RESUMO
Tumors display increased uptake and processing of nutrients to fulfill the demands of rapidly proliferating cancer cells. Seminal studies have shown that the proto-oncogene MYC promotes metabolic reprogramming by altering glutamine uptake and metabolism in cancer cells. How MYC regulates the metabolism of other amino acids in cancer is not fully understood. Using high-performance liquid chromatography (HPLC)-tandem mass spectrometry (LC-MS/MS), we found that MYC increased intracellular levels of tryptophan and tryptophan metabolites in the kynurenine pathway. MYC induced the expression of the tryptophan transporters SLC7A5 and SLC1A5 and the enzyme arylformamidase (AFMID), involved in the conversion of tryptophan into kynurenine. SLC7A5, SLC1A5, and AFMID were elevated in colon cancer cells and tissues, and kynurenine was significantly greater in tumor samples than in the respective adjacent normal tissue from patients with colon cancer. Compared with normal human colonic epithelial cells, colon cancer cells were more sensitive to the depletion of tryptophan. Blocking enzymes in the kynurenine pathway caused preferential death of established colon cancer cells and transformed colonic organoids. We found that only kynurenine and no other tryptophan metabolite promotes the nuclear translocation of the transcription factor aryl hydrocarbon receptor (AHR). Blocking the interaction between AHR and kynurenine with CH223191 reduced the proliferation of colon cancer cells. Therefore, we propose that limiting cellular kynurenine or its downstream targets could present a new strategy to reduce the proliferation of MYC-dependent cancer cells.
Assuntos
Neoplasias do Colo/fisiopatologia , Cinurenina/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Triptofano/metabolismo , Sistema ASC de Transporte de Aminoácidos/genética , Antineoplásicos/farmacologia , Arilformamidase/genética , Linhagem Celular , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica , Humanos , Indóis/farmacologia , Cinurenina/genética , Transportador 1 de Aminoácidos Neutros Grandes/genética , Antígenos de Histocompatibilidade Menor/genética , Oximas/farmacologia , Proto-Oncogene Mas , Sulfonamidas/farmacologiaRESUMO
MYC enhances protein synthesis by regulating genes involved in ribosome biogenesis and protein translation. Here, we show that MYC-induced protein translation is mediated by the transcription factor aryl hydrocarbon receptor (AHR), which is induced by MYC in colonic cells. AHR promotes protein synthesis by activating the transcription of genes required for ribosome biogenesis and protein translation, including OGFOD1 and NOLC1. Using surface sensing of translation (SUnSET) to measure global protein translation, we found that silencing AHR or its targets diminishes protein synthesis. Therefore, targeting AHR or its downstream pathways could provide a novel approach to limit biomass production in MYC-driven tumors.
Assuntos
Nucléolo Celular/metabolismo , Biossíntese de Proteínas , Proteínas Proto-Oncogênicas c-myc/metabolismo , Receptores de Hidrocarboneto Arílico/fisiologia , Animais , Linhagem Celular , Nucléolo Celular/genética , Células Cultivadas , Neoplasias do Colo/genética , Neoplasias do Colo/metabolismo , Humanos , Proteínas Proto-Oncogênicas c-myc/genética , Ratos , Receptores de Hidrocarboneto Arílico/biossíntese , Receptores de Hidrocarboneto Arílico/genética , Ativação TranscricionalRESUMO
The nucleolus is a large nuclear membraneless organelle responsible for ribosome biogenesis. Ribosomes are cytoplasmic macromolecular complexes comprising RNA and proteins that link amino acids together to form new proteins. The biogenesis of ribosomes is an intricate multistep process that involves the transcription of ribosomal DNA (rDNA), the processing of ribosomal RNA (rRNA), and the assembly of rRNA with ribosomal proteins to form active ribosomes. Nearly all steps necessary for ribosome production and maturation occur in the nucleolus. Nucleolar shape, size, and number are directly linked to ribosome biogenesis. Errors in the steps of ribosomal biogenesis are sensed by the nucleolus causing global alterations in nucleolar function and morphology. This phenomenon, known as nucleolar stress, can lead to molecular changes such as stabilization of p53, which in turn activates cell cycle arrest or apoptosis. In this review, we discuss recent work on the association of nucleolar stress with degenerative diseases and developmental defects. In addition, we highlight the importance of de novo nucleotide biosynthesis for the enhanced nucleolar activity of cancer cells and discuss targeting nucleotide biosynthesis as a strategy to activate nucleolar stress to specifically target cancer cells.
