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- Biswas, Dhruva, et al.
(author)
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A clonal expression biomarker associates with lung cancer mortality
- 2019
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In: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 25:10, s. 1540-1548
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Journal article (peer-reviewed)abstract
- An aim of molecular biomarkers is to stratify patients with cancer into disease subtypes predictive of outcome, improving diagnostic precision beyond clinical descriptors such as tumor stage(1). Transcriptomic intratumor heterogeneity (RNA-ITH) has been shown to confound existing expression-based biomarkers across multiple cancer types(2-6). Here, we analyze multi-region whole-exome and RNA sequencing data for 156 tumor regions from 48 patients enrolled in the TRACERx study to explore and control for RNA-ITH in non-small cell lung cancer. We find that chromosomal instability is a major driver of RNA-ITH, and existing prognostic gene expression signatures are vulnerable to tumor sampling bias. To address this, we identify genes expressed homogeneously within individual tumors that encode expression modules of cancer cell proliferation and are often driven by DNA copy-number gains selected early in tumor evolution. Clonal transcriptomic biomarkers overcome tumor sampling bias, associate with survival independent of clinicopathological risk factors, and may provide a general strategy to refine biomarker design across cancer types.
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- Larsson, Chatarina, 1979-, et al.
(author)
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Restoration of KMT2C/MLL3 in human colorectal cancer cells reinforces genome-wide H3K4me1 profiles and influences cell growth and gene expression
- 2020
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In: Clinical Epigenetics. - : Springer Nature. - 1868-7083 .- 1868-7075. ; 12:1
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Journal article (peer-reviewed)abstract
- Background The histone 3 lysine 4 (H3K4) monomethylase KMT2C is mutated across several cancer types; however, the effects of mutations on epigenome organization, gene expression, and cell growth are not clear. A frequently recurring mutation in colorectal cancer (CRC) with microsatellite instability is a single nucleotide deletion within the exon 38 poly-A(9) repeat (c.8390delA) which results in frameshift preceding the functional carboxy-terminal SET domain. To study effects ofKMT2Cexpression in CRC cells, we restored one allele to wild typeKMT2Cin the two CRC cell lines RKO and HCT116, which both are homozygous c.8390delA mutant. Results Gene editing resulted in increasedKMT2Cexpression, increased H3K4me1 levels, altered gene expression profiles, and subtle negative effects on cell growth, where higher dependence and stronger effects ofKMT2Cexpression were observed in RKO compared to HCT116 cells. Surprisingly, we found that the two RKO and HCT116 CRC cell lines have distinct baseline H3K4me1 epigenomic profiles. In RKO cells, a flatter genome-wide H3K4me1 profile was associated with more increased H3K4me1 deposition at enhancers, reduced cell growth, and more differential gene expression relative to HCT116 cells when KMT2C was restored. Profiling of H3K4me1 did not indicate a highly specific regulation of gene expression as KMT2C-induced H3K4me1 deposition was found globally and not at a specific enhancer sub-set in the engineered cells. Although we observed variation in differentially regulated gene sets between cell lines and individual clones, differentially expressed genes in both cell lines included genes linked to known cancer signaling pathways, estrogen response, hypoxia response, and aspects of immune system regulation. Conclusions Here, KMT2C restoration reduced CRC cell growth and reinforced genome-wide H3K4me1 deposition at enhancers; however, the effects varied depending upon the H3K4me1 status of KMT2C deficient cells. Results indicate that KMT2C inactivation may promote colorectal cancer development through transcriptional dysregulation in several pathways with known cancer relevance.
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- Sutton, LA, et al.
