RESUMO
Bromodomain-containing protein 4 (BRD4) has emerged as a promising therapeutic target in prostate cancer (PCa). Understanding the mechanisms of BRD4 stability could enhance the clinical response to BRD4-targeted therapy. In this study, we report that BRD4 protein levels are significantly decreased during mitosis in a PLK1-dependent manner. Mechanistically, we show that BRD4 is primarily phosphorylated at T1186 by the CDK1/cyclin B complex, recruiting PLK1 to phosphorylate BRD4 at S24/S1100, which are recognized by the APC/CCdh1 complex for proteasome pathway degradation. We find that PLK1 overexpression lowers SPOP mutation-stabilized BRD4, consequently rendering PCa cells re-sensitized to BRD4 inhibitors. Intriguingly, we report that sequential treatment of docetaxel and JQ1 resulted in significant inhibition of PCa. Collectively, the results support that PLK1-phosphorylated BRD4 triggers its degradation at M phase. Sequential treatment of docetaxel and JQ1 overcomes BRD4 accumulation-associated bromodomain and extra-terminal inhibitor (BETi) resistance, which may shed light on the development of strategies to treat PCa.
Assuntos
Azepinas , Proteínas de Ciclo Celular , Docetaxel , Resistencia a Medicamentos Antineoplásicos , Mitose , Quinase 1 Polo-Like , Neoplasias da Próstata , Proteínas Serina-Treonina Quinases , Proteínas Proto-Oncogênicas , Fatores de Transcrição , Triazóis , Humanos , Proteínas de Ciclo Celular/metabolismo , Masculino , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/genética , Fosforilação , Proteínas Proto-Oncogênicas/metabolismo , Mitose/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Fatores de Transcrição/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Linhagem Celular Tumoral , Azepinas/farmacologia , Triazóis/farmacologia , Docetaxel/farmacologia , Proteólise/efeitos dos fármacos , Proteínas Nucleares/metabolismo , Animais , Proteína Quinase CDC2/metabolismo , Camundongos Nus , Camundongos , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas que Contêm Bromodomínio , Proteínas RepressorasRESUMO
BACKGROUND: Androgen signaling inhibitors (ASI) have been approved for treatment of metastatic castration-resistant prostate cancer (mCRPC). However, the limited success of ASI in clinic justifies an urgent need to identify new targets and develop novel approaches for treatment. EZH2 significantly increases in prostate cancer (PCa). Little is understood, however, regarding the roles of EZH2 in Enzalutamide-resistant (EnzR) mCRPC. METHODS: We firstly investigated the levels of EZH2 and the altered pathways in public database which was comprised with primary and metastatic PCa patient tumors. To elucidate the roles of EZH2 in mCRPC, we manipulated EZH2 in EnzR PCa cell lines to examine epithelial-mesenchymal transition (EMT). To dissect the underlying mechanisms, we measured the transcription levels of EMT-associated transcription factors (TFs). RESULTS: We found that EZH2 was highly expressed in mCRPC than that of primary PCa tumors and that EnzR PCa cells gained more EMT characteristics than those of enzalutamide-sensitive counterparts. Further, loss of EZH2-induced inhibition of EMT is independent of polycomb repressive complex 2 (PRC2). Mechanistically, downregulation of EZH2 inhibits transcription of EMT-associated TFs by repressing formation of H3K4me3 to the promotor regions of the TFs. CONCLUSION: We identified the novel roles of EZH2 in EnzR mCRPC. EnzR PCa gains more EMT properties than that of enzalutamide-sensitive PCa. Loss of EZH2-assocaited inhibition of EMT is PRC2 independent. Downregulation of EZH2 suppresses EMT by impairing formation of H3K4me3 at the promotor regions, thus repressing expression of EMT-associated TFs.
