| 1. |
- A, Teschendorff, et al.
(författare)
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The dynamics of DNA methylation covariation patterns in carcinogenesis
- 2014
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Ingår i: PLoS Computational Biology. - : Public Library of Science (PLoS). - 1553-734X .- 1553-7358. ; 10:7
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Tidskriftsartikel (refereegranskat)abstract
- Recently it has been observed that cancer tissue is characterised by an increased variability in DNA methylation patterns. However, how the correlative patterns in genome-wide DNA methylation change during the carcinogenic progress has not yet been explored. Here we study genome-wide inter-CpG correlations in DNA methylation, in addition to single site variability, during cervical carcinogenesis. We demonstrate how the study of changes in DNA methylation covariation patterns across normal, intra-epithelial neoplasia and invasive cancer allows the identification of CpG sites that indicate the risk of neoplastic transformation in stages prior to neoplasia. Importantly, we show that the covariation in DNA methylation at these risk CpG loci is maximal immediately prior to the onset of cancer, supporting the view that high epigenetic diversity in normal cells increases the risk of cancer. Consistent with this, we observe that invasive cancers exhibit increased covariation in DNA methylation at the risk CpG sites relative to normal tissue, but lower levels relative to pre-cancerous lesions. We further show that the identified risk CpG sites undergo preferential DNA methylation changes in relation to human papilloma virus infection and age. Results are validated in independent data including prospectively collected samples prior to neoplastic transformation. Our data are consistent with a phase transition model of carcinogenesis, in which epigenetic diversity is maximal prior to the onset of cancer. The model and algorithm proposed here may allow, in future, network biomarkers predicting the risk of neoplastic transformation to be identified.
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| 2. |
- Ahamed, MT, et al.
(författare)
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MethPed: an R package for the identification of pediatric brain tumor subtypes
- 2016
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Ingår i: Bmc Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: DNA methylation profiling of pediatric brain tumors offers a new way of diagnosing and subgrouping these tumors which improves current clinical diagnostics based on histopathology. We have therefore developed the MethPed classifier, which is a multiclass random forest algorithm, based on DNA methylation profiles from many subgroups of pediatric brain tumors. Results: We developed an R package that implements the MethPed classifier, making it easily available and accessible. The package can be used for estimating the probability that an unknown sample belongs to each of nine pediatric brain tumor diagnoses/subgroups. Conclusions: The MethPed R package efficiently classifies pediatric brain tumors using the developed MethPed classifier. MethPed is available via Bioconductor: http://bioconductor.org/packages/MethPed/
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| 3. |
- Arrizabalaga, O., et al.
(författare)
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High expression of MKP1/DUSP1 counteracts glioma stem cell activity and mediates HDAC inhibitor response
- 2017
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Ingår i: Oncogenesis. - : Springer Science and Business Media LLC. - 2157-9024. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The elucidation of mechanisms involved in resistance to therapies is essential to improve the survival of patients with malignant gliomas. A major feature possessed by glioma cells that may aid their ability to survive therapy and reconstitute tumors is the capacity for self-renewal. We show here that glioma stem cells (GSCs) express low levels of MKP1, a dual-specificity phosphatase, which acts as a negative inhibitor of JNK, ERK1/2, and p38 MAPK, while induction of high levels of MKP1 expression are associated with differentiation of GSC. Notably, we find that high levels of MKP1 correlate with a subset of glioblastoma patients with better prognosis and overall increased survival. Gain of expression studies demonstrated that elevated MKP1 impairs self-renewal and induces differentiation of GSCs while reducing tumorigenesis in vivo. Moreover, we identified that MKP1 is epigenetically regulated and that it mediates the anti-tumor activity of histone deacetylase inhibitors (HDACIs) alone or in combination with temozolomide. In summary, this study identifies MKP1 as a key modulator of the interplay between GSC self-renewal and differentiation and provides evidence that the activation of MKP1, through epigenetic regulation, might be a novel therapeutic strategy to overcome therapy resistance in glioblastoma.
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| 4. |
- Benson, Mikael, 1954, et al.
