Grade II and III gliomas are generally slowly progressing brain cancers, many of which eventually transform into more aggressive tumors. Despite recent findings of frequent mutations in IDH1 and ...other genes, knowledge about their pathogenesis is still incomplete. Here, combining two large sets of high-throughput sequencing data, we delineate the entire picture of genetic alterations and affected pathways in these glioma types, with sensitive detection of driver genes. Grade II and III gliomas comprise three distinct subtypes characterized by discrete sets of mutations and distinct clinical behaviors. Mutations showed significant positive and negative correlations and a chronological hierarchy, as inferred from different allelic burdens among coexisting mutations, suggesting that there is functional interplay between the mutations that drive clonal selection. Extensive serial and multi-regional sampling analyses further supported this finding and also identified a high degree of temporal and spatial heterogeneity generated during tumor expansion and relapse, which is likely shaped by the complex but ordered processes of multiple clonal selection and evolutionary events.
Clear-cell renal cell carcinoma (ccRCC) is the most prevalent kidney cancer and its molecular pathogenesis is incompletely understood. Here we report an integrated molecular study of ccRCC in which ...≥100 ccRCC cases were fully analyzed by whole-genome and/or whole-exome and RNA sequencing as well as by array-based gene expression, copy number and/or methylation analyses. We identified a full spectrum of genetic lesions and analyzed gene expression and DNA methylation signatures and determined their impact on tumor behavior. Defective VHL-mediated proteolysis was a common feature of ccRCC, which was caused not only by VHL inactivation but also by new hotspot TCEB1 mutations, which abolished Elongin C-VHL binding, leading to HIF accumulation. Other newly identified pathways and components recurrently mutated in ccRCC included PI3K-AKT-mTOR signaling, the KEAP1-NRF2-CUL3 apparatus, DNA methylation, p53-related pathways and mRNA processing. This integrated molecular analysis unmasked new correlations between DNA methylation, gene mutation and/or gene expression and copy number profiles, enabling the stratification of clinical risks for patients with ccRCC.
Genetic alterations, including mutations and copy-number alterations, are central to the pathogenesis of myelodysplastic syndromes and related diseases (myelodysplasia), but their roles in allogeneic ...stem cell transplantation have not fully been studied in a large cohort of patients. We enrolled 797 patients who had been diagnosed with myelodysplasia at initial presentation and received transplantation via the Japan Marrow Donor Program. Targeted-capture sequencing was performed to identify mutations in 69 genes, together with copy-number alterations, whose effects on transplantation outcomes were investigated. We identified 1776 mutations and 927 abnormal copy segments among 617 patients (77.4%). In multivariate modeling using Cox proportional-hazards regression, genetic factors explained 30% of the total hazards for overall survival; clinical characteristics accounted for 70% of risk. TP53 and RAS-pathway mutations, together with complex karyotype (CK) as detected by conventional cytogenetics and/or sequencing-based analysis, negatively affected posttransplant survival independently of clinical factors. Regardless of disease subtype, TP53-mutated patients with CK were characterized by unique genetic features and associated with an extremely poor survival with frequent early relapse, whereas outcomes were substantially better in TP53-mutated patients without CK. By contrast, the effects of RAS-pathway mutations depended on disease subtype and were confined to myelodysplastic/myeloproliferative neoplasms (MDS/MPNs). Our results suggest that TP53 and RAS-pathway mutations predicted a dismal prognosis, when associated with CK and MDS/MPNs, respectively. However, for patients with mutated TP53 or CK alone, long-term survival could be obtained with transplantation. Clinical sequencing provides vital information for accurate prognostication in transplantation.
•TP53 and RAS-pathway mutations predict very poor survival, when seen with CK and MDS/MPNs, respectively.•For patients with mutated TP53 or CK alone, long-term survival could be obtained with stem cell transplantation.
Background Autoimmune diseases in children are rare and can be difficult to diagnose. Autoimmune lymphoproliferative syndrome (ALPS) is a well-characterized pediatric autoimmune disease caused by ...mutations in genes associated with the FAS-dependent apoptosis pathway. In addition, various genetic alterations are associated with the ALPS-like phenotype. Objective The aim of the present study was to elucidate the genetic cause of the ALPS-like phenotype. Methods Candidate genes associated with the ALPS-like phenotype were screened by using whole-exome sequencing. The functional effect of the identified mutations was examined by analyzing the activity of related signaling pathways. Results A de novo heterozygous frameshift mutation of TNF-α–induced protein 3 (TNFAIP3, A20), a negative regulator of the nuclear factor κB pathway, was identified in one of the patients exhibiting the ALPS-like phenotype. Increased activity of the nuclear factor κB pathway was associated with haploinsufficiency of TNFAIP3 (A20). Conclusion Haploinsufficiency of TNFAIP3 (A20) by a germline heterozygous mutation leads to the ALPS phenotype.
Most cases of adult myeloid neoplasms are routinely assumed to be sporadic. Here, we describe an adult familial acute myeloid leukemia (AML) syndrome caused by germline mutations in the DEAD/H-box ...helicase gene DDX41. DDX41 was also found to be affected by somatic mutations in sporadic cases of myeloid neoplasms as well as in a biallelic fashion in 50% of patients with germline DDX41 mutations. Moreover, corresponding deletions on 5q35.3 present in 6% of cases led to haploinsufficient DDX41 expression. DDX41 lesions caused altered pre-mRNA splicing and RNA processing. DDX41 is exemplary of other RNA helicase genes also affected by somatic mutations, suggesting that they constitute a family of tumor suppressor genes.
