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1.
J Med Chem ; 63(9): 4716-4731, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32314924

RESUMO

Histone acetyltransferase (HAT) p300 and its paralog CBP acetylate histone lysine side chains and play critical roles in regulating gene transcription. The HAT domain of p300/CBP is a potential drug target for cancer. Through compound screening and medicinal chemistry, novel inhibitors of p300/CBP HAT with their IC50 values as low as 620 nM were discovered. The most potent inhibitor is competitive against histone substrates and exhibits a high selectivity for p300/CBP. It inhibited cellular acetylation and had strong activity with EC50 of 1-3 µM against proliferation of several tumor cell lines. Gene expression profiling in estrogen receptor (ER)-positive breast cancer MCF-7 cells showed that inhibitor treatment recapitulated siRNA-mediated p300 knockdown, inhibited ER-mediated gene transcription, and suppressed expression of numerous cancer-related gene signatures. These results demonstrate that the inhibitor is not only a useful probe for biological studies of p300/CBP HAT but also a pharmacological lead for further drug development targeting cancer.

3.
Transl Cancer Res ; 8(Suppl 2): S198-S203, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31360645
4.
Nat Metab ; 1(1): 70-85, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31198906

RESUMO

Specific metabolic underpinnings of androgen receptor (AR)-driven growth in prostate adenocarcinoma (PCa) are largely undefined, hindering the development of strategies to leverage the metabolic dependencies of this disease when hormonal manipulations fail. Here we show that the mitochondrial pyruvate carrier (MPC), a critical metabolic conduit linking cytosolic and mitochondrial metabolism, is transcriptionally regulated by AR. Experimental MPC inhibition restricts proliferation and metabolic outputs of the citric acid cycle (TCA) including lipogenesis and oxidative phosphorylation in AR-driven PCa models. Mechanistically, metabolic disruption resulting from MPC inhibition activates the eIF2α/ATF4 integrated stress response (ISR). ISR signaling prevents cell cycle progression while coordinating salvage efforts, chiefly enhanced glutamine assimilation into the TCA, to regain metabolic homeostasis. We confirm that MPC function is operant in PCa tumors in-vivo using isotopomeric metabolic flux analysis. In turn, we apply a clinically viable small molecule targeting the MPC, MSDC0160, to pre-clinical PCa models and find that MPC inhibition suppresses tumor growth in hormone-responsive and castrate-resistant conditions. Collectively, our findings characterize the MPC as a tractable therapeutic target in AR-driven prostate tumors.

5.
Clin Cancer Res ; 25(2): 881-891, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30254080

RESUMO

PURPOSE: The impact of androgen receptor (AR) activity in breast cancer biology is unclear. We characterized and tested a novel therapy to an AR-governed target in breast cancer.Experimental Design: We evaluated the expression of prototypical AR gene products human kallikrein 2 (hK2) and PSA in breast cancer models. We screened 13 well-characterized breast cancer cell lines for hK2 and PSA production upon in vitro hormone stimulation by testosterone [dihydrotestosterone (DHT)]. AR-positive lines were further evaluated by exposure to estrogen (17ß-Estradiol) and the synthetic progestin D-Norgestrel. We then evaluated an anti-hK2-targeted radiotherapy platform (hu11B6), labeled with alpha (α)-particle emitting Actinium-225, to specifically treat AR-expressing breast cancer xenografts under hormone stimulation. RESULTS: D-Norgestrel and DHT activated the AR pathway, while 17ß-Estradiol did not. Competitive binding for AR protein showed similar affinity between DHT and D-Norgestrel, indicating direct AR-ligand interaction. In vivo production of hK2 was sufficient to achieve site-specific delivery of therapeutic radionuclide to tumor tissue at >20-fold over background muscle uptake; effecting long-term local tumor control. CONCLUSIONS: [225Ac]hu11B6 targeted radiotherapy was potentiated by DHT and by D-Norgestrel in murine xenograft models of breast cancer. AR activity in breast cancer correlates with kallikrein-related peptidase-2 and can be activated by D-Norgestrel, a common contraceptive, and AR induction can be harnessed for hK2-targeted breast cancer α-emitter radiotherapy.


