| 1. |
- Kaderi, Mohd Arifin, et al.
(författare)
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LPL is the strongest prognostic factor in a comparative analysis of RNA-based markers in early chronic lymphocytic leukemia
- 2011
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 0390-6078 .- 1592-8721. ; 96:8, s. 1153-1160
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:The expression levels of LPL, ZAP70, TCL1A, CLLU1 and MCL1 have recently been proposed as prognostic factors in chronic lymphocytic leukemia. However, few studies have systematically compared these different RNA-based markers.DESIGN AND METHODS:Using real-time quantitative PCR, we measured the mRNA expression levels of these genes in unsorted samples from 252 newly diagnosed chronic lymphocytic leukemia patients and correlated our data with established prognostic markers (for example Binet stage, CD38, IGHV gene mutational status and genomic aberrations) and clinical outcome.RESULTS:High expression levels of all RNA-based markers, except MCL1, predicted shorter overall survival and time to treatment, with LPL being the most significant. In multivariate analysis including the RNA-based markers, LPL expression was the only independent prognostic marker for overall survival and time to treatment. When studying LPL expression and the established markers, LPL expression retained its independent prognostic strength for overall survival. All of the RNA-based markers, albeit with varying ability, added prognostic information to established markers, with LPL expression giving the most significant results. Notably, high LPL expression predicted a worse outcome in good-prognosis subgroups, such as patients with mutated IGHV genes, Binet stage A, CD38 negativity or favorable cytogenetics. In particular, the combination of LPL expression and CD38 could further stratify Binet stage A patients.CONCLUSIONS:LPL expression is the strongest RNA-based prognostic marker in chronic lymphocytic leukemia that could potentially be applied to predict outcome in the clinical setting, particularly in the large group of patients with favorable prognosis.
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| 2. |
- Kanduri, Meena, 1974, et al.
(författare)
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Distinct transcriptional control in major immunogenetic subsets of chronic lymphocytic leukemia exhibiting subset-biased global DNA methylation profiles.
- 2012
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Ingår i: Epigenetics. - : Informa UK Limited. - 1559-2294 .- 1559-2308. ; 7:12, s. 1435-42
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Tidskriftsartikel (refereegranskat)abstract
- Chronic lymphocytic leukemia (CLL) can be divided into prognostic subgroups based on the IGHV gene mutational status, and is further characterized by multiple subsets of cases with quasi-identical or stereotyped B cell receptors that also share clinical and biological features. We recently reported differential DNA methylation profiles in IGHV-mutated and IGHV-unmutated CLL subgroups. For the first time, we here explore the global methylation profiles of stereotyped subsets with different prognosis, by applying high-resolution methylation arrays on CLL samples from three major stereotyped subsets: the poor-prognostic subsets #1 (n = 15) and #2 (n = 9) and the favorable-prognostic subset #4 (n = 15). Overall, the three subsets exhibited significantly different methylation profiles, which only partially overlapped with those observed in our previous study according to IGHV gene mutational status. Specifically, gene ontology analysis of the differentially methylated genes revealed a clear enrichment of genes involved in immune response, such as B cell activation (e.g., CD80, CD86 and IL10), with higher methylation levels in subset #1 than subsets #2 and #4. Accordingly, higher expression of the co-stimulatory molecules CD80 and CD86 was demonstrated in subset #4 vs. subset #1, pointing to a key role for these molecules in the crosstalk of CLL subset #4 cells with the microenvironment. In summary, investigation of three prototypic, stereotyped CLL subsets revealed distinct DNA methylation profiles for each subset, which suggests subset-biased patterns of transcriptional control and highlights a key role for epigenetics during leukemogenesis.
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| 3. |
- Deneberg, Stefan, et al.
(författare)
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microRNA-34b/c on chromosome 11q23 is aberrantly methylated in chronic lymphocytic leukemia
- 2014
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Ingår i: Epigenetics. - : Informa UK Limited. - 1559-2294 .- 1559-2308. ; 9:6, s. 910-917
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Tidskriftsartikel (refereegranskat)abstract
- A commonly deleted region in chronic lymphocytic leukemia (CLL) is the 11q22-23 region, which encompasses the ATM gene. Evidence suggests that tumor suppressor genes other than ATM are likely to be involved in CLL with del(11q). A microRNA (miR) cluster including the miR-34b and miR-34c genes is located, among other genes, within the commonly deleted region (CDR) at 11q. Interestingly, these miRs are part of the TP53 network and have been shown to be epigenetically regulated. In this study, we investigated the expression and methylation status of these miRs in a well-characterized cohort of CLL, including cases with/without 11q-deletion. We show that the miR-34b/c promoter was aberrantly hypermethylated in a large proportion of CLL cases (48%, 25/52 cases). miR-34b/c expression correlated inversely to DNA methylation (P = 0.003), and presence of high H3K37me3 further suppressed expression regardless of methylation status. Furthermore, increased miR-34b/c methylation inversely correlated with the presence of 11q-deletion, indicating that methylation and del(11q) independently silence these miRs. Finally, 5-azacytidine and trichostatin A exposure synergistically increased the expression of miR-34b/c in CLL cells, and transfection of miR-34b or miR-34c into HG3 CLL cells significantly increased apoptosis. Altogether, our novel data suggest that miR-34b/c is a candidate tumor suppressor that is epigenetically silenced in CLL.
