes was rPT beta/zeta. The expression of the rPTP beta/zeta protein in oligodendrogliomas and astrocytomas was further validated by immunohistochemistry in an independent set of tumors. All 11 oligodendrogliomas of this set displayed strong staining. In contrast, neoplastic astrocytes were mostly negative for rPTP beta/zeta staining. In summary, this study demonstrates a correlation between gene expression pattern and histological subtype in grade 11 gliomas. Furthermore, the results from the immunohistochemical analyses of rPTP beta/zeta expression should prompt further evaluation of this protein as a novel oligodendroglioma marker.
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| 6. |
- Hägerstrand, Daniel
(författare)
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Molecular determinants of glioma subsets with distinct histology or sensitivity to signal transduction inhibitors
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gliomas are brain tumors that currently are treated with surgery, radiation and chemotherapy. Less than 7.5% of patients with GBM survive more than 2 years after diagnosis. The conclusion, from several decades of intense research on glioma biology, is that gliomas are tumors with high genetic, morphological and clinical variation, which makes them hard to diagnose and treat. Predicative markers are therefore highly warranted. In this thesis we identified new molecular characteristics of glioma subsets with distinct histology or sensitivity to signal transduction inhibitors. Grade II gliomas are histologically diverse and are commonly divided into astrocytomas, oligodendrogliomas and oligoastrocytomas. We have identified rPTPb/z as a novel marker for grade II oligodendrogliomas, which is the type with better survival and response to chemotherapy. Glioblastomas are currently subdivided into primary and secondary glioblastomas, which follow different biological as well as clinical routes. Current knowledge about glioma genetics suggests the need for a refined sub-categorization. We have defined a high grade glioma subtype which is sensitive to PDGFR inhibitor (imatinib, Glivec). This subtype expresses high levels of PDGFR-a and CXCL12. Potentially this subtype constitutes a group of tumors which would best respond to imatinib treatment. IGF-1R signaling has been shown to be important for glioma growth. NVP-AEW541 is a novel small-molecule inhibitor of IGF-1R. Analysis of the effects of NVP-AEW541 on a panel of high grade glioma cell cultures revealed differences in sensitivity. PIK3CA, PTEN and AKT status was analyzed to investigate their effect on NVP-AEW541 sensitivity. 3/4 high-sensitive cultures demonstrated serum-dependent AKT phosphorylation, whereas AKT phosphorylation was only affected in 1/5 cultures with low sensitivity. Exon 9 mutations in PIK3CA were found in 2/2 sensitive and in 3/5 low sensitive. PTEN expression varied more than ten-fold between cultures, in a manner not associated with drug sensitivity. Interestingly down-regulation of PTEN decreased sensitivity to NVP-AEW541. CD133-expressing tumor cells with stem cell characteristics have been identified and isolated from several malignancies including glioblastomas. These are suggested to be responsible for the tumor formation. Two novel CD133+ glioma cell subsets were identified. These subsets differed with regard to marker gene expression, ability to grow as neurospheres and in sensitivity to tyrosine kinase inhibitors. Furthermore, genes defining these two subsets were found to be co-expressed in glioblastoma tissue. These studies have thus generated a series of novel observations relevant for the continued rational development of new treatment strategies, and improved diagnosis, of different types of gliomas. Furthermore, the identification of two novel types of tentative brain cancer stem cells should possibly aid in the ultimate identification of the cell types that undergo the initial transformation in glioma formation.
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| 7. |
- Mega, Alessandro, et al.
(författare)
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Astrocytes enhance glioblastoma growth.
