Abstract:Cancer is characterized by gene expression aberrations. Studies have largely focused on coding sequences and promoters, despite the fact that distal regulatory elements play a central role in controlling transcription patterns. Here we utilize the histone mark H3K4me1 to analyze gain and loss of enhancer activity genome wide in primary colon cancer lines relative to normal colon crypts. We identified thousands of variant enhancer loci (VELs) that comprise a signature that is robustly predictive of the in vivo … Show more
“…Using these criteria, we identified 17,497 putative promoters and 66,448 putative enhancers (Fig. 1A), numbers comparable with previous studies in other tumor types (43)(44)(45). The numbers of defined promoters and enhancers reached saturation after 4 and 16 samples, respectively, suggesting that a sample size of 20 (10 tumor/ normal pairs) is sufficiently powered to discover the majority of cis-regulatory elements in ccRCC (Supplementary Fig.…”
Section: Cis-regulatory Landscapes In Ccrcc Tumors Are Aberrantsupporting
Protein-coding mutations in clear cell renal cell carcinoma (ccRCC) have been extensively characterized, frequently involving inactivation of the von Hippel-Lindau ( VHL ) tumor suppressor. Roles for noncoding cis -regulatory aberrations in ccRCC tumorigenesis, however, remain unclear. Analyzing 10 primary tumor/normal pairs and 9 cell lines across 79 chromatin profi les, we observed pervasive enhancer malfunction in ccRCC, with cognate enhancer-target genes associated with tissue-specifi c aspects of malignancy. Superenhancer profi ling identifi ed ZNF395 as a ccRCCspecifi c and VHL-regulated master regulator whose depletion causes near-complete tumor elimination in vitro and in vivo . VHL loss predominantly drives enhancer/superenhancer deregulation more so than promoters, with acquisition of active enhancer marks (H3K27ac, H3K4me1) near ccRCC hallmark genes. Mechanistically, VHL loss stabilizes HIF2α-HIF1β heterodimer binding at enhancers, subsequently recruiting histone acetyltransferase p300 without overtly affecting preexisting promoter-enhancer interactions. Subtype-specifi c driver mutations such as VHL may thus propagate unique pathogenic dependencies in ccRCC by modulating epigenomic landscapes and cancer gene expression.
SIGnIFICAnCE:Comprehensive epigenomic profi ling of ccRCC establishes a compendium of somatically altered cis -regulatory elements, uncovering new potential targets including ZNF395, a ccRCC master regulator. Loss of VHL , a ccRCC signature event, causes pervasive enhancer malfunction, with binding of enhancer-centric HIF2α and recruitment of histone acetyltransferase p300 at preexisting lineage-specifi c promoter-enhancer complexes. Cancer Discov; 7(11); 1284-305.
“…Using these criteria, we identified 17,497 putative promoters and 66,448 putative enhancers (Fig. 1A), numbers comparable with previous studies in other tumor types (43)(44)(45). The numbers of defined promoters and enhancers reached saturation after 4 and 16 samples, respectively, suggesting that a sample size of 20 (10 tumor/ normal pairs) is sufficiently powered to discover the majority of cis-regulatory elements in ccRCC (Supplementary Fig.…”
Section: Cis-regulatory Landscapes In Ccrcc Tumors Are Aberrantsupporting
Protein-coding mutations in clear cell renal cell carcinoma (ccRCC) have been extensively characterized, frequently involving inactivation of the von Hippel-Lindau ( VHL ) tumor suppressor. Roles for noncoding cis -regulatory aberrations in ccRCC tumorigenesis, however, remain unclear. Analyzing 10 primary tumor/normal pairs and 9 cell lines across 79 chromatin profi les, we observed pervasive enhancer malfunction in ccRCC, with cognate enhancer-target genes associated with tissue-specifi c aspects of malignancy. Superenhancer profi ling identifi ed ZNF395 as a ccRCCspecifi c and VHL-regulated master regulator whose depletion causes near-complete tumor elimination in vitro and in vivo . VHL loss predominantly drives enhancer/superenhancer deregulation more so than promoters, with acquisition of active enhancer marks (H3K27ac, H3K4me1) near ccRCC hallmark genes. Mechanistically, VHL loss stabilizes HIF2α-HIF1β heterodimer binding at enhancers, subsequently recruiting histone acetyltransferase p300 without overtly affecting preexisting promoter-enhancer interactions. Subtype-specifi c driver mutations such as VHL may thus propagate unique pathogenic dependencies in ccRCC by modulating epigenomic landscapes and cancer gene expression.
