RESUMEN
IFNγ, a pleiotropic cytokine produced not only by activated lymphocytes but also in response to cancer immunotherapies, has both antitumor and tumor-promoting functions. In ovarian cancer (OC) cells, the tumor-promoting functions of IFNγ are mediated by IFNγ-induced expression of Bcl3, PD-L1 and IL-8/CXCL8, which have long been known to have critical cellular functions as a proto-oncogene, an immune checkpoint ligand and a chemoattractant, respectively. However, overwhelming evidence has demonstrated that these three genes have tumor-promoting roles far beyond their originally identified functions. These tumor-promoting mechanisms include increased cancer cell proliferation, invasion, angiogenesis, metastasis, resistance to chemotherapy and immune escape. Recent studies have shown that IFNγ-induced Bcl3, PD-L1 and IL-8 expression is regulated by the same JAK1/STAT1 signaling pathway: IFNγ induces the expression of Bcl3, which then promotes the expression of PD-L1 and IL-8 in OC cells, resulting in their increased proliferation and migration. In this review, we summarize the recent findings on how IFNγ affects the tumor microenvironment and promotes tumor progression, with a special focus on ovarian cancer and on Bcl3, PD-L1 and IL-8/CXCL8 signaling. We also discuss promising novel combinatorial strategies in clinical trials targeting Bcl3, PD-L1 and IL-8 to increase the effectiveness of cancer immunotherapies.
RESUMEN
The DNA damage response (DDR) is an evolutionarily conserved process essential for cell survival. The transcription changes triggered by DDR depend on the nature of DNA damage, activation of checkpoint kinases, and the stage of cell cycle. The transcription changes can be localized and affect only damaged DNA, but they can be also global and affect genes that are not damaged. While the purpose of localized transcription inhibition is to avoid transcription of damaged genes and make DNA accessible for repair, the purpose and mechanisms of global transcription inhibition of undamaged genes are less well understood. We show here that a brief cell treatment with hydroxyurea (HU) globally inhibits RNA synthesis and transcription by RNA polymerase I, II, and III (RNAPI, RNAPII, and RNAPIII). HU reduces efficiency of transcription termination and inhibits pre-mRNA cleavage at the polyadenylation (pA) sites, destabilizes mRNAs, and shortens poly(A) tails of mRNAs, indicating defects in pre-mRNA 3' end processing. Inactivation of the checkpoint kinase Mec1p downregulates the efficiency of transcription termination and reduces the efficiency of pre-mRNAs clevage at the pA sites, suggesting the involvement of DNA damage checkpoint in transcription termination and pre-mRNA 3' end processing.
Asunto(s)
Proteínas de Saccharomyces cerevisiae , Saccharomycetales , Quinasa de Punto de Control 2/metabolismo , Hidroxiurea/farmacología , Poliadenilación , ARN Polimerasa II/metabolismo , Precursores del ARN/genética , Precursores del ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomycetales/genética , Transcripción GenéticaRESUMEN
One of the key outcomes of activation of DNA replication checkpoint (DRC) or DNA damage checkpoint (DDC) is the increased synthesis of the deoxyribonucleoside triphosphates (dNTPs), which is a prerequisite for normal progression through the S phase and for effective DNA repair. We have recently shown that DDC increases aerobic metabolism and activates the electron transport chain (ETC) to elevate ATP production and dNTP synthesis by repressing transcription of histone genes, leading to globally altered chromatin architecture and increased transcription of genes encoding enzymes of tricarboxylic acid (TCA) cycle and the ETC. The aim of this study was to determine whether DRC activates ETC. We show here that DRC activates ETC by a checkpoint kinase Dun1p-dependent mechanism. DRC induces transcription of RNR1-4 genes and elevates mtDNA copy number. Inactivation of RRM3 or SGS1, two DNA helicases important for DNA replication, activates DRC but does not render cells dependent on ETC. However, fitness of rrm3Δ and sgs1Δ cells requires Dun1p. The slow growth of rrm3Δdun1Δ and sgs1Δdun1Δ cells can be suppressed by introducing sml1Δ mutation, indicating that the slow growth is due to low levels of dNTPs. Interestingly, inactivation of ETC in dun1Δ cells results in a synthetic growth defect that can be suppressed by sml1Δ mutation, suggesting that ETC is important for dNTP synthesis in the absence of Dun1p function. Together, our results reveal an unexpected connection between ETC, replication stress, and Dun1p kinase.