Assuntos
Nucléolo Celular , Neoplasias , Humanos , Ribossomos/metabolismo , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/metabolismo , RNA Ribossômico/genética , RNA Ribossômico/metabolismo , Neoplasias/metabolismo , NucleotídeosRESUMO
The nucleolus, a membrane-less organelle, is responsible for ribosomal RNA transcription, ribosomal RNA processing, and ribosome assembly. Nucleolar size and number are indicative of a cell's protein synthesis rate and proliferative capacity, and abnormalities in the nucleolus have been linked to neurodegenerative diseases and cancer. In this study, we demonstrated that the nucleolar protein ZNF692 directly interacts with nucleophosmin 1 (NPM1). Knocking down ZNF692 resulted in the nucleolar redistribution of NPM1 in ring-like structures and reduced protein synthesis. Purified NPM1 forms spherical condensates in vitro but mixing it with ZNF692 produces irregular condensates more closely resembling living cell nucleoli. Our findings indicate that ZNF692, by interacting with NPM1, plays a critical role in regulating nucleolar architecture and function in living cells.
Assuntos
Nucléolo Celular , Proteínas de Ligação a DNA , Nucleofosmina , Fatores de Transcrição , Nucléolo Celular/genética , Nucléolo Celular/metabolismo , Proteínas Nucleares/metabolismo , Ligação Proteica , RNA Ribossômico/metabolismo , Humanos , Fatores de Transcrição/metabolismo , Proteínas de Ligação a DNA/metabolismoRESUMO
The Myc oncoprotein family comprises transcription factors that control multiple cellular functions and are widely involved in oncogenesis. Here we report the identification of Myc-nick, a cytoplasmic form of Myc generated by calpain-dependent proteolysis at lysine 298 of full-length Myc. Myc-nick retains conserved Myc box regions but lacks nuclear localization signals and the bHLHZ domain essential for heterodimerization with Max and DNA binding. Myc-nick induces alpha-tubulin acetylation and altered cell morphology by recruiting histone acetyltransferase GCN5 to microtubules. During muscle differentiation, while the levels of full-length Myc diminish, Myc-nick and acetylated alpha-tubulin levels are increased. Ectopic expression of Myc-nick accelerates myoblast fusion, triggers the expression of myogenic markers, and permits Myc-deficient fibroblasts to transdifferentiate in response to MyoD. We propose that the cleavage of Myc by calpain abrogates the transcriptional inhibition of differentiation by full-length Myc and generates Myc-nick, a driver of cytoplasmic reorganization and differentiation.
Assuntos
Proteínas Proto-Oncogênicas c-myc/metabolismo , Tubulina (Proteína)/metabolismo , Acetilação , Animais , Diferenciação Celular , Linhagem Celular Tumoral , Células Cultivadas , Citosol/metabolismo , Humanos , Camundongos , RatosRESUMO
The ligand-activated transcription factor aryl hydrocarbon receptor (AHR) regulates cellular detoxification, proliferation and immune evasion in a range of cell types and tissues, including cancer cells. In this study, we used RNA-sequencing to identify the signature of the AHR target genes regulated by the pollutant 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and the endogenous ligand kynurenine (Kyn), a tryptophan-derived metabolite. This approach identified a signature of six genes (CYP1A1, ALDH1A3, ABCG2, ADGRF1 and SCIN) as commonly activated by endogenous or exogenous ligands of AHR in multiple colon cancer cell lines. Among these, the actin-severing protein scinderin (SCIN) was necessary for cell proliferation; SCIN downregulation limited cell proliferation and its expression increased it. SCIN expression was elevated in a subset of colon cancer patient samples, which also contained elevated ß-catenin levels. Remarkably, SCIN expression promoted nuclear translocation of ß-catenin and activates the WNT pathway. Our study identifies a new mechanism for adhesion-mediated signaling in which SCIN, likely via its ability to alter the actin cytoskeleton, facilitates the nuclear translocation of ß-catenin. This article has an associated First Person interview with the first authors of the paper.
