| 1. |
- Bin Kaderi, Mohamed Arifin, 1978-
(författare)
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Assessment of Novel Molecular Prognostic Markers in Chronic Lymphocytic Leukemia
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The clinical course of chronic lymphocytic leukemia (CLL) is highly heterogeneous, which has prompted the search for biomarkers that can predict prognosis in this disease. The IGHV gene mutation status and certain genomic aberrations have been identified as reliable prognostic markers of clinical outcome for this disorder. However, the search for more feasible prognostic markers in CLL is still being pursued. Recently, certain single nucleotide polymorphisms (SNPs) in the GNAS1, BCL2 and MDM2 genes and the RNA expression levels of the LPL, ZAP70, TCL1, CLLU1 and MCL1 genes were suggested as novel prognostic markers in CLL. In papers I-III, we performed genotyping analyses of the GNAS1 T393C, BCL2 -938C>A and MDM2 SNP309 polymorphisms in 268-418 CLL patients and related the genotypes with clinical data. Association studies between the polymorphisms and established prognostic markers (i.e. IGHV mutation status, genomic aberrations, CD38 expression) were also performed. Our studies did not find any significant relationship between these SNPs with either clinical outcome or other known prognostic markers in CLL. In paper IV, we measured the RNA expression levels of LPL, ZAP70, TCL1, CLLU1 and MCL1 in 252 CLL cases and correlated these levels with clinical outcome. Here, we verified that high expression of all these RNA-based markers, except MCL1, were associated with an unfavourable prognosis. We also confirmed a close relationship between IGHV mutation status and the RNA-based markers, especially for LPL and CLLU1 expression. Among the RNA-based markers, multivariate analysis revealed LPL expression as the strongest independent prognostic marker for overall survival and time to treatment. Furthermore, the RNA-based markers could add further prognostic information to established markers in subgroups of patients, with LPL expression status giving the most significant results. In summary, data from papers I-III could not verify the GNAS1 T393C, BCL2 -938C>A and MDM2 SNP309 polymorphisms as prognostic markers in CLL. Future SNP markers must hence be confirmed in large, independent cohorts before being proposed as prognostic marker in CLL. In paper IV, we conclude that LPL expression appears to be the strongest among the RNA-based markers for CLL prognostication. Further efforts to standardize LPL quantification are required before it can be applied in the clinical laboratory to predict clinical outcome in this disease.
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| 2. |
- Norberg, Maria, 1976-
(författare)
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In Vitro Drug Sensitivity and Apoptosis in Chronic Lymphocytic Leukemia
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chronic lymphocytic leukemia (CLL) is a heterogeneous malignancy displaying varying clinical outcome, where molecular markers today can divide patients into prognostic subgroups. Despite the introduction of new agents for treatment, remissions are usually not sustained in CLL and resistance towards treatment can partly be explained by aberrant apoptosis. The aim of this thesis was to find new drugs for CLL patients resistant to conventional therapy and to analyze genes involved in apoptosis within different prognostic subgroups. In paper I-II, the in vitro activity of substances was investigated using the fluorometric microculture cytotoxicity assay (FMCA). When evaluating rapamycin (paper I), an inhibitor of mTOR, in 97 tumor samples from different entities, CLL was found to be one of the most sensitive tumor types. Combination experiments on patient CLL cells indicated that rapamycin acted synergistically with the CLL drugs vincristine and chlorambucil. An investigation of 20 anti-cancer agents in cells from 40 CLL patients (paper II) revealed that prednisolone and rolipram displayed high activity in poor-prognostic patients, in particular IGHV unmutated CLL. Furthermore, when used in combination these agents were found to produce a synergistic effect. In paper III, the anti-apoptotic BCL2 family member BFL1 was evaluated in 37 CLL cases. Levels of BFL1 were higher in fludarabine-resistant patients compared to fludarabine-sensitive patients. In addition, the high expression of BFL1 inversely correlated to fludarabine-induced apoptosis in CLL cells. A single nucleotide polymorphism in the anti-apoptotic BCL2 gene (-938C>A) has been suggested as a novel poor-prognostic marker in CLL. In paper IV, we investigated this BCL2 polymorphism in 268 CLL patients and correlated genotypes to clinical data. However, no association could be confirmed between this polymorphism and clinical outcome or established prognostic markers. In conclusion, this thesis has shown that rapamycin is a potential drug for treatment in CLL. Furthermore, prednisolone and rolipram were identified as interesting candidates for treatment of poor-prognostic patients. Finally, the anti-apoptotic protein BFL1 may contribute to chemoresistance and hence represents a potential therapeutic target in CLL, whereas from our data, the BCL2 -938C>A polymorphism does not appear to have any prognostic significance.
