RESUMO
An "induced PARP inhibitor (PARPi) sensitivity by epigenetic modulation" strategy is being evaluated in the clinic to sensitize homologous recombination (HR)-proficient tumors to PARPi treatments. To expand its clinical applications and identify more efficient combinations, we performed a drug screen by combining PARPi with 74 well-characterized epigenetic modulators that target five major classes of epigenetic enzymes. Both type I PRMT inhibitor and PRMT5 inhibitor exhibit high combination and clinical priority scores in our screen. PRMT inhibition significantly enhances PARPi treatment-induced DNA damage in HR-proficient ovarian and breast cancer cells. Mechanistically, PRMTs maintain the expression of genes associated with DNA damage repair and BRCAness and regulate intrinsic innate immune pathways in cancer cells. Analyzing large-scale genomic and functional profiles from TCGA and DepMap further confirms that PRMT1, PRMT4, and PRMT5 are potential therapeutic targets in oncology. Finally, PRMT1 and PRMT5 inhibition act synergistically to enhance PARPi sensitivity. Our studies provide a strong rationale for the clinical application of a combination of PRMT and PARP inhibitors in patients with HR-proficient ovarian or breast cancer.
RESUMO
p53 was discovered 45 years ago as an SV40 large T antigen binding protein, coded by the most frequently mutated TP53 gene in human cancers. As a transcription factor, p53 is tightly regulated by a rich network of post-translational modifications to execute its diverse functions in tumor suppression. Although early studies established p53-mediated cell-cycle arrest, apoptosis, and senescence as the classic barriers in cancer development, a growing number of new functions of p53 have been discovered and the scope of p53-mediated anti-tumor activity is largely expanded. Here, we review the complexity of different layers of p53 regulation, and the recent advance of the p53 pathway in metabolism, ferroptosis, immunity, and others that contribute to tumor suppression. We also discuss the challenge regarding how to activate p53 function specifically effective in inhibiting tumor growth without harming normal homeostasis for cancer therapy.
Assuntos
Neoplasias , Proteína Supressora de Tumor p53 , Humanos , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Animais , Ferroptose/genética , Transdução de Sinais , Apoptose , Processamento de Proteína Pós-TraducionalRESUMO
The androgen receptor (AR) is a ligand-responsive transcription factor that binds at enhancers to drive terminal differentiation of the prostatic luminal epithelia. By contrast, in tumors originating from these cells, AR chromatin occupancy is extensively reprogrammed to drive hyper-proliferative, metastatic, or therapy-resistant phenotypes, the molecular mechanisms of which remain poorly understood. Here, we show that the tumor-specific enhancer circuitry of AR is critically reliant on the activity of Nuclear Receptor Binding SET Domain Protein 2 (NSD2), a histone 3 lysine 36 di-methyltransferase. NSD2 expression is abnormally gained in prostate cancer cells and its functional inhibition impairs AR trans-activation potential through partial off-loading from over 40,000 genomic sites, which is greater than 65% of the AR tumor cistrome. The NSD2-dependent AR sites distinctly harbor a chimeric AR-half motif juxtaposed to a FOXA1 element. Similar chimeric motifs of AR are absent at the NSD2-independent AR enhancers and instead contain the canonical palindromic motifs. Meta-analyses of AR cistromes from patient tumors uncovered chimeric AR motifs to exclusively participate in tumor-specific enhancer circuitries, with a minimal role in the physiological activity of AR. Accordingly, NSD2 inactivation attenuated hallmark cancer phenotypes that were fully reinstated upon exogenous NSD2 re-expression. Inactivation of NSD2 also engendered increased dependency on its paralog NSD1, which independently maintained AR and MYC hyper-transcriptional programs in cancer cells. Concordantly, a dual NSD1/2 PROTAC degrader, called LLC0150, was preferentially cytotoxic in AR-dependent prostate cancer as well as NSD2-altered hematologic malignancies. Altogether, we identify NSD2 as a novel subunit of the AR neo-enhanceosome that wires prostate cancer gene expression programs, positioning NSD1/2 as viable paralog co-targets in advanced prostate cancer.