Asunto(s)
Ribonucleótido Reductasas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolismo , Transporte de Electrón/genética , Fase S , Mutación , Nucleótidos/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , RecQ Helicasas/genética , RecQ Helicasas/metabolismo , Ribonucleótido Reductasas/genética , Ribonucleótido Reductasas/metabolismo , ADN Helicasas/metabolismoRESUMEN
Heme is an essential cofactor for enzymes of the electron transport chain (ETC) and ATP synthesis in mitochondrial oxidative phosphorylation (OXPHOS). Heme also binds to and destabilizes Bach1, a transcription regulator that controls expression of several groups of genes important for glycolysis, ETC, and metastasis of cancer cells. Heme synthesis can thus affect pathways through which cells generate energy and precursors for anabolism. In addition, increased heme synthesis may trigger oxidative stress. Since many cancers are characterized by a high glycolytic rate regardless of oxygen availability, targeting glycolysis, ETC, and OXPHOS have emerged as a potential therapeutic strategy. Here, we report that enhancing heme synthesis through exogenous supplementation of heme precursor 5-aminolevulinic acid (ALA) suppresses oxidative metabolism as well as glycolysis and significantly reduces proliferation of both ovarian and breast cancer cells. ALA supplementation also destabilizes Bach1 and inhibits migration of both cell types. Our data indicate that the underlying mechanisms differ in ovarian and breast cancer cells, but involve destabilization of Bach1, AMPK activation, and induction of oxidative stress. In addition, there appears to be an inverse correlation between the activity of oxidative metabolism and ALA sensitivity. Promoting heme synthesis by ALA supplementation may thus represent a promising new anti-cancer strategy, particularly in cancers that are sensitive to altered redox signaling, or in combination with strategies that target the antioxidant systems or metabolic weaknesses of cancer cells.
Asunto(s)
Neoplasias de la Mama/metabolismo , Hemo/metabolismo , Neoplasias Ováricas/metabolismo , Estrés Oxidativo , Vías Biosintéticas , Línea Celular Tumoral , Femenino , Glucólisis , Humanos , Efecto Warburg en OncologíaRESUMEN
Proliferating cells coordinate histone and DNA synthesis to maintain correct stoichiometry for chromatin assembly. Histone mRNA levels must be repressed when DNA replication is inhibited to prevent toxicity and genome instability due to free non-chromatinized histone proteins. In mammalian cells, replication stress triggers degradation of histone mRNAs, but it is unclear if this mechanism is conserved from other species. The aim of this study was to identify the histone mRNA decay pathway in the yeast Saccharomyces cerevisiae and determine the mechanism by which DNA replication stress represses histone mRNAs. Using reverse transcription-quantitative PCR and chromatin immunoprecipitation-quantitative PCR, we show here that histone mRNAs can be degraded by both 5' â 3' and 3' â 5' pathways; however, replication stress does not trigger decay of histone mRNA in yeast. Rather, replication stress inhibits transcription of histone genes by removing the histone gene-specific transcription factors Spt10p and Spt21p from histone promoters, leading to disassembly of the preinitiation complexes and eviction of RNA Pol II from histone genes by a mechanism facilitated by checkpoint kinase Rad53p and histone chaperone Asf1p. In contrast, replication stress does not remove SCB-binding factor transcription complex, another activator of histone genes, from the histone promoters, suggesting that Spt10p and Spt21p have unique roles in the transcriptional downregulation of histone genes during replication stress. Together, our data show that, unlike in mammalian cells, replication stress in yeast does not trigger decay of histone mRNAs but inhibits histone transcription.