Assuntos
Partículas alfa/uso terapêutico , Neoplasias da Mama/metabolismo , Imunoconjugados/administração & dosagem , Receptores Androgênicos/metabolismo , Transdução de Sinais , Animais , Biomarcadores Tumorais , Neoplasias da Mama/mortalidade , Neoplasias da Mama/patologia , Neoplasias da Mama/terapia , Linhagem Celular Tumoral , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Relação Dose-Resposta à Radiação , Feminino , Hexoquinase/antagonistas & inibidores , Humanos , Imunoconjugados/farmacocinética , Camundongos , Terapia de Alvo Molecular , Radioimunoterapia , Radiometria , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/efeitos da radiação , Distribuição Tecidual , Ensaios Antitumorais Modelo de Xenoenxerto
6.
Trends Endocrinol Metab ; 29(6): 366-368, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29605661

RESUMO

Androgen receptor signaling is critical for prostate adenocarcinoma, even after androgen deprivation therapy. Persistence of intratumoral androgens has been found in castration-resistant prostate cancer and attributed to increased in situ synthesis. Recently, Sharifi and colleagues reported an additional mechanism that can enhance local androgenic exposure: downregulation of an androgen-inactivating enzyme.


Assuntos
Androgênios , Receptores Androgênicos/genética , Regulação para Baixo/efeitos dos fármacos , Humanos , Masculino , Proteína Multifuncional do Peroxissomo-2 , Neoplasias da Próstata , Neoplasias de Próstata Resistentes à Castração , Isoformas de Proteínas
7.
Invest Ophthalmol Vis Sci ; 59(1): 132-143, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29332125

RESUMO

Purpose: Uveal melanoma (UM) is uniformly refractory to all available systemic chemotherapies, thus creating an urgent need for novel therapeutics. In this study, we investigated the sensitivity of UM cells to ICG-001, a small molecule reported to suppress the Wnt/ß-catenin-mediated transcriptional program. Methods: We used a panel of UM cell lines to examine the effects of ICG-001 on cellular proliferation, migration, and gene expression. In vivo efficacy of ICG-001 was evaluated in a UM xenograft model. Results: ICG-001 exerted strong antiproliferative activity against UM cells, leading to cell cycle arrest, apoptosis, and inhibition of migration. Global gene expression profiling revealed strong suppression of genes associated with cell cycle proliferation, DNA replication, and G1/S transition. Gene set enrichment analysis revealed that ICG-001 suppressed Wnt, mTOR, and MAPK signaling. Strikingly, ICG-001 suppressed the expression of genes associated with UM aggressiveness, including CDH1, CITED1, EMP1, EMP3, SDCBP, and SPARC. Notably, the transcriptomic footprint of ICG-001, when applied to a UM patient dataset, was associated with better clinical outcome. Lastly, ICG-001 exerted anticancer activity against a UM tumor xenograft in mice. Conclusions: Using in vitro and in vivo experiments, we demonstrate that ICG-001 has strong anticancer activity against UM cells and suppresses transcriptional programs critical for the cancer cell. Our results suggest that ICG-001 holds promise and should be examined further as a novel therapeutic agent for UM.


Assuntos
Apoptose/efeitos dos fármacos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Genes Neoplásicos/genética , Melanoma/tratamento farmacológico , Neoplasias Experimentais , Pirimidinonas/farmacologia , Neoplasias Uveais/tratamento farmacológico , Animais , Ciclo Celular , Linhagem Celular Tumoral , Proliferação de Células , Melanoma/genética , Melanoma/metabolismo , Camundongos Nus , Neoplasias Uveais/genética , Neoplasias Uveais/metabolismo
8.
JAMA Oncol ; 3(11): e170231, 2017 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-28358937