(författare)
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DNA microarray analysis of chromosomal susceptibility regions to identify candidate genes for allergic disease: A pilot study
- 2004
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Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 1651-2251 .- 0001-6489. ; 124:7, s. 813-819
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Tidskriftsartikel (refereegranskat)abstract
- Objective-To examine whether DNA microarray analysis of chromosomal susceptibility regions for allergy can help to identify candidate genes. Material and Methods-Nasal biopsies were obtained from 23 patients with allergic rhinitis and 12 healthy controls. RNA was extracted from the biopsies and pooled into three patient and three control pools. These were then analysed in duplicate with DNA microarrays containing 12626 genes. Candidate genes were further examined in nasal biopsies (real-time polymerase chain reaction) and blood samples (single nucleotide polymorphisms) from other patients with allergic rhinitis and from controls. Results-A total of 37 differentially expressed genes were identified according to criteria involving both the size and consistency of the gene expression levels. The chromosomal location of these genes was compared with the chromosomal susceptibility regions for allergic disease. Using a statistical method, five genes were identified in these regions, including serine protease inhibitor, Kazal type, 5 (SPINK5) and HLA-DRB2. The relevance of these genes was examined in other patients with allergic rhinitis and in controls; none of the genes were differentially expressed in nasal biopsies. Moreover, no association between allergic rhinitis and SPINK5 polymorphisms was found, at either the genotype or haplotype level. Conclusions-DNA microarray analysis of chromosomal susceptibility regions did not lead to identification of candidate genes that could be validated in a new material. However, because gene polymorphisms may cause differential gene expression, further studies, including validation data, are needed to examine this approach.
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| 5. |
- Bergman, Annika, et al.
(författare)
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Germline mutation screening of the Saethre-Chotzen-associated genes TWIST1 and FGFR3 in families with BRCA1/2-negative breast cancer
- 2009
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Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Taylor & Francis. - 0284-4311 .- 1651-2073. ; 43:5, s. 251-255
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Tidskriftsartikel (refereegranskat)abstract
- Saethre-Chotzen syndrome is one of the most common craniosynostosis syndromes. It is an autosomal dominantly inherited disorder with variable expression that is caused by germline mutations in the TWIST1 gene or more rarely in the FGFR2 or FGFR3 genes. We have previously reported that patients with Saethre-Chotzen syndrome have an increased risk of developing breast cancer. Here we have analysed a cohort of 26 women with BRCA1/2-negative hereditary breast cancer to study whether a proportion of these families might have mutations in Saethre-Chotzen-associated genes. DNA sequence analysis of TWIST1 showed no pathogenic mutations in the coding sequence in any of the 26 patients. MLPA (multiplex ligation-dependent probe amplification)-analysis also showed no alterations in copy numbers in any of the craniofacial disorder genes MSX2, ALX4, RUNX2, EFNB1, TWIST1, FGFR1, FGFR2,FGFR3, or FGFR4. Taken together, our findings indicate that mutations in Saethre-Chotzen-associated genes are uncommon or absent in BRCA1/2-negative patients with hereditary breast cancer.
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| 6. |
- Carén, Helena, 1979, et al.
(författare)
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A cluster of genes located in 1p36 are down-regulated in neuroblastomas with poor prognosis, but not due to CpG island methylation.
- 2005
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Ingår i: Molecular cancer. - : Springer Science and Business Media LLC. - 1476-4598. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: A common feature of neuroblastoma tumours are partial deletions of the short arm of chromosome 1 (1p-deletions). This is indicative of a neuroblastoma tumour suppressor gene being located in the region. Several groups including our have been studying candidate neuroblastoma genes in the region, but no gene/genes have yet been found that fulfil the criteria for being a neuroblastoma tumour suppressor. Since frequent mutations have not been detected, we have now analyzed the expression and promoter CpG island methylation status of the genes UBE4B, KIF1B, PGD, APITD1, DFFA and PEX14 in the 1p36.22 region in order to find an explanation for a possible down-regulation of this region. RESULTS: The current study shows that gene transcripts in high stage neuroblastoma tumours are significantly down-regulated compared to those in low stage tumours in the 1p36.22 region. CpG island methylation does not seem to be the mechanism of down-regulation for most of the genes tested, since no methylation was detected in the fragments analyzed. One exception is the CpG island of APITD1. Methylation of this gene is also seen in blood from control individuals and is therefore not believed to participate in tumour development. CONCLUSION: The genes UBE4B, KIF1B, PGD, APITD1, DFFA and PEX14 are down-regulated in high stage NB tumours, a feature that can not be explained by CpG island methylation.
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| 7. |
- Carén, Helena, 1979, et al.
(författare)
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Differentiation therapy for glioblastoma - too many obstacles?
- 2016
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Ingår i: Molecular & cellular oncology. - : Informa UK Limited. - 2372-3556. ; 3:2
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Forskningsöversikt (refereegranskat)abstract
- The therapeutic potential of differentiation therapy for glioblastoma will depend on the robustness and stability of the differentiated state. We recently reported several obstacles to bone morphogenetic protein (BMP)-induced differentiation therapy. Improved understanding of the mechanisms that tumor cells use to escape differentiation commitment is urgently needed.
