RESUMEN
Many types of human cancers suppress the expression of argininosuccinate synthase 1 (ASS1), a rate-limiting enzyme for arginine production. Although dependency on exogenous arginine can be harnessed by arginine-deprivation therapies, the impact of ASS1 suppression on the quality of the tumor proteome is unknown. We therefore interrogated proteomes of cancer patients for arginine codon reassignments (substitutants) and surprisingly identified a strong enrichment for cysteine (R>C) in lung tumors specifically. Most R>C events did not coincide with genetically encoded R>C mutations but were likely products of tRNA misalignments. The expression of R>C substitutants was highly associated with oncogenic kelch-like epichlorohydrin (ECH)-associated protein 1 (KEAP1)-pathway mutations and suppressed by intact-KEAP1 in KEAP1-mutated cancer cells. Finally, functional interrogation indicated a key role for R>C substitutants in cell survival to cisplatin, suggesting that regulatory codon reassignments endow cancer cells with more resilience to stress. Thus, we present a mechanism for enriching lung cancer proteomes with cysteines that may affect therapeutic decisions.
Asunto(s)
Arginina , Cisteína , Proteína 1 Asociada A ECH Tipo Kelch , Neoplasias Pulmonares , Proteoma , Humanos , Cisteína/metabolismo , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/patología , Proteína 1 Asociada A ECH Tipo Kelch/metabolismo , Proteína 1 Asociada A ECH Tipo Kelch/genética , Proteoma/metabolismo , Arginina/metabolismo , Mutación , Argininosuccinato Sintasa/metabolismo , Argininosuccinato Sintasa/genética , Cisplatino/farmacología , Línea Celular Tumoral , Proteómica/métodos , Regulación Neoplásica de la Expresión Génica , Supervivencia Celular/efectos de los fármacos , ARN de Transferencia/metabolismo , ARN de Transferencia/genéticaRESUMEN
mRNA translation is a highly conserved and tightly controlled mechanism for protein synthesis. Despite protein quality control mechanisms, amino acid shortage in melanoma induces aberrant proteins by ribosomal frameshifting. The extent and the underlying mechanisms related to this phenomenon are yet unknown. Here, we show that tryptophan depletion-induced ribosomal frameshifting is a widespread phenomenon in cancer. We termed this event sloppiness and strikingly observed its association with MAPK pathway hyperactivation. Sloppiness is stimulated by RAS activation in primary cells, suppressed by pharmacological inhibition of the oncogenic MAPK pathway in sloppy cells, and restored in cells with acquired resistance to MAPK pathway inhibition. Interestingly, sloppiness causes aberrant peptide presentation at the cell surface, allowing recognition and specific killing of drug-resistant cancer cells by T lymphocytes. Thus, while oncogenes empower cancer progression and aggressiveness, they also expose a vulnerability by provoking the production of aberrant peptides through sloppiness.
Asunto(s)
Neoplasias/genética , Oncogenes , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Linfocitos T/citología , Animales , Carcinogénesis , Membrana Celular/metabolismo , Progresión de la Enfermedad , Resistencia a Antineoplásicos , Mutación del Sistema de Lectura , Sistema de Lectura Ribosómico , Humanos , Inmunoterapia/métodos , Sistema de Señalización de MAP Quinasas , Melanoma/metabolismo , Ratones , Neoplasias/metabolismo , Péptidos/química , Inhibidores de Proteínas Quinasas , Ribosomas/metabolismo , Linfocitos T/metabolismo , Triptófano/química , Triptófano/metabolismoRESUMEN
Extensive tumour inflammation, which is reflected by high levels of infiltrating T cells and interferon-γ (IFNγ) signalling, improves the response of patients with melanoma to checkpoint immunotherapy1,2. Many tumours, however, escape by activating cellular pathways that lead to immunosuppression. One such mechanism is the production of tryptophan metabolites along the kynurenine pathway by the enzyme indoleamine 2,3-dioxygenase 1 (IDO1), which is induced by IFNγ3-5. However, clinical trials using inhibition of IDO1 in combination with blockade of the PD1 pathway in patients with melanoma did not improve the efficacy of treatment compared to PD1 pathway blockade alone6,7, pointing to an incomplete understanding of the role of IDO1 and the consequent degradation of tryptophan in mRNA translation and cancer progression. Here we used ribosome profiling in melanoma cells to investigate the effects of prolonged IFNγ treatment on mRNA translation. Notably, we observed accumulations of ribosomes downstream of tryptophan codons, along with their expected stalling at the tryptophan codon. This suggested that ribosomes bypass tryptophan codons in the absence of tryptophan. A detailed examination of these tryptophan-associated accumulations of ribosomes-which we term 'W-bumps'-showed that they were characterized by ribosomal frameshifting events. Consistently, reporter assays combined with proteomic and immunopeptidomic analyses demonstrated the induction of ribosomal frameshifting, and the generation and presentation of aberrant trans-frame peptides at the cell surface after treatment with IFNγ. Priming of naive T cells from healthy donors with aberrant peptides induced peptide-specific T cells. Together, our results suggest that IDO1-mediated depletion of tryptophan, which is induced by IFNγ, has a role in the immune recognition of melanoma cells by contributing to diversification of the peptidome landscape.