RESUMO
Oncology drug combinations can improve therapeutic responses and increase treatment options for patients. The number of possible combinations is vast and responses can be context-specific. Systematic screens can identify clinically relevant, actionable combinations in defined patient subtypes. We present data for 109 anticancer drug combinations from AstraZeneca's oncology small molecule portfolio screened in 755 pan-cancer cell lines. Combinations were screened in a 7 × 7 concentration matrix, with more than 4 million measurements of sensitivity, producing an exceptionally data-rich resource. We implement a new approach using combination Emax (viability effect) and highest single agent (HSA) to assess combination benefit. We designed a clinical translatability workflow to identify combinations with clearly defined patient populations, rationale for tolerability based on tumor type and combination-specific "emergent" biomarkers, and exposures relevant to clinical doses. We describe three actionable combinations in defined cancer types, confirmed in vitro and in vivo, with a focus on hematologic cancers and apoptotic targets. SIGNIFICANCE: We present the largest cancer drug combination screen published to date with 7 × 7 concentration response matrices for 109 combinations in more than 750 cell lines, complemented by multi-omics predictors of response and identification of "emergent" combination biomarkers. We prioritize hits to optimize clinical translatability, and experimentally validate novel combination hypotheses. This article is featured in Selected Articles from This Issue, p. 695.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica , Neoplasias , Humanos , Linhagem Celular Tumoral , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêuticoRESUMO
Since Mdm2 (Mouse double minute 2) inhibitors show serious toxicity in clinic studies, different approaches to achieve therapeutic reactivation of p53-mediated tumor suppression in cancers need to be explored. Here, we identify the USP2 (ubiquitin specific peptidase 2)-VPRBP (viral protein R binding protein) axis as an important pathway for p53 regulation. Like Mdm2, VPRBP is a potent repressor of p53 but VPRBP stability is controlled by USP2. Interestingly, the USP2-VPRBP axis also regulates PD-L1 (programmed death-ligand 1) expression. Strikingly, the combination of a small-molecule USP2 inhibitor and anti-PD1 monoclonal antibody leads to complete regression of the tumors expressing wild-type p53. In contrast to Mdm2, knockout of Usp2 in mice has no obvious effect in normal tissues. Moreover, no obvious toxicity is observed upon the USP2 inhibitor treatment in vivo as Mdm2-mediated regulation of p53 remains intact. Our study reveals a promising strategy for p53-based therapy by circumventing the toxicity issue.
Assuntos
Neoplasias , Proteína Supressora de Tumor p53 , Camundongos , Animais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Neoplasias/tratamento farmacológico , Neoplasias/genética , Proteínas de Transporte , Ubiquitina Tiolesterase/genética , Ubiquitina Tiolesterase/metabolismo , Proteínas Serina-Treonina Quinases/metabolismoRESUMO
Although it is well-established that p53-mediated tumor suppression mainly acts through its ability in transcriptional regulation, the molecular mechanisms of this regulation are not completely understood. Among a number of regulatory modes, acetylation of p53 attracts great interests. p53 was one of the first non-histone proteins found to be functionally regulated by acetylation and deacetylation, and subsequent work has established that reversible acetylation is a general mechanism for regulation of non-histone proteins. Unlike other types of posttranslational modifications occurred during stress responses, the role of p53 acetylation has been recently validated in vivo by using the knock-in mice with both acetylation-defective and acetylation-mimicking p53 mutants. Here, we review the role of acetylation in p53-mediated activities, with a focus on which specific acetylation sites are critical for p53-dependent transcription regulation during tumor suppression and how acetylation of p53 recruits specific "readers" to execute its promoter-specific regulation of different targets. We also discuss the role of p53 acetylation in differentially regulating its classic activities in cell cycle arrest, senescence and apoptosis as well as newly identified unconventional functions such as cell metabolism and ferroptosis.