Assuntos
Neoplasias do Colo , Poluentes Ambientais , Dibenzodioxinas Policloradas , Humanos , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , beta Catenina/genética , beta Catenina/metabolismo , Via de Sinalização Wnt/genética , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Ligantes , Cinurenina , Triptofano , Actinas/metabolismo , Neoplasias do Colo/genética , RNARESUMO
INTRODUCTION: Inflammation plays a significant role in various cancers, including lung cancer, where the inflammatory cytokine IL-1ß is often elevated in the tumor microenvironment. Patients with lung adenocarcinoma show higher levels of serum IL-1ß compared to healthy individual. Moreover, IL-1ß blockade reduces the incidence and mortality of lung cancer. Our prior studies revealed that alveolar type-II cells, the precursors for lung adenocarcinoma, display an induction in the expression of the enzyme tryptophan 2,3-dioxygenase (TDO2) during normal lung development. This induction of TDO2 coincides with an increase in IL-1ß levels and is likely caused by IL-1ß. Given that cancer cells can co-opt developmentally regulated pathways, we hypothesized that IL-1ß may exert its pro-tumoral function by stimulating TDO2 and indoleamine 2, 3-dioxygenase-1 (IDO1), parallel enzymes involved in the conversion of tryptophan (Trp) into the immune-suppressive oncometabolite kynurenine (Kyn). Our goal was to determine whether IL-1ß is a common upstream regulator of immune checkpoint regulators. METHODS: To determine whether IL-1ß regulates IDO1, TDO2, PD-L1, and PD-L2, we measured mRNA and protein levels in lung adenocarcinoma cells lines (A549, H1792, H1838, H2347, H2228, HCC364 and HCC827) grown in 2D or 3D and in immortalized normal lung epithelial cells (HBEC3-KT and HSAEC1-KT). To determine the importance of the NFκB pathway in mediating IL-1ß -regulated cellular effects, we used siRNA to knockdown RelA/p65 in IL-1ß treated cells. The levels of Trp and Kyn in the IL-1ß-treated cells and media were measured by mass spectrometry. RESULTS: Upon IL-1ß stimulation, lung adenocarcinoma cells exhibited significant increases in IDO1 mRNA and protein levels, a response that depended on the NFκB pathway. Interestingly, this induction was more pronounced in 3D spheroid cultures compared to monolayer cultures and was not observed in normal immortalized lung epithelial cells. Furthermore, the conversion of Trp to Kyn increased in cells exposed to IL-1ß, aligning with the heightened IDO1 expression. Remarkably, IL-1ß also upregulated the expression of programmed death ligand-1 (PD-L1) and PD-L2 in multiple cell lines, indicating that IL-1ß triggers parallel immune-suppressive mechanisms in lung adenocarcinoma cells. CONCLUSIONS: Our studies demonstrate that lung adenocarcinoma cells, but not normal immortalized lung epithelial cells, respond to IL-1ß signaling by inducing the expression of parallel immune checkpoint proteins that have the potential to promote immune evasion. Video Abstract.
Assuntos
Adenocarcinoma de Pulmão , Neoplasias Pulmonares , Humanos , Adenocarcinoma de Pulmão/metabolismo , Antígeno B7-H1/metabolismo , Cinurenina/metabolismo , Neoplasias Pulmonares/patologia , RNA Mensageiro , Triptofano , Microambiente TumoralRESUMO
Glioblastoma is the most common and aggressive type of cancer in the brain; its poor prognosis is often marked by reoccurrence due to resistance to the chemotherapeutic agent temozolomide, which is triggered by an increase in the expression of DNA repair enzymes such as MGMT. The poor prognosis and limited therapeutic options led to studies targeted at understanding specific vulnerabilities of glioblastoma cells. Metabolic adaptations leading to increased synthesis of nucleotides by de novo biosynthesis pathways are emerging as key alterations driving glioblastoma growth. In this study, we show that enzymes necessary for the de novo biosynthesis of pyrimidines, DHODH and UMPS, are elevated in high grade gliomas and in glioblastoma cell lines. We demonstrate that DHODH's activity is necessary to maintain ribosomal DNA transcription (rDNA). Pharmacological inhibition of DHODH with the specific inhibitors brequinar or ML390 effectively depleted the pool of pyrimidines in glioblastoma cells grown in vitro and in vivo and impaired rDNA transcription, leading to nucleolar stress. Nucleolar stress was visualized by the aberrant redistribution of the transcription factor UBF and the nucleolar organizer nucleophosmin 1 (NPM1), as well as the stabilization of the transcription factor p53. Moreover, DHODH inhibition decreased the proliferation of glioblastoma cells, including temozolomide-resistant cells. Importantly, the addition of exogenous uridine, which reconstitutes the cellular pool of pyrimidine by the salvage pathway, to the culture media recovered the impaired rDNA transcription, nucleolar morphology, p53 levels, and proliferation of glioblastoma cells caused by the DHODH inhibitors. Our in vivo data indicate that while inhibition of DHODH caused a dramatic reduction in pyrimidines in tumor cells, it did not affect the overall pyrimidine levels in normal brain and liver tissues, suggesting that pyrimidine production by the salvage pathway may play an important role in maintaining these nucleotides in normal cells. Our study demonstrates that glioblastoma cells heavily rely on the de novo pyrimidine biosynthesis pathway to generate ribosomal RNA (rRNA) and thus, we identified an approach to inhibit ribosome production and consequently the proliferation of glioblastoma cells through the specific inhibition of the de novo pyrimidine biosynthesis pathway.
