RESUMO
Belantamab mafodotin (belamaf) is a BCMA-targeted antibody-drug conjugate recently approved as monotherapy for adults with relapsed/refractory multiple myeloma who have received ≥4 prior therapies. Belamaf binds to BCMA and eliminates myeloma cells by multimodal mechanisms of action. The cytotoxic and potential immunomodulatory properties of belamaf have led to novel combination studies with other anticancer therapies. Here, we describe the rationale and design of DREAMM-5, an ongoing Phase I/II platform study evaluating the safety and efficacy of belamaf combined with novel agents, including GSK3174998 (OX40 agonist), feladilimab (an ICOS; GSK3359609), nirogacestat (a gamma-secretase inhibitor; PF-03084014) and dostarlimab (a PD-1 blocker) versus belamaf monotherapy for patients with relapsed/refractory multiple myeloma. Clinical trial registration: NCT04126200 (ClinicalTrials.gov).
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Antígeno de Maturação de Linfócitos B/antagonistas & inibidores , Mieloma Múltiplo/tratamento farmacológico , Recidiva Local de Neoplasia/tratamento farmacológico , Receptores OX40/antagonistas & inibidores , Projetos de Pesquisa/normas , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais Humanizados/administração & dosagem , Ensaios Clínicos Fase I como Assunto , Ensaios Clínicos Fase II como Assunto , Resistencia a Medicamentos Antineoplásicos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Multicêntricos como Assunto , Mieloma Múltiplo/imunologia , Mieloma Múltiplo/patologia , Recidiva Local de Neoplasia/imunologia , Recidiva Local de Neoplasia/patologia , Ensaios Clínicos Controlados Aleatórios como Assunto , Tetra-Hidronaftalenos/administração & dosagem , Valina/administração & dosagem , Valina/análogos & derivados , Adulto JovemRESUMO
PURPOSE: Systemic androgen-signaling inhibition added to ongoing androgen-deprivation therapy (ADT) improved clinical outcomes in patients with nonmetastatic castration-resistant prostate cancer without detectable metastases by conventional imaging (nmCRPC). Prostate-specific membrane antigen ligand positron emission tomography (PSMA-PET) detects prostate cancer with superior sensitivity to conventional imaging, but its performance in nmCRPC remains largely unknown. We characterized cancer burden in high-risk patients with nmCRPC using PSMA-PET. EXPERIMENTAL DESIGN: We retrospectively included 200 patients with nmCRPC, prostate-specific antigen (PSA) >2 ng/mL, and high risk for metastatic disease [PSA doubling time (PSADT) of ≤10 months and/or Gleason score of ≥8] from six high-volume PET centers. We centrally reviewed PSMA-PET detection rate for pelvic disease and distant metastases (M1). We further evaluated SPARTAN patients stratified by risk factors for PSMA-PET-detected M1 disease. RESULTS: PSMA-PET was positive in 196 of 200 patients. Overall, 44% had pelvic diseases, including 24% with local prostate bed recurrence, and 55% had M1 disease despite negative conventional imaging. Interobserver agreement was very high (κ: 0.81-0.91). PSA ≥ 5.5 ng/mL, locoregional nodal involvement determined by pathology (pN1), prior primary radiation, and prior salvage radiotherapy independently predicted M1 disease (all P < 0.05). CONCLUSIONS: PSMA-PET detected any disease in nearly all patients and M1 disease in 55% of patients previously diagnosed with nmCRPC, including subgroups with PSADT of ≤10 months and Gleason score of ≥8. The value of PSMA-PET imaging for treatment guidance should be tested in future studies.