Assuntos
Neoplasias de Próstata Resistentes à Castração , Masculino , Humanos , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Neoplasias de Próstata Resistentes à Castração/metabolismo , Transição Epitelial-Mesenquimal , Regulação para Baixo , Linhagem Celular Tumoral , Nitrilas , Antagonistas de Androgênios/farmacologia , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismoRESUMO
CXCR7 is an atypical chemokine receptor that recruits ß-arrestin (ARRB2) and internalizes into clathrin-coated intracellular vesicles where the complex acts as a scaffold for cytoplasmic kinase assembly and signal transduction. Here, we report that CXCR7 was elevated in the majority of prostate cancer (PCa) cases with neuroendocrine features (NEPC). CXCR7 markedly induced mitotic spindle and cell cycle gene expression. Mechanistically, we identified Aurora Kinase A (AURKA), a key regulator of mitosis, as a novel target that was bound and activated by the CXCR7-ARRB2 complex. CXCR7 interacted with proteins associated with microtubules and golgi, and, as such, the CXCR7-ARRB2-containing vesicles trafficked along the microtubules to the pericentrosomal golgi apparatus, where the complex interacted with AURKA. Accordingly, CXCR7 promoted PCa cell proliferation and tumor growth, which was mitigated by AURKA inhibition. In summary, our study reveals a critical role of CXCR7-ARRB2 in interacting and activating AURKA, which can be targeted by AURKA inhibitors to benefit a subset of patients with NEPC.
Assuntos
Neoplasias da Próstata , Receptores CXCR , Masculino , Humanos , Aurora Quinase A/genética , Aurora Quinase A/metabolismo , Transdução de Sinais , Receptores CXCR/genética , Receptores CXCR/metabolismo , Neoplasias da Próstata/patologia , Proliferação de Células , Linhagem Celular TumoralRESUMO
OBJECTIVE: To determine the prevalence of mitochondrial diseases (MD) in Hong Kong (HK) and to evaluate the clinical characteristics and genetic landscape of MD patients in the region. METHODS: This study retrospectively reviewed the phenotypic and molecular characteristics of MD patients from participating public hospitals in HK between January 1985 to October 2020. Molecularly and/or enzymatically confirmed MD cases of any age were recruited via the Clinical Analysis and Reporting System (CDARS) using relevant keywords and/or International Classification of Disease (ICD) codes under the HK Hospital Authority or through the personal recollection of treating clinicians among the investigators. RESULTS: A total of 119 MD patients were recruited and analyzed in the study. The point prevalence of MD in HK was 1.02 in 100,000 people (95% confidence interval 0.81-1.28 in 100,000). 110 patients had molecularly proven MD and the other nine were diagnosed by OXPHOS enzymology analysis or mitochondrial DNA depletion analysis with unknown molecular basis. Pathogenic variants in the mitochondrial genome (72 patients) were more prevalent than those in the nuclear genome (38 patients) in our cohort. The most commonly involved organ system at disease onset was the neurological system, in which developmental delay, seizures or epilepsy, and stroke-like episodes were the most frequently reported presentations. The mortality rate in our cohort was 37%. CONCLUSION: This study is a territory-wide overview of the clinical and genetic characteristics of MD patients in a Chinese population, providing the first available prevalence rate of MD in Hong Kong. The findings of this study aim to facilitate future in-depth evaluation of MD and lay the foundation to establish a local MD registry.
Assuntos
Povo Asiático , Doenças Mitocondriais , Humanos , Hong Kong , Prevalência , Estudos RetrospectivosRESUMO
PALI1 is a newly identified accessory protein of the Polycomb repressive complex 2 (PRC2) that catalyzes H3K27 methylation. However, the roles of PALI1 in cancer are yet to be defined. Here, we report that PALI1 is upregulated in advanced prostate cancer (PCa) and competes with JARID2 for binding to the PRC2 core subunit SUZ12. PALI1 further interacts with the H3K9 methyltransferase G9A, bridging the formation of a unique G9A-PALI1-PRC2 super-complex that occupies a subset of G9A-target genes to mediate dual H3K9/K27 methylation and gene repression. Many of these genes are developmental regulators required for cell differentiation, and their loss in PCa predicts poor prognosis. Accordingly, PALI1 and G9A drive PCa cell proliferation and invasion in vitro and xenograft tumor growth in vivo. Collectively, our study shows that PALI1 harnesses two central epigenetic mechanisms to suppress cellular differentiation and promote tumorigenesis, which can be targeted by dual EZH2 and G9A inhibition.