Assuntos
Neoplasias , Proteína Supressora de Tumor p53/metabolismo , Acetilação , Animais , Apoptose/genética , Pontos de Checagem do Ciclo Celular , Humanos , Camundongos , Neoplasias/genética , Processamento de Proteína Pós-Traducional , Proteína Supressora de Tumor p53/genéticaRESUMO
By combining 6 druggable genome resources, we identify 6,083 genes as potential druggable genes (PDGs). We characterize their expression, recurrent genomic alterations, cancer dependencies, and therapeutic potentials by integrating genome, functionome, and druggome profiles across cancers. 81.5% of PDGs are reliably expressed in major adult cancers, 46.9% show selective expression patterns, and 39.1% exhibit at least one recurrent genomic alteration. We annotate a total of 784 PDGs as dependent genes for cancer cell growth. We further quantify 16 cancer-related features and estimate a PDG cancer drug target score (PCDT score). PDGs with higher PCDT scores are significantly enriched for genes encoding kinases and histone modification enzymes. Importantly, we find that a considerable portion of high PCDT score PDGs are understudied genes, providing unexplored opportunities for drug development in oncology. By integrating the druggable genome and the cancer genome, our study thus generates a comprehensive blueprint of potential druggable genes across cancers.
Assuntos
Antineoplásicos , Neoplasias , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Genoma , Genômica , Humanos , Iluminação , Neoplasias/tratamento farmacológico , Neoplasias/genéticaRESUMO
The nuclear receptor (NR) superfamily is one of the major druggable gene families, representing targets of approximately 13.5% of approved drugs. Certain NRs, such as estrogen receptor and androgen receptor, have been well demonstrated to be functionally involved in cancer and serve as informative biomarkers and therapeutic targets in oncology. However, the spectrum of NR dysregulation across cancers remains to be comprehensively characterized. Through computational integration of genetic, genomic, and pharmacologic profiles, we characterized the expression, recurrent genomic alterations, and cancer dependency of NRs at a large scale across primary tumor specimens and cancer cell lines. Expression levels of NRs were highly cancer-type specific and globally downregulated in tumors compared with corresponding normal tissue. Although the majority of NRs showed copy-number losses in cancer, both recurrent focal gains and losses were identified in select NRs. Recurrent mutations and transcript fusions of NRs were observed in a small portion of cancers, serving as actionable genomic alterations. Analysis of large-scale CRISPR and RNAi screening datasets identified 10 NRs as strongly selective essential genes for cancer cell growth. In a subpopulation of tumor cells, growth dependencies correlated significantly with expression or genomic alterations. Overall, our comprehensive characterization of NRs across cancers may facilitate the identification and prioritization of potential biomarkers and therapeutic targets, as well as the selection of patients for precision cancer treatment. SIGNIFICANCE: Computational analysis of nuclear receptors across multiple cancer types provides a series of biomarkers and therapeutic targets within this protein family.
Assuntos
Biomarcadores Tumorais/genética , Genômica/métodos , Neoplasias/genética , Receptores Citoplasmáticos e Nucleares/genética , HumanosRESUMO
Cell-surface proteins (SPs) are a rich source of immune and targeted therapies. By systematically integrating single-cell and bulk genomics, functional studies and target actionability, in the present study we comprehensively identify and annotate genes encoding SPs (GESPs) pan-cancer. We characterize GESP expression patterns, recurrent genomic alterations, essentiality, receptor-ligand interactions and therapeutic potential. We also find that mRNA expression of GESPs is cancer-type specific and positively correlates with protein expression, and that certain GESP subgroups function as common or specific essential genes for tumor cell growth. We also predict receptor-ligand interactions substantially deregulated in cancer and, using systems biology approaches, we identify cancer-specific GESPs with therapeutic potential. We have made this resource available through the Cancer Surfaceome Atlas ( http://fcgportal.org/TCSA ) within the Functional Cancer Genome data portal.