Assuntos
Antagonistas de Androgênios/uso terapêutico , Antígenos de Superfície/metabolismo , Glutamato Carboxipeptidase II/metabolismo , Recidiva Local de Neoplasia/diagnóstico por imagem , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/métodos , Neoplasias de Próstata Resistentes à Castração/diagnóstico por imagem , Compostos Radiofarmacêuticos/metabolismo , Idoso , Idoso de 80 Anos ou mais , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/metabolismo , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Estudos RetrospectivosRESUMO
BACKGROUND: Apalutamide is an inhibitor of the ligand-binding domain of the androgen receptor. Whether the addition of apalutamide to androgen-deprivation therapy (ADT) would prolong radiographic progression-free survival and overall survival as compared with placebo plus ADT among patients with metastatic, castration-sensitive prostate cancer has not been determined. METHODS: In this double-blind, phase 3 trial, we randomly assigned patients with metastatic, castration-sensitive prostate cancer to receive apalutamide (240 mg per day) or placebo, added to ADT. Previous treatment for localized disease and previous docetaxel therapy were allowed. The primary end points were radiographic progression-free survival and overall survival. RESULTS: A total of 525 patients were assigned to receive apalutamide plus ADT and 527 to receive placebo plus ADT. The median age was 68 years. A total of 16.4% of the patients had undergone prostatectomy or received radiotherapy for localized disease, and 10.7% had received previous docetaxel therapy; 62.7% had high-volume disease, and 37.3% had low-volume disease. At the first interim analysis, with a median of 22.7 months of follow-up, the percentage of patients with radiographic progression-free survival at 24 months was 68.2% in the apalutamide group and 47.5% in the placebo group (hazard ratio for radiographic progression or death, 0.48; 95% confidence interval [CI], 0.39 to 0.60; P<0.001). Overall survival at 24 months was also greater with apalutamide than with placebo (82.4% in the apalutamide group vs. 73.5% in the placebo group; hazard ratio for death, 0.67; 95% CI, 0.51 to 0.89; P = 0.005). The frequency of grade 3 or 4 adverse events was 42.2% in the apalutamide group and 40.8% in the placebo group; rash was more common in the apalutamide group. CONCLUSIONS: In this trial involving patients with metastatic, castration-sensitive prostate cancer, overall survival and radiographic progression-free survival were significantly longer with the addition of apalutamide to ADT than with placebo plus ADT, and the side-effect profile did not differ substantially between the two groups. (Funded by Janssen Research and Development; TITAN ClinicalTrials.gov number, NCT02489318.).
Assuntos
Adenocarcinoma/tratamento farmacológico , Antagonistas de Androgênios/uso terapêutico , Antagonistas de Receptores de Andrógenos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Próstata/tratamento farmacológico , Tioidantoínas/uso terapêutico , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Adenocarcinoma/secundário , Adulto , Idoso , Idoso de 80 Anos ou mais , Antagonistas de Androgênios/efeitos adversos , Antagonistas de Receptores de Andrógenos/efeitos adversos , Método Duplo-Cego , Exantema/induzido quimicamente , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Intervalo Livre de Progressão , Neoplasias da Próstata/mortalidade , Neoplasias da Próstata/patologia , Qualidade de Vida , Radiografia , Tioidantoínas/efeitos adversosRESUMO
BACKGROUND: Src kinase-mediated interactions between prostate cancer cells and osteoclasts might promote bone metastasis. Dasatinib inhibits tyrosine kinases, including Src kinases. Data suggests that dasatinib kinase inhibition leads to antitumour activity, affects osteoclasts, and has synergy with docetaxel, a first-line chemotherapy for metastatic castration-resistant prostate cancer. We assessed whether dasatinib plus docetaxel in chemotherapy-naive men with metastatic castration-resistant prostate cancer led to greater efficacy than with docetaxel alone. METHODS: In this double-blind, randomised, placebo-controlled phase 3 study, we enrolled men of 18 years or older with chemotherapy-naive, metastatic, castration-resistant prostate cancer, and adequate organ function from 186 centres across 25 countries. Eligible patients were randomly assigned (1:1) via an interactive voice response system to receive docetaxel (75 mg/m(2) intravenously every 3 weeks, plus oral prednisone 5 mg twice daily), plus either dasatinib (100 mg orally once daily) or placebo until disease progression or unacceptable toxicity. Randomisation was stratified by Eastern Cooperative Oncology Group performance status (0-1 vs 2), bisphosphonate use (yes vs no), and urinary N-telopeptide (uNTx) value (<60 µmol/mol creatinine vs ≥60 µmol/mol creatinine). All patients, investigators, and personnel involved in study conduct and data analyses were blinded to treatment allocation. The primary endpoint was overall survival, analysed by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00744497. FINDINGS: Between Oct 30, 2008, and April 11, 2011, 1522 eligible patients were randomly assigned to treatment; 762 patients were assigned to dasatinib and 760 to placebo. At final analysis, median follow-up was 19·0 months (IQR 11·2-25·1) and 914 patients had died. Median overall survival was 21·5 months (95% CI 20·3-22·8) in the dasatinib group and 21·2 months (20·0-23·4) in the placebo group (stratified hazard ratio [HR] 0·99, 95·5% CI 0·87-1·13; p=0·90). The most common grade 3-4 adverse events included diarrhoea (58 [8%] patients in the dasatinib group vs 27 [4%] patients in the placebo group), fatigue (62 [8%] vs 42 [6%]), and asthenia (40 [5%] vs 23 [3%]); grade 3-4 pleural effusions were uncommon (ten [1%] vs three [<1%]). INTERPRETATION: The addition of dasatinib to docetaxel did not improve overall survival for chemotherapy-naive men with metastatic castration-resistant prostate cancer. This study does not support the combination of dasatinib and docetaxel in this population of patients. FUNDING: Bristol-Myers Squibb.