Asunto(s)
Replicación del ADN , ADN de Hongos , Histona Acetiltransferasas , Histonas , Regiones Promotoras Genéticas , ARN de Hongos , ARN Mensajero , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Factores de Transcripción , Transcripción Genética , ADN de Hongos/biosíntesis , ADN de Hongos/genética , Histona Acetiltransferasas/genética , Histona Acetiltransferasas/metabolismo , Histonas/biosíntesis , Histonas/genética , ARN de Hongos/biosíntesis , ARN de Hongos/genética , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoAsunto(s)
Acetilcoenzima A/biosíntesis , Adenosina Trifosfato/biosíntesis , Respiración de la Célula/fisiología , Acetilcoenzima A/metabolismo , Acetilación , Adenosina Trifosfato/metabolismo , Mitocondrias/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomycetales/metabolismoRESUMEN
Interferon-γ (IFNγ) is a pleiotropic cytokine that signals to many different cell types. IFNγ has both antitumor functions and pro-tumorigenic effects and regulates different aspects of cell physiology, including metabolism. Cancer cells undergo a complex rearrangement of metabolic pathways that allows them to satisfy the needs of increased proliferation, and many cancer cells redirect glucose metabolism from oxidative phosphorylation to aerobic glycolysis. In this chapter, we describe a protocol that utilizes the Agilent Seahorse XFp Analyzer to assess mitochondrial respiration and glycolysis in ovarian cancer cells treated with IFNγ.
Asunto(s)
Metabolismo Energético/efectos de los fármacos , Interferón gamma/farmacología , Neoplasias Ováricas/metabolismo , Técnicas de Cultivo de Célula , Línea Celular Tumoral , Análisis de Datos , Espacio Extracelular , Femenino , Glucosa/metabolismo , Humanos , Concentración de Iones de Hidrógeno , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Fosforilación Oxidativa/efectos de los fármacos , Consumo de Oxígeno , Programas Informáticos , Estrés FisiológicoRESUMEN
The DNA damage response (DDR) is an evolutionarily conserved process essential for cell survival. Previously, we found that decreased histone expression induces mitochondrial respiration, raising the question whether the DDR also stimulates respiration. Here, using oxygen consumption and ATP assays, RT-qPCR and ChIP-qPCR methods, and dNTP analyses, we show that DDR activation in the budding yeast Saccharomyces cerevisiae, either by genetic manipulation or by growth in the presence of genotoxic chemicals, induces respiration. We observed that this induction is conferred by reduced transcription of histone genes and globally decreased DNA nucleosome occupancy. This globally altered chromatin structure increased the expression of genes encoding enzymes of tricarboxylic acid cycle, electron transport chain, oxidative phosphorylation, elevated oxygen consumption, and ATP synthesis. The elevated ATP levels resulting from DDR-stimulated respiration drove enlargement of dNTP pools; cells with a defect in respiration failed to increase dNTP synthesis and exhibited reduced fitness in the presence of DNA damage. Together, our results reveal an unexpected connection between respiration and the DDR and indicate that the benefit of increased dNTP synthesis in the face of DNA damage outweighs possible cellular damage due to increased oxygen metabolism.
Asunto(s)
Daño del ADN , Nucleótidos/metabolismo , Fosforilación Oxidativa , Consumo de Oxígeno , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/crecimiento & desarrollo , Adenosina Trifosfato/metabolismo , Supervivencia Celular , Ensamble y Desensamble de Cromatina , Regulación Fúngica de la Expresión Génica , Histonas/metabolismo , Mitocondrias/metabolismo , Saccharomyces cerevisiae/metabolismoRESUMEN