RESUMO

Importance: Men with metastatic prostate cancer who have a poor response to initial androgen-deprivation therapy (ADT), as reflected by a prostate-specific antigen (PSA) level higher than 4.0 ng/mL after 7 months of ADT, have a poor prognosis, based on historical controls. Objective: To determine the efficacy of abiraterone acetate with prednisone in these high-risk patients with a suboptimal response to hormonal induction. Design, Setting, and Participants: A phase 2 single-arm study was conducted through the National Clinical Trials Network-Southwest Oncology Group. Eligible patients had metastatic prostate cancer and a PSA level higher than 4.0 ng/mL between 6 and 12 months after starting ADT. The PSA level could be rising or falling at the time of enrollment, but had to be higher than 4.0 ng/mL. No previous chemotherapy or secondary hormonal therapies were allowed, except in patients receiving a standard, first-generation antiandrogen agent with a falling PSA level at the time of enrollment; this therapy was continued in this cohort. Abiraterone acetate, 1000 mg, once daily with prednisone, 5 mg, twice daily was administered to all participants. A total of 41 men were enrolled between the trial's activation on August 9, 2011, and closure on August 1, 2013. Data analysis was conducted from March 21 to November 29, 2016. Interventions: Abiraterone acetate, 1000 mg, once daily by mouth with prednisone, 5 mg, by mouth twice daily. Main Outcomes and Measures: The primary end point was a PSA level of 0.2 ng/mL or lower within 12 months of starting abiraterone acetate plus prednisone. A partial response (PR) was a secondary end point, defined as a PSA level reduction to lower than 4.0 ng/mL but higher than 0.2 ng/mL. Results: Of the 41 men enrolled, 1 did not receive any protocol treatment and was excluded from analysis. The median (range) age of the 40 participants was 66 (39-85) years. Five (13%) patients achieved a PSA level of 0.2 ng/mL or lower (95% CI, 4%-27%). Thirteen (33%) additional patients achieved a partial response, with a reduction in the PSA level to lower than 4.0 ng/mL but higher than 0.2 ng/mL. Sixteen (40%) patients had no PSA response and 6 (15%) were not assessable and assumed to be nonresponders. The median progression-free survival was 17.5 months (95% CI, 8.6-25.0 months) and the median overall survival was 25.8 months (95% CI, 15.7-25.8 months). There was 1 incident each of grade 4 adverse events of alanine aminotransferase level elevation and rectal hemorrhage. Eleven patients reported grade 3 adverse events. Conclusions and Relevance: This study did not reach its prescribed level of 6 PSA responses of 0.2 ng/mL or lower, although 5 responses were observed. The overall survival and progression-free survival rates observed in this trial are encouraging compared with historical controls. The therapy was generally well tolerated, without any clear signal of any unexpected adverse effects.


Assuntos
Acetato de Abiraterona/administração & dosagem , Adenocarcinoma/tratamento farmacológico , Antagonistas de Androgênios/administração & dosagem , Antineoplásicos Hormonais/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Próstata/tratamento farmacológico , Acetato de Abiraterona/efeitos adversos , Adenocarcinoma/sangue , Adenocarcinoma/mortalidade , Adenocarcinoma/secundário , Adulto , Idoso , Idoso de 80 Anos ou mais , Antagonistas de Androgênios/efeitos adversos , Antineoplásicos Hormonais/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Progressão da Doença , Intervalo Livre de Doença , Esquema de Medicação , Humanos , Calicreínas/sangue , Masculino , Pessoa de Meia-Idade , Prednisona/administração & dosagem , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Neoplasias da Próstata/mortalidade , Neoplasias da Próstata/patologia , Análise de Sobrevida , Fatores de Tempo , Resultado do Tratamento , Estados Unidos
9.
Cancer Lett ; 385: 207-214, 2017 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-27780719

RESUMO

Recent studies revealed that mutations in SPOP (Speckle-type POZ protein) occur in up to 15% of patients with prostate cancer. However, the physiological role of SPOP in regulating prostate tumorigenesis remains elusive. Here, we identified the Cdc20 oncoprotein as a novel ubiquitin substrate of SPOP. As such, pharmacological inhibition of Cullin-based E3 ligases by MLN4924 could stabilize endogenous Cdc20 in cells. Furthermore, we found that Cullin 3, and, to a less extent, Cullin 1, specifically interacted with Cdc20. Depletion of Cullin 3, but not Cullin 1, could upregulate the abudance of Cdc20 largely via prolonging Cdc20 half-life. Moreover, SPOP, the adaptor protein of Cullin 3 family E3 ligase, specifically interacted with Cdc20, and promoted the poly-ubiquitination and subsequent degradation of Cdc20 in a degron-dependent manner. Importantly, prostate cancer-derived SPOP mutants failed to interact with Cdc20 to promote its degradation. As a result, SPOP-deficient prostate cancer cells with elevated Cdc20 expression became resistant to a pharmacological Cdc20 inhibitor. Therefore, our results revealed a novel role of SPOP in tumorigenesis in part by promoting the degradation of the Cdc20 oncoprotein.


Assuntos
Proteínas Cdc20/metabolismo , Mutação , Proteínas Nucleares/metabolismo , Neoplasias da Próstata/enzimologia , Proteínas Repressoras/metabolismo , Ubiquitinação , Antineoplásicos/farmacologia , Carbamatos/farmacologia , Proteínas Cdc20/antagonistas & inibidores , Proteínas Culina/antagonistas & inibidores , Proteínas Culina/metabolismo , Ciclopentanos/farmacologia , Diaminas/farmacologia , Relação Dose-Resposta a Droga , Resistencia a Medicamentos Antineoplásicos , Inibidores Enzimáticos/farmacologia , Células HeLa , Humanos , Masculino , Terapia de Alvo Molecular , Proteínas Nucleares/genética , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/genética , Neoplasias da Próstata/patologia , Domínios e Motivos de Interação entre Proteínas , Proteólise , Pirimidinas/farmacologia , Proteínas Repressoras/genética , Fatores de Tempo , Transfecção
10.
Oncotarget ; 7(30): 47891-47903, 2016 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-27374105

