RESUMO
The SWI/SNF chromatin remodeler family includes the BAF and PBAF complexes. ARID2, encoding a PBAF complex subunit, is frequently mutated in melanoma independently of BRAF/RAS mutations. Emerging evidence shows that SWI/SNF complexes regulate tumor immunity; for instance, the loss of PBRM1, another PBAF complex subunit, enhances susceptibility to immune checkpoint inhibitors in melanoma. Notably, ARID2 mutations are more frequent in melanoma than PBRM1 mutations. However, the role of ARID2 as a modulator of tumor immunity remains unclear. In this study, we show that ARID2 knockout sensitizes melanoma to immune checkpoint inhibitors. AntiâPD-L1 treatment restricts tumor growth in mice bearing ARID2-knockout melanoma cells, correlating with an increase in the infiltration of cytotoxic CD8+ T cells. Furthermore, ARID2 deficiency leads to signal transducer and activator of transcription 1 upregulation, which subsequently causes increased expression of T-cellâattracting chemokines such as CXCL9, CXCL10, and CCL5. These results demonstrate that ARID2 is an immunomodulator and a potential biomarker that indicates immune checkpoint inhibitor effectiveness in patients with melanoma.
Assuntos
Resistencia a Medicamentos Antineoplásicos/genética , Inibidores de Checkpoint Imunológico/farmacologia , Melanoma/tratamento farmacológico , Neoplasias Cutâneas/tratamento farmacológico , Fatores de Transcrição/deficiência , Animais , Modelos Animais de Doenças , Técnicas de Inativação de Genes , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Melanoma/genética , Melanoma/imunologia , Melanoma/patologia , Camundongos , Mutação , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/imunologia , Neoplasias Cutâneas/patologia , Fatores de Transcrição/genéticaRESUMO
Alterations in components of the SWI/SNF chromatin-remodeling complex occur in ~20% of all human cancers. For example, ARID1A is mutated in up to 62% of clear cell ovarian carcinoma (OCCC), a disease currently lacking effective therapies. Here we show that ARID1A mutation creates a dependence on glutamine metabolism. SWI/SNF represses glutaminase (GLS1) and ARID1A inactivation upregulates GLS1. ARID1A inactivation increases glutamine utilization and metabolism through the tricarboxylic acid cycle to support aspartate synthesis. Indeed, glutaminase inhibitor CB-839 suppresses the growth of ARID1A mutant, but not wildtype, OCCCs in both orthotopic and patient-derived xenografts. In addition, glutaminase inhibitor CB-839 synergizes with immune checkpoint blockade anti-PDL1 antibody in a genetic OCCC mouse model driven by conditional Arid1a inactivation. Our data indicate that pharmacological inhibition of glutaminase alone or in combination with immune checkpoint blockade represents an effective therapeutic strategy for cancers involving alterations in the SWI/SNF complex such as ARID1A mutations.