SIGnIFICAnCE:Comprehensive epigenomic profi ling of ccRCC establishes a compendium of somatically altered cis -regulatory elements, uncovering new potential targets including ZNF395, a ccRCC master regulator. Loss of VHL , a ccRCC signature event, causes pervasive enhancer malfunction, with binding of enhancer-centric HIF2α and recruitment of histone acetyltransferase p300 at preexisting lineage-specifi c promoter-enhancer complexes. Cancer Discov; 7(11); 1284-305.
“…For example, trimethylation of Histone H3 at the Lysine 4 residue (H3K4me3) is a wellcharacterized histone mark that is enriched at gene transcriptional start sites (TSS) and is associated with transcriptionally active genes (16)(17)(18)(19). Levels of H3K4me3 are globally and locally altered during different developmental stages of cancer, and can serve as a predictor for disease recurrence (20)(21)(22)(23)(24)(25)(26). It was also recently determined that increased H3K4me3 and decreased H3K27me3 is important for activation of genes linked to proliferation and invasion of breast cancer such as matrix metalloproteinases (MMP), ERBB3, Six1, Cyclin A1, Pim-1, and CSPG4 (14).…”
Epigenetic alteration is a hallmark of all cancers. Such alterations lead to modulation of fundamental cancer-related functions, such as proliferation, migration, and invasion. In particular, methylation of Histone H3 Lysine 4 (H3K4), a histone mark generally associated with transcriptional activation, is altered during progression of several human cancers. While the depletion of H3K4 demethylases promotes breast cancer metastasis, the effect of H3K4 methyltransferases on metastasis is not clear. Nevertheless, gene duplications in the human SETD1A (hSETD1A) H3K4 methyltransferase are present in almost half of breast cancers. Herein, expression analysis determined that hSETD1A is upregulated in multiple metastatic human breast cancer cell lines and clinical tumor specimens. Ablation of hSETD1A in breast cancer cells led to a decrease in migration and invasion in vitro and to a decrease in metastasis in nude mice. Furthermore, a group of matrix metalloproteinases (including MMP2, MMP9, MMP12, MMP13, and MMP17) were identified which were downregulated upon depletion of hSETD1A and demonstrated a decrease in H3K4me3 at their proximal promoters based on chromatin immunoprecipitation analysis. These results provide evidence for a functional and mechanistic link among hSETD1A, MMPs, and metastasis in breast cancer, thereby supporting an oncogenic role for hSETD1A in cancer.Implications: This study reveals that hSETD1A controls tumor metastasis by activating MMP expression and provides an epigenetic link among hSETD1A, MMPs, and metastasis of breast cancer.
“…Les résultats obtenus par B. AkhtarZaidi et al [1], résumés dans la Figure 2, révèlent l'importance des changements épigénétiques survenus dans des régions fonctionnelles comme fil conducteur du CCR. Plusieurs questions restent toutefois en suspens.…”
Section: Resultsunclassified
“…Cependant, le moteur principal de l'expression génique est situé dans les régions non codantes du génome dont l'analyse était limitée avant l'avènement des techniques de séquençage à haut débit. Dans un article récemment publié dans la revue Science, B. Akhtar-Zaidi et al [1] ont, grâce à ces technologies émergentes, cartographié, à l'échelle du génome, la signature épigénomique des régions régulatrices distales, les enhancers, dans des lignées cellulaires isolées de tumeurs colorectales primaires. Cette signature, qui n'est pas retrouvée dans les cellules épithéliales normales du côlon, dirigerait ainsi un programme transcriptionnel unique, participant à la carcinogenèse colorectale.…”
unclassified
“…La comparaison de la localisation de cette signature chromatinienne dans différents types cellulaires a permis de confirmer la nature spécifique des enhancers pour une cellule donnée [6][7][8]. Ceux-ci sont donc le déterminant majeur de l'expression du programme transcriptionnel responsable de B. Akhtar-Zaidi et al [1] révèlent que ces SNP, enrichis dans des régions enhancers marquées par H3K4me1 et spécifiques aux cellules de la crypte, sont détectés dans des régions de VEL acquis ou perdus dans les cellules CCR. Ces résultats démontrent la convergence de mécanismes de dérégulation géné-tiques et épigénétiques dans des régions clés impliquées dans la carcinogenèse colorectale.…”
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