Assuntos
Neoplasias , Complexo Repressor Polycomb 2 , Humanos , Complexo Repressor Polycomb 2/genética , Complexo Repressor Polycomb 2/metabolismo , Cromatina/genética , Histonas/genética , Histonas/metabolismo , Neoplasias/genética , Epigênese GenéticaRESUMO
Our understanding of prostate cancer (PCa) has shifted from solely caused by a few genetic aberrations to a combination of complex biochemical dysregulations with the prostate metabolome at its core. The role of metabolomics in analyzing the pathophysiology of PCa is indispensable. However, to fully elucidate real-time complex dysregulation in prostate cells, an integrated approach based on metabolomics and other omics is warranted. Individually, genomics, transcriptomics, and proteomics are robust, but they are not enough to achieve a holistic view of PCa tumorigenesis. This review is the first of its kind to focus solely on the integration of metabolomics with multi-omic platforms in PCa research, including a detailed emphasis on the metabolomic profile of PCa. The authors intend to provide researchers in the field with a comprehensive knowledge base in PCa metabolomics and offer perspectives on overcoming limitations of the tool to guide future point-of-care applications.
RESUMO
HOXB13, a homeodomain transcription factor, critically regulates androgen receptor (AR) activities and androgen-dependent prostate cancer (PCa) growth. However, its functions in AR-independent contexts remain elusive. Here we report HOXB13 interaction with histone deacetylase HDAC3, which is disrupted by the HOXB13 G84E mutation that has been associated with early-onset PCa. Independently of AR, HOXB13 recruits HDAC3 to lipogenic enhancers to catalyze histone deacetylation and suppress lipogenic regulators such as fatty acid synthase. Analysis of human tissues reveals that the HOXB13 gene is hypermethylated and downregulated in approximately 30% of metastatic castration-resistant PCa. HOXB13 loss or G84E mutation leads to lipid accumulation in PCa cells, thereby promoting cell motility and xenograft tumor metastasis, which is mitigated by pharmaceutical inhibition of fatty acid synthase. In summary, we present evidence that HOXB13 recruits HDAC3 to suppress de novo lipogenesis and inhibit tumor metastasis and that lipogenic pathway inhibitors may be useful to treat HOXB13-low PCa.
Assuntos
Histona Desacetilases , Proteínas de Homeodomínio , Lipogênese , Neoplasias da Próstata , Androgênios , Linhagem Celular Tumoral , Epigênese Genética , Histona Desacetilases/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Masculino , Neoplasias da Próstata/genética , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Fatores de Transcrição/genéticaRESUMO
The Polycomb group (PcG) protein Enhancer of Zeste Homolog 2 (EZH2) is one of the three core subunits of the Polycomb Repressive Complex 2 (PRC2). It harbors histone methyltransferase activity (MTase) that specifically catalyze histone 3 lysine 27 (H3K27) methylation on target gene promoters. As such, PRC2 are epigenetic silencers that play important roles in cellular identity and embryonic stem cell maintenance. In the past two decades, mounting evidence supports EZH2 mutations and/or over-expression in a wide array of hematological cancers and solid tumors, including prostate cancer. Further, EZH2 is among the most upregulated genes in neuroendocrine prostate cancers, which become abundant due to the clinical use of high-affinity androgen receptor pathway inhibitors. While numerous studies have reported epigenetic functions of EZH2 that inhibit tumor suppressor genes and promote tumorigenesis, discordance between EZH2 and H3K27 methylation has been reported. Further, enzymatic EZH2 inhibitors have shown limited efficacy in prostate cancer, warranting a more comprehensive understanding of EZH2 functions. Here we first review how canonical functions of EZH2 as a histone MTase are regulated and describe the various mechanisms of PRC2 recruitment to the chromatin. We further outline non-histone substrates of EZH2 and discuss post-translational modifications to EZH2 itself that may affect substrate preference. Lastly, we summarize non-canonical functions of EZH2, beyond its MTase activity and/or PRC2, as a transcriptional cofactor and discuss prospects of its therapeutic targeting in prostate cancer.
Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste , Epigênese Genética , Humanos , Masculino , Mutação , Complexo Repressor Polycomb 2 , Neoplasias da PróstataRESUMO
Forkhead box protein A1 (FOXA1) is essential for androgen-dependent prostate cancer (PCa) growth. However, how FOXA1 levels are regulated remains elusive and its therapeutic targeting proven challenging. Here, we report FOXA1 as a nonhistone substrate of enhancer of zeste homolog 2 (EZH2), which methylates FOXA1 at lysine-295. This methylation is recognized by WD40 repeat protein BUB3, which subsequently recruits ubiquitin-specific protease 7 (USP7) to remove ubiquitination and enhance FOXA1 protein stability. They functionally converge in regulating cell cycle genes and promoting PCa growth. FOXA1 is a major therapeutic target of the inhibitors of EZH2 methyltransferase activities in PCa. FOXA1-driven PCa growth can be effectively mitigated by EZH2 enzymatic inhibitors, either alone or in combination with USP7 inhibitors. Together, our study reports EZH2-catalyzed methylation as a key mechanism to FOXA1 protein stability, which may be leveraged to enhance therapeutic targeting of PCa using enzymatic EZH2 inhibitors.