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| 3. |
- Nord, Helena, 1980-
(författare)
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Application of Genomic and Expression Arrays for Identification of new Cancer Genes
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Copy number variation (CNV) comprises a recently discovered kind of variation involving deletion and duplication of DNA segments of variable size, ranging from a few hundred basepairs to several million. By altering gene dosage levels or disrupting proximal or distant regulatory elements CNVs create human diversity. They represent also an important factor in human evolution and play a role in many disorders including cancer. Array-based comparative genomic hybridization as well as expression arrays are powerful and suitable methods for determination of copy number variations or gene expression changes in the human genome. In paper I we established a 32K clone-based genomic array, covering 99% of the current assembly of the human genome with high resolution and applied it in the profiling of 71 healthy individuals from three ethnic groups. Novel and previously reported CNVs, involving ~3.5% of the genome, were identified. Interestingly, 87% of the detected CNV regions overlapped with known genes indicating that they probably have phenotypic consequences. In papers II through IV we applied this platform to different tumor types, namely two collections of brain tumors, glioblastoma (paper II) and medulloblastoma (paper III), and a set of bladder carcinoma (paper IV) to identify chromosomal alterations at the level of DNA copy number that could be related to tumor initiation/progression. Tumors of the central nervous system represent a heterogeneous group of both benign and malignant neoplasms that affect both children and adults. Glioblastoma and medulloblastoma are two malignant forms. Glioblastoma often affects adults while the embryonal tumor medulloblastoma is the most common malignant brain tumor among children. The detailed profiling of 78 glioblastomas, allowed us to identify a complex pattern of aberrations including frequent and high copy number amplicons (detected in 79% of samples) as well as a number of homozygously deleted loci. These regions encompassed not only previously reported oncogenes and tumor suppressor genes but also numerous novel genes. In paper III, a subset of 26 medulloblastomas was analyzed using the same genomic array. We observed that alterations involving chromosome 17, especially isochromosome 17q, were the most common genomic aberrations in this tumor type, but copy number alterations involving other chromosomes: 1, 7 and 8 were also frequent. Focal amplifications, on chromosome 1 and 3, not previously described, were also detected. These loci may encompass novel genes involved in medulloblastoma development. In paper IV we examined for the presence of DNA copy number alterations and their effect on gene expression in a subset of 21 well-characterized Ta bladder carcinomas, selected for the presence or absence of recurrences. We identified a number of novel genes as well as a significant association between amplifications and high-grade and recurrent tumors which might be clinically useful. The results derived from these studies increase our understanding of the genetic alterations leading to the development of these tumor forms and point out candidate genes that may be used in future as targets for new diagnostic and therapeutic strategies.
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| 4. |
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| 5. |
- Olsson, Malin, 1972-
(författare)
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Familial amyloidosis with polyneuropathy : studies of genetic factors modifying the phenotype of the disease
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. Familial Amyloidosis with Polyneuropathy (FAP) is an autosomal dominantly inherited systemic amyloid disease. The disease is caused by mutations in the transthyretin (TTR) gene, where close to 100 different amyloidogenic mutations have been identified. FAP is found worldwide, but endemic areas with a high frequency of patients are found in Portugal, Japan and northern Sweden. Cases from these endemic areas all share the same TTR c.148G>A, p.V50M ("V30M") mutation, but the phenotype of the disease varies between the areas, and also within the endemic areas. The mean onset of the disease is two decades earlier in Portugal and Japan compared to Sweden, but late as well as early age at onset cases occur within all the populations. Interestingly, the different populations all display a maternal anticipation, where an earlier onset is observed for those individuals who inherit the trait from their mother. Since substantial variation in the phenotype is observed for different populations, epigenetic/genetic and/or environmental factors must exert a significant impact on the penetrance of the disease. Amyloid formation is caused by conformational changes of proteins, which facilitates their assembly into fibrils, amyloid. Oxidative stress can mediate conformational changes of proteins and since the mitochondria regulate oxidative processes within the cell, mitochondrial function may affect amyloid formation. The mitochondrial DNA is a non-nuclear DNA, which is entirely maternally inherited, and therefore could be related to the observed maternal anticipation of the disease. In addition, differences within the surrounding regions of the TTR gene may have an impact on the transcription of the gene and thereby on the expression of the different alleles. Material and methods. DNA from