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| 4. |
- Mansouri, Larry, et al.
(författare)
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Frequent NFKBIE deletions are associated with poor outcome in primary mediastinal B-cell lymphoma
- 2016
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 128:23, s. 2666-2670
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Tidskriftsartikel (refereegranskat)abstract
- We recently reported a truncating deletion in the NFKBIE gene, which encodes IκBϵ, a negative feedback regulator of NF-κB, in clinically aggressive chronic lymphocytic leukemia (CLL). Preliminary data indicate enrichment of NFKBIE aberrations in other lymphoid malignancies, hence we screened a large patient cohort (n=1460) diagnosed with different lymphoid neoplasms. While NFKBIE deletions were infrequent in follicular lymphoma, splenic marginal-zone lymphoma, and T-cell acute lymphoblastic leukemia (<2%), slightly higher frequencies were seen in diffuse large B-cell lymphoma, mantle cell lymphoma, and primary CNS lymphoma (3-4%). In contrast, a remarkably high frequency of NFKBIE aberrations (46/203 cases, 22.7%) was observed in primary mediastinal B-cell lymphoma (PMBL) and Hodgkin lymphoma (3/11 cases, 27.3%). NFKBIE-deleted PMBL patients were more often therapy-refractory (P=.022) and displayed inferior outcome compared to wildtype patients (5-year survival: 59% vs. 78%; P=.034); however they appeared to benefit from radiotherapy (P=.022) and rituximab-containing regimens (P=.074). NFKBIEaberrations remained an independent factor in multivariate analysis (P=.003), also when restricting to immunochemotherapy-treated patients (P=.008). Whole-exome sequencing and gene expression-profiling verified the importance of NF-κB deregulation in PMBL. In summary, we identify NFKBIE aberrations as a common genetic event across B-cell malignancies and highlight NFKBIE deletions as a novel poor-prognostic marker in PMBL.
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| 5. |
- Kopparapu, Pradeep Kumar, et al.
(författare)
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Epigenetic silencing of miR-26A1 in chronic lymphocytic leukemia and mantle cell lymphoma: Impact on EZH2 expression. : Epigenetic inactivation of miR - 26A1 in CLL and MCL
- 2016
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Ingår i: Epigenetics. - : Informa UK Limited. - 1559-2294 .- 1559-2308. ; 11:5, s. 335-343
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Tidskriftsartikel (refereegranskat)abstract
- Downregulation of miR26A1 has been reported in various B-cell malignancies; however, the mechanism behind its deregulation remains largely unknown. We investigated miR26A1 methylation and expression levels in a well-characterized series of chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). From 450K methylation arrays, we first observed miR26A1 (cg26054057) as uniformly hypermethylated in MCL (n=24) (all >75%), while CLL (n=18) showed differential methylation between prognostic subgroups. Extended analysis using pyrosequencing confirmed our findings and real-time quantitative PCR verified low miR26A1 expression in both CLL (n=70) and MCL (n=38) compared to normal B-cells. Notably, the level of miR26A1 methylation predicted outcome in CLL, with higher levels seen in poor-prognostic, IGHV-unmutated CLL. Since EZH2 was recently reported as a target for miR26A1, we analyzed the expression levels of both miR26A1 and EZH2 in primary CLL samples and observed an inverse correlation. By overexpression of miR26A1 in CLL and MCL cell lines, reduced EZH2 protein levels were observed using both Western blot and flow cytometry. In contrast, methyl-inhibitor treatment led to upregulated miR26A1 expression with a parallel decrease of EZH2 expression. Finally, increased levels of apoptosis were observed in miR26A1-overexpressing cell lines, further underscoring the functional relevance of miR26A1. In summary, we propose that epigenetic silencing of miR26A1 is required for the maintenance of increased levels of EZH2, which in turn translate into a worse outcome, as shown in CLL, highlighting miR26A1 as a tumor suppressor miRNA.
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| 6. |
- Cahill, Nicola, 1983-, et al.