Asunto(s)
Presentación de Antígeno , Mutación del Sistema de Lectura , Melanoma/inmunología , Péptidos/genética , Péptidos/inmunología , Biosíntesis de Proteínas/inmunología , Linfocitos T/inmunología , Línea Celular , Codón/genética , Sistema de Lectura Ribosómico/efectos de los fármacos , Sistema de Lectura Ribosómico/genética , Sistema de Lectura Ribosómico/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Humanos , Indolamina-Pirrol 2,3,-Dioxigenasa/antagonistas & inhibidores , Indolamina-Pirrol 2,3,-Dioxigenasa/metabolismo , Interferón gamma/inmunología , Interferón gamma/farmacología , Melanoma/patología , Péptidos/química , Biosíntesis de Proteínas/efectos de los fármacos , Biosíntesis de Proteínas/genética , Proteoma , Ribosomas/efectos de los fármacos , Ribosomas/metabolismo , Triptófano/deficiencia , Triptófano/genética , Triptófano/metabolismoRESUMEN
Viruses actively reprogram the metabolism of the host to ensure the availability of sufficient building blocks for virus replication and spreading. However, relatively little is known about how picornaviruses-a large family of small, non-enveloped positive-strand RNA viruses-modulate cellular metabolism for their own benefit. Here, we studied the modulation of host metabolism by coxsackievirus B3 (CVB3), a member of the enterovirus genus, and encephalomyocarditis virus (EMCV), a member of the cardiovirus genus, using steady-state as well as 13C-glucose tracing metabolomics. We demonstrate that both CVB3 and EMCV increase the levels of pyrimidine and purine metabolites and provide evidence that this increase is mediated through degradation of nucleic acids and nucleotide recycling, rather than upregulation of de novo synthesis. Finally, by integrating our metabolomics data with a previously acquired phosphoproteomics dataset of CVB3-infected cells, we identify alterations in phosphorylation status of key enzymes involved in nucleotide metabolism, providing insight into the regulation of nucleotide metabolism during infection.
Asunto(s)
Cardiovirus , Infecciones por Enterovirus , Enterovirus , Picornaviridae , Humanos , Enterovirus/fisiología , Virus de la Encefalomiocarditis/fisiología , Replicación Viral , Enterovirus Humano B/fisiología , Células HeLaRESUMEN
Picornaviridae represent a large family of single-stranded positive RNA viruses of which different members can infect both humans and animals. These include the enteroviruses (e.g., poliovirus, coxsackievirus, and rhinoviruses) as well as the cardioviruses (e.g., encephalomyocarditis virus). Picornaviruses have evolved to interact with, use, and/or evade cellular host systems to create the optimal environment for replication and spreading. It is known that viruses modify kinase activity during infection, but a proteome-wide overview of the (de)regulation of cellular kinases during picornavirus infection is lacking. To study the kinase activity landscape during picornavirus infection, we here applied dedicated targeted mass spectrometry-based assays covering â¼40% of the human kinome. Our data show that upon infection, kinases of the MAPK pathways become activated (e.g., ERK1/2, RSK1/2, JNK1/2/3, and p38), while kinases involved in regulating the cell cycle (e.g., CDK1/2, GWL, and DYRK3) become inactivated. Additionally, we observed the activation of CHK2, an important kinase involved in the DNA damage response. Using pharmacological kinase inhibitors, we demonstrate that several of these activated kinases are essential for the replication of encephalomyocarditis virus. Altogether, the data provide a quantitative understanding of the regulation of kinome activity induced by picornavirus infection, providing a resource important for developing novel antiviral therapeutic interventions.
