RESUMO
The 78-kDa glucose regulated protein (GRP78) commonly upregulated in a wide variety of tumors is an important prognostic marker and a promising target for suppressing tumorigenesis and treatment resistance. While GRP78 is well established as a major endoplasmic reticulum (ER) chaperone with anti-apoptotic properties and a master regulator of the unfolded protein response, its new role as a regulator of oncoprotein expression is just emerging. MYC is dysregulated in about 70 % of human cancers and is the most commonly activated oncoprotein. However, despite recent advances, therapeutic targeting of MYC remains challenging. Here we identify GRP78 as a new target for suppression of MYC expression. Using multiple MYC-dependent cancer models including head and neck squamous cell carcinoma and their cisplatin-resistant clones, breast and pancreatic adenocarcinoma, our studies revealed that GRP78 knockdown by siRNA or inhibition of its activity by small molecule inhibitors (YUM70 or HA15) reduced c-MYC expression, leading to onset of apoptosis and loss of cell viability. This was observed in 2D cell culture, 3D spheroid and in xenograft models. Mechanistically, we determined that the suppression of c-MYC is at the post-transcriptional level and that YUM70 and HA15 treatment potently upregulated the eukaryotic translation inhibitor 4E-BP1, which targets eIF4E critical for c-MYC translation initiation. Furthermore, knock-down of 4E-BP1 via siRNA rescued YUM70-mediated c-MYC suppression. As YUM70 is also capable of suppressing N-MYC expression, this study offers a new approach to suppress MYC protein expression through knockdown or inhibition of GRP78.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Ciclo Celular , Chaperona BiP do Retículo Endoplasmático , Regulação Neoplásica da Expressão Gênica , Proteínas de Choque Térmico , Proteínas Proto-Oncogênicas c-myc , Humanos , Chaperona BiP do Retículo Endoplasmático/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Animais , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Proteínas de Choque Térmico/antagonistas & inibidores , Camundongos , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/antagonistas & inibidores , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/antagonistas & inibidores , Apoptose/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto , Neoplasias/genética , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Neoplasias/patologia , Regulação para Cima/efeitos dos fármacosRESUMO
The Nucleocapsid (N) protein of SARS-CoV-2 plays a crucial role in viral replication and pathogenesis, making it an attractive target for developing antiviral therapeutics. In this study, we used differential scanning fluorimetry to establish a high-throughput screening method for identifying high-affinity ligands of N-terminal domain of the N protein (N-NTD). We screened an FDA-approved drug library of 1813 compounds and identified 102 compounds interacting with N-NTD. The screened compounds were further investigated for their ability to inhibit the nucleic-acid binding activity of the N protein using electrophoretic mobility-shift assays. We have identified three inhibitors, Ceftazidime, Sennoside A, and Tannic acid, that disrupt the N protein's interaction with RNA probe. Ceftazidime and Sennoside A exhibited nano-molar range binding affinities with N protein, determined through surface plasmon resonance. The binding sites of Ceftazidime and Sennoside A were investigated using [1H, 15N]-heteronuclear single quantum coherence (HSQC) NMR spectroscopy. Ceftazidime and Sennoside A bind to the putative RNA binding site of the N protein, thus providing insights into the inhibitory mechanism of these compounds. These findings will contribute to the development of novel antiviral agents targeting the N protein of SARS-CoV-2.
Assuntos
Antivirais , Proteínas do Nucleocapsídeo de Coronavírus , SARS-CoV-2 , Antivirais/farmacologia , Antivirais/química , SARS-CoV-2/efeitos dos fármacos , SARS-CoV-2/metabolismo , Proteínas do Nucleocapsídeo de Coronavírus/química , Proteínas do Nucleocapsídeo de Coronavírus/antagonistas & inibidores , Proteínas do Nucleocapsídeo de Coronavírus/metabolismo , Sítios de Ligação , Humanos , Ligação Proteica , Fosfoproteínas/metabolismo , Fosfoproteínas/química , Fosfoproteínas/antagonistas & inibidores , Taninos/química , Taninos/farmacologia , Tratamento Farmacológico da COVID-19 , Proteínas do Nucleocapsídeo/química , Proteínas do Nucleocapsídeo/antagonistas & inibidores , Proteínas do Nucleocapsídeo/metabolismoRESUMO
Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules consisting of two ligands joined by a linker, enabling them to simultaneously bind with an E3 ligase and a protein of interest (POI) and trigger proteasomal degradation of the POI. Limitations of PROTAC include lack of potent E3 ligands, poor cell selectivity, and low permeability. AS1411 is an antitumor aptamer specifically recognizing a membrane-nucleus shuttling nucleolin (NCL). Here, we repurpose AS1411 as a ligand for an E3 ligase mouse double minute 2 homolog (MDM2) via anchoring the NCL-MDM2 complex. Then, we construct an AS1411-NCL-MDM2-based PROTAC (ANM-PROTAC) by conjugating AS1411 with large-molecular-weight ligands for "undruggable" oncogenic STAT3, c-Myc, p53-R175H, and AR-V7. We show that the ANM-PROTAC efficiently penetrates tumor cells, recruits MDM2 and degrades the POIs. The ANM-PROTAC achieves tumor-selective distribution and exhibits excellent antitumor activity with no systemic toxicity. This is a PROTAC with built-in tumor-targeting and cell-penetrating capacities.
