Excessive transcription-replication conflicts are a vulnerability of BRCA1-mutant cancers
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA724717 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR14311185_1.fastq.gz | Fastqsanger.gz | |||
| SRR14311185_2.fastq.gz | Fastqsanger.gz | |||
| SRR14311186_1.fastq.gz | Fastqsanger.gz | |||
| SRR14311186_2.fastq.gz | Fastqsanger.gz | |||
| SRR14311187_1.fastq.gz | Fastqsanger.gz |
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Project description:Molecular Profiling of BRCA1-and BRCA2-associated Breast Cancers Identifies FGFR2 as a Gene More Highly Expressed in BRCA2-associated Tumors BRCA1- and BRCA2-associated tumors have many morphologic characteristics in common, but appear to have distinct molecular signatures. BRCA1-associated tumors are predominantly basal-like cancers, whereas BRCA2-associated tumors have a predominant luminal-like phenotype. These two molecular signatures reflect in part the two cell types, basal/myoepithelial and luminal, found in the terminal duct lobular unit of the breast. To elucidate novel genes involved in these two spectra of breast cancer tumorigenesis we performed global gene expression analysis on breast tumors from germline BRCA1 and BRCA2 mutation carriers. Breast tumor RNAs from 7 germline BRCA1 and 6 germline BRCA2 carriers were profiled using UHN human 19K cDNA microarrays. Supervised univariate analyses were conducted to identify genes differentially expressed between BRCA1 and BRCA2-associated tumors. Selected discriminatory genes were validated using real time reverse transcription polymerase chain reaction (RT-PCR) in the tumor RNAs, and/or by immunohistochemistry (IHC) or by in situ hybridization (ISH) on tissue microarrays (TMAs) containing an independent set of 58 BRCA1 and 64 BRCA2-associated tumors. Genes more highly expressed in BRCA1-associated tumors included stathmin/oncoprotein 18, osteopontin, TGFß2 and Jagged 1 in addition to genes previously identified as characteristic of basal-like breast cancers. Genes more highly expressed in BRCA2-associated tumors had functions related to transcription, signal transduction (particularly MAPK signaling), cell proliferation, cell adhesion and extracellular matrix remodeling. BRCA2-associated cancers were characterized by the higher relative expression of amongst others, FGF1 and FGFR2. Tissue microarrays were used to validate the expression of FGFR2 protein by immunohistochemistry and Jagged 1 expression by in situ hybridization. BRCA2-associated cancers expressed higher levels of FGFR2 protein than BRCA1-associated cancers (p=0.004); whereas BRCA1-associated tumors exhibited elevated levels of Jagged1 mRNA compared to BRCA2-associated cancers (p=0.02). FGFR2 and FGF1 were more highly expressed in BRCA2-associated cancers compared with BRCA1-associated breast cancers, suggesting the existence of an autocrine or paracrine stimulatory loop. In addition to corroborating the basal-like signature of BRCA1-associated tumors, we identified osteopontin, stathmin/oncoprotein 18, TGFβ2, and Jagged 1 as being more highly expressed in BRCA1-associated tumors. Keywords: Gene expression profiling, genetic comparison
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Project description:We investigated BRCA1-deficient ovarian cancer to understand why homologous recombination deficiency (HRD) is associated with tumor T-cell inflammation. In humans and mice, BRCA1 deficiency led to increased cytoplasmic translocation of nuclear DNA, increased DNA sensing, induction of proinflammatory cytokines and T-cell recruiting chemokines, and increased tumor CD8+ T-cell infiltration. This cascade was mediated by STING and phosphorylation of TBK1, IRF3 and STAT1. BRCA1 loss activated a transcriptional reprogramming of tumor cells, leading to overexpression of the DNA sensing pathway and hyper-responsiveness to cytoplasmic DNA. Genetic alterations of the DNA sensing and interferon pathways modulated the impact of HRD on T-cell inflammation. PARP inhibitor olaparib exacerbated cytoplasmic DNA and the cell-autonomous inflammatory activation of BRCA1-deficient cancers, and rendered them susceptible to PD-1/CTLA-4 blockade. We conclude that HRD and DNA sensing drives the immunogenicity of ovarian carcinomas and predisposes them to immune vulnerability under immune checkpoint blockade.
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Project description:Analysis of miRNA expression in grade 3 luminal, sporadic and BRCA1 associated basal-like breast cancers
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Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
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Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
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Project description:During the S-phase, conflicts of replication forks with RNA Polymerase II (RNAPII) threaten genomic stability. While the PAF complex can resolve such conflicts during elongation, the particularly deleterious conflicts with stalling RNAPII are resolved by an as of yet unknown mechanism. Here we show that the MYCN oncoprotein forms a ternary complex with RNAPII and the nuclear RNA exosome, a 3’‑5’ exoribonuclease complex. Together with TFIIS, this complex restarts promoter‑proximal RNAPII, allows escape from co-directional transcription-replication conflicts and prevents double‑strand break accumulation. In cells lacking RNA exosome function, MYCN globally terminates transcription. MYCN-mediated termination is triggered by ATM‑dependent recruitment of BRCA1, which then stabilizes nuclear mRNA decapping complexes. Disruption of mRNA decapping activates ATR, indicative of head-on transcription-replication conflicts, and inhibits DNA replication. We propose that MYCN resolves transcription-replication conflicts via this two-step mechanism to sustain the rapid proliferation of neuroendocrine tumor cells.
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