Whole-genome analysis approaches are identifying recurrent cancer-associated somatic alterations in noncoding DNA regions. We combined somatic copy number analysis of 12 tumor types with ...tissue-specific epigenetic profiling to identify significant regions of focal amplification harboring super-enhancers. Copy number gains of noncoding regions harboring super-enhancers near KLF5, USP12, PARD6B and MYC are associated with overexpression of these cancer-related genes. We show that two distinct focal amplifications of super-enhancers 3' to MYC in lung adenocarcinoma (MYC-LASE) and endometrial carcinoma (MYC-ECSE) are physically associated with the MYC promoter and correlate with MYC overexpression. CRISPR/Cas9-mediated repression or deletion of a constituent enhancer within the MYC-LASE region led to significant reductions in the expression of MYC and its target genes and to the impairment of anchorage-independent and clonogenic growth, consistent with an oncogenic function. Our results suggest that genomic amplification of super-enhancers represents a common mechanism to activate cancer driver genes in multiple cancer types.
Determining how somatic copy number alterations (SCNAs) promote cancer is an important goal. We characterized SCNA patterns in 4,934 cancers from The Cancer Genome Atlas Pan-Cancer data set. ...Whole-genome doubling, observed in 37% of cancers, was associated with higher rates of every other type of SCNA, TP53 mutations, CCNE1 amplifications and alterations of the PPP2R complex. SCNAs that were internal to chromosomes tended to be shorter than telomere-bounded SCNAs, suggesting different mechanisms underlying their generation. Significantly recurrent focal SCNAs were observed in 140 regions, including 102 without known oncogene or tumor suppressor gene targets and 50 with significantly mutated genes. Amplified regions without known oncogenes were enriched for genes involved in epigenetic regulation. When levels of genomic disruption were accounted for, 7% of region pairs were anticorrelated, and these regions tended to encompass genes whose proteins physically interact, suggesting related functions. These results provide insights into mechanisms of generation and functional consequences of cancer-related SCNAs.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
We describe a comprehensive genomic characterization of adrenocortical carcinoma (ACC). Using this dataset, we expand the catalogue of known ACC driver genes to include PRKAR1A, RPL22, TERF2, CCNE1, ...and NF1. Genome wide DNA copy-number analysis revealed frequent occurrence of massive DNA loss followed by whole-genome doubling (WGD), which was associated with aggressive clinical course, suggesting WGD is a hallmark of disease progression. Corroborating this hypothesis were increased TERT expression, decreased telomere length, and activation of cell-cycle programs. Integrated subtype analysis identified three ACC subtypes with distinct clinical outcome and molecular alterations which could be captured by a 68-CpG probe DNA-methylation signature, proposing a strategy for clinical stratification of patients based on molecular markers.
Display omitted
•Standardized molecular data from 91 cases of adrenocortical carcinoma•Driver genes including TP53, ZNFR3, CTNNB1, PRKAR1A, CCNE1, and TERF2•Whole-genome doubling event is a marker for ACC progression•Three prognostic molecular subtypes captured by a DNA-methylation signature
Zheng et al. perform comprehensive genomic characterization of 91 cases of adrenocortical carcinoma (ACC). This analysis expands the list of driver genes in ACC, reveals whole-genome doubling as a hallmark of ACC progression, and identifies three ACC subtypes with distinct clinical outcome.
DNA damage response and repair (DDR) gene alterations are associated with increased tumor-infiltrating lymphocytes, higher genomic instability, and higher tumor mutational burden (TMB) in cancer. ...Whether DDR alterations are associated with clinical outcomes to programmed death ligand 1 PD-(L)1 blockade in non-small cell lung cancer (NSCLC) is unknown.
Tumors from patients treated with PD-(L)1 inhibitors were analyzed using targeted next-generation sequencing (NGS). Cancers were categorized on the basis of the presence or absence of deleterious mutations across a panel of 53 DDR genes. Clinical outcomes to PD-(L)1 inhibitors were evaluated according to DDR mutation status.