Assuntos
Antineoplásicos , Aptâmeros de Nucleotídeos , Proteólise , Proteínas Proto-Oncogênicas c-mdm2 , Humanos , Proteínas Proto-Oncogênicas c-mdm2/metabolismo , Proteínas Proto-Oncogênicas c-mdm2/antagonistas & inibidores , Animais , Camundongos , Proteólise/efeitos dos fármacos , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/farmacologia , Aptâmeros de Nucleotídeos/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Ligantes , Nucleolina , Proteínas de Ligação a RNA/metabolismo , Reposicionamento de Medicamentos , Feminino , Camundongos Nus , Proliferação de Células/efeitos dos fármacos , Linhagem Celular Tumoral , Camundongos Endogâmicos BALB C , Fosfoproteínas/metabolismo , Fosfoproteínas/antagonistas & inibidores , Fosfoproteínas/química , Ensaios de Seleção de Medicamentos Antitumorais , Quimera de Direcionamento de Proteólise , OligodesoxirribonucleotídeosRESUMO
This study describes the identification and target deconvolution of small molecule inhibitors of oncogenic Yes-associated protein (YAP1)/TAZ activity with potent anti-tumor activity in vivo. A high-throughput screen (HTS) of 3.8 million compounds was conducted using a cellular YAP1/TAZ reporter assay. Target deconvolution studies identified the geranylgeranyltransferase-I (GGTase-I) complex as the direct target of YAP1/TAZ pathway inhibitors. The small molecule inhibitors block the activation of Rho-GTPases, leading to subsequent inactivation of YAP1/TAZ and inhibition of cancer cell proliferation in vitro. Multi-parameter optimization resulted in BAY-593, an in vivo probe with favorable PK properties, which demonstrated anti-tumor activity and blockade of YAP1/TAZ signaling in vivo.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Antineoplásicos , Proliferação de Células , Ensaios de Triagem em Larga Escala , Transdução de Sinais , Fatores de Transcrição , Proteínas de Sinalização YAP , Humanos , Fatores de Transcrição/metabolismo , Fatores de Transcrição/antagonistas & inibidores , Proteínas de Sinalização YAP/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Transdução de Sinais/efeitos dos fármacos , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/antagonistas & inibidores , Animais , Proliferação de Células/efeitos dos fármacos , Camundongos , Proteínas rho de Ligação ao GTP/metabolismo , Proteínas rho de Ligação ao GTP/antagonistas & inibidores , Linhagem Celular Tumoral , Fosfoproteínas/metabolismo , Fosfoproteínas/antagonistas & inibidores , Ensaios de Seleção de Medicamentos Antitumorais , Alquil e Aril Transferases/antagonistas & inibidores , Alquil e Aril Transferases/metabolismo , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Descoberta de Drogas , Camundongos Nus , Aciltransferases/antagonistas & inibidores , Aciltransferases/metabolismo , Fenótipo , Relação Estrutura-Atividade , Proteínas com Motivo de Ligação a PDZ com Coativador TranscricionalRESUMO
Yes-associated protein (YAP) is an important regulator of cellular proliferation and transdifferentiation. However, little is known about the mechanisms underlying myofibroblast transdifferentiation in dilated cardiomyopathy (DCM). We investigated the role of YAP in the pathological process of cardiac matrix remodeling. A classic model of DCM was established in BALB/c mice by immunization with porcine cardiac myosin. Cardiac fibroblasts were isolated from neonatal Sprague-Dawley rats by density gradient centrifugation. The expression levels of α-smooth muscle actin (α-SMA) and collagen volume fraction (CVF) were significantly increased in DCM mice. Angiotensin II (Ang II)-mediated YAP activation promoted the proliferation and transdifferentiation of neonatal rat cardiac fibroblasts, and this effect was significantly suppressed in the shRNA YAP + Ang II group compared with the shRNA Control + Ang II group in vitro (2.98±0.34 ×105 vs 5.52±0.82 ×105, P<0.01). Inhibition of endogenous Ang II-stimulated YAP improved the cardiac function by targeting myofibroblast transdifferentiation to attenuate matrix remodeling in vivo. In the valsartan group, left ventricular ejection fraction and fractional shortening were significantly increased compared with the DCM group (52.72±5.51% vs 44.46±3.01%, P<0.05; 34.84±3.85% vs 26.65±3.12%, P<0.01). Our study demonstrated that YAP was a regulator of cardiac myofibroblast differentiation, and regulation of YAP signaling pathway contributed to improve cardiac function of DCM mice, possibly in part by decreasing myofibroblast transdifferentiation to inhibit matrix remodeling.