Adenosine monophosphate (AMP)-activated protein kinase (AMPK) serves as an energy sensor and master regulator of metabolism. In general, AMPK inhibits anabolism to minimize energy consumption and activates catabolism to increase ATP production. One of the mechanisms employed by AMPK to regulate metabolism is protein acetylation. AMPK regulates protein acetylation by at least five distinct mechanisms. First, AMPK phosphorylates and inhibits acetyl-CoA carboxylase (ACC) and thus regulates acetyl-CoA homeostasis. Since acetyl-CoA is a substrate for all lysine acetyltransferases (KATs), AMPK affects the activity of KATs by regulating the cellular level of acetyl-CoA. Second, AMPK activates histone deacetylases (HDACs) sirtuins by increasing the cellular concentration of NADâº, a cofactor of sirtuins. Third, AMPK inhibits class I and II HDACs by upregulating hepatic synthesis of α-hydroxybutyrate, a natural inhibitor of HDACs. Fourth, AMPK induces translocation of HDACs 4 and 5 from the nucleus to the cytoplasm and thus increases histone acetylation in the nucleus. Fifth, AMPK directly phosphorylates and downregulates p300 KAT. On the other hand, protein acetylation regulates AMPK activity. Sirtuin SIRT1-mediated deacetylation of liver kinase B1 (LKB1), an upstream kinase of AMPK, activates LKB1 and AMPK. AMPK phosphorylates and inactivates ACC, thus increasing acetyl-CoA level and promoting LKB1 acetylation and inhibition. In yeast cells, acetylation of Sip2p, one of the regulatory ß-subunits of the SNF1 complex, results in inhibition of SNF1. This results in activation of ACC and reduced cellular level of acetyl-CoA, which promotes deacetylation of Sip2p and activation of SNF1. Thus, in both yeast and mammalian cells, AMPK/SNF1 regulate protein acetylation and are themselves regulated by protein acetylation.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Acetilcoenzima A/metabolismo , Acetilación , Animales , Epigenómica , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Humanos , Proteínas Serina-Treonina Quinasas/genéticaRESUMEN
The proto-oncogene Bcl3 induces survival and proliferation in cancer cells; however, its function and regulation in ovarian cancer (OC) remain unknown. Here, we show that Bcl3 expression is increased in human OC tissues. Surprisingly, however, we found that in addition to promoting survival, proliferation, and migration of OC cells, Bcl3 promotes both constitutive and interferon-γ (IFN)-induced expression of the immune checkpoint molecule PD-L1. The Bcl3 expression in OC cells is further increased by IFN, resulting in increased PD-L1 transcription. The mechanism consists of an IFN-induced, Bcl3- and p300-dependent PD-L1 promoter occupancy by Lys-314/315 acetylated p65 NF-κB. Blocking PD-L1 by neutralizing antibody reduces proliferation of OC cells overexpressing Bcl3, suggesting that the pro-proliferative effect of Bcl3 in OC cells is partly mediated by PD-L1. Together, this work identifies PD-L1 as a novel target of Bcl3, and links Bcl3 to IFNγ signaling and PD-L1-mediated immune escape.
Asunto(s)
Antígeno B7-H1/genética , Puntos de Control del Ciclo Celular/inmunología , Células Epiteliales/inmunología , Regulación Neoplásica de la Expresión Génica , Proteínas Proto-Oncogénicas/genética , Factores de Transcripción/genética , Escape del Tumor/genética , Anticuerpos Neutralizantes/farmacología , Apoptosis/efectos de los fármacos , Proteínas del Linfoma 3 de Células B , Antígeno B7-H1/antagonistas & inhibidores , Antígeno B7-H1/inmunología , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Proteína p300 Asociada a E1A , Células Epiteliales/efectos de los fármacos , Células Epiteliales/patología , Femenino , Humanos , Interferón gamma/farmacología , Ovario/inmunología , Ovario/patología , Regiones Promotoras Genéticas , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas/inmunología , Transducción de Señal , Factor de Transcripción ReIA/genética , Factor de Transcripción ReIA/inmunología , Factores de Transcripción/inmunología , Transcripción GenéticaRESUMEN
Metformin has been a frontline therapy for type 2 diabetes (T2D) for many years. Its effectiveness in T2D treatment is mostly attributed to its suppression of hepatic gluconeogenesis; however, the mechanistic aspects of metformin action remain elusive. In addition to its glucose-lowering effect, metformin possesses other pleiotropic health-promoting effects that include reduced cancer risk and tumorigenesis. Metformin inhibits the electron transport chain (ETC) and ATP synthesis; however, recent data reveal that metformin regulates AMP-activated protein kinase (AMPK) and the mechanistic target of rapamycin complex 1 (mTORC1) by multiple, mutually nonexclusive mechanisms that do not necessarily depend on the inhibition of ETC and the cellular ATP level. In this review, we discuss recent advances in elucidating the molecular mechanisms that are relevant for metformin use in cancer treatment.