Of 266 patients with successful NGS who received PD-(L)1 inhibitors, 132 (49.6%) were identified as having deleterious DDR mutations (DDR-positive). DDR-positive and DDR-negative groups were similar in terms of baseline clinicopathologic characteristics. The median TMB was significantly higher in the DDR-positive group compared with the DDR-negative group (12.1 vs. 7.6 mutations/megabase;
< 0.001). Compared with DDR-negative patients (
= 134), DDR-positive patients had a significantly higher objective response rate (30.3% vs. 17.2%;
= 0.01), longer median progression-free survival PFS; 5.4 vs. 2.2 months; HR, 0.58 (95% confidence interval (CI), 0.45-0.76);
< 0.001, and longer median overall survival OS; 18.8 vs. 9.9 months; HR, 0.57 (95% CI, 0.42-0.77);
< 0.001 with PD-(L)1 therapy. After adjusting for PD-L1, TMB, performance status, tobacco use, and line of therapy, DDR-positive status was associated with a significantly longer PFS HR, 0.68 (95% CI, 0.51-0.92);
= 0.01 and OS HR, 0.60 (95% CI, 0.43-0.85);
= 0.004 in multivariate analysis.
Deleterious DDR mutations are frequent in NSCLC and are associated with improved clinical outcomes in patients with NSCLC treated with PD-(L)1 blockade.
We describe the landscape of somatic genomic alterations of 66 chromophobe renal cell carcinomas (ChRCCs) on the basis of multidimensional and comprehensive characterization, including mtDNA and ...whole-genome sequencing. The result is consistent that ChRCC originates from the distal nephron compared with other kidney cancers with more proximal origins. Combined mtDNA and gene expression analysis implicates changes in mitochondrial function as a component of the disease biology, while suggesting alternative roles for mtDNA mutations in cancers relying on oxidative phosphorylation. Genomic rearrangements lead to recurrent structural breakpoints within TERT promoter region, which correlates with highly elevated TERT expression and manifestation of kataegis, representing a mechanism of TERT upregulation in cancer distinct from previously observed amplifications and point mutations.
•Comprehensive molecular analysis is performed on 66 kidney chromophobe cases•Global molecular patterns provide clues as to this cancer’s cell of origin•mtDNA sequencing reveals loss-of-function mutations in NADH dehydrogenase subunits•Genomic structural rearrangements involving TERT promoter region are assessed
Davis et al. describe the landscape of somatic genomic alterations of chromophobe renal cell carcinomas, showing that changes in mitochondrial function are an inherent component of the disease biology and identifying genomic rearrangement as a mechanism for elevated TERT expression.
Systematic exploration of cancer cell vulnerabilities can inform the development of novel cancer therapeutics. Here, through analysis of genome-scale loss-of-function datasets, we identify adenosine ...deaminase acting on RNA (ADAR or ADAR1) as an essential gene for the survival of a subset of cancer cell lines. ADAR1-dependent cell lines display increased expression of interferon-stimulated genes. Activation of type I interferon signaling in the context of ADAR1 deficiency can induce cell lethality in non-ADAR1-dependent cell lines. ADAR deletion causes activation of the double-stranded RNA sensor, protein kinase R (PKR). Disruption of PKR signaling, through inactivation of PKR or overexpression of either a wildtype or catalytically inactive mutant version of the p150 isoform of ADAR1, partially rescues cell lethality after ADAR1 loss, suggesting that both catalytic and non-enzymatic functions of ADAR1 may contribute to preventing PKR-mediated cell lethality. Together, these data nominate ADAR1 as a potential therapeutic target in a subset of cancers.
Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem growth of benign tumours and other hamartomatous lesions, which leads to diverse and debilitating clinical symptoms. ...Patients are born with TSC1 or TSC2 mutations, and somatic inactivation of wild-type alleles drives MTOR activation; however, second hits to TSC1/TSC2 are not always observed. Here, we present the genomic landscape of TSC hamartomas. We determine that TSC lesions contain a low somatic mutational burden relative to carcinomas, a subset feature large-scale chromosomal aberrations, and highly conserved molecular signatures for each type exist. Analysis of the molecular signatures coupled with computational approaches reveals unique aspects of cellular heterogeneity and cell origin. Using immune data sets, we identify significant neuroinflammation in TSC-associated brain tumours. Taken together, this molecular catalogue of TSC serves as a resource into the origin of these hamartomas and provides a framework that unifies genomic and transcriptomic dimensions for complex tumours.