Assuntos
Genômica , Neoplasias , Genoma , Humanos , Ligantes , Neoplasias/tratamento farmacológico , ProteômicaRESUMO
PURPOSE: Targeting Bcl-2 family members upregulated in multiple cancers has emerged as an important area of cancer therapeutics. While venetoclax, a Bcl-2-selective inhibitor, has had success in the clinic, another family member, Bcl-xL, has also emerged as an important target and as a mechanism of resistance. Therefore, we developed a dual Bcl-2/Bcl-xL inhibitor that broadens the therapeutic activity while minimizing Bcl-xL-mediated thrombocytopenia. EXPERIMENTAL DESIGN: We used structure-based chemistry to design a small-molecule inhibitor of Bcl-2 and Bcl-xL and assessed the activity against in vitro cell lines, patient samples, and in vivo models. We applied pharmacokinetic/pharmacodynamic (PK/PD) modeling to integrate our understanding of on-target activity of the dual inhibitor in tumors and platelets across dose levels and over time. RESULTS: We discovered AZD4320, which has nanomolar affinity for Bcl-2 and Bcl-xL, and mechanistically drives cell death through the mitochondrial apoptotic pathway. AZD4320 demonstrates activity in both Bcl-2- and Bcl-xL-dependent hematologic cancer cell lines and enhanced activity in acute myeloid leukemia (AML) patient samples compared with the Bcl-2-selective agent venetoclax. A single intravenous bolus dose of AZD4320 induces tumor regression with transient thrombocytopenia, which recovers in less than a week, suggesting a clinical weekly schedule would enable targeting of Bcl-2/Bcl-xL-dependent tumors without incurring dose-limiting thrombocytopenia. AZD4320 demonstrates monotherapy activity in patient-derived AML and venetoclax-resistant xenograft models. CONCLUSIONS: AZD4320 is a potent molecule with manageable thrombocytopenia risk to explore the utility of a dual Bcl-2/Bcl-xL inhibitor across a broad range of tumor types with dysregulation of Bcl-2 prosurvival proteins.
Assuntos
Antineoplásicos/farmacologia , Benzamidas/farmacologia , Neoplasias Hematológicas/tratamento farmacológico , Piperidinas/farmacologia , Proteínas Proto-Oncogênicas c-bcl-2/antagonistas & inibidores , Sulfonas/farmacologia , Trombocitopenia/tratamento farmacológico , Proteína bcl-X/antagonistas & inibidores , Animais , Antineoplásicos/uso terapêutico , Apoptose , Benzamidas/uso terapêutico , Proliferação de Células , Feminino , Neoplasias Hematológicas/metabolismo , Neoplasias Hematológicas/patologia , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Piperidinas/uso terapêutico , Sulfonas/uso terapêutico , Trombocitopenia/metabolismo , Trombocitopenia/patologia , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
We report the first disclosure of IRAK3 degraders in the scientific literature. Taking advantage of an opportune byproduct obtained during our efforts to identify IRAK4 inhibitors, we identified ready-to-use, selective IRAK3 ligands in our compound collection with the required properties for conversion into proteolysis-targeting chimera (PROTAC) degraders. This work culminated with the discovery of PROTAC 23, which we demonstrated to be a potent and selective degrader of IRAK3 after 16 h in THP1 cells. 23 induced proteasome-dependent degradation of IRAK3 and required both CRBN and IRAK3 binding for activity. We conclude that PROTAC 23 constitutes an excellent in vitro tool with which to interrogate the biology of IRAK3.
Assuntos
Quinases Associadas a Receptores de Interleucina-1/metabolismo , Ftalimidas/farmacologia , Proteólise/efeitos dos fármacos , Pirróis/farmacologia , Triazinas/farmacologia , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Humanos , Ligantes , Ftalimidas/síntese química , Pirróis/síntese química , Células THP-1 , Triazinas/síntese química , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The last 40 years have witnessed how p53 rose from a viral binding protein to a central factor in both stress responses and tumor suppression. The exquisite regulation of p53 functions is of vital importance for cell fate decisions. Among the multiple layers of mechanisms controlling p53 function, posttranslational modifications (PTMs) represent an efficient and precise way. Major p53 PTMs include phosphorylation, ubiquitination, acetylation, and methylation. Meanwhile, other PTMs like sumoylation, neddylation, O-GlcNAcylation, adenosine diphosphate (ADP)-ribosylation, hydroxylation, and ß-hydroxybutyrylation are also shown to play various roles in p53 regulation. By independent action or interaction, PTMs affect p53 stability, conformation, localization, and binding partners. Deregulation of the PTM-related pathway is among the major causes of p53-associated developmental disorders or diseases, especially in cancers. This review focuses on the roles of different p53 modification types and shows how these modifications are orchestrated to produce various outcomes by modulating p53 activities or targeted to treat different diseases caused by p53 dysregulation.