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Biomarcadores Tumorais/sangue , Dasatinibe , Progressão da Doença , Docetaxel , Método Duplo-Cego , Esquema de Medicação , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Antígeno Prostático Específico/sangue , Neoplasias de Próstata Resistentes à Castração/sangue , Neoplasias de Próstata Resistentes à Castração/patologia , Pirimidinas/administração & dosagem , Pirimidinas/efeitos adversos , Taxoides/administração & dosagem , Taxoides/efeitos adversos , Tiazóis/administração & dosagem , Tiazóis/efeitos adversos , Falha de TratamentoRESUMO
PURPOSE: BMS-641988 is an androgen receptor antagonist with increased potency relative to bicalutamide in both in vitro and in vivo prostate cancer models. A first-in-man phase I study was conducted to define the safety and tolerability of oral BMS-641988 in patients with castration-resistant prostate cancer (CRPC). EXPERIMENTAL DESIGN: Doses were escalated from 5 to 150 mg based on discrete pharmacokinetic parameters in cohorts of three to six subjects. After establishing safety with 20 mg of BMS-641988 in the United States, a companion study was opened in Japan to assess differences in drug metabolism between populations. RESULTS: Sixty-one men with CRPC were treated with daily BMS-641988. The pharmacokinetics (PK) of BMS-641988 and its active metabolites were proportional to dose. One patient experienced an epileptic seizure at a dose of 60 mg administered twice. Despite achieving target drug exposures, antitumor activity was limited to one partial response. Seventeen of 23 evaluable patients (74%) exhibited stable disease on imaging (median 15 weeks; range 8-32), and 10 of 61 patients (16%) achieved a ≥ 30% decline in levels of prostate-specific antigen (PSA). Partial agonism was seen within the context of this study upon removal of the drug as evidenced by a decrease in PSA. CONCLUSIONS: Although the clinical outcomes of predominantly stable disease and partial agonism were similar to what was observed in the preclinical evaluation of the compound, the limited antitumor activity of BMS-641988 at therapeutic dose levels coupled with an episode of seizure activity led to study closure.
Assuntos
Antagonistas de Androgênios/administração & dosagem , Neoplasias Ósseas/secundário , Compostos Bicíclicos Heterocíclicos com Pontes/administração & dosagem , Imidas/administração & dosagem , Neoplasias da Próstata/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Antagonistas de Androgênios/efeitos adversos , Antagonistas de Androgênios/farmacocinética , Neoplasias Ósseas/patologia , Compostos Bicíclicos Heterocíclicos com Pontes/efeitos adversos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacocinética , Humanos , Imidas/efeitos adversos , Imidas/farmacocinética , Masculino , Pessoa de Meia-Idade , Orquiectomia , Antígeno Prostático Específico/metabolismo , Neoplasias da Próstata/patologia , Resultado do TratamentoRESUMO
PURPOSE: Antiproliferative and antiosteoclastic activity from preclinical models show potential for dasatinib, an oral SRC and SRC family kinase inhibitor, as a targeted therapy for patients with prostate cancer. This phase II study investigated the activity of dasatinib in patients with metastatic castration-resistant prostate cancer (CRPC). EXPERIMENTAL DESIGN: Chemotherapy-naive men with CRPC and increasing prostate-specific antigen were treated with dasatinib 100 or 70 mg twice daily. Endpoints included changes in prostate-specific antigen, bone scans, measurable disease (Response Evaluation Criteria in Solid Tumor), and markers of bone metabolism. Following Prostate Cancer Working Group 2 guidelines, lack of progression according to Response Evaluation Criteria in Solid Tumor and bone scan was determined and reported at 12 and 24 weeks. RESULTS: Forty-seven patients were enrolled and received dasatinib (initial dose 100 mg twice daily, n = 25; 70 mg twice daily, n = 22), of whom 41 (87%) had bone disease. Lack of progression was achieved in 20 (43%) patients at week 12 and in 9 (19%) patients at week 24. Of 41 evaluable patients, 21 (51%) patients achieved > or =40% reduction in urinary N-telopeptide by week 12, with 33 (80%) achieving some level of reduction anytime on study. Of 15 patients with elevated urinary N-telopeptide at baseline, 8 (53%) normalized on study. Of 40 evaluable patients, 24 (60%) had reduction in bone alkaline phosphatase at week 12 and 25 (63%) achieved some reduction on study. Dasatinib was generally well tolerated and treatment-related adverse events were moderate. CONCLUSIONS: This study provides encouraging evidence of dasatinib activity in bone and reasonable tolerability in chemotherapy-naive patients with metastatic CRPC.