Alterations in non-driver genes represent an emerging class of potential therapeutic targets in cancer. Hundreds to thousands of non-driver genes undergo loss of heterozygosity (LOH) events per ...tumor, generating discrete differences between tumor and normal cells. Here we interrogate LOH of polymorphisms in essential genes as a novel class of therapeutic targets. We hypothesized that monoallelic inactivation of the allele retained in tumors can selectively kill cancer cells but not somatic cells, which retain both alleles. We identified 5664 variants in 1278 essential genes that undergo LOH in cancer and evaluated the potential for each to be targeted using allele-specific gene-editing, RNAi, or small-molecule approaches. We further show that allele-specific inactivation of either of two essential genes (PRIM1 and EXOSC8) reduces growth of cells harboring that allele, while cells harboring the non-targeted allele remain intact. We conclude that LOH of essential genes represents a rich class of non-driver cancer vulnerabilities.
Aneuploidies-whole-chromosome or whole-arm imbalances-are the most prevalent alteration in cancer genomes
. However, it is still debated whether their prevalence is due to selection or ease of ...generation as passenger events
. Here we developed a method, BISCUT, that identifies loci subject to fitness advantages or disadvantages by interrogating length distributions of telomere- or centromere-bounded copy-number events. These loci were significantly enriched for known cancer driver genes, including genes not detected through analysis of focal copy-number events, and were often lineage specific. BISCUT identified the helicase-encoding gene WRN as a haploinsufficient tumour-suppressor gene on chromosome 8p, which is supported by several lines of evidence. We also formally quantified the role of selection and mechanical biases in driving aneuploidy, finding that rates of arm-level copy-number alterations are most highly correlated with their effects on cellular fitness
. These results provide insight into the driving forces behind aneuploidy and its contribution to tumorigenesis.
Women having BRCA1 germ-line mutations develop cancer in breast and ovary, estrogen-regulated tissues, with high penetrance. Binding of estrogens to the estrogen receptor (ER) transiently induces DNA ...double-strand breaks (DSBs) by topoisomerase II (TOP2) and controls gene transcription. TOP2 resolves catenated DNA by transiently generating DSBs, TOP2-cleavage complexes (TOP2ccs), where TOP2 covalently binds to 5′ ends of DSBs. TOP2 frequently fails to complete its catalysis, leading to formation of pathological TOP2ccs. We have previously shown that the endonucleolytic activity of MRE11 plays a key role in removing 5′ TOP2 adducts in G1 phase. We show here that BRCA1 promotes MRE11-mediated removal of TOP2 adducts in G₁ phase. We disrupted the BRCA1 gene in 53BP1-deficient ER-positive breast cancer and B cells. The loss of BRCA1 caused marked increases of pathological TOP2ccs in G₁ phase following exposure to etoposide, which generates pathological TOP2ccs. We conclude that BRCA1 promotes the removal of TOP2 adducts from DSB ends for subsequent nonhomologous end joining. BRCA1-deficient cells showed a decrease in etoposide-induced MRE11 foci in G₁ phase, suggesting that BRCA1 repairs pathological TOP2ccs by promoting the recruitment of MRE11 to TOP2cc sites. BRCA1 depletion also leads to the increase of unrepaired DSBs upon estrogen treatment both in vitro in G₁-arrested breast cancer cells and in vivo in epithelial cells of mouse mammary glands. BRCA1 thus plays a critical role in removing pathological TOP2ccs induced by estrogens aswell as etoposide. We propose that BRCA1 suppresses tumorigenesis by removing estrogen-induced pathological TOP2ccs throughout the cell cycle.
PDF
