BRAF oncogene is mutated in ~50% of human cutaneous melanomas. The BRAF V600E mutation leads to constitutive activation of the mitogen-activated protein kinase (MAPK) pathway fuelling cancer growth. The inhibitors of BRAF V600E (BRAFi), lead to massive and high response rate. However, BRAFi-resistant cells that operate as a cellular reservoir for relapses severely limits the duration of the clinical response. The recent depiction of these resistant cells did not identify druggable targets to ensure long-term survival under BRAFi. Here, we identify the aryl hydrocarbon receptor (AhR) as a target to eradicate resistant cells. We show that BRAFi bind to AhR on a new site, named beta-pocket, and reprogram gene expression independently of its partner ARNT. beta-pocket activation induces a pigmentation signature, which is associated to BRAFi-induced cell death of sensitive BRAF V600E melanoma cells and tumour shrinkage. Intriguingly, in resistant cells, BRAFi does not induced a pigmentation signature since these cells display another AhR program; AhR-ARNT dependant. By this way, AhR directs several key BRAFi-resistant genes. At single cell level, this constitutive activation of AhR-ARNT is identified in rare cells before BRAFi-treatment of melanoma tumours and an enrichment of these alpha-cells is observed under BRAFi. Our data strongly suggest that an endogenous AhR ligand activates AhR-ARNT via the canonical AhR pocket (alpha-pocket), thus favouring BRAFi-resistant gene expression. Importantly, we identify the clinically compatible AhR antagonist, the resveratrol (RSV), able to abrogate the deleterious constitutive activation of AhR and to reduce the cellular reservoir for the relapse. Taken together, this work reveals that constitutive AhR signalling drives BRAFi resistance and constitutes a therapeutic target to achieve long-term patient survival under BRAFi. More broadly, the constitutive activation of AhR by endogenous ligands is in line with the ability of UV radiations to generate potent AhR ligands and to favour melanoma onset. Overall design: Total RNA isolated from 12 human melanoma cell lines (501Mel) after different treatments was subjected to multiplexed RNA-sequencing using Illumina NextSeq500 sequencing tehnology.
Sustained activation of the Aryl hydrocarbon Receptor transcription factor promotes resistance to BRAF-inhibitors in melanoma.
Specimen part, Cell line, Subject
View SamplesNeural stem cells were sorted according to their activated or quiescent state by flow cytometry using a set of 3 markers (LeX, CD24 and EGFR)
Distinct Molecular Signatures of Quiescent and Activated Adult Neural Stem Cells Reveal Specific Interactions with Their Microenvironment.
Sex, Specimen part
View SamplesWe are investigating hepatic transcriptional responses associated with castration and tumorigenic hepatitis induced by Helicobacter hepaticus infection in mature male A/JCr mice
Hepatocellular carcinoma associated with liver-gender disruption in male mice.
No sample metadata fields
View SamplesGenome wide mRNA expression profiling of 94 gastric tumours derived from Australian based cohort was performed. . From this data we identified a cluster of co-expressed genes termed the stromal response cluster which almost perfectly differentiates tumor from its non-malignant gastric tissue and hence can be regarded as a highly tumor-specific gene expression signature. We show that these genes are consistently co-expressed across a range of independent gastric datasets as well as other cancer types suggesting a conserved functional role in cancer.
A signature predicting poor prognosis in gastric and ovarian cancer represents a coordinated macrophage and stromal response.
Specimen part
View SamplesWe used microarrays to compared gene expression profilings in various tumors of the kidney.
Balanced Translocations Disrupting SMARCB1 Are Hallmark Recurrent Genetic Alterations in Renal Medullary Carcinomas.
Specimen part
View SamplesGene expression analysis, a) comparing isogenic karyotypically normal iPSCs to del7q-iPSCs, b) comparing del7q-iPSCs to spontaneously corrected iPSCs. The chr7q deletion results in reduced expression levels of a large number of genes in the chr7q deleted region
Functional analysis of a chromosomal deletion associated with myelodysplastic syndromes using isogenic human induced pluripotent stem cells.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Genome-wide nucleosome specificity and function of chromatin remodellers in ES cells.
No sample metadata fields
View SamplesHow various ATP-dependent chromatin remodellers bind to nucleosomes to regulate transcription is not well defined in mammalian cells. Here, we present genome-wide remodeller-interacting nucleosome profiles for Chd1, Chd2, Chd4, Chd6, Chd8, Chd9, Brg1 and Ep400 in mouse embryonic stem (ES) cells. These remodellers bind to nucleosomes at specific positions, either at one or both nucleosomes that flank each side of nucleosome-free promoter regions (NFRs), at enhancer elements, or within gene bodies. At promoters, bidirectional transcription commonly initiates on either side of remodeller-bound nucleosomes. Transcriptome analysis upon remodeller depletion reveals reciprocal mechanisms of transcriptional regulation by remodellers. At active genes, certain remodellers are positive regulators of transcription, whereas others act as repressors. At bivalent genes, which are bound by repressive Polycomb complexes, the same remodellers act in the opposite way. Together, these findings reveal how remodellers integrate promoter nucleosomal architecture to regulate ES cell transcription programs.
Genome-wide nucleosome specificity and function of chromatin remodellers in ES cells.
No sample metadata fields
View SamplesHow various ATP-dependent chromatin remodellers bind to nucleosomes to regulate transcription is not well defined in mammalian cells. Here, we present genome-wide remodeller-interacting nucleosome profiles for Chd1, Chd2, Chd4, Chd6, Chd8, Chd9, Brg1 and Ep400 in mouse embryonic stem (ES) cells. These remodellers bind to nucleosomes at specific positions, either at one or both nucleosomes that flank each side of nucleosome-free promoter regions (NFRs), at enhancer elements, or within gene bodies. At promoters, bidirectional transcription commonly initiates on either side of remodeller-bound nucleosomes. Transcriptome analysis upon remodeller depletion reveals reciprocal mechanisms of transcriptional regulation by remodellers. At active genes, certain remodellers are positive regulators of transcription, whereas others act as repressors. At bivalent genes, which are bound by repressive Polycomb complexes, the same remodellers act in the opposite way. Together, these findings reveal how remodellers integrate promoter nucleosomal architecture to regulate ES cell transcription programs.
Genome-wide nucleosome specificity and function of chromatin remodellers in ES cells.
No sample metadata fields
View SamplesGp130 receptor engagement on neoplastic cells provides a link by which an inflammatory microenvironment facilitates tumour promotion. Although hyperactivation of the gp130-dependent Stat3 signalling node is commonly observed in solid tumours, Stat3 remains a challenging therapeutic target. To mimic excessive Stat3 signalling, we molecularly validate the gp130FF mouse as a preclinical model for inflammation-associated intestinal-type gastric cancer (IGC), with aberrant mammalian target of rapamycin (mTOR) pathway activity as shared feature. Accordingly, administration of the mTorc1 inhibitor RAD001 reversibly reduced IGC burden in gp130FF mice and suppressed colitis-associated cancer in wild-type mice. Since the therapeutic effect of RAD001 occurs independently of Stat3 hyperactivation, which is also dispensable for gp130-dependent engagement of the PI3K/Akt/mTorc1 pathway, we conclude that mTorc1 signalling limits tumour promoting Stat3 activity
mTORC1 inhibition restricts inflammation-associated gastrointestinal tumorigenesis in mice.
Specimen part
View Samples