Asunto(s)
Infecciones por Picornaviridae , Picornaviridae , Humanos , Picornaviridae/fisiología , Picornaviridae/enzimología , Infecciones por Picornaviridae/virología , Infecciones por Picornaviridae/metabolismo , Células HeLa , Proteoma/metabolismo , Proteínas Quinasas/metabolismo , Replicación Viral , FosforilaciónRESUMEN
Unsaturated fatty acids (UFA) are crucial for T-cell effector functions, as they can affect the growth, differentiation, survival, and function of T cells. Nonetheless, the mechanisms by which UFA affects T-cell behavior are ill-defined. Therefore, we analyzed the processing of oleic acid, a prominent UFA abundantly present in blood, adipocytes, and the fat pads surrounding lymph nodes, in CD4+ T cells. We found that exogenous oleic acid increases proliferation and enhances the calcium flux response upon CD3/CD28 activation. By using a variety of techniques, we found that the incorporation of oleic acid into membrane lipids, rather than regulation of cellular metabolism or TCR expression, is essential for its effects on CD4+ T cells. These results provide novel insights into the mechanism through which exogenous oleic acid enhances CD4+ T-cell function.
RESUMEN
Multiple myeloma (MM) is the second most prevalent hematologic malignancy and is incurable because of the inevitable development of drug resistance. Methionine adenosyltransferase 2α (MAT2A) is the primary producer of the methyl donor S-adenosylmethionine (SAM) and several studies have documented MAT2A deregulation in different solid cancers. As the role of MAT2A in MM has not been investigated yet, the aim of this study was to clarify the potential role and underlying molecular mechanisms of MAT2A in MM, exploring new therapeutic options to overcome drug resistance. By analyzing publicly available gene expression profiling data, MAT2A was found to be more highly expressed in patient-derived myeloma cells than in normal bone marrow plasma cells. The expression of MAT2A correlated with an unfavorable prognosis in relapsed patients. MAT2A inhibition in MM cells led to a reduction in intracellular SAM levels, which resulted in impaired cell viability and proliferation, and induction of apoptosis. Further mechanistic investigation demonstrated that MAT2A inhibition inactivated the mTOR-4EBP1 pathway, accompanied by a decrease in protein synthesis. MAT2A targeting in vivo with the small molecule compound FIDAS-5 was able to significantly reduce tumor burden in the 5TGM1 model. Finally, we found that MAT2A inhibition can synergistically enhance the anti-MM effect of the standard-of-care agent bortezomib on both MM cell lines and primary human CD138+ MM cells. In summary, we demonstrate that MAT2A inhibition reduces MM cell proliferation and survival by inhibiting mTOR-mediated protein synthesis. Moreover, our findings suggest that the MAT2A inhibitor FIDAS-5 could be a novel compound to improve bortezomib-based treatment of MM.
Asunto(s)
Mieloma Múltiple , S-Adenosilmetionina , Humanos , S-Adenosilmetionina/metabolismo , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/genética , Bortezomib/farmacología , Pronóstico , Serina-Treonina Quinasas TOR , Metionina Adenosiltransferasa/genética , Metionina Adenosiltransferasa/metabolismoRESUMEN
L-asparaginase (ASNase) serves as an effective drug for adolescent acute lymphoblastic leukemia. However, many clinical trials indicated severe ASNase toxicity in patients with solid tumors, with resistant mechanisms not well understood. Here, we took a functional genetic approach and identified SLC1A3 as a novel contributor to ASNase resistance in cancer cells. In combination with ASNase, SLC1A3 inhibition caused cell cycle arrest or apoptosis, and myriads of metabolic vulnerabilities in tricarboxylic acid (TCA) cycle, urea cycle, nucleotides biosynthesis, energy production, redox homeostasis, and lipid biosynthesis. SLC1A3 is an aspartate and glutamate transporter, mainly expressed in brain tissues, but high expression levels were also observed in some tumor types. Here, we demonstrate that ASNase stimulates aspartate and glutamate consumptions, and their refilling through SLC1A3 promotes cancer cell proliferation. Lastly, in vivo experiments indicated that SLC1A3 expression promoted tumor development and metastasis while negating the suppressive effects of ASNase by fueling aspartate, glutamate, and glutamine metabolisms despite of asparagine shortage. Altogether, our findings identify a novel role for SLC1A3 in ASNase resistance and suggest that restrictive aspartate and glutamate uptake might improve ASNase efficacy with solid tumors.