early and late onset V30M cases and from non-carriers (the latter utilised as controls) from Swedish, French, Japanese and Portuguese populations were analysed. In addition, DNA from healthy Swedish V30M carriers was analysed. Conventional analytical methods were employed, such as PCR, sequencing and genotyping. Conventional statistical methods used were t-test, Chi-squared test and maximum likelihood. Results. The study of V30M carrier frequency in two counties (Lycksele and Skellefteå) within the Swedish endemic area revealed a carrier frequency of 2.14% and 2.54%, respectively. The mitochondrial haplogroup analysis showed that in populations with generally late onset (French and Swedish), the haplogroup distribution of late onset cases resembled that of the controls derived from the same area, whereas haplogroup distribution for early onset patients was significantly different. The most pronounced difference was for the rare haplogroup K, of which early onset cases had a higher frequency than the controls. Analysis of the Portuguese population, with predominantly early onset, showed that haplogroup distribution for early onset cases were similar to the Portuguese control group, which had a different distribution than the Swedish control group. By analysis of pedigrees from Swedish and Portuguese patients it could be shown that mitochondrial genetic variation entirely could explain maternal anticipation in the Portuguese patients, whereas for Swedish patients, an additional parent of origin effect is present. Our analysis of the TTR gene disclosed a polymorphism (rs62093482) in the 3'UTR region of the Swedish patients. This polymorphism was found in all V30M carriers, irrespective of symptoms. In addition, homozygous TTR V30M carriers were homozygous also for the polymorphism. Since Swedish patients share a common founder this polymorphism thus is localised on the V30M allele. This polymorphism was found in only 4% of the Swedish controls. French controls showed the same frequency, but none of the French V30M patients displayed the polymorphism. In the Japanese population the polymorphism was not present at all. Interestingly, this polymorphism generates a potential binding site for microRNA and thereby possibly could down-regulate the expression of the mutated TTR allele. Conclusions. The carrier frequency in the endemic area is remarkably high, above 2% in the Lycksele and Skellefteå areas. The prevailing haplogroup distributions in the different endemic areas are consistent between the general population and the patient group with the predominant phenotype of that area. Mitochondrial genetic differences may explain maternal anticipation in Portuguese patients, and have an influence in Swedish patients. A polymorphism in the 3'UTR regulatory region of the mutated TTR allele is found in all Swedish patients. This polymorphism may down-regulate TTR V30M expression and thereby contribute to the late onset of the disease noted in the Swedish population.
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| 6. |
- Halldórsdóttir, Anna Margrét, 1973-
(författare)
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Genetic and Epigenetic Profiling of Mantle Cell Lymphoma and Chronic Lymphocytic Leukemia
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) both belong to the group of mature B-cell malignancies. However, MCL is typically clinically aggressive while the clinical course of CLL varies. CLL can be divided into prognostic subgroups based on IGHV mutational status and into multiple subsets based on closely homologous (stereotyped) B-cell receptors. In paper I we investigated 31 MCL cases using high-density 250K single-nucleotide polymorphism arrays and gene expression arrays. Although most copy-number aberrations (CNAs) were previously reported in MCL, a novel deletion was identified at 20q (16%) containing the candidate tumor suppressor gene ZFP64. A high proliferation gene expression signature was associated with poor prognosis, large CNAs, 7p gains and 9q losses. Losses at 1p/8p/13q/17p were associated with increased genomic complexity. In paper II we sequenced exons 4 to 8 of the TP53 gene in 119 MCL cases. 17p copy-number status was known from previous studies or determined by real-time quantitative polymerase chain reaction. TP53 mutations were detected in 14% of cases and were strongly associated with poor survival while 17p deletions were more common (32%) but did not predict survival. In papers III and IV we applied high-resolution genomic 27K methylation arrays to 20 MCL and 39 CLL samples. In paper III MCL displayed a homogenous methylation profile without correlation with the proliferation signature whereas MCL was clearly separated from CLL. Gene ontology analysis revealed enrichment of developmental genes, in particular homeobox transcription factor genes, among targets methylated in MCL. In paper IV we compared three different stereotyped CLL subsets: #1 (IGHV unmutated), #2 (IGHV3-21) and #4 (IGHV mutated). Many genes were differentially methylated between each two subsets and immune response genes (e.g. CD80 and CD86) were enriched among genes methylated in subset #1 but not in subsets #2/#4.In summary, CNAs were frequent and not random in MCL. Specific CNAs correlated with a high proliferation gene expression signature or genomic complexity. TP53 mutations predicted short survival whereas 17p deletions did not. A high proliferation signature was not associated with differential DNA methylation in MCL, which demonstrated a homogeneous methylation pattern. In contrast, genomic methylation patterns differed between MCL and CLL and between stereotyped CLL subsets.