Assuntos
Neoplasias/genética , Neoplasias/metabolismo , Processamento de Proteína Pós-Traducional , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Animais , História do Século XX , História do Século XXI , Humanos , Neoplasias/história , Neoplasias/patologia , Estabilidade Proteica , Proteína Supressora de Tumor p53/históriaRESUMO
It is well established that ferroptosis is primarily controlled by glutathione peroxidase 4 (GPX4). Surprisingly, we observed that p53 activation modulates ferroptotic responses without apparent effects on GPX4 function. Instead, ALOX12 inactivation diminishes p53-mediated ferroptosis induced by reactive oxygen species stress and abrogates p53-dependent inhibition of tumour growth in xenograft models, suggesting that ALOX12 is critical for p53-mediated ferroptosis. The ALOX12 gene resides on human chromosome 17p13.1, a hotspot of monoallelic deletion in human cancers. Loss of one Alox12 allele is sufficient to accelerate tumorigenesis in Eµ-Myc lymphoma models. Moreover, ALOX12 missense mutations from human cancers abrogate its ability to oxygenate polyunsaturated fatty acids and to induce p53-mediated ferroptosis. Notably, ALOX12 is dispensable for ferroptosis induced by erastin or GPX4 inhibitors; conversely, ACSL4 is required for ferroptosis upon GPX4 inhibition but dispensable for p53-mediated ferroptosis. Thus, our study identifies an ALOX12-mediated, ACSL4-independent ferroptosis pathway that is critical for p53-dependent tumour suppression.
Assuntos
Araquidonato 12-Lipoxigenase/genética , Carcinogênese/genética , Glutationa Peroxidase/genética , Proteína Supressora de Tumor p53/genética , Animais , Apoptose/genética , Linhagem Celular Tumoral , Modelos Animais de Doenças , Glutationa Peroxidase/antagonistas & inibidores , Humanos , Peroxidação de Lipídeos/genética , Linfoma/genética , Linfoma/patologia , Camundongos , Mutação de Sentido Incorreto/genética , Fosfolipídeo Hidroperóxido Glutationa Peroxidase , Espécies Reativas de Oxigênio , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Although cell-cycle arrest, senescence, and apoptosis are established mechanisms of tumor suppression, accumulating evidence reveals that ferroptosis, an iron-dependent, nonapoptotic form of cell death, represents a new regulatory pathway in suppressing tumor development. Ferroptosis is triggered by lipid peroxidation and is tightly regulated by SLC7A11, a key component of the cystine-glutamate antiporter. Although many studies demonstrate the importance of transcriptional regulation of SLC7A11 in ferroptotic responses, it remains largely unknown how the stability of SLC7A11 is controlled in human cancers. In this study, we utilized biochemial purification to identify the ubiquitin hydrolase OTUB1 as a key factor in modulating SLC7A11 stability. OTUB1 directly interacted with and stabilized SLC7A11; conversely, OTUB1 knockdown diminished SLC7A11 levels in cancer cells. OTUB1 was overexpressed in human cancers, and inactivation of OTUB1 destabilized SLC7A11 and led to growth suppression of tumor xenografts in mice, which was associated with reduced activation of ferroptosis. Notably, overexpression of the cancer stem cell marker CD44 enhanced the stability of SLC7A11 by promoting the interaction between SLC7A11 and OTUB1; depletion of CD44 partially abrogated this interaction. CD44 expression suppressed ferroptosis in cancer cells in an OTUB1-dependent manner. Together, these results show that OTUB1 plays an essential role in controlling the stability of SLC7A11 and the CD44-mediated effects on ferroptosis in human cancers. SIGNIFICANCE: This study identifies OTUB1 as a key regulator of ferroptosis and implicates it as a potential target in cancer therapy.See related commentary by Gan, p. 1749.