Asunto(s)
Asparaginasa/farmacología , Resistencia a Antineoplásicos/genética , Transportador 1 de Aminoácidos Excitadores/metabolismo , Neoplasias/tratamiento farmacológico , Animales , Antineoplásicos/farmacología , Apoptosis , Sistemas CRISPR-Cas , Proliferación Celular , Transportador 1 de Aminoácidos Excitadores/antagonistas & inhibidores , Transportador 1 de Aminoácidos Excitadores/genética , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Neoplasias/enzimología , Neoplasias/patología , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Stable Foxp3 expression is required for the development of functional regulatory T (Treg) cells. Here, we demonstrate that the expression of the transcription factor Foxp3 can be regulated through the polyubiquitination of multiple lysine residues, resulting in proteasome-mediated degradation. Expression of the deubiquitinase (DUB) USP7 was found to be upregulated and active in Treg cells, being associated with Foxp3 in the nucleus. Ectopic expression of USP7 decreased Foxp3 polyubiquitination and increased Foxp3 expression. Conversely, either treatment with DUB inhibitor or USP7 knockdown decreased endogenous Foxp3 protein expression and decreased Treg-cell-mediated suppression in vitro. Furthermore, in a murine adoptive-transfer-induced colitis model, either inhibition of DUB activity or USP7 knockdown in Treg cells abrogated their ability to resolve inflammation in vivo. Our data reveal a molecular mechanism in which rapid temporal control of Foxp3 expression in Treg cells can be regulated by USP7, thereby modulating Treg cell numbers and function.
Asunto(s)
Colitis/inmunología , Factores de Transcripción Forkhead/metabolismo , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/metabolismo , Ubiquitina Tiolesterasa/metabolismo , Traslado Adoptivo , Animales , Diferenciación Celular/inmunología , Línea Celular , Proteínas de Unión al ADN/genética , Modelos Animales de Enfermedad , Endopeptidasas/metabolismo , Células HEK293 , Proteínas de Homeodominio/genética , Humanos , Proteínas Inmediatas-Precoces/antagonistas & inhibidores , Proteínas Inmediatas-Precoces/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Interferencia de ARN , ARN Interferente Pequeño , Ubiquitina Tiolesterasa/genética , Peptidasa Específica de Ubiquitina 7 , UbiquitinaciónRESUMEN
Membrane transporters and receptors are responsible for balancing nutrient and metabolite levels to aid body homeostasis. Here, we report that proximal tubule cells in kidneys sense elevated endogenous, gut microbiome-derived, metabolite levels through EGF receptors and downstream signaling to induce their secretion by up-regulating the organic anion transporter-1 (OAT1). Remote metabolite sensing and signaling was observed in kidneys from healthy volunteers and rats in vivo, leading to induced OAT1 expression and increased removal of indoxyl sulfate, a prototypical microbiome-derived metabolite and uremic toxin. Using 2D and 3D human proximal tubule cell models, we show that indoxyl sulfate induces OAT1 via AhR and EGFR signaling, controlled by miR-223. Concomitantly produced reactive oxygen species (ROS) control OAT1 activity and are balanced by the glutathione pathway, as confirmed by cellular metabolomic profiling. Collectively, we demonstrate remote metabolite sensing and signaling as an effective OAT1 regulation mechanism to maintain plasma metabolite levels by controlling their secretion.