RESUMO
Castration-resistant prostate cancer (CRPC) that has developed resistance to the new-generation androgen receptor (AR) antagonist enzalutamide is a lethal disease. Transcriptome analysis of multiple prostate cancer models identified CXCR7, an atypical chemokine receptor, as one of the most upregulated genes in enzalutamide-resistant cells. AR directly repressed CXCR7 by binding to an enhancer 110 kb downstream of the gene and expression was restored upon androgen deprivation. We demonstrate that CXCR7 is a critical regulator of prostate cancer sensitivity to enzalutamide and is required for CRPC growth in vitro and in vivo. Elevated CXCR7 activated MAPK/ERK signaling through ligand-independent, but ß-arrestin 2-dependent mechanisms. Examination of patient specimens showed that CXCR7 and pERK levels increased significantly from localized prostate cancer to CRPC and further upon enzalutamide resistance. Preclinical studies revealed remarkable efficacies of MAPK/ERK inhibitors in suppressing enzalutamide-resistant prostate cancer. Overall, these results indicate that CXCR7 may serve as a biomarker of resistant disease in patients with prostate cancer and that disruption of CXCR7 signaling may be an effective strategy to overcome resistance. SIGNIFICANCE: These findings identify CXCR7-mediated MAPK activation as a mechanism of resistance to second-generation antiandrogen therapy, highlighting the therapeutic potential of MAPK/ERK inhibitors in CRPC.
Assuntos
Antineoplásicos/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Sistema de Sinalização das MAP Quinases , Feniltioidantoína/análogos & derivados , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Receptores CXCR/genética , Animais , Benzamidas , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica , Nitrilas , Feniltioidantoína/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Piridonas/farmacologia , Pirimidinonas/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Prostate cancer (PC) progressed to castration resistance (CRPC) is a fatal disease. CRPC tumors develop resistance to new-generation antiandrogen enzalutamide through lineage plasticity, characterized by epithelial-mesenchymal transition (EMT) and a basal-like phenotype. FOXA1 is a transcription factor essential for epithelial lineage differentiation. Here, we demonstrate that FOXA1 loss leads to remarkable upregulation of transforming growth factor beta 3 (TGFB3), which encodes a ligand of the TGF-ß pathway. Mechanistically, this is due to genomic occupancy of FOXA1 on an upstream enhancer of the TGFB3 gene to directly inhibit its transcription. Functionally, FOXA1 downregulation induces TGF-ß signaling, EMT, and cell motility, which is effectively blocked by the TGF-ß receptor I inhibitor galunisertib (LY2157299). Tissue microarray analysis confirmed reduced levels of FOXA1 protein and a concordant increase in TGF-ß signaling, indicated by SMAD2 phosphorylation, in CRPC as compared with primary tumors. Importantly, combinatorial LY2157299 treatment sensitized PC cells to enzalutamide, leading to synergistic effects in inhibiting cell invasion in vitro and xenograft CRPC tumor growth and metastasis in vivo. Therefore, our study establishes FOXA1 as an important regulator of lineage plasticity mediated in part by TGF-ß signaling, and supports a novel therapeutic strategy to control lineage switching and potentially extend clinical response to antiandrogen therapies.