Assuntos
Antineoplásicos/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Nucléolo Celular/efeitos dos fármacos , Glioblastoma/tratamento farmacológico , Pirimidinas/biossíntese , Animais , Antineoplásicos/uso terapêutico , Compostos de Bifenilo/farmacologia , Compostos de Bifenilo/uso terapêutico , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Nucléolo Celular/metabolismo , Di-Hidro-Orotato Desidrogenase , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Glioblastoma/patologia , Humanos , Camundongos , Complexos Multienzimáticos/antagonistas & inibidores , Complexos Multienzimáticos/metabolismo , Nucleofosmina , Orotato Fosforribosiltransferase/antagonistas & inibidores , Orotato Fosforribosiltransferase/metabolismo , Orotidina-5'-Fosfato Descarboxilase/antagonistas & inibidores , Orotidina-5'-Fosfato Descarboxilase/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , RNA Ribossômico/biossíntese , Ribossomos/efeitos dos fármacos , Ribossomos/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Proteína Supressora de Tumor p53/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Evasion of apoptosis is critical in Myc-induced tumor progression. Here we report that cancer cells evade death under stress by activating calpain-mediated proteolysis of Myc. This generates Myc-nick, a cytoplasmic, transcriptionally inactive cleavage product of Myc. We found conversion of Myc into Myc-nick in cell lines and tissues derived from multiple cancers. In colon cancer, the production of Myc-nick is enhanced under stress conditions such as hypoxia and nutrient deprivation. Under these conditions, ectopic expression of Myc-nick promotes anchorage-independent growth and cell survival at least in part by promoting autophagy. Myc-nick also delays colon cancer cell death after treatment with chemotherapeutic drugs such as etoposide, cisplatin, and imatinib. Furthermore, colon cancer cells expressing a cleavage-resistant form of Myc undergo extensive apoptosis but are rescued by overexpression of Myc-nick. We also found that ectopic expression of Myc-nick results in the induction of the actin-bundling protein fascin, formation of filopodia, and increased cell motility-all mediators of tumor metastasis. Myc-nick-induced survival, autophagy, and motility require Myc box II (MBII), a region of Myc-nick that recruits acetyltransferases that in turn modify cytoplasmic proteins, including α-tubulin and ATG3. Our results suggest that Myc-nick-induced survival and motility contribute to colon cancer progression and metastasis.