Asunto(s)
Microbioma Gastrointestinal , Túbulos Renales Proximales/metabolismo , Transducción de Señal , Animales , Aniones , Receptores ErbB/metabolismo , Glutatión/metabolismo , Humanos , Metaboloma , Proteína 1 de Transporte de Anión Orgánico/metabolismo , Ratas , Especies Reactivas de Oxígeno/metabolismo , Receptores de Hidrocarburo de Aril/metabolismoRESUMEN
Fibroblast activation is associated with tumor progression and implicated in metastasis, but the initial triggering signals required to kick-start this process remain largely unknown. Because small cancerous lesions share limited physical contact with neighboring fibroblasts, we reasoned the first tumor-derived signal for fibroblast activation should be secreted and diffusible. By pulsed metabolic labeling and click-chemistry based affinity enrichment, we sieved through the ductal carcinoma secretome for potential fibroblast activators. Using immuno-depletion/supplementation assays on various secreted factors, we pinpointed that tumor-secreted CTGF/VEGFA alone is sufficient to activate paired mammary fibroblasts from the same patient via ROCK1 and JunB signaling. Fibroblasts activated in this manner are distinct in morphology, growth, and adopt a highly tumor-like secretion profile, which in turn promotes tumor migration by counteracting oxidative and lactate stress. These findings reveal a profound division-of-labor between normal and cancer cells under the directive of the latter, and allude to potential metastatic prevention through inhibiting local fibroblast activation.
Asunto(s)
Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Movimiento Celular , Factor de Crecimiento del Tejido Conjuntivo/metabolismo , Fibroblastos/metabolismo , Fibroblastos/patología , Microambiente Tumoral , Factor A de Crecimiento Endotelial Vascular/metabolismo , Carcinoma Ductal de Mama/metabolismo , Carcinoma Ductal de Mama/patología , Adhesión Celular , Línea Celular Tumoral , Femenino , Humanos , Modelos Biológicos , Estrés Oxidativo , Transducción de Señal , Factores de Transcripción/metabolismo , Quinasas Asociadas a rho/metabolismoRESUMEN
Cancer cells modulate their metabolic networks to support cell proliferation and a higher demand of building blocks. These changes may restrict the availability of certain amino acids for protein synthesis, which can be utilized for cancer therapy. However, little is known about the amino acid demand changes occurring during aggressive and invasive stages of cancer. Recently, we developed diricore, an approach based on ribosome profiling that can uncover amino acid limitations. Here, we applied diricore to a cellular model in which epithelial breast cells respond rapidly to TGFß1, a cytokine essential for cancer progression and metastasis, and uncovered shortage of leucine. Further analyses indicated that TGFß1 treatment of human breast epithelial cells reduces the expression of SLC3A2, a subunit of the leucine transporter, which diminishes leucine uptake and inhibits cell proliferation. Thus, we identified a specific amino acid limitation associated with the TGFß1 response, a vulnerability that might be associated with aggressiveness in cancer.
Asunto(s)
Codón , Leucina/genética , Leucina/metabolismo , Biosíntesis de Proteínas , Ribosomas/metabolismo , Factor de Crecimiento Transformador beta1/metabolismo , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Línea Celular Tumoral , Femenino , Cadena Pesada de la Proteína-1 Reguladora de Fusión/genética , Cadena Pesada de la Proteína-1 Reguladora de Fusión/metabolismo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Biosíntesis de Proteínas/efectos de los fármacos , Transducción de Señal , Factor de Crecimiento Transformador beta1/farmacologíaRESUMEN
Pyrroline-5-carboxylate reductase 1 (PYCR1) is the final enzyme involved in the biosynthesis of proline and has been found to be upregulated in various forms of cancer. Due to the role of proline in maintaining the redox balance of cells and preventing apoptosis, PYCR1 is emerging as an attractive oncology target. Previous PYCR1 knockout studies led to a reduction in tumor growth. Accordingly, a small molecule inhibitor of PYCR1 could lead to new treatments for cancer, and a focused screening effort identified pargyline as a fragment-like hit. We report the design and synthesis of the first tool compounds as PYCR1 inhibitors, derived from pargyline, which were assayed to assess their ability to attenuate the production of proline. Structural activity studies have revealed the key determinants of activity, with the most potent compound (4) showing improved activity in vitro in enzyme (IC50â¯=â¯8.8⯵M) and pathway relevant effects in cell-based assays.