RESUMO

GATA transcription factors are essential in mammalian cell lineage determination and have a critical role in cancer development. In cultured prostate cancer cells, GATA2 coordinates with androgen receptor (AR) to regulate gene transcription. In the murine prostate, among six GATA members, GATA2 and GATA3 are expressed. Immunofluorescence staining revealed that both GATA factors predominantly localize in the nuclei of luminal epithelial cells. The pioneer factor FoxA1 is exclusively detected in the luminal cells, whereas AR is detected in both luminal and basal cells. Using genetic engineering, we generated prostate-specific GATA2 and GATA3 knockout (KO) mice. Ablation of single GATA gene had marginal effect on prostate morphology and AR target gene expression, likely due to their genetic compensation. Double KO mice exhibited PIN III to IV lesions, but decreased prostate to body weight ratio, altered AR target gene expression, and expansion of p63-positive basal cells. However, deletion of GATA2 and GATA3 did not reduce the mRNA or protein levels of AR or FoxA1, indicating that GATA factors are not required for AR or FoxA1 expression in adult prostate. Surprisingly, GATA2 and GATA3 exhibit minimal expression in the ventral prostatic (VP) lobe. In contrast, FoxA1 and AR expression levels in VP are at least as high as those in anterior prostatic (AP) and dorsal-lateral prostatic (DLP) lobes. Together, our results indicate that GATA2 and GATA3 are essential for adult murine prostate function and in vivo AR signaling, and the lack of the GATA factor expression in the VP suggests a fundamental difference between VP and other prostatic lobes.


Assuntos
Fatores de Transcrição GATA/metabolismo , Próstata/fisiologia , Receptores Androgênicos/metabolismo , Animais , Fatores de Transcrição GATA/genética , Engenharia Genética/métodos , Fator 3-alfa Nuclear de Hepatócito/biossíntese , Fator 3-alfa Nuclear de Hepatócito/genética , Humanos , Masculino , Camundongos , Camundongos Knockout , Próstata/metabolismo , Receptores Androgênicos/genética
11.
Nat Commun ; 7: 11612, 2016 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-27194471

RESUMO

The precise molecular alterations driving castration-resistant prostate cancer (CRPC) are not clearly understood. Using a novel network-based integrative approach, here, we show distinct alterations in the hexosamine biosynthetic pathway (HBP) to be critical for CRPC. Expression of HBP enzyme glucosamine-phosphate N-acetyltransferase 1 (GNPNAT1) is found to be significantly decreased in CRPC compared with localized prostate cancer (PCa). Genetic loss-of-function of GNPNAT1 in CRPC-like cells increases proliferation and aggressiveness, in vitro and in vivo. This is mediated by either activation of the PI3K-AKT pathway in cells expressing full-length androgen receptor (AR) or by specific protein 1 (SP1)-regulated expression of carbohydrate response element-binding protein (ChREBP) in cells containing AR-V7 variant. Strikingly, addition of the HBP metabolite UDP-N-acetylglucosamine (UDP-GlcNAc) to CRPC-like cells significantly decreases cell proliferation, both in-vitro and in animal studies, while also demonstrates additive efficacy when combined with enzalutamide in-vitro. These observations demonstrate the therapeutic value of targeting HBP in CRPC.


Assuntos
Hexosaminas/biossíntese , Neoplasias de Próstata Resistentes à Castração/metabolismo , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Linhagem Celular , Humanos , Masculino , Camundongos , Camundongos SCID , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt/metabolismo
12.
Cancer Res ; 76(6): 1463-75, 2016 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-26833126