Cohesin is a multimeric protein complex that is involved in the cohesion of sister chromatids, post-replicative DNA repair and transcriptional regulation. Here we report recurrent mutations and ...deletions involving multiple components of the cohesin complex, including STAG2, RAD21, SMC1A and SMC3, in different myeloid neoplasms. These mutations and deletions were mostly mutually exclusive and occurred in 12.1% (19/157) of acute myeloid leukemia, 8.0% (18/224) of myelodysplastic syndromes, 10.2% (9/88) of chronic myelomonocytic leukemia, 6.3% (4/64) of chronic myelogenous leukemia and 1.3% (1/77) of classical myeloproliferative neoplasms. Cohesin-mutated leukemic cells showed reduced amounts of chromatin-bound cohesin components, suggesting a substantial loss of cohesin binding sites on chromatin. The growth of leukemic cell lines harboring a mutation in RAD21 (Kasumi-1 cells) or having severely reduced expression of RAD21 and STAG2 (MOLM-13 cells) was suppressed by forced expression of wild-type RAD21 and wild-type RAD21 and STAG2, respectively. These findings suggest a role for compromised cohesin functions in myeloid leukemogenesis.
Background & Aims Esophageal squamous cell carcinoma (ESCC) is the predominant form of esophageal cancer in Japan. Smoking and drinking alcohol are environmental risk factors for ESCC, whereas single ...nucleotide polymorphisms in ADH1B and ALDH2 , which increase harmful intermediates produced by drinking alcohol, are genetic risk factors. We conducted a large-scale genomic analysis of ESCCs from patients in Japan to determine the mutational landscape of this cancer. Methods We performed whole-exome sequence analysis of tumor and nontumor esophageal tissues collected from 144 patients with ESCC who underwent surgery at 5 hospitals in Japan. We also performed single-nucleotide polymorphism array-based copy number profile and germline genotype analyses of polymorphisms in ADH1B and ALDH2 . Polymorphisms in CYP2A6, which increase harmful effects of smoking, were analyzed. Functions of TET2 mutants were evaluated in KYSE410 and HEK293FT cells. Results A high proportion of mutations in the 144 tumor samples were C to T substitution in CpG dinucleotides (called the CpG signature) and C to G/T substitutions with a flanking 5′ thymine (called the APOBEC signature). Based on mutational signatures, patients were assigned to 3 groups, which associated with environmental (drinking and smoking) and genetic (polymorphisms in ALDH2 and CYP2A6 ) factors. Many tumors contained mutations in genes that regulate the cell cycle ( TP53, CCND1, CDKN2A , FBXW7 ); epigenetic processes ( MLL2, EP300, CREBBP , TET2 ); and the NOTCH ( NOTCH1 , NOTCH3 ), WNT ( FAT1 , YAP1 , AJUBA ) and receptor-tyrosine kinase−phosphoinositide 3-kinase signaling pathways ( PIK3CA , EGFR , ERBB2 ). Mutations in EP300 and TET2 correlated with shorter survival times, and mutations in ZNF750 associated with an increased number of mutations of the APOBEC signature. Expression of mutant forms of TET2 did not increase cellular levels of 5-hydroxymethylcytosine in HEK293FT cells, whereas knockdown of TET2 increased the invasive activity of KYSE410 ESCC cells. Computational analyses associated the mutations in NFE2L2 we identified with transcriptional activation of its target genes. Conclusions We associated environmental and genetic factors with base substitution patterns of somatic mutations and provide a registry of genes and pathways that are disrupted in ESCCs. These findings might be used to design specific treatments for patients with esophageal squamous cancers.
Spliceosome mutations are frequently found in myelodysplasia. Splicing alterations induced by these mutations, their precise targets, and the effect at the transcript level have not been fully ...elucidated. Here we report transcriptomic analyses of 265 bone marrow samples from myelodysplasia patients, followed by a validation using CRISPR/Cas9-mediated gene editing and an assessment of nonsense-mediated decay susceptibility. Small but widespread reduction of intron-retaining isoforms is the most frequent splicing alteration in SF3B1-mutated samples. SF3B1 mutation is also associated with 3' splice site alterations, leading to the most pronounced reduction of canonical transcripts. Target genes include tumor suppressors and genes of mitochondrial iron metabolism or heme biosynthesis. Alternative exon usage is predominant in SRSF2- and U2AF1-mutated samples. Usage of an EZH2 cryptic exon harboring a premature termination codon is increased in both SRSF2- and U2AF1-mutated samples. Our study reveals a landscape of splicing alterations and precise targets of various spliceosome mutations.
Recent advances in high-throughput sequencing technologies have enabled a comprehensive dissection of the cancer genome clarifying a large number of somatic mutations in a wide variety of cancer ...types. A number of methods have been proposed for mutation calling based on a large amount of sequencing data, which is accomplished in most cases by statistically evaluating the difference in the observed allele frequencies of possible single nucleotide variants between tumours and paired normal samples. However, an accurate detection of mutations remains a challenge under low sequencing depths or tumour contents. To overcome this problem, we propose a novel method, Empirical Bayesian mutation Calling (https://github.com/friend1ws/EBCall), for detecting somatic mutations. Unlike previous methods, the proposed method discriminates somatic mutations from sequencing errors based on an empirical Bayesian framework, where the model parameters are estimated using sequencing data from multiple non-paired normal samples. Using 13 whole-exome sequencing data with 87.5-206.3 mean sequencing depths, we demonstrate that our method not only outperforms several existing methods in the calling of mutations with moderate allele frequencies but also enables accurate calling of mutations with low allele frequencies (≤ 10%) harboured within a minor tumour subpopulation, thus allowing for the deciphering of fine substructures within a tumour specimen.
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