Assuntos
Fator 3-alfa Nuclear de Hepatócito , Proteínas de Neoplasias , Neoplasias de Próstata Resistentes à Castração , Pirazóis/farmacologia , Quinolinas/farmacologia , Transdução de Sinais , Fator de Crescimento Transformador beta3 , Animais , Linhagem Celular Tumoral , Perfilação da Expressão Gênica , Fator 3-alfa Nuclear de Hepatócito/antagonistas & inibidores , Fator 3-alfa Nuclear de Hepatócito/genética , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Humanos , Masculino , Camundongos , Camundongos SCID , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/genética , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Receptor do Fator de Crescimento Transformador beta Tipo I/antagonistas & inibidores , Receptor do Fator de Crescimento Transformador beta Tipo I/genética , Receptor do Fator de Crescimento Transformador beta Tipo I/metabolismo , Fator de Crescimento Transformador beta3/genética , Fator de Crescimento Transformador beta3/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Enhancer of Zeste 2 (EZH2) is the enzymatic subunit of Polycomb Repressive Complex 2 (PRC2), which catalyzes histone H3 lysine 27 trimethylation (H3K27me3) at target promoters for gene silencing. Here, we report that EZH2 activates androgen receptor (AR) gene transcription through direct occupancy at its promoter. Importantly, this activating role of EZH2 is independent of PRC2 and its methyltransferase activities. Genome-wide assays revealed extensive EZH2 occupancy at promoters marked by either H3K27ac or H3K27me3, leading to gene activation or repression, respectively. Last, we demonstrate enhanced efficacy of enzymatic EZH2 inhibitors when used in combination with AR antagonists in blocking the dual roles of EZH2 and suppressing prostate cancer progression in vitro and in vivo. Taken together, our study reports EZH2 as a transcriptional activator, a key target of which is AR, and suggests a drug-combinatory approach to treat advanced prostate cancer.
Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Transativadores/metabolismo , Androgênios/metabolismo , Animais , Sequência de Bases , Carcinogênese/metabolismo , Carcinogênese/patologia , Linhagem Celular Tumoral , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Histona Metiltransferases/metabolismo , Humanos , Masculino , Metilação , Camundongos Endogâmicos NOD , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Ligação Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Transdução de Sinais , Transcrição GênicaRESUMO
TRIM24 is an effector substrate of the E3 ubiquitin ligase adaptor SPOP and becomes stabilized in prostate cancer (PCa) with SPOP mutations. However, how TRIM24 protein is regulated in the vast majority of SPOP-wildtype PCa is unknown. Here we report TRIM28 as a critical upstream regulator of TRIM24. TRIM28 protein interacts with TRIM24 to prevent its ubiquitination and degradation by SPOP. Further, TRIM28 facilitates TRIM24 occupancy on the chromatin and, like TRIM24, augments AR signaling. TRIM28 promotes PCa cell proliferation in vitro and xenograft tumor growth in vivo. Importantly, TRIM28 is upregulated in aggressive PCa and associated with elevated levels of TRIM24 and worse clinical outcome. TRIM24 and AR coactivated gene signature of SPOP-mutant PCa is similarly activated in human PCa with high TRIM28 expression. Taken together, this study provides a novel mechanism to broad TRIM24 protein stabilization and establishes TRIM28 as a promising therapeutic target.
Assuntos
Proteínas de Transporte/metabolismo , Progressão da Doença , Proteínas Nucleares/metabolismo , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Proteólise , Proteínas Repressoras/metabolismo , Proteína 28 com Motivo Tripartido/metabolismo , Carcinogênese/patologia , Linhagem Celular Tumoral , Humanos , Masculino , Ligação Proteica , Estabilidade Proteica , Receptores Androgênicos/metabolismo , Transdução de Sinais , Transcrição Gênica , Ubiquitinação , Regulação para CimaRESUMO
Microtubules are polar cytoskeleton filaments that extend via growth at their plus ends. Microtubule plus-end-tracking proteins (+TIPs) accumulate at these growing plus ends to control microtubule dynamics and attachment. The +TIP end-binding protein 1 (EB1) and its homologs possess an autonomous plus-end-tracking mechanism and interact with other known +TIPs, which then recruit those +TIPs to the growing plus ends. A major +TIP class contains the SXIP (Ser-X-Ile-Pro, with X denoting any amino acid residue) motif, known to interact with EB1 and its homologs for plus-end tracking, but the role of SXIP in regulating EB1 activities is unclear. We show here that an interaction of EB1 with the SXIP-containing +TIP CDK5 regulatory subunit-associated protein 2 (CDK5RAP2) regulates several EB1 activities, including microtubule plus-end tracking, dynamics at microtubule plus ends, microtubule and α/ß-tubulin binding, and microtubule polymerization. The SXIP motif fused with a dimerization domain from CDK5RAP2 significantly enhanced EB1 plus-end-tracking and microtubule-polymerizing and bundling activities, but the SXIP motif alone failed to do so. An SXIP-binding-deficient EB1 mutant displayed significantly lower microtubule plus-end tracking than the wild-type protein in transfected cells. These results suggest that EB1 cooperates with CDK5RAP2 and perhaps other SXIP-containing +TIPs in tracking growing microtubule tips. We also generated plus-end-tracking chimeras of CDK5RAP2 and the adenomatous polyposis coli protein (APC) and found that overexpression of the dimerization domains interfered with microtubule plus-end tracking of their respective SXIP-containing chimeras. Our results suggest that disruption of SXIP dimerization enables detailed investigations of microtubule plus-end-associated functions of individual SXIP-containing +TIPs.