RESUMO

Approximately 20% of early-stage breast cancers display amplification or overexpression of the ErbB2/HER2 oncogene, conferring poor prognosis and resistance to endocrine therapy. Targeting HER2(+) tumors with trastuzumab or the receptor tyrosine kinase (RTK) inhibitor lapatinib significantly improves survival, yet tumor resistance and progression of metastatic disease still develop over time. Although the mechanisms of cytosolic HER2 signaling are well studied, nuclear signaling components and gene regulatory networks that bestow therapeutic resistance and limitless proliferative potential are incompletely understood. Here, we use biochemical and bioinformatic approaches to identify effectors and targets of HER2 transcriptional signaling in human breast cancer. Phosphorylation and activity of the Steroid Receptor Coactivator-3 (SRC-3) is reduced upon HER2 inhibition, and recruitment of SRC-3 to regulatory elements of endogenous genes is impaired. Transcripts regulated by HER2 signaling are highly enriched with E2F1 binding sites and define a gene signature associated with proliferative breast tumor subtypes, cell-cycle progression, and DNA replication. We show that HER2 signaling promotes breast cancer cell proliferation through regulation of E2F1-driven DNA metabolism and replication genes together with phosphorylation and activity of the transcriptional coactivator SRC-3. Furthermore, our analyses identified a cyclin-dependent kinase (CDK) signaling node that, when targeted using the CDK4/6 inhibitor palbociclib, defines overlap and divergence of adjuvant pharmacologic targeting. Importantly, lapatinib and palbociclib strictly block de novo synthesis of DNA, mostly through disruption of E2F1 and its target genes. These results have implications for rational discovery of pharmacologic combinations in preclinical models of adjuvant treatment and therapeutic resistance.


Assuntos
Proliferação de Células/genética , DNA/genética , Fator de Transcrição E2F1/genética , Coativador 3 de Receptor Nuclear/genética , Fosforilação/genética , Receptor ErbB-2/genética , Antineoplásicos/farmacologia , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/genética , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/genética , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Quinases Ciclina-Dependentes/genética , Replicação do DNA/efeitos dos fármacos , Replicação do DNA/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Humanos , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Ativação Transcricional/efeitos dos fármacos , Ativação Transcricional/genética
13.
Annu Rev Med ; 67: 29-43, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26768236

RESUMO

Somatic activating mutations in the B-Raf kinase (BRAF mutations) are present in hairy-cell leukemia, cutaneous melanoma, thyroid carcinomas and, less commonly, in ovarian, colon, lung, and other malignancies. These mutations-in particular the most common substitution, V600E-are oncogenic drivers and important therapeutic targets. The development of small-molecule Raf inhibitors allowed rapid translation of basic advances to the clinic. In BRAF-mutant melanomas, orally bioavailable B-Raf inhibitors, such as vemurafenib, achieve dramatic responses initially, but this is followed by rapid emergence of resistance driven by numerous mechanisms and requiring second-generation treatment approaches. In tumors with wild-type B-Raf, vemurafenib paradoxically activates downstream signaling and cell proliferation and is thus contraindicated, highlighting again the importance of genotype-based clinical decision making. These advances were greatly facilitated by the study of biopsied tumor tissue, especially at the time of drug resistance. Combinatorial approaches targeting the Raf pathway hold promise for even more substantial clinical benefits in the future.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias do Colo/tratamento farmacológico , Indóis/uso terapêutico , Melanoma/tratamento farmacológico , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Sulfonamidas/uso terapêutico , Neoplasias da Glândula Tireoide/tratamento farmacológico , Antineoplásicos/efeitos adversos , Resistencia a Medicamentos Antineoplásicos , Humanos , Imidazóis/uso terapêutico , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Niacinamida/análogos & derivados , Niacinamida/uso terapêutico , Oximas/uso terapêutico , Compostos de Fenilureia/uso terapêutico , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/efeitos dos fármacos , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , Sorafenibe , Vemurafenib
14.
Horm Cancer ; 7(2): 84-103, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26728473

RESUMO

Medical or surgical castration serves as the backbone of systemic therapy for advanced and metastatic prostate cancer, taking advantage of the importance of androgen signaling in this disease. Unfortunately, resistance to castration emerges almost universally. Despite the development and approval of new and more potent androgen synthesis inhibitors and androgen receptor (AR) antagonists, prostate cancers continue to develop resistance to these therapeutics, while often maintaining their dependence on the AR signaling axis. This highlights the need for innovative therapeutic approaches that aim to continue disrupting AR downstream signaling but are orthogonal to directly targeting the AR itself. In this review, we discuss the preclinical research that has been done, as well as clinical trials for prostate cancer, on inhibiting several important families of AR-interacting proteins, including chaperones (such as heat shock protein 90 (HSP90) and FKBP52), pioneer factors (including forkhead box protein A1 (FOXA1) and GATA-2), and AR transcriptional coregulators such as the p160 steroid receptor coactivators (SRCs) SRC-1, SRC-2, SRC-3, as well as lysine deacetylases (KDACs) and lysine acetyltransferases (KATs). Researching the effect of-and developing new therapeutic agents that target-the AR signaling axis is critical to advancing our understanding of prostate cancer biology, to continue to improve treatments for prostate cancer and for overcoming castration resistance.