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| 7. |
- Zainuddin, Norafiza, 1978-
(författare)
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Molecular Genetic Analysis in B-cell Lymphomas : A Focus on the p53 Pathway and p16INK4a
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The presence of TP53 mutations has been associated with inferior outcome in diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL). In DLBCL, the impact of the TP53 codon 72 polymorphism and MDM2 SNP309 has not been clearly elucidated, whereas MDM2 SNP309 was suggested as a poor-prognostic marker in CLL. In addition, p16INK4a promoter hypermethylation has been implicated as a negative prognostic factor in DLBCL. The aim of this thesis was to further evaluate these molecular markers in well-characterised materials of DLBCL and CLL. In paper I, we investigated the prognostic role of TP53 mutation, codon 72 polymorphism and MDM2 SNP309 in DLBCL (n=102). The presence of TP53 mutations (12.7%) correlated with a poor lymphoma-specific and progression-free survival, and a particularly pronounced effect was observed in the germinal center subtype. Neither the MDM2 SNP309 nor the TP53 codon 72 polymorphism had an impact on age of onset or survival. In paper II, we applied pyrosequencing to measure the level of p16INK4a methylation in DLBCL (n=113). Thirty-seven percent of cases displayed p16INK4a methylation; however, no clear association could be observed between degree of methylation and clinical characteristics or lymphoma-specific survival. In papers III–IV, we investigated the prognostic role of MDM2 SNP309 (n=418) and TP53 mutation (n=268) in CLL. No correlation was observed between any particular MDM2 SNP309 genotype and time to treatment and overall survival. Furthermore, no association was found between the different MDM2 SNP309 genotypes and established CLL prognostic markers. TP53 mutations were detected in 3.7% of CLL patients; where the majority showed a concomitant 17p-deletion and only three carried TP53 mutations without 17p-deletion. We confirmed a significantly shorter overall survival and time to treatment in patients with both TP53 mutation and 17p-deletion. Altogether, our studies could confirm the negative prognostic impact of TP53 mutations in DLBCL, whereas MDM2 SNP309 and TP53 codon 72 polymorphisms appear to lack clinical relevance. We also question the role of p16INKa methylation as a poor-prognostic factor in DLBCL. Finally, the presence of TP53 mutation in CLL appears to be rare at disease onset and instead arise during disease progression.
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| 8. |
- Voisin, Sarah, 1989-
(författare)
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Bioinformatic and Biostatistic Analysis of Epigenetic Data from Humans and Mice in the Context of Obesity and its Complications
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Worldwide obesity has more than doubled since 1980 and at least 2.8 million people die each year as a result of being overweight or obese. An elevated body weight is the result of the interplay between susceptibility gene variants and an obesogenic environment, and recent evidence shows that epigenetic processes are likely involved. The growing availability of high-throughput technologies has made it possible to assess quickly the entire epigenome of large samples at a relatively low cost. As a result, vast amounts of data have been generated and researchers are now confronted to both bioinformatic and biostatistic challenges to make sense of such data in the context of obesity and its complications. In this doctoral thesis, we explored associations between the human blood methylome and obesity-associated gene variants as well as dietary fat quality and quantity. We used well described preprocessing techniques and statistical methods, along with publicly available data from consortiums and other research groups, as well as tools for pathway enrichment and chromatin state inference. We found associations between obesityassociated SNPs and methylation levels at proximal promoters and enhancers, and some of these associations were replicated in multiple tissues. We also found that contrary to dietary fat quantity, dietary fat quality associates with methylation levels in the promoter of genes involved in metabolic pathways. Then, using a gene-targeted approach, we looked at the impact of an acute environmental stress (sleep loss) on the methylation and transcription levels of circadian clock genes in skeletal muscle and adipose tissue of healthy men. We found that a single night of wakefulness can alter the epigenetic and transcriptional profile of core circadian clock genes in a tissue-specific manner. Finally, we looked at the effects of chronic maternal obesity and subsequent weight loss on the transcription of epigenetic machinery genes in the fetus and placenta of mice. We found that the transcription of epigenetic machinery genes is highly sensitive to maternal weight trajectories, and particularly those of the histone acetylation pathway. Overall, this thesis demonstrated that genetics, obesogenic environment stimuli and maternal programming impact epigenetic marks at genomic locations relevant in the pathogenesis of obesity.