(författare)
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IGHV3-21 Gene Frequency in a Swedish Cohort of Patients With Newly Diagnosed Chronic Lymphocytic Leukemia
- 2012
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Ingår i: Clinical Lymphoma, Myeloma & Leukemia. - : Elsevier BV. - 2152-2650 .- 2152-2669. ; 12:3, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- The IGHV3-21 gene has been shown to be overrepresented in Scandinavian patients with chronic lymphocytic leukemia (CLL). By investigating a population-based cohort of 337 Swedish patients with CLL, a lower (6.5%) IGHV3-21 frequency was determined relative to our previous hospital-based studies (10.1%-12.7%), yet this frequency remained higher compared to other Western CLL cohorts (2.6%-4.1%). Furthermore, we confirmed the poor outcome for patients with IGHV3-21 to be independent of mutational and stereotypy status. Background: Scandinavian patients with CLL have shown an overrepresentation of the poor-prognostic IGHV3-21 gene. Furthermore, approximately 50% of patients with IGHV3-21 carry stereotyped B-cell receptors, which implicate antigen selection in leukemogenesis. These patients have also been reported to have shorter time to progression than patients with nonstereotyped IGHV3-21. Materials and Methods: To investigate the IGHV3-21 frequency and the clinical impact of IGHV3-21 stereotypy, 337 newly diagnosed Swedish CLL patients from a population-based cohort were analyzed. Results: Interestingly, the IGHV3-21 frequency was indeed lower (6.5%) in this indolent patient cohort than in our previous hospital-based cohort studies (10.1%-12.7%). Hence, a selection bias of more-aggressive cases rendered a higher proportion of IGHV3-21 cases in our original studies. Nevertheless, the Swedish IGHV3-21 frequency still remained higher when compared with other larger European or American studies (2.6%-4.1%). Finally, we confirmed the poor outcome for IGHV3-21 patients to be independent of mutational status and found stereotypy to have no impact on survival or time to treatment. Conclusion: The Swedish geographic bias in IGHV3-21 gene frequency was validated albeit at a lower frequency than previously reported. Moreover, no prognostic value could be attributed to IGHV3-21 stereotype status.
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| 7. |
- Sava, Georgina P., et al.
(författare)
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rs2072135, a low-penetrance variant for chronic lymphocytic leukaemia?
- 2013
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Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 162:2, s. 221-228
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Tidskriftsartikel (refereegranskat)abstract
- Recent multi-stage genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) that are robustly associated with chronic lymphocytic leukaemia (CLL) risk. Given that most of these SNPs map to non-coding regions of the genome, it suggests that the functional basis of many GWAS signals will be through differential gene expression. By referencing publically accessible expression quantitative trait loci (eQTL) data on lymphoblastoid cells lines (LCLs) we have globally demonstrated an association between GWAS P-values and eQTLs, consistent with much of the variation in CLL risk being defined by variants impacting on gene expression. To explore using eQTL data to select GWAS SNPs for replication, we genotyped rs2072135 (GWAS P-value=00024, eQTL P-value=1510(-19)) in five independent case-control series totalling 1968 cases and 3538 controls. While not attaining statistical significance (combined P-value=1x10(-4)), rs2072135 defines a promising risk locus for CLL. Incorporating eQTL information offers an attractive strategy for selecting SNPs from GWAS for validation.
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| 8. |
- Cahill, Nicola, 1983-
(författare)
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Molecular Genetic and DNA Methylation Profiling of Chronic Lymphocytic Leukaemia : A Focus on Divergent Prognostic Subgroups and Subsets
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advancements in prognostication have improved the subdivision of chronic lymphocytic leukaemia (CLL) into diverse prognostic subgroups. In CLL, IGHV unmutated and IGHV3-21 genes are associated with a poor-prognosis, conversely, IGHV mutated genes with a favourable outcome. The finding of multiple CLL subsets expressing ‘stereotyped’ B-cell receptors (BCRs) has suggested a role for antigen(s) in leukemogenesis. Patients belonging to certain stereotyped subsets share clinical and biological characteristics, yet limited knowledge exists regarding the genetic and epigenetic events that may influence their clinical behaviour. This thesis aimed to, further investigate Swedish IGHV3-21-utilising patients, screen for genetic and DNA-methylation events in CLL subgroups/subsets and study DNA methylation over time and within different CLL compartments. In paper I, IGHV gene sequencing of 337 CLL patients from a Swedish population-based cohort revealed a lower (6.5%) IGHV3-21 frequency relative to previous Swedish hospital-based studies (10.1-12.7%). Interestingly, this frequency remained higher compared to other Western CLL (2.6-4.1%) hospital-based cohorts. Furthermore, we confirmed the poor-outcome for IGHV3-21 patients to be independent of mutational and stereotypy status. In paper II, genomic events in stereotyped IGHV3-21-subset #2, IGHV4-34-subset #4 and subset #16 and their non-stereotyped counterparts were investigated via SNP arrays (n=101). Subset #2 and non-subset #2 carried a higher frequency of events compared to subset #4. A high frequency of del(11q) was evident in IGHV3-21 patients particularly subset #2 cases, which may partially explain their poor-prognosis. In contrast, the lower prevalence of aberrations and absence of poor-prognostic alterations may reflect the inherent low-proliferative disease seen in subset #4 cases. In papers III and IV, differential methylation profiles in IGHV mutated and IGHV unmutated patients were identified using DNA-methylation microarrays. CLL prognostic genes (CLLU1, LPL), tumor-suppressor genes (TSGs) (ABI3, WISP3) and genes belonging to TGF-ß and NF-kB/TNFR1 pathways were differentially methylated between the subgroups. Additionally, the re-expression of methylated TSGs by use of methyl and deacetyl inhibitors was demonstrated. Interestingly, analysis of patient-paired diagnostic/follow-up samples and patient-matched lymph node (LN) and peripheral blood (PB) cases revealed global DNA methylation to be relatively stable over time and remarkably similar within the different compartments. Altogether, this thesis provides insight into the aberrant genomic and DNA methylation events in divergent CLL subgroups. Moreover this thesis helps distinguish the extent to which DNA methylation changes with respect to time and microenvironment in CLL.