Assuntos
Antineoplásicos/farmacologia , Terapia de Alvo Molecular/métodos , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Receptores Androgênicos/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Antineoplásicos/uso terapêutico , Ensaios Clínicos como Assunto , Humanos , Masculino , Chaperonas Moleculares/antagonistas & inibidores , Neoplasias de Próstata Resistentes à Castração/metabolismo , Fatores de Transcrição/antagonistas & inibidores
15.
Mol Endocrinol ; 29(8): 1170-83, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26066330

RESUMO

The p160 family of steroid receptor coactivators (SRCs) are pleiotropic transcription factor coactivators and "master regulators" of gene expression that promote cancer cell proliferation, survival, metabolism, migration, invasion, and metastasis. Cancers with high p160 SRC expression exhibit poor clinical outcomes and resistance to therapy, highlighting the SRCs as critical oncogenic drivers and, thus, therapeutic targets. microRNAs are important epigenetic regulators of protein expression. To examine the regulation of p160 SRCs by microRNAs, we used and combined 4 prediction algorithms to identify microRNAs that could target SRC1, SRC2, and SRC3 expression. For validation of these predictions, we assessed p160 SRC protein expression and cell viability after transfection of corresponding microRNA mimetics in breast cancer, uveal melanoma, and prostate cancer (PC) cell lines. Transfection of selected microRNA mimetics into breast cancer, uveal melanoma, and PC cells depleted SRC protein expression levels and exerted potent antiproliferative activity in these cell types. In particular, microRNA-137 (miR-137) depleted expression of SRC1, SRC2, and very potently, SRC3. The latter effect can be attributed to the presence of 3 miR-137 recognition sequences within the SRC3 3'-untranslated region. Using reverse phase protein array analysis, we identified a network of proteins, in addition to SRC3, that were modulated by miR-137 in PC cells. We also found that miR-137 and its host gene are epigenetically silenced in human cancer specimens and cell lines. These results support the development and testing of microRNA-based therapies (in particular based on restoring miR-137 levels) for targeting the oncogenic family of p160 SRCs in cancer.


Assuntos
Proliferação de Células , MicroRNAs/metabolismo , Coativador 1 de Receptor Nuclear/metabolismo , Coativador 2 de Receptor Nuclear/metabolismo , Coativador 3 de Receptor Nuclear/metabolismo , Linhagem Celular Tumoral , Biologia Computacional , Metilação de DNA , Epigênese Genética , Feminino , Regulação Neoplásica da Expressão Gênica , Inativação Gênica , Células HEK293 , Histonas/química , Humanos , Células MCF-7 , Masculino , Mutação , Proteômica , Ativação Transcricional
16.
J Clin Invest ; 125(3): 1174-88, 2015 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-25664849

RESUMO

Metabolic pathway reprogramming is a hallmark of cancer cell growth and survival and supports the anabolic and energetic demands of these rapidly dividing cells. The underlying regulators of the tumor metabolic program are not completely understood; however, these factors have potential as cancer therapy targets. Here, we determined that upregulation of the oncogenic transcriptional coregulator steroid receptor coactivator 2 (SRC-2), also known as NCOA2, drives glutamine-dependent de novo lipogenesis, which supports tumor cell survival and eventual metastasis. SRC-2 was highly elevated in a variety of tumors, especially in prostate cancer, in which SRC-2 was amplified and overexpressed in 37% of the metastatic tumors evaluated. In prostate cancer cells, SRC-2 stimulated reductive carboxylation of α-ketoglutarate to generate citrate via retrograde TCA cycling, promoting lipogenesis and reprogramming of glutamine metabolism. Glutamine-mediated nutrient signaling activated SRC-2 via mTORC1-dependent phosphorylation, which then triggered downstream transcriptional responses by coactivating SREBP-1, which subsequently enhanced lipogenic enzyme expression. Metabolic profiling of human prostate tumors identified a massive increase in the SRC-2-driven metabolic signature in metastatic tumors compared with that seen in localized tumors, further implicating SRC-2 as a prominent metabolic coordinator of cancer metastasis. Moreover, SRC-2 inhibition in murine models severely attenuated the survival, growth, and metastasis of prostate cancer. Together, these results suggest that the SRC-2 pathway has potential as a therapeutic target for prostate cancer.