Assuntos
Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/cirurgia , Pirimidinas/uso terapêutico , Tiazóis/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Proliferação de Células , Dasatinibe , Progressão da Doença , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Orquiectomia , Antígeno Prostático Específico/biossíntese , Inibidores de Proteínas Quinases/uso terapêutico , Resultado do TratamentoRESUMO
PURPOSE: This phase I study was conducted to determine the toxicities, pharmacokinetics, and pharmacodynamics of BMS-214662, a farnesyl transferase inhibitor, in combination with paclitaxel and carboplatin, in patients with advanced solid tumors. EXPERIMENTAL DESIGN: Patients with solid tumors received one of six escalating dose levels of BMS-214662 infused over 1 hour given following paclitaxel and carboplatin on the first day of a 21-day cycle. Toxicities were graded by the National Cancer Institute common toxicity criteria and recorded as maximum grade per patient for each treatment cycle. Inhibition of farnesyl transferase activity in peripheral blood mononuclear cells (PBMCs) was evaluated. Accumulation of unfarnesylated HDJ-2 in PBMCs of patients was evaluated as a marker of farnesyl transferase inhibition by BMS-214662. RESULTS: Thirty patients received 141 cycles of treatment through six dose levels. Dose-limiting toxicities were neutropenia, thrombocytopenia, nausea, and vomiting. There was no pharmacokinetic interaction between BMS-214662 and paclitaxel. The maximum tolerated dose was established as BMS-214662 (160 mg/m(2)), paclitaxel (225 mg/m(2)) and carboplatin (area under the curve = 6 on day 1), every 21 days. Inhibition of HDJ-2 farnesylation in PBMCs of patients was shown. One measurable partial response was observed in a patient with taxane-resistant esophageal cancer. There was partial regression of evaluable disease in two other patients (endometrial and ovarian cancer). Stable disease (> 4 cycles) occurred in eight other patients. CONCLUSIONS: The combination of BMS-214662 with paclitaxel and carboplatin was well tolerated, with broad activity in solid tumors. There was no correlation between dose level and accumulation of unfarnesylated HDJ-2 in PBMCs nor tumor response.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Benzodiazepinas/efeitos adversos , Benzodiazepinas/farmacocinética , Imidazóis/efeitos adversos , Imidazóis/farmacocinética , Neoplasias/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Benzodiazepinas/farmacologia , Carboplatina/administração & dosagem , Esquema de Medicação , Feminino , Humanos , Imidazóis/farmacologia , Masculino , Dose Máxima Tolerável , Pessoa de Meia-Idade , Paclitaxel/administração & dosagemRESUMO
The androgen receptor (AR) activates target gene expression in the presence of agonist ligands via the recruitment of transcriptional coactivators, but recent work shows that overexpression of the nuclear corepressors NCoR and SMRT attenuates this agonist-mediated AR activation. Here we demonstrate using NCoR siRNA and chromatin immunoprecipitation that endogenous NCoR is recruited to and represses the dihydrotestosterone (DHT)-liganded AR. Furthermore this study shows that NCoR and coactivators compete for AR in the presence of DHT. AR antagonists such as bicalutamide that are currently in use for prostate cancer treatment can also mediate NCoR recruitment, but mifepristone (RU486) at nanomolar concentrations is unique in its ability to markedly enhance the AR-NCoR interaction. The RU486-liganded AR interacted with a C-terminal fragment of NCoR, and this interaction was mediated by the two most C-terminal nuclear receptor interacting domains (RIDs) present in NCoR. Significantly, in addition to the AR ligand binding domain, the AR N terminus was also required for this interaction. Mutagenesis studies demonstrate that the N-terminal surface of the AR-mediating NCoR recruitment was distinct from tau5 and from the FXXLF motif that mediates agonist-induced N-C-terminal interaction. Taken together these data demonstrate that NCoR is a physiological regulator of the AR and reveal a new mechanism for AR antagonism that may be exploited for the development of more potent AR antagonists.