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Multimerização Proteica/fisiologia , Proteína da Polipose Adenomatosa do Colo/genética , Proteína da Polipose Adenomatosa do Colo/metabolismo , Motivos de Aminoácidos , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Associadas aos Microtúbulos/genética , Microtúbulos/genética , Proteínas do Tecido Nervoso/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
The lethal phenotype of castration-resistant prostate cancer (CRPC) is generally caused by augmented signaling from the androgen receptor (AR). Here, we report that the AR-repressed gene CCN3/NOV inhibits AR signaling and acts in a negative feedback loop to block AR function. Mechanistically, a cytoplasmic form of CCN3 interacted with the AR N-terminal domain to sequester AR in the cytoplasm of prostate cancer cells, thereby reducing AR transcriptional activity and inhibiting cell growth. However, constitutive repression of CCN3 by the Polycomb group protein EZH2 disrupted this negative feedback loop in both CRPC and enzalutamide-resistant prostate cancer cells. Notably, restoring CCN3 was sufficient to effectively reduce CPRC cell proliferation in vitro and to abolish xenograft tumor growth in vivo Taken together, our findings establish CCN3 as a pivotal regulator of AR signaling and prostate cancer progression and suggest a functional intersection between Polycomb and AR signaling in CRPC. Cancer Res; 77(2); 412-22. ©2016 AACR.
Assuntos
Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Proteína Sobre-Expressa em Nefroblastoma/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Receptores Androgênicos/metabolismo , Animais , Western Blotting , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Retroalimentação Fisiológica/fisiologia , Xenoenxertos , Humanos , Imunoprecipitação , Masculino , Camundongos , Reação em Cadeia da Polimerase , Neoplasias de Próstata Resistentes à Castração/metabolismoRESUMO
Forkhead box A1 (FOXA1) is an FKHD family protein that plays pioneering roles in lineage-specific enhancer activation and gene transcription. Through genome-wide location analyses, here we show that FOXA1 expression and occupancy are, in turn, required for the maintenance of these epigenetic signatures, namely DNA hypomethylation and histone 3 lysine 4 methylation. Mechanistically, this involves TET1, a 5-methylcytosine dioxygenase. We found that FOXA1 induces TET1 expression via direct binding to its cis-regulatory elements. Further, FOXA1 physically interacts with the TET1 protein through its CXXC domain. TET1 thus co-occupies FOXA1-dependent enhancers and mediates local DNA demethylation and concomitant histone 3 lysine 4 methylation, further potentiating FOXA1 recruitment. Consequently, FOXA1 binding events are markedly reduced following TET1 depletion. Together, our results suggest that FOXA1 is not only able to recognize but also remodel the epigenetic signatures at lineage-specific enhancers, which is mediated, at least in part, by a feed-forward regulatory loop between FOXA1 and TET1.
Assuntos
Linhagem da Célula/genética , Elementos Facilitadores Genéticos , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Oxigenases de Função Mista/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Linhagem Celular Tumoral , Epigênese Genética , Células HEK293 , Fator 3-alfa Nuclear de Hepatócito/genética , Humanos , Oxigenases de Função Mista/genética , Modelos Biológicos , Ligação Proteica/genética , Proteínas Proto-Oncogênicas/genética , Transcrição GênicaRESUMO
Understanding the mechanisms of androgen receptor (AR) activation in the milieu of low androgen is critical to effective treatment of castration-resistant prostate cancer (CRPC). Here, we report HOTAIR as an androgen-repressed lncRNA, and, as such, it is markedly upregulated following androgen deprivation therapies and in CRPC. We further demonstrate a distinct mode of lncRNA-mediated gene regulation, wherein HOTAIR binds to the AR protein to block its interaction with the E3 ubiquitin ligase MDM2, thereby preventing AR ubiquitination and protein degradation. Consequently, HOTAIR expression is sufficient to induce androgen-independent AR activation and drive the AR-mediated transcriptional program in the absence of androgen. Functionally, HOTAIR overexpression increases, whereas HOTAIR knockdown decreases, prostate cancer cell growth and invasion. Taken together, our results provide compelling evidence of lncRNAs as drivers of androgen-independent AR activity and CRPC progression, and they support the potential of lncRNAs as therapeutic targets.