Asunto(s)
Antineoplásicos/farmacología , Hipoglucemiantes/farmacología , Metformina/farmacología , Proteínas Quinasas Activadas por AMP/metabolismo , Animales , Antineoplásicos/uso terapéutico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/metabolismo , Complejo I de Transporte de Electrón/metabolismo , Humanos , Hipoglucemiantes/uso terapéutico , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Metformina/uso terapéutico , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismoRESUMEN
The rationale for developing histone deacetylase (HDAC) inhibitors (HDACi) as anticancer agents was based on their ability to induce apoptosis and cell cycle arrest in cancer cells. However, while HDACi have been remarkably effective in the treatment of hematological malignancies, clinical studies with HDACi as single agents in solid cancers have been disappointing. Recent studies have shown that, in addition to inducing apoptosis in cancer cells, class I HDACi induce IκB kinase (IKK)-dependent expression of proinflammatory chemokines, such as interleukin-8 (IL8; CXCL8), resulting in the increased proliferation of tumor cells, and limiting the effectiveness of HDACi in solid tumors. Here, we discuss the mechanisms responsible for HDACi-induced CXCL8 expression, and opportunities for combination therapies targeting HDACs and IKK in solid tumors.
Asunto(s)
Antineoplásicos/uso terapéutico , Inhibidores de Histona Desacetilasas/uso terapéutico , Quinasa I-kappa B/antagonistas & inhibidores , Neoplasias/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/farmacología , Protocolos de Quimioterapia Combinada Antineoplásica , Apoptosis/efectos de los fármacos , Inhibidores de Histona Desacetilasas/administración & dosificación , Inhibidores de Histona Desacetilasas/farmacología , Humanos , Quinasa I-kappa B/metabolismo , Interleucina-8/metabolismo , Neoplasias/metabolismo , Inhibidores de Proteínas Quinasas/administración & dosificación , Inhibidores de Proteínas Quinasas/farmacologíaRESUMEN
Phospholipase C (Plc1p) in Saccharomyces cerevisiae is required for normal degradation of repressor Mth1p and expression of the HXT genes encoding cell membrane transporters of glucose. Plc1p is also required for normal localization of glucose transporters to the cell membrane. Consequently, plc1Δ cells display histone hypoacetylation and transcriptional defects due to reduced uptake and metabolism of glucose to acetyl-CoA, a substrate for histone acetyltransferases. In the presence of glucose, Mth1p is phosphorylated by casein kinase I Yck1/2p, ubiquitinated by the SCFGrr1 complex and degraded by the proteasome. Here, we show that while Plc1p does not affect the function of the SCFGrr1 complex or the proteasome, it is required for normal protein level of Yck2p. Since stability of Yck1/2p is regulated by a glucose-dependent mechanism, PLC1 inactivation results in destabilization of Yck1/2p and defect in Mth1p degradation. Based on our results and published data, we propose a model in which plc1Δ mutation causes increased internalization of glucose transporters, decreased transport of glucose into the cells, and consequently decreased stability of Yck1/2p, increased stability of Mth1p and decreased expression of the HXT genes.
Asunto(s)
Quinasa de la Caseína I/química , Quinasa de la Caseína I/metabolismo , Proteínas de Transporte de Monosacáridos/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Fosfolipasas de Tipo C/metabolismo , Estabilidad de Enzimas , Proteínas de Transporte de Monosacáridos/genética , Proteínas Recombinantes/genética , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/químicaRESUMEN
Regulation of mitochondrial biogenesis and respiration is a complex process that involves several signaling pathways and transcription factors as well as communication between the nuclear and mitochondrial genomes. Under aerobic conditions, the budding yeast Saccharomyces cerevisiae metabolizes glucose predominantly by glycolysis and fermentation. We have recently shown that altered chromatin structure in yeast induces respiration by a mechanism that requires transport and metabolism of pyruvate in mitochondria. However, how pyruvate controls the transcriptional responses underlying the metabolic switch from fermentation to respiration is unknown. Here, we report that this pyruvate effect involves heme. We found that heme induces transcription of HAP4, the transcriptional activation subunit of the Hap2/3/4/5p complex, required for growth on nonfermentable carbon sources, in a Hap1p- and Hap2/3/4/5p-dependent manner. Increasing cellular heme levels by inactivating ROX1, which encodes a repressor of many hypoxic genes, or by overexpressing HEM3 or HEM12 induced respiration and elevated ATP levels. Increased heme synthesis, even under conditions of glucose repression, activated Hap1p and the Hap2/3/4/5p complex and induced transcription of HAP4 and genes required for the tricarboxylic acid (TCA) cycle, electron transport chain, and oxidative phosphorylation, leading to a switch from fermentation to respiration. Conversely, inhibiting metabolic flux into the TCA cycle reduced cellular heme levels and HAP4 transcription. Together, our results indicate that the glucose-mediated repression of respiration in budding yeast is at least partly due to the low cellular heme level.