Assuntos
Antagonistas de Hormônios/farmacologia , Mifepristona/farmacologia , Proteínas Nucleares/metabolismo , Receptores Androgênicos/metabolismo , Proteínas Repressoras/metabolismo , Antagonistas de Receptores de Andrógenos , Sítios de Ligação , Ligação Competitiva , Linhagem Celular , Linhagem Celular Tumoral , Di-Hidrotestosterona/metabolismo , Humanos , Proteínas Nucleares/fisiologia , Correpressor 1 de Receptor Nuclear , Regiões Promotoras Genéticas , Ligação Proteica/efeitos dos fármacos , Proteínas Repressoras/fisiologia , TransfecçãoRESUMO
T cell factor (Tcf) proteins bind beta-catenin and are downstream effectors of Wnt/beta-catenin signals. A recently demonstrated interaction between beta-catenin and the androgen receptor (AR) ligand binding domain has suggested that AR may be a Tcf-independent Wnt/beta-catenin effector. This study demonstrates that there is a direct interaction between the AR DNA binding domain (DBD) and Tcf4. Tcf4 bound specifically to a glutathione S-transferase-ARDBD fusion protein and could be coimmunoprecipitated with beta-catenin and transfected AR or endogenous AR in prostate cancer cells. Transfected Tcf4 repressed the transcriptional activity of full-length AR and a VP16-ARDBD fusion protein, and this repression was only partially reversed by transfected beta-catenin. AR activation by cyproterone acetate, a partial agonist that did not support beta-catenin binding to the AR, was also repressed by Tcf4, further indicating that repression was not due to beta-catenin sequestration. Tcf4 could recruit beta-catenin to the AR DBD in vitro and to the cyproterone acetate-liganded AR in vivo. Chromatin immunoprecipitation experiments in LNCaP prostate cancer cells showed that endogenous AR was bound to a Tcf4-responsive element in the c-myc promoter. These findings indicate that AR and Tcf4 can interact directly and that this interaction may occur on the promoters or enhancers of particular genes. The direct AR-Tcf4 interaction, in conjunction AR- and Tcf4-beta-catenin binding, provides a mechanism for cooperative and selective gene regulation by AR and the Wnt/beta-catenin-Tcf pathway that may contribute to normal and neoplastic prostate growth.
Assuntos
Proteínas do Citoesqueleto/metabolismo , Neoplasias da Próstata , Receptores Androgênicos/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/metabolismo , Proteínas de Peixe-Zebra , Antagonistas de Androgênios/metabolismo , Antagonistas de Androgênios/farmacologia , Acetato de Ciproterona/metabolismo , Acetato de Ciproterona/farmacologia , Humanos , Ligantes , Masculino , Ligação Proteica/fisiologia , Proteínas Proto-Oncogênicas/metabolismo , Receptores Androgênicos/genética , Transdução de Sinais/fisiologia , Fatores de Transcrição TCF , Proteína 2 Semelhante ao Fator 7 de Transcrição , Fatores de Transcrição/genética , Ativação Transcricional/fisiologia , Transfecção , Células Tumorais Cultivadas , Proteínas Wnt , beta CateninaRESUMO
SHRs function as hormone activated, sequence specific DNA binding transcription factors that recruit multiple coactivator and other proteins to specific genes and generally stimulate transcription of these genes. SHR may have further genomic actions, that do not involve direct DNA binding, through protein-protein interactions with other sequence specific transcription factors, although these may still involve weak binding to nonconsensus steroid responsive elements in vivo. SHRs also appear to have nongenomic effects mediated through interactions with cytoplasmic signaling proteins. The major functions of SHRs in normal adult tissues appear to involve stimulation of differentiation, rather than proliferation. In contrast, the ER alpha and AR directly stimulate the growth of breast and prostate cancers, respectively, indicating a critical change in their functions. The ER alpha and AR appear to undergo further adaptation in tumor cells in response to hormonal therapies, that render these therapies ineffective. Understanding the molecular basis for these changes in SHR function during cancer development and progression may provide new targets for the generation of drugs to prevent and treat steroid stimulated cancers.