Assuntos
Adenocarcinoma de Células Claras , Neoplasias Ovarianas , Adenocarcinoma de Células Claras/tratamento farmacológico , Animais , Proteínas de Ligação a DNA/genética , Feminino , Glutaminase/genética , Glutamina/uso terapêutico , Humanos , Inibidores de Checkpoint Imunológico , Camundongos , Proteínas Nucleares/genética , Neoplasias Ovarianas/tratamento farmacológico , Fatores de Transcrição/genéticaRESUMO
Epithelial ovarian cancer (EOC) is the most lethal of gynecologic malignancies. The standard-of-care treatment for EOC is platinum-based chemotherapy such as cisplatin. Platinum-based chemotherapy induces cellular senescence. Notably, therapy-induced senescence contributes to chemoresistance by inducing cancer stem-like cells (CSC). However, therapeutic approaches targeting senescence-associated CSCs remain to be explored. Here, we show that nicotinamide phosphoribosyltransferase (NAMPT) inhibition suppresses senescence-associated CSCs induced by platinum-based chemotherapy in EOC. Clinically applicable NAMPT inhibitors suppressed the outgrowth of cisplatin-treated EOC cells both in vitro and in vivo. Moreover, a combination of the NAMPT inhibitor FK866 and cisplatin improved the survival of EOC-bearing mice. These phenotypes correlated with inhibition of the CSCs signature, which consists of elevated expression of ALDH1A1 and stem-related genes, high aldehyde dehydrogenase activity, and CD133 positivity. Mechanistically, NAMPT regulates EOC CSCs in a paracrine manner through the senescence-associated secretory phenotype. Our results suggest that targeting NAMPT using clinically applicable NAMPT inhibitors, such as FK866, in conjunction with platinum-based chemotherapy represents a promising therapeutic strategy by suppressing therapy-induced senescence-associated CSCs. SIGNIFICANCE: This study highlights the importance of NAMPT-mediated NAD+ biosynthesis in the production of cisplatin-induced senescence-associated cancer stem cells, as well as tumor relapse after cisplatin treatment.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Carcinoma Epitelial do Ovário/tratamento farmacológico , Citocinas/antagonistas & inibidores , Células-Tronco Neoplásicas/efeitos dos fármacos , Nicotinamida Fosforribosiltransferase/antagonistas & inibidores , Neoplasias Ovarianas/tratamento farmacológico , Acrilamidas/farmacologia , Acrilamidas/uso terapêutico , Família Aldeído Desidrogenase 1/metabolismo , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma Epitelial do Ovário/patologia , Linhagem Celular Tumoral , Senescência Celular/efeitos dos fármacos , Cisplatino/farmacologia , Cisplatino/uso terapêutico , Citocinas/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Humanos , Camundongos , Células-Tronco Neoplásicas/patologia , Nicotinamida Fosforribosiltransferase/metabolismo , Neoplasias Ovarianas/patologia , Piperidinas/farmacologia , Piperidinas/uso terapêutico , Retinal Desidrogenase/metabolismo , Esferoides Celulares , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Cyclic cGMP-AMP synthase (cGAS) is a pattern recognition cytosolic DNA sensor that is essential for cellular senescence. cGAS promotes inflammatory senescence-associated secretory phenotype (SASP) through recognizing cytoplasmic chromatin during senescence. cGAS-mediated inflammation is essential for the antitumor effects of immune checkpoint blockade. However, the mechanism by which cGAS recognizes cytoplasmic chromatin is unknown. Here we show that topoisomerase 1-DNA covalent cleavage complex (TOP1cc) is both necessary and sufficient for cGAS-mediated cytoplasmic chromatin recognition and SASP during senescence. TOP1cc localizes to cytoplasmic chromatin and TOP1 interacts with cGAS to enhance the binding of cGAS to DNA. Retention of TOP1cc to cytoplasmic chromatin depends on its stabilization by the chromatin architecture protein HMGB2. Functionally, the HMGB2-TOP1cc-cGAS axis determines the response of orthotopically transplanted ex vivo therapy-induced senescent cells to immune checkpoint blockade in vivo. Together, these findings establish a HMGB2-TOP1cc-cGAS axis that enables cytoplasmic chromatin recognition and response to immune checkpoint blockade.
Assuntos
Senescência Celular/imunologia , DNA Topoisomerases Tipo I/metabolismo , Proteína HMGB2/metabolismo , Nucleotidiltransferases/metabolismo , Animais , Antígeno B7-H1/imunologia , Linhagem Celular , Cromatina/imunologia , Cromatina/metabolismo , Citosol/imunologia , Citosol/metabolismo , DNA/imunologia , DNA/metabolismo , Dano ao DNA/imunologia , DNA Topoisomerases Tipo I/genética , Técnicas de Silenciamento de Genes , Proteína HMGB2/genética , Humanos , Inflamação , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Neoplasias/imunologia , Nucleotidiltransferases/genética , Ligação Proteica , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
In response to DNA double-strand breaks, MAD2L2-containing shieldin complex plays a critical role in the choice between homologous recombination (HR) and non-homologous end-joining (NHEJ)-mediated repair. Here we show that EZH2 inhibition upregulates MAD2L2 and sensitizes HR-proficient epithelial ovarian cancer (EOC) to poly(adenosine diphosphate-ribose) polymerase (PARP) inhibitor in a CARM1-dependent manner. CARM1 promotes MAD2L2 silencing by driving the switch from the SWI/SNF complex to EZH2 through methylating the BAF155 subunit of the SWI/SNF complex on the MAD2L2 promoter. EZH2 inhibition upregulates MAD2L2 to decrease DNA end resection, which increases NHEJ and chromosomal abnormalities, ultimately causing mitotic catastrophe in PARP inhibitor treated HR-proficient cells. Significantly, EZH2 inhibitor sensitizes CARM1-high, but not CARM-low, EOCs to PARP inhibitors in both orthotopic and patient-derived xenografts.
Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Recombinação Homóloga/efeitos dos fármacos , Neoplasias Ovarianas/tratamento farmacológico , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Antineoplásicos/uso terapêutico , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA por Junção de Extremidades/efeitos dos fármacos , Inibidores Enzimáticos/uso terapêutico , Feminino , Humanos , Neoplasias Ovarianas/genética , Proteína-Arginina N-Metiltransferases/efeitos dos fármacos , Reparo de DNA por Recombinação/efeitos dos fármacosRESUMO
Despite the high initial response rates to PARP inhibitors (PARPi) in BRCA-mutated epithelial ovarian cancers (EOC), PARPi resistance remains a major challenge. Chemical modifications of RNAs have emerged as a new layer of epigenetic gene regulation. N6-methyladenosine (m6A) is the most abundant chemical modification of mRNA, yet the role of m6A modification in PARPi resistance has not previously been explored. Here, we show that m6A modification of FZD10 mRNA contributes to PARPi resistance by upregulating the Wnt/ß-catenin pathway in BRCA-mutated EOC cells. Global m6A profile revealed a significant increase in m6A modification in FZD10 mRNA, which correlated with increased FZD10 mRNA stability and an upregulation of the Wnt/ß-catenin pathway. Depletion of FZD10 or inhibition of the Wnt/ß-catenin sensitizes resistant cells to PARPi. Mechanistically, downregulation of m6A demethylases FTO and ALKBH5 was sufficient to increase FZD10 mRNA m6A modification and reduce PARPi sensitivity, which correlated with an increase in homologous recombination activity. Moreover, combined inhibition of PARP and Wnt/ß-catenin showed synergistic suppression of PARPi-resistant cells in vitro and in vivo in a xenograft EOC mouse model. Overall, our results show that m6A contributes to PARPi resistance in BRCA-deficient EOC cells by upregulating the Wnt/ß-catenin pathway via stabilization of FZD10. They also suggest that inhibition of the Wnt/ß-catenin pathway represents a potential strategy to overcome PARPi resistance. SIGNIFICANCE: These findings elucidate a novel regulatory mechanism of PARPi resistance in EOC by showing that m6A modification of FZD10 mRNA contributes to PARPi resistance in BRCA-deficient EOC cells via upregulation of Wnt/ß-catenin pathway.