Asunto(s)
Antineoplásicos/farmacología , Inhibidores Enzimáticos/farmacología , Pargilina/farmacología , Pirrolina Carboxilato Reductasas/antagonistas & inhibidores , Bibliotecas de Moléculas Pequeñas/farmacología , Antineoplásicos/síntesis química , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Humanos , Estructura Molecular , Pargilina/síntesis química , Pargilina/química , Pirrolina Carboxilato Reductasas/metabolismo , Bibliotecas de Moléculas Pequeñas/síntesis química , Bibliotecas de Moléculas Pequeñas/química , Relación Estructura-Actividad , delta-1-Pirrolina-5-Carboxilato ReductasaRESUMEN
Cancer cells acquire distinct metabolic adaptations to survive stress associated with tumour growth and to satisfy the anabolic demands of proliferation. The tumour suppressor protein p53 (also known as TP53) influences a range of cellular metabolic processes, including glycolysis, oxidative phosphorylation, glutaminolysis and anti-oxidant response. In contrast to its role in promoting apoptosis during DNA-damaging stress, p53 can promote cell survival during metabolic stress, a function that may contribute not only to tumour suppression but also to non-cancer-associated functions of p53. Here we show that human cancer cells rapidly use exogenous serine and that serine deprivation triggered activation of the serine synthesis pathway and rapidly suppressed aerobic glycolysis, resulting in an increased flux to the tricarboxylic acid cycle. Transient p53-p21 (also known as CDKN1A) activation and cell-cycle arrest promoted cell survival by efficiently channelling depleted serine stores to glutathione synthesis, thus preserving cellular anti-oxidant capacity. Cells lacking p53 failed to complete the response to serine depletion, resulting in oxidative stress, reduced viability and severely impaired proliferation. The role of p53 in supporting cancer cell proliferation under serine starvation was translated to an in vivo model, indicating that serine depletion has a potential role in the treatment of p53-deficient tumours.
Asunto(s)
Metabolismo Energético , Neoplasias/metabolismo , Neoplasias/patología , Estrés Oxidativo , Serina/deficiencia , Proteína p53 Supresora de Tumor/metabolismo , Aerobiosis , Animales , Antioxidantes/metabolismo , Puntos de Control del Ciclo Celular , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular , Células Cultivadas , Ciclo del Ácido Cítrico , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/metabolismo , Modelos Animales de Enfermedad , Femenino , Fase G1 , Glutatión/biosíntesis , Glucólisis/efectos de los fármacos , Células HCT116 , Humanos , Ratones , Trasplante de Neoplasias , Nucleótidos/metabolismo , Regiones Promotoras Genéticas/genética , Serina/biosíntesis , Serina/metabolismo , Serina/farmacología , Inanición , Proteína p53 Supresora de Tumor/deficiencia , Proteína p53 Supresora de Tumor/genéticaRESUMEN
Background The hexapeptide 4A6 (Ac-Thr(tBu)-His(Bzl)-Thr(Bzl)-Nle-Glu(OtBu)-Gly-Bza) was isolated from a peptide library constructed to identify peptide-based transport inhibitors of multidrug resistance (MDR) efflux pumps including P-glycoprotein and Multidrug Resistance-associated Protein 1. 4A6 proved to be a substrate but not an inhibitor of these MDR efflux transporters. In fact, 4A6 and related peptides displayed potent cytotoxic activity via an unknown mechanism. Objective To decipher the mode of cytotoxic activity of 4A6. Methods Screening of 4A6 activity was performed against the NCI60 panel of cancer cell lines. Possible interactions of 4A6 with the 26S proteasome were assessed via proteasome activity and affinity labeling, and cell growth inhibition studies with leukemic cells resistant to the proteasome inhibitor bortezomib (BTZ). Results The NCI60 panel COMPARE analysis revealed that 4A6 had an activity profile overlapping with BTZ. Consistently, 4A6 proved to be a selective and reversible inhibitor of ß5 subunit (PSMB5)-associated chymotrypsin-like activity of the 26S proteasome. This conclusion is supported by several lines of evidence: (i) inhibition of chymotrypsin-like proteasome activity by 4A6 and related peptides correlated with their cell growth inhibition potencies; (ii) 4A6 reversibly inhibited functional ß5 active site labeling with the affinity probe BodipyFL-Ahx3L3VS; and (iii) human myeloid THP1 cells with acquired BTZ resistance due to mutated PSMB5 were highly (up to 287-fold) cross-resistant to 4A6 and its related peptides. Conclusion 4A6 is a novel specific inhibitor of the ß5 subunit-associated chymotrypsin-like proteasome activity. Further exploration of 4A6 as a lead compound for development as a novel proteasome-targeted drug is warranted.