Assuntos
Sistema y+ de Transporte de Aminoácidos , Neoplasias , Animais , Apoptose , Morte Celular , Humanos , Ferro , Peroxidação de Lipídeos , CamundongosRESUMO
NRF2 (nuclear factor erythroid 2-related factor 2) is a transcription factor which plays a major role in oxidative stress responses by regulating antioxidant gene expression. We have recently identified the ARF tumor suppressor as a key regulator of NRF2. ARF can significantly inhibit NRF2 transcriptional activities, and the ARF-NRF2 interaction may function as a novel checkpoint for oxidative stress responses.
RESUMO
Inhibition of Mdm2 function is a validated approach to restore p53 activity for cancer therapy; nevertheless, inhibitors of Mdm2 such as Nutlin-3 have certain limitations, suggesting that additional targets in this pathway need to be further elucidated. Our finding that the Herpesvirus-Associated Ubiquitin-Specific Protease (HAUSP, also called USP7) interacts with the p53/Mdm2 protein complex, was one of the first examples that deubiquitinases (DUBs) exhibit a specific role in regulating protein stability. Here, we show that inhibitors of HAUSP and Nutlin-3 can synergistically activate p53 function and induce p53-dependent apoptosis in human cancer cells. Notably, HAUSP can also target the N-Myc oncoprotein in a p53-independent manner. Moreover, newly synthesized HAUSP inhibitors are more potent than the commercially available inhibitors to suppress N-Myc activities in p53 mutant cells for growth suppression. Taken together, our study demonstrates the utility of HAUSP inhibitors to target cancers in both a p53-depdentent and -independent manner.
Assuntos
Antineoplásicos/farmacologia , Regulação Neoplásica da Expressão Gênica , Inibidores de Proteases/farmacologia , Proteínas Proto-Oncogênicas c-mdm2/genética , Proteína Supressora de Tumor p53/genética , Peptidase 7 Específica de Ubiquitina/genética , Apoptose , Linhagem Celular Tumoral , Células HCT116 , Humanos , Imidazóis/farmacologia , Indenos/farmacologia , Terapia de Alvo Molecular , Proteína Proto-Oncogênica N-Myc/genética , Proteína Proto-Oncogênica N-Myc/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Neurônios/patologia , Piperazinas/farmacologia , Estabilidade Proteica , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Pirazinas/farmacologia , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Tiofenos/farmacologia , Proteína Supressora de Tumor p53/deficiência , Peptidase 7 Específica de Ubiquitina/antagonistas & inibidores , Peptidase 7 Específica de Ubiquitina/metabolismoRESUMO
Mdm2 and Mdmx, both major repressors of p53 in human cancers, are predominantly localized to the nucleus and cytoplasm, respectively. The mechanism by which subcellular localization of Mdmx is regulated remains unclear. In this study, we identify the E3 ligase Peli1 as a major binding partner and regulator of Mdmx in human cells. Peli1 bound Mdmx in vitro and in vivo and promoted high levels of ubiquitination of Mdmx. Peli1-mediated ubiquitination was degradation-independent, promoting cytoplasmic localization of Mdmx, which in turn resulted in p53 activation. Consistent with this, knockdown or knockout Peli1 in human cancer cells induced nuclear localization of Mdmx and suppressed p53 activity. Myc-induced tumorigenesis was accelerated in Peli1-null mice and associated with downregulation of p53 function. Clinical samples of human cutaneous melanoma had decreased Peli1 expression, which was associated with poor overall survival. Together, these results demonstrate that Peli1 acts as a critical factor for the Mdmx-p53 axis by modulating the subcellular localization and activity of Mdmx, thus revealing a novel mechanism of Mdmx deregulation in human cancers.Significance: Peli1-mediated regulation of Mdmx, a major inhibitor of p53, provides critical insight into activation of p53 function in human cancers. Cancer Res; 78(11); 2897-910. ©2018 AACR.