Asunto(s)
Fermentación/fisiología , Regulación Fúngica de la Expresión Génica/fisiología , Hemo/biosíntesis , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Factores de Transcripción/metabolismo , Glucosa/metabolismo , Hemo/genética , Consumo de Oxígeno/fisiología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Factores de Transcripción/genéticaRESUMEN
Overexpression of the pro-angiogenic chemokine IL-8 (CXCL8) is associated with a poor prognosis in several solid tumors, including epithelial ovarian cancer (EOC). Even though histone deacetylase (HDAC) inhibition has shown remarkable antitumor activity in hematological malignancies, it has been less effective in solid tumors, including EOC. Here we report results that may explain the decreased efficiency of HDAC inhibition in EOC, based on our data demonstrating that HDAC inhibition specifically induces expression of IL-8/CXCL8 in SKOV3, CAOV3, and OVCAR3 cells. Suppression or neutralization of vorinostat-induced IL-8/CXCL8 potentiates the vorinostat inhibitory effect on cell viability and proliferation. The IL-8/CXCL8 expression induced by vorinostat in EOC cells is dependent on IκB kinase (IKK) activity and associated with a gene-specific recruitment of IKKß and IKK-dependent recruitment of p65 NFκB to the IL-8/CXCL8 promoter. In addition, HDAC inhibition induces acetylation of p65 and histone H3 and their IL-8/CXCL8 promoter occupancy. In vivo results demonstrate that combining vorinostat and the IKK inhibitor Bay 117085 significantly reduces tumor growth in nude mice compared with control untreated mice or either drug alone. Mice in the combination group had the lowest IL-8/CXCL8 tumor levels and the lowest tumor expression of the murine neutrophil [7/4] antigen, indicating reduced neutrophil infiltration. Together, our results demonstrate that HDAC inhibition specifically induces IL-8/CXCL8 expression in EOC cells and that the mechanism involves IKK, suggesting that using IKK inhibitors may increase the effectiveness of HDAC inhibitors when treating ovarian cancer and other solid tumors characterized by increased IL-8/CXCL8 expression.
Asunto(s)
Antineoplásicos/farmacología , Inhibidores de Histona Desacetilasas/farmacología , Ácidos Hidroxámicos/farmacología , Quinasa I-kappa B/inmunología , Interleucina-8/genética , Neoplasias Ováricas/tratamiento farmacológico , Regulación hacia Arriba/efectos de los fármacos , Acetilación/efectos de los fármacos , Animales , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Femenino , Inhibidores de Histona Desacetilasas/uso terapéutico , Humanos , Ácidos Hidroxámicos/uso terapéutico , Interleucina-8/inmunología , Ratones Desnudos , Neoplasias Ováricas/genética , Neoplasias Ováricas/inmunología , Neoplasias Ováricas/patología , Ovario/efectos de los fármacos , Ovario/inmunología , Ovario/patología , Regiones Promotoras Genéticas/efectos de los fármacos , VorinostatRESUMEN
AMP-activated protein kinase (AMPK) is an energy sensor and master regulator of metabolism. AMPK functions as a fuel gauge monitoring systemic and cellular energy status. Activation of AMPK occurs when the intracellular AMP/ATP ratio increases and leads to a metabolic switch from anabolism to catabolism. AMPK phosphorylates and inhibits acetyl-CoA carboxylase (ACC), which catalyzes carboxylation of acetyl-CoA to malonyl-CoA, the first and rate-limiting reaction in de novo synthesis of fatty acids. AMPK thus regulates homeostasis of acetyl-CoA, a key metabolite at the crossroads of metabolism, signaling, chromatin structure, and transcription. Nucleocytosolic concentration of acetyl-CoA affects histone acetylation and links metabolism and chromatin structure. Here we show that activation of AMPK with the widely used antidiabetic drug metformin or with the AMP mimetic 5-aminoimidazole-4-carboxamide ribonucleotide increases the inhibitory phosphorylation of ACC and decreases the conversion of acetyl-CoA to malonyl-CoA, leading to increased protein acetylation and altered gene expression in prostate and ovarian cancer cells. Direct inhibition of ACC with allosteric inhibitor 5-(tetradecyloxy)-2-furoic acid also increases acetylation of histones and non-histone proteins. Because AMPK activation requires liver kinase B1, metformin does not induce protein acetylation in liver kinase B1-deficient cells. Together, our data indicate that AMPK regulates the availability of nucleocytosolic acetyl-CoA for protein acetylation and that AMPK activators, such as metformin, have the capacity to increase protein acetylation and alter patterns of gene expression, further expanding the plethora of metformin's physiological effects.