- 2020
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Ingår i: Glia. - : Wiley. - 0894-1491 .- 1098-1136. ; 68:2, s. 316-327
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma (GBM) is a deadly disease with a need for deeper understanding and new therapeutic approaches. The microenvironment of glioblastoma has previously been shown to guide glioblastoma progression. In this study, astrocytes were investigated with regard to their effect on glioblastoma proliferation through correlative analyses of clinical samples and experimental in vitro and in vivo studies. Co-culture techniques were used to investigate the GBM growth enhancing potential of astrocytes. Cell sorting and RNA sequencing were used to generate a GBM-associated astrocyte signature and to investigate astrocyte-induced GBM genes. A NOD scid GBM mouse model was used for in vivo studies. A gene signature reflecting GBM-activated astrocytes was associated with poor prognosis in the TCGA GBM dataset. Two genes, periostin and serglycin, induced in GBM cells upon exposure to astrocytes were expressed at higher levels in cases with high "astrocyte signature score". Astrocytes were shown to enhance glioblastoma cell growth in cell lines and in a patient-derived culture, in a manner dependent on cell-cell contact and involving increased cell proliferation. Furthermore, co-injection of astrocytes with glioblastoma cells reduced survival in an orthotopic GBM model in NOD scid mice. In conclusion, this study suggests that astrocytes contribute to glioblastoma growth and implies this crosstalk as a candidate target for novel therapies.
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| 8. |
- Pudelko, Linda, et al.
(författare)
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Glioblastoma and glioblastoma stem cells are dependent on functional MTH1
- 2017
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Ingår i: Oncotarget. - : Impact Journals LLC. - 1949-2553. ; 8:49, s. 84671-84684
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma multiforme (GBM) is an aggressive form of brain cancer with poor prognosis. Cancer cells are characterized by a specific redox environment that adjusts metabolism to its specific needs and allows the tumor to grow and metastasize. As a consequence, cancer cells and especially GBM cells suffer from elevated oxidative pressure which requires antioxidant-defense and other sanitation enzymes to be upregulated. MTH1, which degrades oxidized nucleotides, is one of these defense enzymes and represents a promising cancer target. We found MTH1 expression levels elevated and correlated with GBM aggressiveness and discovered that siRNA knock-down or inhibition of MTH1 with small molecules efficiently reduced viability of patient-derived GBM cultures. The effect of MTH1 loss on GBM viability was likely mediated through incorporation of oxidized nucleotides and subsequent DNA damage. We revealed that MTH1 inhibition targets GBM independent of aggressiveness as well as potently kills putative GBM stem cells in vitro. We used an orthotopic zebrafish model to confirm our results in vivo and light-sheet microscopy to follow the effect of MTH1 inhibition in GBM in real time. In conclusion, MTH1 represents a promising target for GBM therapy and MTH1 inhibitors may also be effective in patients that suffer from recurring disease.
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| 9. |
- Sjöberg, Elin, et al.
(författare)
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A Novel ACKR2-Dependent Role of Fibroblast-Derived CXCL14 in Epithelial-to-Mesenchymal Transition and Metastasis of Breast Cancer
- 2019
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 25:12, s. 3702-3717
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Fibroblasts expressing the orphan chemokine CXCL14 have been previously shown to associate with poor breast cancer prognosis and promote cancer growth. This study explores the mechanism underlying the poor survival associations of stromal CXCL14.Experimental Design: Tumor cell epithelial-to-mesenchymal transition (EMT), invasion, and metastasis were studied in in vitro and in vivo models together with fibroblasts overexpressing CXCL14. An approach for CXCL14 receptor identification included loss-of-function studies followed by molecular and functional endpoints. The clinical relevance was further explored in publicly available gene expression datasets.Results: CXCL14 fibroblasts stimulated breast cancer EMT, migration, and invasion in breast cancer cells and in a xenograft model. Furthermore, tumor cells primed by CXCL14 fibroblasts displayed enhanced lung colonization after tailvein injection. By loss-of function experiments, the atypical G-protein-coupled receptor ACKR2 was identified to mediate CXCL14-stimulated responses. Downregulation of ACKR2, or CXCL14-induced NOS1, attenuated the pro-EMT and migratory capacity. CXCL14/ACKR2 expression correlated with EMT and survival in gene expression datasets. 'Conclusions: Collectively, the findings imply an autocrine fibroblast CXCL14/ACKR2 pathway as a clinically relevant stimulator of EMT, tumor cell invasion, and metastasis. The study also identifies ACKR2 as a novel mediator for CXCL14 function and thereby defines a pathway with drug target potential.
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