Assuntos
Hormônios/metabolismo , Neoplasias Hormônio-Dependentes/metabolismo , Neoplasias/metabolismo , Receptores de Superfície Celular/metabolismo , Transdução de Sinais , Animais , Feminino , Humanos , MasculinoRESUMO
Nuclear receptor corepressor (NCoR) mediates transcriptional repression by unliganded nuclear receptors and certain steroid hormone receptors (SHRs) bound to nonphysiological antagonists, but has not been found to regulate SHRs bound to their natural ligands. This report demonstrates that NCoR interacts directly with the androgen receptor (AR) and represses dihydrotestosterone-stimulated AR transcriptional activity. The NCoR C terminus, containing the receptor interacting domains, was necessary for repression, which was ablated by mutations in the corepressor nuclear receptor (CoRNR) boxes. In contrast, the NCoR N terminus, containing domains that can recruit histone deacetylases, was not necessary for repression. Binding studies in vitro with a series of glutathione-S-transferase-NCoR and -AR fusion proteins demonstrated a direct interaction that was similarly dependent upon the NCoR corepressor nuclear receptor boxes and AR ligand binding domain and was independent of ligand and helix 12 in the AR ligand binding domain. This NCoR-AR interaction was further demonstrated in mammalian two-hybrid assays and by coimmunoprecipitation of the endogenous proteins from a prostate cancer cell line. Finally, AR transcriptional activity could be enhanced in vivo by sequestration of endogenous NCoR with unliganded thyroid hormone receptor. These results demonstrate that AR, in contrast to other SHRs, is regulated by NCoR and suggest the possibility of developing selective AR modulators that enhance this interaction.
Assuntos
Di-Hidrotestosterona/metabolismo , Proteínas Nucleares/metabolismo , Receptores Androgênicos/genética , Proteínas Repressoras/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Células Cultivadas , Di-Hidrotestosterona/farmacologia , Histona Desacetilases/metabolismo , Humanos , Mamíferos , Dados de Sequência Molecular , Mutação , Proteínas Nucleares/genética , Correpressor 1 de Receptor Nuclear , Receptores Androgênicos/efeitos dos fármacos , Receptores Androgênicos/metabolismo , Proteínas Repressoras/genética , Transcrição Gênica , Técnicas do Sistema de Duplo-HíbridoRESUMO
Prostate cancers (PCa) that relapse after androgen deprivation therapy invariably express high levels of androgen receptor (AR) and AR-regulated genes. Most do not respond to secondary hormonal therapies, including AR antagonists, and the mechanisms of AR activation in these clinically androgen-independent tumors are unclear. Bicalutamide, the most widely used AR antagonist, is a competitive antagonist shown previously to stabilize AR association with cytosolic heat shock protein complexes. This study found nuclear AR expression in bicalutamide-treated androgen-independent PCa and found that bicalutamide could stimulate AR nuclear translocation. Moreover, specific DNA binding by the bicalutamide-liganded AR was demonstrated in vivo using a VP16-AR fusion protein and was confirmed by chromatin immunoprecipitation showing binding to the prostate-specific antigen enhancer in LNCaP PCa cells. Nonetheless, bicalutamide could not stimulate interactions between the AR N and C termini or recruitment of steroid receptor coactivator proteins (SRC-1 or -2), although SRC transfection augmented AR activity in the presence of dihydrotestosterone and inhibitory concentrations of bicalutamide. These results demonstrate that bicalutamide stimulates the assembly of a transcriptionally inactive AR on DNA and support altered coactivator (or corepressor) expression as a mechanism of bicalutamide-resistant androgen-independent PCa.