Assuntos
Neoplasias Pulmonares/metabolismo , Coativador 2 de Receptor Nuclear/fisiologia , Neoplasias da Próstata/metabolismo , Animais , Sobrevivência Celular , Metabolismo Energético , Regulação Neoplásica da Expressão Gênica , Glutamina/metabolismo , Células HeLa , Humanos , Lipogênese , Neoplasias Pulmonares/secundário , Masculino , Camundongos Nus , Camundongos SCID , Transplante de Neoplasias , Oxirredução , Neoplasias da Próstata/patologia , Transcrição Genética
17.
Proc Natl Acad Sci U S A ; 111(51): 18261-6, 2014 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-25489091

RESUMO

The androgen receptor (AR) is a key driver of prostate cancer (PC), even in the state of castration-resistant PC (CRPC) and frequently even after treatment with second-line hormonal therapies such as abiraterone and enzalutamide. The persistence of AR activity via both ligand-dependent and ligand-independent mechanisms (including constitutively active AR splice variants) highlights the unmet need for alternative approaches to block AR signaling in CRPC. We investigated the transcription factor GATA-binding protein 2 (GATA2) as a regulator of AR signaling and an actionable therapeutic target in PC. We demonstrate that GATA2 directly promotes expression of both full-length and splice-variant AR, resulting in a strong positive correlation between GATA2 and AR expression in both PC cell lines and patient specimens. Conversely, GATA2 expression is repressed by androgen and AR, suggesting a negative feedback regulatory loop that, upon androgen deprivation, derepresses GATA2 to contribute to AR overexpression in CRPC. Simultaneously, GATA2 is necessary for optimal transcriptional activity of both full-length and splice-variant AR. GATA2 colocalizes with AR and Forkhead box protein A1 on chromatin to enhance recruitment of steroid receptor coactivators and formation of the transcriptional holocomplex. In agreement with these important functions, high GATA2 expression and transcriptional activity predicted worse clinical outcome in PC patients. A GATA2 small molecule inhibitor suppressed the expression and transcriptional function of both full-length and splice-variant AR and exerted potent anticancer activity against PC cell lines. We propose pharmacological inhibition of GATA2 as a first-in-field approach to target AR expression and function and improve outcomes in CRPC.


Assuntos
Fator de Transcrição GATA2/fisiologia , Coativadores de Receptor Nuclear/metabolismo , Receptores Androgênicos/metabolismo , Proliferação de Células , Cromatina/metabolismo , Elementos Facilitadores Genéticos , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Humanos , Masculino , Prognóstico , Receptores Androgênicos/fisiologia , Transdução de Sinais , Transcrição Genética/fisiologia
18.
Cancer Res ; 74(19): 5631-43, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-25274033

RESUMO

Somatic missense mutations in the substrate-binding pocket of the E3 ubiquitin ligase adaptor SPOP are present in up to 15% of human prostate adenocarcinomas, but are rare in other malignancies, suggesting a prostate-specific mechanism of action. SPOP promotes ubiquitination and degradation of several protein substrates, including the androgen receptor (AR) coactivator SRC-3. However, the relative contributions that SPOP substrates may make to the pathophysiology of SPOP-mutant (mt) prostate adenocarcinomas are unknown. Using an unbiased bioinformatics approach, we determined that the gene expression profile of prostate adenocarcinoma cells engineered to express mt-SPOP overlaps greatly with the gene signature of both SRC-3 and AR transcriptional output, with a stronger similarity to AR than SRC-3. This finding suggests that in addition to its SRC-3-mediated effects, SPOP also exerts SRC-3-independent effects that are AR-mediated. Indeed, we found that wild-type (wt) but not prostate adenocarcinoma-associated mutants of SPOP promoted AR ubiquitination and degradation, acting directly through a SPOP-binding motif in the hinge region of AR. In support of these results, tumor xenografts composed of prostate adenocarcinoma cells expressing mt-SPOP exhibited higher AR protein levels and grew faster than tumors composed of prostate adenocarcinoma cells expressing wt-SPOP. Furthermore, genetic ablation of SPOP was sufficient to increase AR protein levels in mouse prostate. Examination of public human prostate adenocarcinoma datasets confirmed a strong link between transcriptomic profiles of mt-SPOP and AR. Overall, our studies highlight the AR axis as the key transcriptional output of SPOP in prostate adenocarcinoma and provide an explanation for the prostate-specific tumor suppressor role of wt-SPOP.