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| 8. |
- Carén, Helena, 1979, et al.
(författare)
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Genetic and epigenetic changes in the common 1p36 deletion in neuroblastoma tumours.
- 2007
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827.
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Tidskriftsartikel (refereegranskat)abstract
- Chromosome 1p is frequently deleted in neuroblastoma (NB) tumours. The commonly deleted region has been narrowed down by loss of heterozygosity studies undertaken by different groups. Based on earlier mapping data, we have focused on a region on 1p36 (chr1: 7 765 595-11 019 814) and performed an analysis of 30 genes by exploring features such as epigenetic regulation, that is DNA methylation and histone deacetylation, mutations at the DNA level and mRNA expression. Treatment of NB cell lines with the histone deacetylase inhibitor trichostatin A led to increased gene transcription of four of the 30 genes, ERRFI1 (MIG-6), PIK3CD, RBP7 (CRBPIV) and CASZ1, indicating that these genes could be affected by epigenetic downregulation in NBs. Two patients with nonsynonymous mutations in the PIK3CD gene were detected. One patient harboured three variations in the same exon, and p.R188W. The other patient had the variation p.M655I. In addition, synonymous variations and one variation in an intronic sequence were also found. The mRNA expression of this gene is downregulated in unfavourable, compared to favourable, NBs. One nonsynonymous mutation was also identified in the ERRFI1 gene, p.N343S, and one synonymous. None of the variations above were found in healthy control individuals. In conclusion, of the 30 genes analysed, the PIK3CD gene stands out as one of the most interesting for further studies of NB development and progression.British Journal of Cancer advance online publication, 16 October 2007; doi:10.1038/sj.bjc.6604032 www.bjcancer.com.
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| 9. |
- Carén, Helena, 1979, et al.
(författare)
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Glioblastoma stem cells respond to differentiation cues but fail to undergo differentiation commitment and terminal cell cycle arrest
- 2015
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Ingår i: STEM CELL REPORTS. - : Elsevier BV. - 2213-6711. ; 5:5, s. 829-842
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma (GBM) is an aggressive brain tumor whose growth is driven by stem cell-like cells. BMP signaling triggers cell-cycle exit and differentiation of GBM stem cells (GSCs) and, therefore, might have therapeutic value. However, the epigenetic mechanisms that accompany differentiation remain poorly defined. It is also unclear whether cell-cycle arrest is terminal. Here we find only a subset of GSC cultures exhibit astrocyte differentiation in response to BMP. Although overtly differentiated non-cycling astrocytes are generated, they remain vulnerable to cell-cycle re-entry and fail to appropriately reconfigure DNA methylation patterns. Chromatin accessibility mapping identified loci that failed to alter in response to BMP and these were enriched in SOX transcription factor-binding motifs. SOX transcription factors, therefore, may limit differentiation commitment. A similar propensity for cell-cycle re-entry and de-differentiation was observed in GSC-derived oligodendrocyte-like cells. These findings highlight significant obstacles to BMP-induced differentiation as therapy for GBM.
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| 10. |
- Carén, Helena, 1979, et al.
(författare)
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High incidence of DNA mutations and gene amplifications of the ALK gene in advanced sporadic neuroblastoma tumours.
- 2008
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Ingår i: The Biochemical journal. - : Portland Press Ltd.. - 1470-8728 .- 0264-6021. ; 416:2, s. 153-9
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Tidskriftsartikel (refereegranskat)abstract
- ALK (anaplastic lymphoma kinase) is oncogenic in several tumours and has recently been identified as a predisposition gene for familial NB (neuroblastoma) harbouring mutations in the TKD (tyrosine kinase domain). We have analysed a large set of sporadic human NB primary tumours of all clinical stages for chromosomal re-arrangements using a CGH (comparative genomic hybridization) array (n=108) and mutations of the ALK gene (n=90), and expression of ALK and related genes (n=19). ALK amplification or in-gene re-arrangements were found in 5% of NB tumours and mutations were found in 11%, including two novel not previously published mutations in the TKD, c.3733T>A and c.3735C>A. DNA mutations in the TKD and gene amplifications were only found in advanced large primary tumours or metastatic tumours, and correlated with the expression levels of ALK and downstream genes as well as other unfavourable features, and poor outcome. The results of the present study support that the ALK protein contributes to NB oncogenesis providing a highly interesting putative therapeutic target in a subset of unfavourable NB tumours.
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