Assuntos
Adenosina/metabolismo , Resistencia a Medicamentos Antineoplásicos/genética , Receptores Frizzled/genética , Neoplasias Ovarianas/tratamento farmacológico , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Homólogo AlkB 5 da RNA Desmetilase/genética , Dioxigenase FTO Dependente de alfa-Cetoglutarato/genética , Animais , Proteína BRCA2/genética , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Receptores Frizzled/metabolismo , Compostos Heterocíclicos com 3 Anéis/farmacologia , Humanos , Metilação , Camundongos SCID , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Ftalazinas/farmacologia , Piperazinas/farmacologia , RNA Mensageiro/metabolismo , Via de Sinalização Wnt/efeitos dos fármacos , Via de Sinalização Wnt/genética , Ensaios Antitumorais Modelo de Xenoenxerto , beta Catenina/genética , beta Catenina/metabolismoRESUMO
ARID1A, encoding a subunit of the SWI/SNF complex, is the most frequently mutated epigenetic regulator in human cancers and is mutated in more than 50% of ovarian clear cell carcinomas (OCCC), a disease that currently has no effective therapy. Inhibition of histone deacetylase 6 (HDAC6) suppresses the growth of ARID1A-mutated tumors and modulates tumor immune microenvironment. Here, we show that inhibition of HDAC6 synergizes with anti-PD-L1 immune checkpoint blockade in ARID1A-inactivated ovarian cancer. ARID1A directly repressed transcription of CD274, the gene encoding PD-L1. Reduced tumor burden and improved survival were observed in ARID1Aflox/flox/PIK3CAH1047R OCCC mice treated with the HDAC6 inhibitor ACY1215 and anti-PD-L1 immune checkpoint blockade as a result of activation and increased presence of IFNγ-positive CD8 T cells. We confirmed that the combined treatment limited tumor progression in a cytotoxic T-cell-dependent manner, as depletion of CD8+ T cells abrogated these antitumor effects. Together, these findings indicate that combined HDAC6 inhibition and immune checkpoint blockade represents a potential treatment strategy for ARID1A-mutated cancers. SIGNIFICANCE: These findings offer a mechanistic rationale for combining epigenetic modulators and existing immunotherapeutic interventions against a disease that has been so far resistant to checkpoint blockade as a monotherapy.See related commentary by Prokunina-Olsson, p. 5476.
Assuntos
Adenocarcinoma de Células Claras , Neoplasias Ovarianas , Animais , Antígeno B7-H1 , Linfócitos T CD8-Positivos , Proteínas de Ligação a DNA , Feminino , Desacetilase 6 de Histona , Humanos , Camundongos , Proteínas Nucleares , Fatores de Transcrição , Microambiente TumoralRESUMO
Cellular senescence is a stable growth arrest that is implicated in tissue ageing and cancer. Senescent cells are characterized by an upregulation of proinflammatory cytokines, which is termed the senescence-associated secretory phenotype (SASP). NAD+ metabolism influences both tissue ageing and cancer. However, the role of NAD+ metabolism in regulating the SASP is poorly understood. Here, we show that nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD+ salvage pathway, governs the proinflammatory SASP independent of senescence-associated growth arrest. NAMPT expression is regulated by high mobility group A (HMGA) proteins during senescence. The HMGA-NAMPT-NAD+ signalling axis promotes the proinflammatory SASP by enhancing glycolysis and mitochondrial respiration. HMGA proteins and NAMPT promote the proinflammatory SASP through NAD+-mediated suppression of AMPK kinase, which suppresses the p53-mediated inhibition of p38 MAPK to enhance NF-κB activity. We conclude that NAD+ metabolism governs the proinflammatory SASP. Given the tumour-promoting effects of the proinflammatory SASP, our results suggest that anti-ageing dietary NAD+ augmentation should be administered with precision.
Assuntos
Senescência Celular , Citocinas/metabolismo , Mediadores da Inflamação/metabolismo , NAD/metabolismo , Animais , Linhagem Celular , Citocinas/genética , Fibroblastos/metabolismo , Regulação da Expressão Gênica , Humanos , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Nicotinamida Fosforribosiltransferase/genética , Nicotinamida Fosforribosiltransferase/metabolismo , Fenótipo , Transdução de Sinais , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
ARID1A, a subunit of the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin-remodeling complex, localizes to both promoters and enhancers to influence transcription. However, the role of ARID1A in higher-order spatial chromosome partitioning and genome organization is unknown. Here, we show that ARID1A spatially partitions interphase chromosomes and regulates higher-order genome organization. The SWI/SNF complex interacts with condensin II, and they display significant colocalizations at enhancers. ARID1A knockout drives the redistribution of condensin II preferentially at enhancers, which positively correlates with changes in transcription. ARID1A and condensin II contribute to transcriptionally inactive B-compartment formation, while ARID1A weakens the border strength of topologically associated domains. Condensin II redistribution induced by ARID1A knockout positively correlates with chromosome sizes, which negatively correlates with interchromosomal interactions. ARID1A loss increases the trans interactions of small chromosomes, which was validated by three-dimensional interphase chromosome painting. These results demonstrate that ARID1A is important for large-scale genome folding and spatially partitions interphase chromosomes.