(author)
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Comparative analysis of targeted next-generation sequencing panels for the detection of gene mutations in chronic lymphocytic leukemia: an ERIC multi-center study
- 2021
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In: Haematologica. - : Ferrata Storti Foundation (Haematologica). - 1592-8721 .- 0390-6078. ; 106:3, s. 682-691
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Journal article (peer-reviewed)abstract
- Next-generation sequencing (NGS) has transitioned from research to clinical routine, yet the comparability of different technologies for mutation profiling remains an open question. We performed a European multicenter (n=6) evaluation of three amplicon-based NGS assays targeting 11 genes recurrently mutated in chronic lymphocytic leukemia. Each assay was assessed by two centers using 48 pre-characterized chronic lymphocytic leukemia samples; libraries were sequenced on the Illumina MiSeq instrument and bioinformatics analyses were centralized. Across all centers the median percentage of target reads ≥100x ranged from 94.2-99.8%. To rule out assay-specific technical variability, we first assessed variant calling at the individual assay level i.e. pairwise analysis of variants detected amongst partner centers. After filtering for variants present in the paired normal sample and removal of PCR/sequencing artefacts, the panels achieved 96.2% (Multiplicom), 97.7% (TruSeq) and 90% (HaloPlex) concordance at a VAF >0.5%. Reproducibility was assessed by looking at the inter-laboratory variation in detecting mutations and 107/115 (93% concordance) of mutations were detected by all 6 centers, while the remaining 8/115 (7%) variants were undetected by a single center and 6/8 of these variants concerned minor subclonal mutations (VAF <5%). We sought to investigate low-frequency mutations further by using a high-sensitivity assay containing unique molecular identifiers, which confirmed the presence of several minor subclonal mutations. Thus, while amplicon-based approaches can be adopted for somatic mutation detection with VAFs >5%, after rigorous validation, the use of unique molecular identifiers may be necessary to reach a higher sensitivity and ensure consistent and accurate detection of low-frequency variants.
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- Wincent, J, et al.
(author)
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CHD7 mutation spectrum in 28 Swedish patients diagnosed with CHARGE syndrome
- 2008
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In: Clinical Genetics. - : Wiley. - 0009-9163 .- 1399-0004. ; 74:1, s. 31-38
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Journal article (peer-reviewed)abstract
- CHARGE syndrome is a disorder characterized by Coloboma, Heart defect, Atresia choanae, Retarded growth and/or development, Genital hypoplasia and Ear anomalies. Heterozygous mutations in the chromodomain helicase DNA-binding protein 7 (CHD7) gene have been identified in about 60% of individuals diagnosed with CHARGE syndrome. We performed a CHD7 mutation screening by direct exon sequencing in 28 index patients (26 sporadic cases, 1 familial case consisting of a brother and sister and 1 case consisting of monozygotic twins) diagnosed with CHARGE syndrome in order to determine the mutations in a cohort of Swedish CHARGE syndrome patients. The patients without a detectable CHD7 mutation, or with a missense mutation, were further investigated by multiplex ligation-dependent probe amplification (MLPA) in order to search for intragenic deletions or duplications. Thirteen novel mutations and five previously reported mutations were detected. The mutations were scattered throughout the gene and included nonsense, frameshift and missense mutations as well as intragenic deletions. In conclusion, CHD7 mutations were detected in a large proportion (64%) of cases diagnosed with CHARGE syndrome. Screening for intragenic deletions with MLPA is recommended in cases where mutations are not found by sequencing. In addition, a CDH7 mutation was found in an individual without temporal bone malformation.
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- Zhou, X.-L., et al.
(author)
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Germline mutations in the MYH gene in Swedish familial and sporadic colorectal cancer
- 2005
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In: Genetic Testing. - : Mary Ann Liebert Inc. - 1090-6576 .- 1557-7473. ; 9:2, s. 147-151
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Journal article (peer-reviewed)abstract
- Biallelic germline mutations in the base excision repair gene MYH have been shown to predispose to a proportion of multiple colorectal adenomas and cancer. To evaluate the contribution of MYH mutations to non-FAP, non-HNPCC familial colorectal cancer, 84 unrelated Swedish individuals affected with colorectal cancer from such families were screened for germline mutations in the coding sequence of the gene. None of the cases was found to carry any pathogenic sequence change. We then determined the prevalence of the two most common pathogenic MYH mutations found in Caucasians, Y165C and G382D, in 450 Swedish sporadic colorectal cancer cases and 480 Swedish healthy controls. The frequency of both variants in Swedish cases and controls was similar to those previously reported. In addition, we found that previously unknown sequence variations at the position of amino acid 423 (R423Q, R423P, and R423R) appear to occur more frequently in cases than in controls (p = 0.02), a finding that warrants future studies. © Mary Ann Liebert, Inc.
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