Assuntos
Melanoma/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Neoplasias Cutâneas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Proteínas de Ciclo Celular , Linhagem Celular , Linhagem Celular Tumoral , Citoplasma/metabolismo , Células HEK293 , Humanos , Camundongos , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Ubiquitinação/fisiologia , Melanoma Maligno CutâneoRESUMO
BACKGROUND: It has been reported that USP7 (ubiquitin-specific protease 7) prevents ubiquitylation and degradation of DNA methyltransferase 1 (DNMT1) by direct binding of USP7 to the glycine-lysine (GK) repeats that join the N-terminal regulatory domain of DNMT1 to the C-terminal methyltransferase domain. The USP7-DNMT1 interaction was reported to be mediated by acetylation of lysine residues within the (GK) repeats. RESULTS: We found that DNMT1 is present at normal levels in mouse and human cells that contain undetectable levels of USP7. Substitution of the (GK) repeats by (GQ) repeats prevents lysine acetylation but does not affect the stability of DNMT1 or the ability of the mutant protein to restore genomic methylation levels when expressed in Dnmt1-null ES cells. Furthermore, both USP7 and PCNA are recruited to sites of DNA replication independently of the presence of DNMT1, and there is no evidence that DNMT1 is degraded in cycling cells after S phase. CONCLUSIONS: Multiple lines of evidence indicate that homeostasis of DNMT1 in somatic cells is controlled primarily at the level of transcription and that interaction of USP7 with the (GK) repeats of DNMT1 is unlikely to play a major role in the stabilization of DNMT1 protein.
Assuntos
DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Replicação do DNA , DNA/genética , Lisina/química , Peptidase 7 Específica de Ubiquitina/metabolismo , Acetilação , Animais , Sítios de Ligação , Linhagem Celular , DNA (Citosina-5-)-Metiltransferase 1/química , Humanos , Camundongos , Células-Tronco Embrionárias Murinas , Mutação , Ligação Proteica , Estabilidade Proteica , Peptidase 7 Específica de Ubiquitina/químicaRESUMO
Although ARF can suppress tumor growth by activating p53 function, the mechanisms by which it suppresses tumor growth independently of p53 are not well understood. Here, we identified ARF as a key regulator of nuclear factor E2-related factor 2 (NRF2) through complex purification. ARF inhibits the ability of NRF2 to transcriptionally activate its target genes, including SLC7A11, a component of the cystine/glutamate antiporter that regulates reactive oxygen species (ROS)-induced ferroptosis. As a consequence, ARF expression sensitizes cells to ferroptosis in a p53-independent manner while ARF depletion induces NRF2 activation and promotes cancer cell survival in response to oxidative stress. Moreover, the ability of ARF to induce p53-independent tumor growth suppression in mouse xenograft models is significantly abrogated upon NRF2 overexpression. These results demonstrate that NRF2 is a major target of p53-independent tumor suppression by ARF and also suggest that the ARF-NRF2 interaction acts as a new checkpoint for oxidative stress responses.
Assuntos
Sistema y+ de Transporte de Aminoácidos/genética , Neoplasias Ósseas/genética , Inibidor de Quinase Dependente de Ciclina p18/genética , Regulação Neoplásica da Expressão Gênica , Fator 2 Relacionado a NF-E2/genética , Sistema y+ de Transporte de Aminoácidos/metabolismo , Animais , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Inibidor p16 de Quinase Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p18/metabolismo , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Células HEK293 , Xenoenxertos , Humanos , Camundongos , Camundongos Nus , Fator 2 Relacionado a NF-E2/metabolismo , Osteoblastos/metabolismo , Osteoblastos/patologia , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
Acetylation of non-histone proteins plays important roles in regulating protein functions but the mechanisms of action are poorly understood. Our recent study uncovered a previously unknown mechanism by which C-terminal domain (CTD) acetylation of p53 serves as a "switch" to determine the interaction between a unique group of acidic domain-containing proteins and p53, as well as revealed that acidic domains may act as a novel class of "readers" for unacetylated p53. However, the properties of acidic domain "readers" are not well elucidated yet. Here, we identified that the charge effect between acidic domain "readers" and the p53 CTD is necessary for their interaction. Both the length and the amino acid composition of a given acidic domain contributed to its ability to recognize the p53 CTD. Finally, we summarized the characteristic features of our identified acidic domains, which would distinguish this kind of "readers" from other types of acidic amino acid-containing domains.