Assuntos
Neoplasias do Colo/fisiopatologia , Regulação Neoplásica da Expressão Gênica , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Estresse Fisiológico/fisiologia , Acetilação , Animais , Antineoplásicos/farmacologia , Autofagia/genética , Hipóxia Celular/fisiologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Neoplasias do Colo/patologia , Citoplasma/metabolismo , Perfilação da Expressão Gênica , Instabilidade Genômica/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Camundongos , ProteóliseRESUMO
The transcription factor AHR (aryl hydrocarbon receptor) drives the expression of genes involved in detoxification pathways in cells exposed to pollutants and other small molecules. Moreover, AHR supports transcriptional programs that promote ribosome biogenesis and protein synthesis in cells stimulated to proliferate by the oncoprotein MYC. Thus, AHR is necessary for the proliferation of MYC-overexpressing cells. To define metabolic pathways in which AHR cooperates with MYC in supporting cell growth, here we used LC-MS-based metabolomics to examine the metabolome of MYC-expressing cells upon AHR knockdown. We found that AHR knockdown reduced lactate, S-lactoylglutathione, N-acetyl-l-alanine, 2-hydroxyglutarate, and UMP levels. Using our previously obtained RNA sequencing data, we found that AHR mediates the expression of the UMP-generating enzymes dihydroorotate dehydrogenase (quinone) (DHODH) and uridine monophosphate synthetase (UMPS), as well as lactate dehydrogenase A (LDHA), establishing a mechanism by which AHR regulates lactate and UMP production in MYC-overexpressing cells. AHR knockdown in glioblastoma cells also reduced the expression of LDHA (and lactate), DHODH, and UMPS but did not affect UMP levels, likely because of compensatory mechanisms in these cells. Our results indicate that AHR contributes to the regulation of metabolic pathways necessary for the proliferation of transformed cells.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Redes e Vias Metabólicas , Proteínas Proto-Oncogênicas c-myc/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Linhagem Celular Tumoral , Di-Hidro-Orotato Desidrogenase , Regulação Enzimológica da Expressão Gênica , Técnicas de Silenciamento de Genes , Humanos , L-Lactato Desidrogenase/biossíntese , L-Lactato Desidrogenase/genética , Complexos Multienzimáticos/biossíntese , Complexos Multienzimáticos/genética , Orotato Fosforribosiltransferase/biossíntese , Orotato Fosforribosiltransferase/genética , Orotidina-5'-Fosfato Descarboxilase/biossíntese , Orotidina-5'-Fosfato Descarboxilase/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/biossíntese , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Proteínas Proto-Oncogênicas c-myc/genética , Receptores de Hidrocarboneto Arílico/genéticaRESUMO
BACKGROUND: While regulated WNT activity is required for normal development and stem cell maintenance, mutations that lead to constitutive activation of the WNT pathway cause cellular transformation and drive colorectal cancer. Activation of the WNT pathway ultimately leads to the nuclear translocation of ß-catenin which, in complex with TCF/LEF factors, promotes the transcription of genes necessary for growth. The proto-oncogene MYC is one of the most critical genes activated downstream the WNT pathway in colon cancer. Here, we investigate the converse regulation of the WNT pathway by MYC. METHODS: We performed RNA-seq analyses to identify genes regulated in cells expressing MYC. We validated the regulation of genes in the WNT pathway including LEF1 by MYC using RT-qPCR, Western blotting, and ChIP-seq. We investigated the importance of LEF1 for the viability of MYC-expressing cells in in fibroblasts, epithelial cells, and colon cells. Bioinformatic analyses were utilized to define the expression of MYC-regulated genes in human colon cancer and metabolomics analyses were used to identify pathways regulated by LEF1 in MYC expressing cells. RESULTS: MYC regulates the levels of numerous WNT-related genes, including the ß-catenin co-transcription factor LEF1. MYC activates the transcription of LEF1 and is required for LEF1 expression in colon cancer cells and in primary colonic cells transformed by APC loss of function, a common mutation in colon cancer patients. LEF1 caused the retention of ß-catenin in the nucleus, leading to the activation of the WNT pathway in MYC-expressing cells. Consequently, MYC-expressing cells were sensitive to LEF1 inhibition. Moreover, we describe two examples of genes induced in MYC-expressing cells that require LEF1 activity: the peroxisome proliferator activated receptor delta (PPARδ) and the Acyl CoA dehydrogenase 9 (ACAD9). CONCLUSIONS: We demonstrated that MYC is a transcriptional regulator of LEF1 in colonic cells. Our work proposes a novel pathway by which MYC regulates proliferation through activating LEF1 expression which in turn activates the WNT pathway.