Assuntos
Cromossomos/ultraestrutura , Proteínas de Ligação a DNA/fisiologia , Interfase/genética , Fatores de Transcrição/fisiologia , Adenosina Trifosfatases/química , Sítios de Ligação , Linhagem Celular Tumoral , Cromatina/química , Análise por Conglomerados , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Elementos Facilitadores Genéticos , Perfilação da Expressão Gênica , Humanos , Complexos Multiproteicos/química , Regiões Promotoras Genéticas , Ligação Proteica , RNA-Seq , Serina Endopeptidases/química , Fatores de Transcrição/genéticaRESUMO
ARID1A inactivation causes mitotic defects. Paradoxically, cancers with high ARID1A mutation rates typically lack copy number alterations (CNAs). Here, we show that ARID1A inactivation causes defects in telomere cohesion, which selectively eliminates gross chromosome aberrations during mitosis. ARID1A promotes the expression of cohesin subunit STAG1 that is specifically required for telomere cohesion. ARID1A inactivation causes telomere damage that can be rescued by STAG1 expression. Colony formation capability of single cells in G2/M, but not G1 phase, is significantly reduced by ARID1A inactivation. This correlates with an increase in apoptosis and a reduction in tumor growth. Compared with ARID1A wild-type tumors, ARID1A-mutated tumors display significantly less CNAs across multiple cancer types. Together, these results show that ARID1A inactivation is selective against gross chromosome aberrations through causing defects in telomere cohesion, which reconciles the long-standing paradox between the role of ARID1A in maintaining mitotic integrity and the lack of genomic instability in ARID1A-mutated cancers.
Assuntos
Instabilidade Genômica , Mutação , Proteínas Nucleares/genética , Neoplasias Ovarianas/genética , Telômero/genética , Fatores de Transcrição/genética , Animais , Apoptose/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Variações do Número de Cópias de DNA , Proteínas de Ligação a DNA , Feminino , Humanos , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Camundongos Transgênicos , Proteínas Nucleares/metabolismo , Neoplasias Ovarianas/metabolismo , Neoplasias Ovarianas/patologia , Telômero/metabolismo , Fatores de Transcrição/metabolismo , Transplante Heterólogo/métodos , Carga Tumoral/genética , CoesinasRESUMO
Inactivation of the subunits of SWI/SNF complex such as ARID1A is synthetically lethal with inhibition of EZH2 activity. However, mechanisms of de novo resistance to EZH2 inhibitors in cancers with inactivating SWI/SNF mutations are unknown. Here we show that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 drives resistance to EZH2 inhibitors in ARID1A-mutated cells. SMARCA4 loss upregulates anti-apoptotic genes in the EZH2 inhibitor-resistant cells. EZH2 inhibitor-resistant ARID1A-mutated cells are hypersensitive to BCL2 inhibitors such as ABT263. ABT263 is sufficient to overcome resistance to an EZH2 inhibitor. In addition, ABT263 synergizes with an EZH2 inhibitor in vivo in ARID1A-inactivated ovarian tumor mouse models. Together, these data establish that the switch of the SWI/SNF catalytic subunits from SMARCA4 to SMARCA2 underlies the acquired resistance to EZH2 inhibitors. They suggest BCL2 inhibition alone or in combination with EZH2 inhibition represents urgently needed therapeutic strategy for ARID1A-mutated cancers.
