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1.
Blood ; 131(25): 2789-2802, 2018 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-29653964

RESUMO

Tumors accumulate high levels of mutant p53 (mutp53), which contributes to mutp53 gain-of-function properties. The mechanisms that underlie such excessive accumulation are not fully understood. To discover regulators of mutp53 protein accumulation, we performed a large-scale RNA interference screen in a Burkitt lymphoma cell line model. We identified transformation/transcription domain-associated protein (TRRAP), a constituent of several histone acetyltransferase complexes, as a critical positive regulator of both mutp53 and wild-type p53 levels. TRRAP silencing attenuated p53 accumulation in lymphoma and colon cancer models, whereas TRRAP overexpression increased mutp53 levels, suggesting a role for TRRAP across cancer entities and p53 mutations. Through clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 screening, we identified a 109-amino-acid region in the N-terminal HEAT repeat region of TRRAP that was crucial for mutp53 stabilization and cell proliferation. Mass spectrometric analysis of the mutp53 interactome indicated that TRRAP silencing caused degradation of mutp53 via the MDM2-proteasome axis. This suggests that TRRAP is vital for maintaining mutp53 levels by shielding it against the natural p53 degradation machinery. To identify drugs that alleviated p53 accumulation similarly to TRRAP silencing, we performed a small-molecule drug screen and found that inhibition of histone deacetylases (HDACs), specifically HDAC1/2/3, decreased p53 levels to a comparable extent. In summary, here we identify TRRAP as a key regulator of p53 levels and link acetylation-modifying complexes to p53 protein stability. Our findings may provide clues for therapeutic targeting of mutp53 in lymphoma and other cancers.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Linfoma/metabolismo , Proteínas Nucleares/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Acetilação , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Humanos , Linfoma/genética , Mutação , Proteínas Nucleares/química , Proteínas Nucleares/genética , Domínios Proteicos , Estabilidade Proteica , Transporte Proteico , Proteólise , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Proteína Supressora de Tumor p53/genética , Ubiquitinação
2.
Mol Syst Biol ; 12(8): 879, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27482057

RESUMO

Reverse genetic screens have driven gene annotation and target discovery in model organisms. However, many disease-relevant genotypes and phenotypes cannot be studied in lower organisms. It is therefore essential to overcome technical hurdles associated with large-scale reverse genetics in human cells. Here, we establish a reverse genetic approach based on highly robust and sensitive multiplexed RNA sequencing of mutant human cells. We conduct 10 parallel screens using a collection of engineered haploid isogenic cell lines with knockouts covering tyrosine kinases and identify known and unexpected effects on signaling pathways. Our study provides proof of concept for a scalable approach to link genotype to phenotype in human cells, which has broad applications. In particular, it clears the way for systematic phenotyping of still poorly characterized human genes and for systematic study of uncharacterized genomic features associated with human disease.


Assuntos
Perfilação da Expressão Gênica/métodos , Proteínas Tirosina Quinases/genética , Genética Reversa/métodos , Análise de Sequência de RNA/métodos , Linhagem Celular , Técnicas de Inativação de Genes , Genótipo , Humanos , Anotação de Sequência Molecular , Fenótipo
3.
Nat Struct Mol Biol ; 30(11): 1640-1652, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37735617

RESUMO

The SS18-SSX fusion drives oncogenic transformation in synovial sarcoma by bridging SS18, a member of the mSWI/SNF (BAF) complex, to Polycomb repressive complex 1 (PRC1) target genes. Here we show that the ability of SS18-SSX to occupy H2AK119ub1-rich regions is an intrinsic property of its SSX C terminus, which can be exploited by fusion to transcriptional regulators beyond SS18. Accordingly, SS18-SSX recruitment occurs in a manner that is independent of the core components and catalytic activity of BAF. Alternative SSX fusions are also recruited to H2AK119ub1-rich chromatin and reproduce the expression signatures of SS18-SSX by engaging with transcriptional activators. Variant Polycomb repressive complex 1.1 (PRC1.1) acts as the main depositor of H2AK119ub1 and is therefore required for SS18-SSX occupancy. Importantly, the SSX C terminus not only depends on H2AK119ub1 for localization, but also further increases it by promoting PRC1.1 complex stability. Consequently, high H2AK119ub1 levels are a feature of murine and human synovial sarcomas. These results uncover a critical role for SSX-C in mediating gene deregulation in synovial sarcoma by providing specificity to chromatin and further enabling oncofusion binding by enhancing PRC1.1 stability and H2AK119ub1 deposition.