Assuntos
Fator 1 de Ligação ao Facilitador Linfoide/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Ativação Transcricional , Via de Sinalização Wnt , Acil-CoA Desidrogenases/genética , Linhagem Celular , Proliferação de Células , Neoplasias do Colo/patologia , Técnicas de Silenciamento de Genes , Humanos , Fator 1 de Ligação ao Facilitador Linfoide/deficiência , PPAR delta/genética , Proto-Oncogene Mas , beta Catenina/metabolismoRESUMO
MYC-nick is a cytoplasmic, transcriptionally inactive member of the MYC oncoprotein family, generated by a proteolytic cleavage of full-length MYC. MYC-nick promotes migration and survival of cells in response to chemotherapeutic agents or withdrawal of glucose. Here we report that MYC-nick is abundant in colonic and intestinal tumors derived from mouse models with mutations in the Wnt, TGF-ß, and PI3K pathways. Moreover, MYC-nick is elevated in colon cancer cells deleted for FBWX7, which encodes the major E3 ligase of full-length MYC frequently mutated in colorectal cancers. MYC-nick promotes the migration of colon cancer cells assayed in 3D cultures or grown as xenografts in a zebrafish metastasis model. MYC-nick accelerates migration by activating the Rho GTPase Cdc42 and inducing fascin expression. MYC-nick, fascin, and Cdc42 are frequently up-regulated in cells present at the invasive front of human colorectal tumors, suggesting a coordinated role for these proteins in tumor migration.
Assuntos
Proteínas de Transporte/genética , Neoplasias Colorretais/genética , Proteínas dos Microfilamentos/genética , Proteínas Proto-Oncogênicas c-myc/genética , Neoplasias Gástricas/genética , Proteína cdc42 de Ligação ao GTP/genética , Animais , Linhagem Celular Tumoral , Movimento Celular/genética , Neoplasias Colorretais/patologia , Proteína 7 com Repetições F-Box-WD/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Metástase Neoplásica , Transdução de Sinais , Neoplasias Gástricas/patologia , Ativação Transcricional/genética , Peixe-ZebraRESUMO
The actin filament (F-actin) bundling protein fascin-1 is highly enriched in many metastatic cancers. Fascin's contribution to metastasis have been ascribed to its enhancement of cell migration and invasion. However, mouse genetic studies clearly point to functions also in tumorigenesis, yet without mechanistic underpinnings. Here, we show that fascin expression promotes the formation of a non-canonical signaling complex that enables anchorage-independent proliferation. This complex shares similarities to focal adhesions and we refer to them as pseudo-adhesion signaling scaffolds (PASS). PASS are enriched with tyrosine phosphorylated proteins and require fascin's F-actin-bundling activity for its assembly. PASS serve as hubs for the Rac1/PAK/JNK proliferation signaling axis, driven by PASS-associated Rac-specific GEFs. Experimental disruption of either fascin or RacGEF function abrogates sustained proliferation of aggressive cancers in vitro and in vivo . These results add a new molecular element to the growing arsenal of metabolic and oncogenic signaling programs regulated by the cytoskeleton architecture.
RESUMO
Neuroblastoma poses significant challenges in clinical management. Despite its relatively low incidence, this malignancy contributes disproportionately to cancer-related childhood mortality. Tailoring treatments based on risk stratification, including MYCN oncogene amplification, remains crucial, yet high-risk cases often confront therapeutic resistance and relapse. Here, we explore the aryl hydrocarbon receptor (AHR), a versatile transcription factor implicated in diverse physiological functions such as xenobiotic response, immune modulation, and cell growth. Despite its varying roles in malignancies, AHR's involvement in neuroblastoma remains elusive. Our study investigates the interplay between AHR and its ligand kynurenine (Kyn) in neuroblastoma cells. Kyn is generated from tryptophan (Trp) by the activity of the enzymes indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase (TDO2). We found that neuroblastoma cells displayed sensitivity to the TDO2 inhibitor 680C91, exposing potential vulnerabilities. Furthermore, combining TDO2 inhibition with retinoic acid or irinotecan (two chemotherapeutic agents used to treat neuroblastoma patients) revealed synergistic effects in select cell lines. Importantly, clinical correlation analysis using patient data established a link between elevated expression of Kyn-AHR pathway genes and adverse prognosis, particularly in older children. These findings underscore the significance of the Kyn-AHR pathway in neuroblastoma progression, emphasizing its potential role as a therapeutic target.