Assuntos
Proteínas Cromossômicas não Histona/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Indóis/farmacologia , Proteínas Nucleares/metabolismo , Piridonas/farmacologia , Fatores de Transcrição/metabolismo , Compostos de Anilina/administração & dosagem , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Linhagem Celular Tumoral , Proteínas Cromossômicas não Histona/genética , DNA Helicases/genética , DNA Helicases/metabolismo , Proteínas de Ligação a DNA , Resistencia a Medicamentos Antineoplásicos/genética , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Indóis/administração & dosagem , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Mutação , Proteínas Nucleares/genética , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , Piridonas/administração & dosagem , Sulfonamidas/administração & dosagem , Fatores de Transcrição/genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto/métodosRESUMO
ARID1A, a subunit of the SWI/SNF complex, is among the most frequently mutated genes across cancer types. ARID1A is mutated in more than 50% of ovarian clear cell carcinomas (OCCCs), diseases that have no effective therapy. Here, we show that ARID1A mutation confers sensitivity to pan-HDAC inhibitors such as SAHA in ovarian cancers. This correlated with enhanced growth suppression induced by the inhibition of HDAC2 activity in ARID1A-mutated cells. HDAC2 interacts with EZH2 in an ARID1A status-dependent manner. HDAC2 functions as a co-repressor of EZH2 to suppress the expression of EZH2/ARID1A target tumor suppressor genes such as PIK3IP1 to inhibit proliferation and promote apoptosis. SAHA reduced the growth and ascites of the ARID1A-inactivated OCCCs in both orthotopic and genetic mouse models. This correlated with a significant improvement of survival of mice bearing ARID1A-mutated OCCCs. These findings provided preclinical rationales for repurposing FDA-approved pan-HDAC inhibitors for treating ARID1A-mutated cancers.
Assuntos
Reposicionamento de Medicamentos , Inibidores de Histona Desacetilases/farmacologia , Mutação , Proteínas Nucleares/genética , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/genética , Fatores de Transcrição/genética , Animais , Proteínas de Ligação a DNA , Feminino , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Nucleares/metabolismo , Neoplasias Ovarianas/patologia , Fatores de Transcrição/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
PARP inhibition is known to be an effective clinical strategy in BRCA mutant cancers, but PARP inhibition has not been applied to BRCA-proficient tumors. Here, we show the synergy of BET bromodomain inhibition with PARP inhibition in BRCA-proficient ovarian cancers due to mitotic catastrophe. Treatment of BRCA-proficient ovarian cancer cells with the BET inhibitor JQ1 downregulated the G2-M cell-cycle checkpoint regulator WEE1 and the DNA-damage response factor TOPBP1. Combining PARP inhibitor Olaparib with the BET inhibitor, we observed a synergistic increase in DNA damage and checkpoint defects, which allowed cells to enter mitosis despite the accumulation of DNA damage, ultimately causing mitotic catastrophe. Moreover, JQ1 and Olaparib showed synergistic suppression of growth of BRCA-proficient cancer in vivo in a xenograft ovarian cancer mouse model. Our findings indicate that a combination of BET inhibitor and PARP inhibitor represents a potential therapeutic strategy for BRCA-proficient cancers.
Assuntos
Azepinas/farmacologia , Neoplasias Ovarianas/metabolismo , Ftalazinas/farmacologia , Piperazinas/farmacologia , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , Proteínas/antagonistas & inibidores , Triazóis/farmacologia , Animais , Proteína BRCA1/genética , Proteína BRCA2/genética , Ciclo Celular/efeitos dos fármacos , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Dano ao DNA , Sinergismo Farmacológico , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Feminino , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Proteínas Nucleares/metabolismo , Neoplasias Ovarianas/genética , Poli(ADP-Ribose) Polimerases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Proteínas/metabolismoRESUMO
UNLABELLED: The majority of patients with melanoma harbor mutations in the BRAF oncogene, thus making it a clinically relevant target. However, response to mutant BRAF inhibitors (BRAFi) is relatively short-lived with progression-free survival of only 6 to 7 months. Previously, we reported high expression of ribonucleotide reductase M2 (RRM2), which is rate-limiting for de novo dNTP synthesis, as a poor prognostic factor in patients with mutant BRAF melanoma. In this study, the notion that targeting de novo dNTP synthesis through knockdown of RRM2 could prolong the response of melanoma cells to BRAFi was investigated. Knockdown of RRM2 in combination with the mutant BRAFi PLX4720 (an analog of the FDA-approved drug vemurafenib) inhibited melanoma cell proliferation to a greater extent than either treatment alone. This occurred in vitro in multiple mutant BRAF cell lines and in a novel patient-derived xenograft (PDX) model system. Mechanistically, the combination increased DNA damage accumulation, which correlated with a global decrease in DNA damage repair (DDR) gene expression and increased apoptotic markers. After discontinuing PLX4720 treatment, cells showed marked recurrence. However, knockdown of RRM2 attenuated this rebound growth both in vitro and in vivo, which correlated with maintenance of the senescence-associated cell-cycle arrest. IMPLICATIONS: Inhibition of RRM2 converts the transient response of melanoma cells to BRAFi to a stable response and may be a novel combinatorial strategy to prolong therapeutic response of patients with melanoma. Mol Cancer Res; 14(9); 767-75. ©2016 AACR.