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Antineoplásicos/farmacología , Oligopéptidos/farmacología , Inhibidores de Proteasoma/farmacología , Animales , Apoptosis/efectos de los fármacos , Bortezomib/farmacología , Línea Celular , Resistencia a Antineoplásicos , Humanos , Ratones , Biblioteca de PéptidosRESUMEN
We describe a two-dimensional thermal proteome profiling strategy that can be combined with an orthogonal chemoproteomics approach to enable comprehensive target profiling of the marketed histone deacetylase inhibitor panobinostat. The N-hydroxycinnamide moiety is identified as critical for potent and tetrahydrobiopterin-competitive inhibition of phenylalanine hydroxylase leading to increases in phenylalanine and decreases in tyrosine levels. These findings provide a rationale for adverse clinical observations and suggest repurposing of the drug for treatment of tyrosinemia.
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Inhibidores de Histona Desacetilasas/farmacología , Ácidos Hidroxámicos/farmacología , Indoles/farmacología , Fenilalanina Hidroxilasa/antagonistas & inhibidores , Temperatura , Relación Dosis-Respuesta a Droga , Células Hep G2 , Inhibidores de Histona Desacetilasas/química , Humanos , Ácidos Hidroxámicos/química , Indoles/química , Estructura Molecular , Panobinostat , Fenilalanina Hidroxilasa/química , Fenilalanina Hidroxilasa/metabolismo , Relación Estructura-ActividadRESUMEN
Photodynamic therapy (PDT) is an established palliative treatment for perihilar cholangiocarcinoma that is clinically promising. However, tumors tend to regrow after PDT, which may result from the PDT-induced activation of survival pathways in sublethally afflicted tumor cells. In this study, tumor-comprising cells (i.e., vascular endothelial cells, macrophages, perihilar cholangiocarcinoma cells, and EGFR-overexpressing epidermoid cancer cells) were treated with the photosensitizer zinc phthalocyanine that was encapsulated in cationic liposomes (ZPCLs). The post-PDT survival pathways and metabolism were studied following sublethal (LC50) and supralethal (LC90) PDT. Sublethal PDT induced survival signaling in perihilar cholangiocarcinoma (SK-ChA-1) cells via mainly HIF-1-, NF-кB-, AP-1-, and heat shock factor (HSF)-mediated pathways. In contrast, supralethal PDT damage was associated with a dampened survival response. PDT-subjected SK-ChA-1 cells downregulated proteins associated with EGFR signaling, particularly at LC90. PDT also affected various components of glycolysis and the tricarboxylic acid cycle as well as metabolites involved in redox signaling. In conclusion, sublethal PDT activates multiple pathways in tumor-associated cell types that transcriptionally regulate cell survival, proliferation, energy metabolism, detoxification, inflammation/angiogenesis, and metastasis. Accordingly, tumor cells sublethally afflicted by PDT are a major therapeutic culprit. Our multi-omic analysis further unveiled multiple druggable targets for pharmacological co-intervention.
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Redes y Vías Metabólicas , Metabolómica/métodos , Fotoquimioterapia , Proteómica/métodos , Transducción de Señal , Animales , Muerte Celular/efectos de los fármacos , Línea Celular , Supervivencia Celular/efectos de los fármacos , Regulación hacia Abajo/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Receptores ErbB/metabolismo , Humanos , Redes y Vías Metabólicas/efectos de los fármacos , Metaboloma/efectos de los fármacos , Ratones , Oxidación-Reducción/efectos de los fármacos , Fármacos Fotosensibilizantes/farmacología , Transducción de Señal/efectos de los fármacos , Factores de Tiempo , Transcripción Genética/efectos de los fármacos , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Phospho-MurNAc-pentapeptide translocase (MraY) catalyzes the synthesis of Lipid I, a bacterial peptidoglycan precursor. As such, MraY is essential for bacterial survival and therefore is an ideal target for developing novel antibiotics. However, the understanding of its catalytic mechanism, despite the recently determined crystal structure, remains limited. In the present study, the kinetic properties of Bacillus subtilis MraY (BsMraY) were investigated by fluorescence enhancement using dansylated UDP-MurNAc-pentapeptide and heptaprenyl phosphate (C35-P, short-chain homolog of undecaprenyl phosphate, the endogenous substrate of MraY) as second substrate. Varying the concentrations of both of these substrates and fitting the kinetics data to two-substrate models showed that the concomitant binding of both UDP-MurNAc-pentapeptide-DNS and C35-P to the enzyme is required before the release of the two products, Lipid I and UMP. We built a model of BsMraY and performed docking studies with the substrate C35-P to further deepen our understanding of how MraY accommodates this lipid substrate. Based on these modeling studies, a novel catalytic role was put forward for a fully conserved histidine residue in MraY (His-289 in BsMraY), which has been experimentally confirmed to be essential for MraY activity. Using the current model of BsMraY, we propose that a small conformational change is necessary to relocate the His-289 residue, such that the translocase reaction can proceed via a nucleophilic attack of the phosphate moiety of C35-P on bound UDP-MurNAc-pentapeptide.