Assuntos
Cinurenina , Neuroblastoma , Receptores de Hidrocarboneto Arílico , Humanos , Cinurenina/metabolismo , Neuroblastoma/patologia , Neuroblastoma/metabolismo , Neuroblastoma/genética , Neuroblastoma/tratamento farmacológico , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/antagonistas & inibidores , Linhagem Celular Tumoral , Triptofano Oxigenase/metabolismo , Triptofano Oxigenase/genética , Triptofano Oxigenase/antagonistas & inibidores , Tretinoína/farmacologia , Transdução de Sinais/efeitos dos fármacos , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/genética , Indolamina-Pirrol 2,3,-Dioxigenase/antagonistas & inibidores , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/antagonistas & inibidores , Proliferação de Células/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacosRESUMO
Cancer cells exhibit distinct metabolic activities and nutritional dependencies compared to normal cells. Thus, characterization of nutrient demands by individual tumor types may identify specific vulnerabilities that can be manipulated to target the destruction of cancer cells. We find that MYC-driven liver tumors rely on augmented tryptophan (Trp) uptake, yet Trp utilization to generate metabolites in the kynurenine (Kyn) pathway is reduced. Depriving MYC-driven tumors of Trp through a No-Trp diet not only prevents tumor growth but also restores the transcriptional profile of normal liver cells. Despite Trp starvation, protein synthesis remains unhindered in liver cancer cells. We define a crucial role for the Trp-derived metabolite indole 3-pyruvate (I3P) in liver tumor growth. I3P supplementation effectively restores the growth of liver cancer cells starved of Trp. These findings suggest that I3P is a potential therapeutic target in MYC-driven cancers. Developing methods to target this metabolite represents a potential avenue for liver cancer treatment.
Assuntos
Carcinogênese , Indóis , Neoplasias Hepáticas , Proteínas Proto-Oncogênicas c-myc , Triptofano , Triptofano/metabolismo , Animais , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/patologia , Indóis/metabolismo , Indóis/farmacologia , Humanos , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteínas Proto-Oncogênicas c-myc/genética , Camundongos , Carcinogênese/metabolismo , Carcinogênese/genética , Linhagem Celular Tumoral , Cinurenina/metabolismo , Camundongos Endogâmicos C57BL , Fígado/metabolismo , Fígado/patologia , MasculinoRESUMO
Within the growing field of amino acid metabolism, tryptophan (Trp) catabolism is an area of increasing interest. Trp is essential for protein synthesis, and its metabolism gives rise to biologically active catabolites including serotonin and numerous metabolites in the kynurenine (Kyn) pathway. In normal tissues, the production of Trp metabolites is directly regulated by the tissue-specific expression of Trp-metabolizing enzymes. Alterations of these enzymes in cancers can shift the balance and lead to an increased production of specific byproducts that can function as oncometabolites. For example, increased expression of the enzyme indoleamine 2,3-dioxygenase, which converts Trp into Kyn, leads to an increase in Kyn levels in numerous cancers. Kyn functions as an oncometabolite in cancer cells by promoting the activity of the transcription factor aryl hydrocarbon receptor, which regulates progrowth genes. Moreover, Kyn also inhibits T-cell activity and thus allows cancer cells to evade clearance by the immune system. Therefore, targeting the Kyn pathway has become a therapeutic focus as a novel means to abrogate tumor growth and immune resistance. This review summarizes the biological role and regulation of Trp metabolism and its catabolites with an emphasis on tumor cell growth and immune evasion and outlines areas for future research focus.
Assuntos
Neoplasias , Triptofano , Humanos , Triptofano/metabolismo , Cinurenina/metabolismo , Neoplasias/genética , Neoplasias/terapia , Triptofano Oxigenase/genética , Linfócitos T/metabolismo , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismoRESUMO
A select group of patients with hepatocellular carcinomas (HCC) benefit from surgical, radiologic, and systemic therapies that include a combination of anti-angiogenic and immune-checkpoint inhibitors. However, because HCC is generally asymptomatic in its early stages, this not only leads to late diagnosis, but also to therapy resistance. The nucleoside analogue 6-thio-dG (THIO) is a first-in-class telomerase-mediated telomere-targeting anticancer agent. In telomerase expressing cancer cells, THIO is converted into the corresponding 5'-triphosphate, which is efficiently incorporated into telomeres by telomerase, activating telomere damage responses and apoptotic pathways. Here, we show how THIO is effective in controlling tumor growth and, when combined with immune checkpoint inhibitors, is even more effective in a T-cell-dependent manner. We also show telomere stress induced by THIO increases both innate sensing and adaptive antitumor immunity in HCC. Importantly, the extracellular high-mobility group box 1 protein acts as a prototypical endogenous DAMP (Damage Associated Molecular Pattern) in eliciting adaptive immunity by THIO. These results provide a strong rationale for combining telomere-targeted therapy with immunotherapy.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Telomerase , Humanos , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Telomerase/genética , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Telômero/genética , Imunidade AdaptativaRESUMO
Increased nucleolar size and activity correlate with aberrant ribosome biogenesis and enhanced translation in cancer cells. One of the first and rate-limiting steps in translation is the interaction of the 40S small ribosome subunit with mRNAs. Here, we report the identification of the zinc finger protein 692 (ZNF692), a MYC-induced nucleolar scaffold that coordinates the final steps in the biogenesis of the small ribosome subunit. ZNF692 forms a hub containing the exosome complex and ribosome biogenesis factors specialized in the final steps of 18S rRNA processing and 40S ribosome maturation in the granular component of the nucleolus. Highly proliferative cells are more reliant on ZNF692 than normal cells; thus, we conclude that effective production of small ribosome subunits is critical for translation efficiency in cancer cells.