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| 9. |
- Dahlberg, Johan, 1988-
(författare)
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Genetic Cartography at Massively Parallel Scale
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Massively parallel sequencing (MPS) is revolutionizing genomics. In this work we use, refine, and develop new tools for the discipline.MPS has led to the discovery of multiple novel subtypes in Acute Lymphoblastic Leukemia (ALL). In Study I we screen for fusion genes in 134 pediatric ALL patients, including patients without an assigned subtype. In approximately 80% of these patients we detect novel or known fusion gene families, most of which display distinct methylation and expression patterns. This shows the potential for improvements in the clinical stratification of ALL. Large sample sizes are important to detect recurrent somatic variation. In Study II we investigate if a non-index overlapping pooling schema can be used to increase sample size and detect somatic variation. We designed a schema for 172 ALL samples and show that it is possible to use this method to call somatic variants.Around the globe there are many ongoing and completed genome projects. In Study III we sequenced the genome of 1000 Swedes to create a reference data set for the Swedish population. We identified more than 10 million variants that were not present in publicly available databases, highlighting the need for population-specific resources. Data, and the tools developed during this study, have been made publicly available as a resource for genomics in Sweden and abroad.The increased amount of sequencing data has created a greater need for automation. In Study IV we present Arteria, a computational automation system for sequencing core facilities. This system has been adopted by multiple facilities and has been used to analyze thousands of samples. In Study V we developed CheckQC, a program that provides automated quality control of Illumina sequencing runs. These tools make scaling up MPS less labour intensive, a key to unlocking the full future potential of genomics.The tools, and data presented here are a valuable contribution to the scientific community. Collectively they showcase the power of MPS and genomics to bring about new knowledge of human health and disease.
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| 10. |
- Jiao, Xiang
(författare)
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Somatic Mutations in Breast Cancer Genomes : Discovery and Validation of Breast Cancer Genes
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Breast cancer is the most common cancer in women worldwide. However, the genetic alterations that lead to breast cancer are not fully understood. This thesis aims to identify novel genes of potential mechanistic, diagnostic or therapeutic interest in breast cancers by mutational analysis and whole-genome sequencing.In paper I, sequencing of 36 previously identified candidate genes in 96 breast tumors with patient-matched normal DNA determined the somatic mutation prevalence of these candidate genes and identified additional mutations in Notch, NF-κB, PI3K, and Hedgehog pathways as well as in processes mediating DNA methylation, RNA processing and calcium signaling.In paper II, comparison of massively parallel mate-pair sequencing results of a human genome before and after phi29-mediated multiple displacement amplification (MDA) revealed that MDA introduces structural alteration artifacts, with an emphasis on false positive inversions, and impairs the sensitivity to detect true inversions. Therefore, MDA has limited value in sample preparation for whole-genome sequencing for structural alteration detection.In paper III, massively parallel paired-end sequencing identified gene rearrangements in 15 hormone receptor negative breast cancers. Forty validated rearrangements were predicted to directly affect 30 genes, involved in epigenetic regulation, cell mitosis, signalling transduction and glycolytic flux. RNA interference-based assays revealed the potential roles in cell growth of some affected genes, among which DDX10 was implicated to be involved in apoptosis.In paper IV, a method for statistical evaluation of putative translocations detected by massively parallel paired-end sequencing was proposed. In an application of this method to analyse translocations detected by cancer genome deep paired-end sequencing, 76 putative translocations were classified into four categories, with the majority likely to be caused by mismapping due to repetitive regions.Taken together, this thesis provides insights into genes and pathways mutated in sporadic breast cancer genomes, which broaden our understanding of the genetic basis of breast cancer and may ultimately facilitate the diagnosis and treatment of this disease.
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