Asunto(s)
Bacillus subtilis/enzimología , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Transferasas/química , Transferasas/metabolismo , Sustitución de Aminoácidos , Bacillus subtilis/genética , Proteínas Bacterianas/genética , Catálisis , Cinética , Modelos Moleculares , Monosacáridos/metabolismo , Mutagénesis Sitio-Dirigida , Oligopéptidos/metabolismo , Fosfatos de Poliisoprenilo/metabolismo , Conformación Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidad por Sustrato , Transferasas/genética , Transferasas (Grupos de Otros Fosfatos Sustitutos) , Uridina Difosfato Ácido N-Acetilmurámico/análogos & derivados , Uridina Difosfato Ácido N-Acetilmurámico/metabolismo , Uridina Monofosfato/metabolismoRESUMEN
The proteasome is able to create spliced Ags, in which two distant parts of a protein are excised and ligated together to form a novel peptide, for presentation by MHC class I molecules. These noncontiguous epitopes are generated via a transpeptidation reaction catalyzed by the proteasomal active sites. Transpeptidation reactions in the proteasome follow explicit rules and occur particularly efficiently when the C-terminal ligation partner contains a lysine or arginine residue at the site of ligation. Lysine contains two amino groups that theoretically may both participate in ligation reactions, implying that potentially not only peptide but also isopeptide linkages could be formed. Using nuclear magnetic resonance spectroscopy, we demonstrate in the present study that the proteasome can use the ε-amino group of an N-terminal lysine residue in transpeptidation reactions to create a novel type of posttranslationally modified epitopes. We show that the overall efficiency of ε ligation is only 10-fold lower as compared with α ligation, suggesting that the proteasome can produce sufficient isopeptide Ag to evoke a T cell response. Additionally, we show that isopeptides are more stable toward further proteasomal processing than are normal peptides, and we demonstrate that isopeptides can bind to HLA-A2.1 and HLA-A3 with high affinity. These properties likely increase the fraction of ε-ligated peptides presented on the cell surface for CD8(+) T cell surveillance. Finally, we show that isopeptide Ags are immunogenic in vivo. We postulate that ε ligation is a genuine posttranslational modification, suggesting that the proteasome can create a novel type of Ag that is likely to play a role in immunity.
Asunto(s)
Péptidos/química , Complejo de la Endopetidasa Proteasomal/química , Empalme de Proteína , Humanos , Espectroscopía de Resonancia Magnética , Péptidos/inmunología , Complejo de la Endopetidasa Proteasomal/inmunología , Isoformas de Proteínas/química , Isoformas de Proteínas/inmunología , Procesamiento Proteico-Postraduccional , Linfocitos T/inmunologíaRESUMEN
Peptide splicing, in which two distant parts of a protein are excised and then ligated to form a novel peptide, can generate unique MHC class I-restricted responses. Because these peptides are not genetically encoded and the rules behind proteasomal splicing are unknown, it is difficult to predict these spliced Ags. In the current study, small libraries of short peptides were used to identify amino acid sequences that affect the efficiency of this transpeptidation process. We observed that splicing does not occur at random, neither in terms of the amino acid sequences nor through random splicing of peptides from different sources. In contrast, splicing followed distinct rules that we deduced and validated both in vitro and in cells. Peptide ligation was quantified using a model peptide and demonstrated to occur with up to 30% ligation efficiency in vitro, provided that optimal structural requirements for ligation were met by both ligating partners. In addition, many splicing products could be formed from a single protein. Our splicing rules will facilitate prediction and detection of new spliced Ags to expand the peptidome presented by MHC class I Ags.