Assuntos
Regulação Neoplásica da Expressão Gênica , Próstata/metabolismo , Neoplasias de Próstata Resistentes à Castração/genética , Proteínas Proto-Oncogênicas c-mdm2/genética , RNA Longo não Codificante/genética , Receptores Androgênicos/genética , Androgênios/metabolismo , Sítios de Ligação , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Sobrevivência Celular , Imunoprecipitação da Cromatina , Humanos , Hibridização In Situ , Masculino , Próstata/patologia , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Proteólise , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , RNA Longo não Codificante/metabolismo , Receptores Androgênicos/metabolismo , Transdução de Sinais , Ativação TranscricionalRESUMO
BACKGROUND: Because of the limitation of on-site neurology workforce, telestroke was implemented to overcome this barrier. We explored the efficacy and safety of intravenous (IV) stroke thrombolysis service by telestroke when neurologist was not available on-site. METHODS: From January 2009 to December 2012, we compared patients treated with IV stroke thrombolysis by telestroke in the form of telephone consultation with teleradiology, to patients treated after in-person assessment by the same team of neurologists in a regional hospital. Door-to-needle time, symptomatic intracranial hemorrhage, and functional outcome at 3 months were prospectively collected and compared between the groups. RESULTS: In all, 152 patients were treated with IV thrombolysis; 102 patients were treated with neurologist on-site; whereas 50 patients were treated by internists with telestroke. Fifty-two percent of the telemedical group achieved excellent outcome compared to 43% of the neurologist on-site group (P = .30). Symptomatic intracranial hemorrhage rate (4.0% versus 4.9%, P = 1.0) and mortality (8.3% versus 11.9%, P = .49) were comparable. Using the multiple logistic regression analysis, age, baseline stroke severity, and extent of early ischemic change on brain computed tomography scan, are independent predictors for excellent outcome, whereas the presence of neurologist on-site is not correlated with the outcome. CONCLUSIONS: Patients treated without neurologist on-site achieved similar outcome. Telephone consultation and teleradiology-guided IV stroke thrombolysis, with the support of on-site internist appeared safe and efficacious.
Assuntos
Isquemia Encefálica/tratamento farmacológico , Fibrinolíticos/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Telemedicina/métodos , Terapia Trombolítica/métodos , Ativador de Plasminogênio Tecidual/uso terapêutico , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Encaminhamento e Consulta , Telefone , Telerradiologia/métodos , Resultado do TratamentoRESUMO
Cockayne syndrome (CS) is a human DNA repair-deficient disease that involves transcription coupled repair (TCR), in which three gene products, Cockayne syndrome A (CSA), Cockayne syndrome B (CSB), and ultraviolet stimulated scaffold protein A (UVSSA) cooperate in relieving RNA polymerase II arrest at damaged sites to permit repair of the template strand. Mutation of any of these three genes results in cells with increased sensitivity to UV light and defective TCR. Mutations in CSA or CSB are associated with severe neurological disease but mutations in UVSSA are for the most part only associated with increased photosensitivity. This difference raises questions about the relevance of TCR to neurological disease in CS. We find that CSB-mutated cells, but not UVSSA-deficient cells, have increased levels of intramitochondrial reactive oxygen species (ROS), especially when mitochondrial complex I is inhibited by rotenone. Increased ROS would result in oxidative damage to mitochondrial proteins, lipids, and DNA. CSB appears to behave as an electron scavenger in the mitochondria whose absence leads to increased oxidative stress. Mitochondrial ROS, however, did not cause detectable nuclear DNA damage even when base excision repair was blocked by an inhibitor of polyADP ribose polymerase. Neurodegeneration in Cockayne syndrome may therefore be associated with ROS-induced damage in the mitochondria, independent of nuclear TCR. An implication of our present results is that mitochondrial dysfunction involving ROS has a major impact on CS-B pathology, whereas nuclear TCR may have a minimal role.