Assuntos
Proteínas de Ligação a DNA , Biossíntese de Proteínas , Proteínas Ribossômicas , Subunidades Ribossômicas Menores de Eucariotos , Fatores de Transcrição , Nucléolo Celular/metabolismo , Proteínas Ribossômicas/metabolismo , Subunidades Ribossômicas Menores de Eucariotos/metabolismo , Ribossomos/metabolismo , RNA Ribossômico 18S/genética , RNA Ribossômico 18S/metabolismo , Humanos , Animais , Ratos , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The origin of metazoans required the evolution of mechanisms for maintaining differentiated cell types within a multicellular individual, in part through spatially differentiated patterns of gene transcription. The unicellular ancestor of metazoans was presumably capable of regulating gene expression temporally in response to changing environmental conditions, and spatial cell differentiation in metazoans may represent a co-option of preexisting regulatory mechanisms. Myc is a critical regulator of cell growth, proliferation, and death that is found in all metazoans but absent in other multicellular lineages, including fungi and plants. Homologs of Myc and its binding partner, Max, exist in two of the closest living relatives of animals, the choanoflagellate Monosiga brevicollis (Mb) and Capsaspora owczarzaki, a unicellular opisthokont that is closely related to metazoans and choanoflagellates. We find that Myc and Max from M. brevicollis heterodimerize and bind to both canonical and noncanonical E-boxes, the DNA-binding sites through which metazoan Myc proteins act. Moreover, in M. brevicollis, MbMyc protein can be detected in nuclear and flagellar regions. Like metazoan Max proteins, MbMax can form homodimers that bind to E-boxes. However, cross-species dimerization between Mb and human Myc and Max proteins was not observed, suggesting that the binding interface has diverged. Our results reveal that the Myc/Max network arose before the divergence of the choanoflagellate and metazoan lineages. Furthermore, core features of metazoan Myc function, including heterodimerization with Max, binding to E-box sequences in DNA, and localization to the nucleus, predate the origin of metazoans.
Assuntos
Fatores de Transcrição de Zíper de Leucina Básica/genética , Placozoa/genética , Proteínas Proto-Oncogênicas c-myc/genética , Anêmonas-do-Mar/genética , Sequência de Aminoácidos , Animais , Fatores de Transcrição de Zíper de Leucina Básica/química , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Sequência Conservada , Elementos E-Box , Evolução Molecular , Microscopia de Fluorescência , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Proteínas Proto-Oncogênicas c-myc/química , Proteínas Proto-Oncogênicas c-myc/metabolismo , Alinhamento de Sequência , Especificidade da EspécieRESUMO
The nucleolus harbors the machinery necessary to produce new ribosomes which are critical for protein synthesis. Nucleolar size, shape, and density are highly dynamic and can be adjusted to accommodate ribosome biogenesis according to the needs for protein synthesis. In cancer, cells undergo continuous proliferation; therefore, nucleolar activity is elevated due to their high demand for protein synthesis. The transcription factor and universal oncogene MYC promotes nucleolar activity by enhancing the transcription of ribosomal DNA (rDNA) and ribosomal proteins. This review summarizes the importance of nucleolar activity in mammalian cells, MYC's role in nucleolar regulation in cancer, and discusses how a better understanding (and the potential inhibition) of aberrant nucleolar activity in cancer cells could lead to novel therapeutics.