Assuntos
Adenocarcinoma/fisiopatologia , Genes Supressores de Tumor , Proteínas Nucleares/genética , Neoplasias da Próstata/fisiopatologia , Receptores Androgênicos/fisiologia , Proteínas Repressoras/genética , Transcrição Genética/fisiologia , Adenocarcinoma/genética , Androgênios/fisiologia , Perfilação da Expressão Gênica , Humanos , Masculino , Mutação , Coativador 3 de Receptor Nuclear/fisiologia , Neoplasias da Próstata/genética
19.
Cell Res ; 24(7): 809-19, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24874954

RESUMO

Tamoxifen has been a frontline treatment for estrogen receptor alpha (ERα)-positive breast tumors in premenopausal women. However, resistance to tamoxifen occurs in many patients. ER still plays a critical role in the growth of breast cancer cells with acquired tamoxifen resistance, suggesting that ERα remains a valid target for treatment of tamoxifen-resistant (Tam-R) breast cancer. In an effort to identify novel regulators of ERα signaling, through a small-scale siRNA screen against histone methyl modifiers, we found WHSC1, a histone H3K36 methyltransferase, as a positive regulator of ERα signaling in breast cancer cells. We demonstrated that WHSC1 is recruited to the ERα gene by the BET protein BRD3/4, and facilitates ERα gene expression. The small-molecule BET protein inhibitor JQ1 potently suppressed the classic ERα signaling pathway and the growth of Tam-R breast cancer cells in culture. Using a Tam-R breast cancer xenograft mouse model, we demonstrated in vivo anti-breast cancer activity by JQ1 and a strong long-lasting effect of combination therapy with JQ1 and the ER degrader fulvestrant. Taken together, we provide evidence that the epigenomic proteins BRD3/4 and WHSC1 are essential regulators of estrogen receptor signaling and are novel therapeutic targets for treatment of Tam-R breast cancer.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Receptor alfa de Estrogênio/fisiologia , Histona-Lisina N-Metiltransferase/metabolismo , Proteínas Repressoras/metabolismo , Tamoxifeno/uso terapêutico , Animais , Azepinas/uso terapêutico , Neoplasias da Mama/genética , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Epigenômica , Estradiol/análogos & derivados , Estradiol/uso terapêutico , Receptor alfa de Estrogênio/biossíntese , Feminino , Fulvestranto , Humanos , Camundongos , Proteínas Nucleares/fisiologia , Proteínas de Ligação a RNA/fisiologia , Transdução de Sinais/efeitos dos fármacos , Tamoxifeno/farmacologia , Fatores de Transcrição/fisiologia , Triazóis/uso terapêutico
20.
Invest Ophthalmol Vis Sci ; 55(4): 2130-9, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24595385

RESUMO

PURPOSE: Uveal melanoma (UM) tumors require large doses of radiation therapy (RT) to achieve tumor ablation, which frequently results in damage to adjacent normal tissues, leading to vision-threatening complications. Approximately 50% of UM patients present with activating somatic mutations in the gene encoding for G protein αq-subunit (GNAQ), which lead to constitutive activation of downstream pathways, including protein kinase C (PKC). In this study, we investigated the impact of small-molecule PKC inhibitors bisindolylmaleimide I (BIM) and sotrastaurin (AEB071), combined with ionizing radiation (IR), on survival in melanoma cell lines. METHODS: Cellular radiosensitivity was determined by using a combination of proliferation, viability, and clonogenic assays. Cell-cycle effects were measured by flow cytometry. Transcriptomic and proteomic profiling were performed by quantitative real-time PCR, reverse-phase protein array analysis, and immunofluorescence. RESULTS: We found that the PKC inhibitors combined with IR significantly decreased the viability, proliferation, and clonogenic potential of GNAQ(mt), but not GNAQ(wt)/BRAF(mt) cells, compared with IR alone. Combined treatment increased the antiproliferative and proapoptotic effects of IR in GNAQ(mt) cells through delayed DNA-damage resolution and enhanced induction of proteins involved in cell-cycle arrest, cell-growth arrest, and apoptosis. CONCLUSIONS: Our preclinical results suggest that combined modality treatment may allow for reductions in the total RT dose and/or fraction size, which may lead to better functional organ preservation in the treatment of primary GNAQ(mt) UM. These findings suggest future clinical trials combining PKC inhibitors with RT in GNAQ(mt) UM warrant consideration.


Assuntos
DNA de Neoplasias/genética , Subunidades alfa de Proteínas de Ligação ao GTP/genética , Melanoma/enzimologia , Mutação , Inibidores de Proteínas Quinases/farmacologia , Neoplasias Uveais/enzimologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Apoptose/efeitos da radiação , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/efeitos da radiação , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Terapia Combinada , Citometria de Fluxo , Subunidades alfa de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa de Proteínas de Ligação ao GTP/efeitos da radiação , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP , Humanos , Melanoma/genética , Melanoma/terapia , Radiação Ionizante , Reação em Cadeia da Polimerase em Tempo Real , Neoplasias Uveais/genética , Neoplasias Uveais/terapia
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