Assuntos
Melanoma/terapia , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Ribonucleosídeo Difosfato Redutase/genética , Animais , Processos de Crescimento Celular/efeitos dos fármacos , Processos de Crescimento Celular/genética , Linhagem Celular Tumoral , Técnicas de Silenciamento de Genes , Humanos , Indóis/farmacologia , Masculino , Melanoma/enzimologia , Melanoma/genética , Melanoma/patologia , Camundongos , Terapia de Alvo Molecular , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas B-raf/genética , Distribuição Aleatória , Ribonucleosídeo Difosfato Redutase/deficiência , Sulfonamidas/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Cellular senescence is a stable cell growth arrest that is characterized by the silencing of proliferation-promoting genes through compaction of chromosomes into senescence-associated heterochromatin foci (SAHF). Paradoxically, senescence is also accompanied by increased transcription of certain genes encoding for secreted factors such as cytokines and chemokines, known as the senescence-associated secretory phenotype (SASP). How SASP genes are excluded from SAHF-mediated global gene silencing remains unclear. In this study, we report that high mobility group box 2 (HMGB2) orchestrates the chromatin landscape of SASP gene loci. HMGB2 preferentially localizes to SASP gene loci during senescence. Loss of HMGB2 during senescence blunts SASP gene expression by allowing for spreading of repressive heterochromatin into SASP gene loci. This correlates with incorporation of SASP gene loci into SAHF. Our results establish HMGB2 as a novel master regulator that orchestrates SASP through prevention of heterochromatin spreading to allow for exclusion of SASP gene loci from a global heterochromatin environment during senescence.
Assuntos
Senescência Celular , Cromatina/metabolismo , Loci Gênicos , Proteína HMGB2/metabolismo , Via Secretória , Pontos de Checagem do Ciclo Celular/genética , Linhagem Celular , Senescência Celular/genética , Regulação da Expressão Gênica , Heterocromatina/metabolismo , Humanos , Fenótipo , Ligação Proteica , Via Secretória/genéticaRESUMO
ARID1A is a subunit of the Switch/Sucrose Non-Fermentable (SWI/SNF) chromatin-remodeling complex that regulates gene expression by controlling gene accessibility. ARID1A shows one of the highest mutation rates across different human cancer types. For example, ARID1A is mutated in â¼ 50% of ovarian clear cell carcinoma (OCCC). There is considerable interest in developing cancer therapeutics that correlate with ARID1A mutational status. A recent study demonstrated a synthetic lethality by targeting EZH2 histone methyltransferase activity in ARID1A-mutated OCCC using a clinically applicable small-molecule inhibitor. The observed synthetic lethality correlated with inhibition of PI3K/AKT signaling. In addition, there is evidence indicating that ARID1A-mutated cancer may also be subjected to therapeutic intervention by targeting residual SWI/SNF activity, the PI3K/AKT pathway, the DNA damage response, the tumor immunological microenvironment and stabilizing wild-type p53. In summary, we propose EZH2 inhibitor-based combinatorial strategies for targeting ARID1A-mutated cancers.