RESUMO
Purpose: Alteration in cell death is a hallmark of cancer. A functional role regulating survival, apoptosis, and necroptosis has been attributed to RIP1/3 complexes.Experimental Design: We have investigated the role of RIP1 and the effects of MC2494 in cell death induction, using different methods as flow cytometry, transcriptome analysis, immunoprecipitation, enzymatic assays, transfections, mutagenesis, and in vivo studies with different mice models.Results: Here, we show that RIP1 is highly expressed in cancer, and we define a novel RIP1/3-SIRT1/2-HAT1/4 complex. Mass spectrometry identified five acetylations in the kinase and death domain of RIP1. The novel characterized pan-SIRT inhibitor, MC2494, increases RIP1 acetylation at two additional sites in the death domain. Mutagenesis of the acetylated lysine decreases RIP1-dependent cell death, suggesting a role for acetylation of the RIP1 complex in cell death modulation. Accordingly, MC2494 displays tumor-selective potential in vitro, in leukemic blasts ex vivo, and in vivo in both xenograft and allograft cancer models. Mechanistically, MC2494 induces bona fide tumor-restricted acetylated RIP1/caspase-8-mediated apoptosis. Excitingly, MC2494 displays tumor-preventive activity by blocking 7,12-dimethylbenz(α)anthracene-induced mammary gland hyperproliferation in vivoConclusions: These preventive features might prove useful in patients who may benefit from a recurrence-preventive approach with low toxicity during follow-up phases and in cases of established cancer predisposition. Thus, targeting the newly identified RIP1 complex may represent an attractive novel paradigm in cancer treatment and prevention. Clin Cancer Res; 24(12); 2886-900. ©2018 AACR.
Assuntos
Histona Acetiltransferases/metabolismo , Complexos Multiproteicos/metabolismo , Neoplasias/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Proteínas de Ligação a RNA/metabolismo , Sirtuínas/metabolismo , Acetilação , Animais , Antineoplásicos/farmacologia , Caspase 8/metabolismo , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Expressão Gênica , Histona Acetiltransferases/genética , Humanos , Camundongos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Neoplasias/patologia , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Ligação Proteica , Proteínas de Ligação a RNA/genética , Transdução de Sinais/efeitos dos fármacos , Sirtuínas/genéticaRESUMO
Interactions between DNA and proteins are mainly studied through chemical procedures involving bi-functional reagents, mostly formaldehyde. Chromatin immunoprecipitation is used to identify the binding between transcription factors (TFs) and chromatin, and to evaluate the occurrence and impact of histone/DNA modifications. The current bottleneck in probing DNA-protein interactions using these approaches is caused by the fact that chemical crosslinkers do not discriminate direct and indirect bindings or short-lived chromatin occupancy. Here, we describe a novel application of UV laser-induced (L-) crosslinking and demonstrate that a combination of chemical and L-crosslinking is able to distinguish between direct and indirect DNA-protein interactions in a small number of living cells. The spatial and temporal dynamics of TF bindings to chromatin and their role in gene expression regulation may thus be assessed. The combination of chemical and L-crosslinking offers an exciting and unprecedented tool for biomedical applications.
Assuntos
Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Lasers , Raios Ultravioleta , Linhagem Celular Tumoral , Cromatina/metabolismo , Reagentes de Ligações Cruzadas , Regulação da Expressão Gênica , Humanos , Fatores de Tempo , Fatores de Transcrição/metabolismoRESUMO
We report the case of a 42 year male with history of chronic anaemia who was found to have pernicious anaemia with beta thalassemia trait and had on esophago-gastric-duodenoscopy, gastric carcinoids with gastric atrophy. Pernicious anaemia and gastric carcinoids occurring simultaneously in a single individual is rare. Our case emphasises the need for esophago-gastric-duodenoscopy in cases of pernicious anaemia.
Assuntos
Anemia Perniciosa/complicações , Tumor Carcinoide/complicações , Neoplasias Gástricas/complicações , Adulto , Humanos , MasculinoRESUMO
Serum-to-2i interconversion of mouse embryonic stem cells (mESCs) is a valuable in vitro model for early embryonic development. To assess whether 3D chromatin organization changes during this transition, we established Capture Hi-C with target-sequence enrichment of DNase I hypersensitive sites. We detected extremely long-range intra- and inter-chromosomal interactions between a small subset of H3K27me3 marked bivalent promoters involving the Hox clusters in serum-grown cells. Notably, these promoter-mediated interactions are not present in 2i ground-state pluripotent mESCs but appear upon their further development into primed-like serum mESCs. Reverting serum mESCs to ground-state 2i mESCs removes these promoter-promoter interactions in a spatiotemporal manner. H3K27me3, which is largely absent at bivalent promoters in ground-state 2i mESCs, is necessary, but not sufficient, to establish these interactions, as confirmed by Capture Hi-C on Eed(-/-) serum mESCs. Our results implicate H3K27me3 and PRC2 as critical players in chromatin alteration during priming of ESCs for differentiation.