Assuntos
Sarcoma Sinovial , Humanos , Animais , Camundongos , Sarcoma Sinovial/genética , Sarcoma Sinovial/metabolismo , Complexo Repressor Polycomb 1/genética , Ativação Transcricional , Núcleo Celular/metabolismo , Cromatina/metabolismo , Proteínas de Fusão Oncogênica/metabolismo , Proteínas de Ciclo Celular/metabolismo
4.
Leukemia ; 36(4): 1035-1047, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34795418

RESUMO

Numerous targeted therapies have been developed for diffuse large B-cell lymphoma, but the results of late-stage clinical trials were mostly disappointing and have led to very few new regulatory approvals. Here, we use single and combinatorial drug response profiling to show that the combined inhibition of the anti-apoptotic protein Bcl-2 and of the tyrosine kinase BTK with the small molecules venetoclax and ibrutinib efficiently kills DLBCL cells in vitro. High Bcl-2 expression due to either BCL2 amplifications or translocations, in conjunction with chronic active BCR signaling accurately predict responses to dual Bcl-2/BTK inhibition. Orthotopic xenotransplantation and patient-derived xenograft models confirm that the combinatorial is superior to single-agent treatment in reducing the lymphoma burden. Combinatorial treatment further efficiently overcomes both primary and acquired resistance to venetoclax, which we could link to reduced expression of the Bcl-2 family members Bcl-XL and Bcl-2A1 under ibrutinib. We found in a Swiss DLBCL cohort that ~15% of patients are projected to respond to the venetoclax/ibrutinib combination based on their high Bcl-2 expression and nuclear NF-κB localization. Our data show that drug sensitivities exposed by drug response profiling can be attributed to specific mutational signatures and immunohistochemical biomarkers, and point to combined Bcl-2/BTK inhibition as a promising therapeutic strategy in DLBCL.


Assuntos
Apoptose , Linfoma Difuso de Grandes Células B , Tirosina Quinase da Agamaglobulinemia , Humanos , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Linfoma Difuso de Grandes Células B/patologia , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/uso terapêutico , Transplante Heterólogo
5.
Cell Death Dis ; 8(6): e2875, 2017 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-28617445

RESUMO

BRCA2 encodes a protein with a fundamental role in homologous recombination that is essential for normal development. Carrier status of mutations in BRCA2 is associated with familial breast and ovarian cancer, while bi-allelic BRCA2 mutations can cause Fanconi anemia (FA), a cancer predisposition syndrome with cellular cross-linker hypersensitivity. Cancers associated with BRCA2 mutations can acquire chemo-resistance on relapse. We modeled acquired cross-linker resistance with an FA-derived BRCA2-mutated acute myeloid leukemia (AML) platform. Associated with acquired cross-linker resistance was the expression of a functional BRCA2 protein variant lacking exon 5 and exon 7 (BRCA2ΔE5+7), implying a role for BRCA2 splicing for acquired chemo-resistance. Integrated network analysis of transcriptomic and proteomic differences for phenotyping of BRCA2 disruption infers impact on transcription and chromatin remodeling in addition to the DNA damage response. The striking overlap with transcriptional profiles of FA patient hematopoiesis and BRCA mutation associated ovarian cancer helps define and explicate the 'BRCAness' profile.


Assuntos
Processamento Alternativo , Proteína BRCA2/genética , Proteína BRCA2/metabolismo , Resistencia a Medicamentos Antineoplásicos , Genes BRCA2 , Mutação , Animais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Dano ao DNA , Éxons , Anemia de Fanconi/tratamento farmacológico , Anemia de Fanconi/genética , Anemia de Fanconi/metabolismo , Feminino , Predisposição Genética para Doença , Humanos , Íntrons , Células K562 , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/metabolismo , Camundongos , Recidiva Local de Neoplasia , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Fenótipo , Splicing de RNA , Transcrição Gênica
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