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Metformina/farmacología , Proteínas de Neoplasias/metabolismo , Neoplasias Ováricas/metabolismo , Neoplasias de la Próstata/metabolismo , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Proteínas Quinasas Activadas por AMP/genética , Acetilcoenzima A/genética , Acetilcoenzima A/metabolismo , Acetilación/efectos de los fármacos , Femenino , Regulación Neoplásica de la Expresión Génica/genética , Células HeLa , Humanos , Masculino , Malonil Coenzima A/genética , Malonil Coenzima A/metabolismo , Proteínas de Neoplasias/genética , Neoplasias Ováricas/genética , Neoplasias de la Próstata/genética , Procesamiento Proteico-Postraduccional/genéticaRESUMEN
Regulation of mitochondrial biogenesis and respiration is a complex process that involves several signaling pathways and transcription factors as well as communication between the nuclear and mitochondrial genomes. Here we show that decreased expression of histones or a defect in nucleosome assembly in the yeast Saccharomyces cerevisiae results in increased mitochondrial DNA (mtDNA) copy numbers, oxygen consumption, ATP synthesis, and expression of genes encoding enzymes of the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS). The metabolic shift from fermentation to respiration induced by altered chromatin structure is associated with the induction of the retrograde (RTG) pathway and requires the activity of the Hap2/3/4/5p complex as well as the transport and metabolism of pyruvate in mitochondria. Together, our data indicate that altered chromatin structure relieves glucose repression of mitochondrial respiration by inducing transcription of the TCA cycle and OXPHOS genes carried by both nuclear and mitochondrial DNA.
Asunto(s)
Ensamble y Desensamble de Cromatina , Histonas/biosíntesis , Mitocondrias/metabolismo , Saccharomyces cerevisiae/metabolismo , Adenosina Trifosfato/biosíntesis , Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/metabolismo , Factor de Unión a CCAAT/metabolismo , Variaciones en el Número de Copia de ADN , ADN de Hongos/metabolismo , ADN Mitocondrial/metabolismo , Fermentación , Regulación Fúngica de la Expresión Génica , Histonas/genética , Fosforilación Oxidativa , Consumo de Oxígeno , Ácido Pirúvico/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMEN
Cells sense and appropriately respond to the physical conditions and availability of nutrients in their environment. This sensing of the environment and consequent cellular responses are orchestrated by a multitude of signaling pathways and typically involve changes in transcription and metabolism. Recent discoveries suggest that the signaling and transcription machineries are regulated by signals which are derived from metabolism and reflect the metabolic state of the cell. Acetyl coenzyme A (CoA) is a key metabolite that links metabolism with signaling, chromatin structure, and transcription. Acetyl-CoA is produced by glycolysis as well as other catabolic pathways and used as a substrate for the citric acid cycle and as a precursor in synthesis of fatty acids and steroids and in other anabolic pathways. This central position in metabolism endows acetyl-CoA with an important regulatory role. Acetyl-CoA serves as a substrate for lysine acetyltransferases (KATs), which catalyze the transfer of acetyl groups to the epsilon-amino groups of lysines in histones and many other proteins. Fluctuations in the concentration of acetyl-CoA, reflecting the metabolic state of the cell, are translated into dynamic protein acetylations that regulate a variety of cell functions, including transcription, replication, DNA repair, cell cycle progression, and aging. This review highlights the synthesis and homeostasis of acetyl-CoA and the regulation of transcriptional and signaling machineries in yeast by acetylation.