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| 9. |
- Vlachonikola, Elisavet, et al.
(författare)
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T cell receptor gene repertoire profiles in subgroups of patients with chronic lymphocytic leukemia bearing distinct genomic aberrations
- 2023
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Ingår i: Frontiers in Oncology. - : Frontiers Media S.A.. - 2234-943X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: Microenvironmental interactions of the malignant clone with T cells are critical throughout the natural history of chronic lymphocytic leukemia (CLL). Indeed, clonal expansions of T cells and shared clonotypes exist between different CLL patients, strongly implying clonal selection by antigens. Moreover, immunogenic neoepitopes have been isolated from the clonotypic B cell receptor immunoglobulin sequences, offering a rationale for immunotherapeutic approaches. Here, we interrogated the T cell receptor (TR) gene repertoire of CLL patients with different genomic aberration profiles aiming to identify unique signatures that would point towards an additional source of immunogenic neoepitopes for T cells.Experimental design: TR gene repertoire profiling using next generation sequencing in groups of patients with CLL carrying one of the following copy-number aberrations (CNAs): del(11q), del(17p), del(13q), trisomy 12, or gene mutations in TP53 or NOTCH1.Results: Oligoclonal expansions were found in all patients with distinct recurrent genomic aberrations; these were more pronounced in cases bearing CNAs, particularly trisomy 12, rather than gene mutations. Shared clonotypes were found both within and across groups, which appeared to be CLL-biased based on extensive comparisons against TR databases from various entities. Moreover, in silico analysis identified TR clonotypes with high binding affinity to neoepitopes predicted to arise from TP53 and NOTCH1 mutations.Conclusions: Distinct TR repertoire profiles were identified in groups of patients with CLL bearing different genomic aberrations, alluding to distinct selection processes. Abnormal protein expression and gene dosage effects associated with recurrent genomic aberrations likely represent a relevant source of CLL-specific selecting antigens.
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| 10. |
- Baliakas, Panagiotis, 1977-, et al.
(författare)
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Tailored approaches grounded on immunogenetic features for refined prognostication in chronic lymphocytic leukemia
- 2019
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Ingår i: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 104:2, s. 360-369
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Tidskriftsartikel (refereegranskat)abstract
- Chronic lymphocytic leukemia (CLL) patients with differential somatic hypermutation status of the immunoglobulin heavy variable genes, namely mutated or unmutated, display fundamental clinico-biological differences. Considering this, we assessed prognosis separately within mutated (M-CLL) and unmutated (U-CLL) CLL in 3015 patients, hypothesizing that the relative significance of relevant indicators may differ between these two categories. Within Binet A M-CLL patients, besides TP53 abnormalities, trisomy 12 and stereotyped subset #2 membership were equivalently associated with the shortest time-to-first-treatment and a treatment probability at five and ten years after diagnosis of 40% and 55%, respectively; the remaining cases exhibited 5-year and 10-year treatment probability of 12% and 25%, respectively. Within Binet A U-CLL patients, besides TP53 abnormalities, del(11q) and/or SF3B1 mutations were associated with the shortest time-to-first-treatment (5- and 10-year treatment probability: 78% and 98%, respectively); in the remaining cases, males had a significantly worse prognosis than females. In conclusion, the relative weight of indicators that can accurately risk stratify early-stage CLL patients differs depending on the somatic hypermutation status of the immunoglobulin heavy variable genes of each patient. This finding highlights the fact that compartmentalized approaches based on immunogenetic features are necessary to refine and tailor prognostication in CLL.
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