RESUMO
Tumor cells and surrounding immune cells undergo metabolic reprogramming, leading to an acidic tumor microenvironment. However, it is unclear how tumor cells adapt to this acidic stress during tumor progression. Here we show that carnosine, a mobile buffering metabolite that accumulates under hypoxia in tumor cells, regulates intracellular pH homeostasis and drives lysosome-dependent tumor immune evasion. A previously unrecognized isoform of carnosine synthase, CARNS2, promotes carnosine synthesis under hypoxia. Carnosine maintains intracellular pH (pHi) homeostasis by functioning as a mobile proton carrier to accelerate cytosolic H+ mobility and release, which in turn controls lysosomal subcellular distribution, acidification and activity. Furthermore, by maintaining lysosomal activity, carnosine facilitates nuclear transcription factor X-box binding 1 (NFX1) degradation, triggering galectin-9 and T-cell-mediated immune escape and tumorigenesis. These findings indicate an unconventional mechanism for pHi regulation in cancer cells and demonstrate how lysosome contributes to immune evasion, thus providing a basis for development of combined therapeutic strategies against hepatocellular carcinoma that exploit disrupted pHi homeostasis with immune checkpoint blockade.
Assuntos
Carcinoma Hepatocelular , Carnosina , Neoplasias Hepáticas , Humanos , Homeostase , Lisossomos , Hipóxia , Concentração de Íons de Hidrogênio , Microambiente TumoralRESUMO
Metabolic reprogramming is an important feature of cancers that has been closely linked to post-translational protein modification (PTM). Lysine succinylation is a recently identified PTM involved in regulating protein functions, whereas its regulatory mechanism and possible roles in tumor progression remain unclear. Here, we show that OXCT1, an enzyme catalyzing ketone body oxidation, functions as a lysine succinyltransferase to contribute to tumor progression. Mechanistically, we find that OXCT1 functions as a succinyltransferase, with residue G424 essential for this activity. We also identified serine beta-lactamase-like protein (LACTB) as a main target of OXCT1-mediated succinylation. Extensive succinylation of LACTB K284 inhibits its proteolytic activity, resulting in increased mitochondrial membrane potential and respiration, ultimately leading to hepatocellular carcinoma (HCC) progression. In summary, this study establishes lysine succinyltransferase function of OXCT1 and highlights a link between HCC prognosis and LACTB K284 succinylation, suggesting a potentially valuable biomarker and therapeutic target for further development.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , beta-Lactamases , Humanos , beta-Lactamases/genética , beta-Lactamases/metabolismo , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Lisina/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , Processamento de Proteína Pós-TraducionalRESUMO
Phosphoglycerate dehydrogenase (PHGDH) is a key serine biosynthesis enzyme whose aberrant expression promotes various types of tumors. Recently, PHGDH has been found to have some non-canonical functions beyond serine biosynthesis, but its specific mechanisms in tumorigenesis remain unclear. Here, we show that PHGDH localizes to the inner mitochondrial membrane and promotes the translation of mitochondrial DNA (mtDNA)-encoded proteins in liver cancer cells. Mechanistically, we demonstrate that mitochondrial PHGDH directly interacts with adenine nucleotide translocase 2 (ANT2) and then recruits mitochondrial elongation factor G2 (mtEFG2) to promote mitochondrial ribosome recycling efficiency, thereby promoting mtDNA-encoded protein expression and subsequent mitochondrial respiration. Moreover, we show that treatment with a mitochondrial translation inhibitor or depletion of mtEFG2 diminishes PHGDH-mediated tumor growth. Collectively, our findings uncover a previously unappreciated function of PHGDH in tumorigenesis acting via promotion of mitochondrial translation and bioenergetics.
Assuntos
Neoplasias Hepáticas , Fosfoglicerato Desidrogenase , Humanos , Fosfoglicerato Desidrogenase/genética , Fosfoglicerato Desidrogenase/metabolismo , Linhagem Celular Tumoral , Serina , Neoplasias Hepáticas/genética , Carcinogênese , DNA MitocondrialRESUMO
Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is an important cellular metabolite-sensing enzyme that can directly sense changes not only in ATP but also in metabolites associated with carbohydrates and fatty acids. However, less is known about whether and how AMPK senses variations in cellular amino acids. Here, we show that cysteine deficiency significantly triggers calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2)-mediated activation of AMPK. In addition, we found that CaMKK2 directly associates with cysteinyl-tRNA synthetase (CARS), which then binds to AMPKγ2 under cysteine deficiency to activate AMPK. Interestingly, we discovered that cysteine inhibits the binding of CARS to AMPKγ2, and thus, under cysteine deficiency conditions wherein the inhibitory effect of cysteine is abrogated, CARS mediates the binding of AMPK to CaMKK2, resulting in the phosphorylation and activation of AMPK by CaMKK2. Importantly, we demonstrate that blocking AMPK activation leads to cell death under cysteine-deficient conditions. In summary, our study is the first to show that CARS senses the absence of cysteine and activates AMPK through the cysteine-CARS-CaMKK2-AMPKγ2 axis, a novel adaptation strategy for cell survival under nutrient deprivation conditions.
Assuntos
Proteínas Quinases Ativadas por AMP/genética , Adaptação Fisiológica/genética , Aminoacil-tRNA Sintetases/genética , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/genética , Cisteína/deficiência , Proteínas Quinases Ativadas por AMP/antagonistas & inibidores , Proteínas Quinases Ativadas por AMP/metabolismo , Acetil-CoA Carboxilase/genética , Acetil-CoA Carboxilase/metabolismo , Trifosfato de Adenosina/metabolismo , Aminoacil-tRNA Sintetases/metabolismo , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Ácidos Graxos/metabolismo , Regulação da Expressão Gênica , Células HEK293 , Humanos , Ligação Proteica , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteína Regulatória Associada a mTOR/genética , Proteína Regulatória Associada a mTOR/metabolismo , Transdução de SinaisRESUMO
Enolase 1 (ENO1) is a glycolytic enzyme that plays essential roles in various pathological activities including cancer development. However, the mechanisms underlying ENO1-contributed tumorigenesis are not well explained. Here, we uncover that ENO1, as an RNA-binding protein, binds to the cytosine-uracil-guanine-rich elements of YAP1 messenger RNA to promote its translation. ENO1 and YAP1 positively regulate alternative arachidonic acid (AA) metabolism by inverse regulation of PLCB1 and HPGD (15-hydroxyprostaglandin dehydrogenase). The YAP1/PLCB1/HPGD axis-mediated activation of AA metabolism and subsequent accumulation of prostaglandin E2 (PGE2) are responsible for ENO1-mediated cancer progression, which can be retarded by aspirin. Finally, aberrant activation of ENO1/YAP1/PLCB1 and decreased HPGD expression in clinical hepatocellular carcinoma samples indicate a potential correlation between ENO1-regulated AA metabolism and cancer development. These findings underline a new function of ENO1 in regulating AA metabolism and tumorigenesis, suggesting a therapeutic potential for aspirin in patients with liver cancer with aberrant expression of ENO1 or YAP1.
Assuntos
Carcinogênese , Neoplasias Hepáticas , Humanos , Ácido Araquidônico , Linhagem Celular Tumoral , Proliferação de Células , Carcinogênese/genética , Transformação Celular Neoplásica , Fosfopiruvato Hidratase/genética , Fosfopiruvato Hidratase/metabolismo , Neoplasias Hepáticas/genética , Aspirina/farmacologia , Proteínas de Ligação a DNA/genética , Biomarcadores Tumorais , Proteínas Supressoras de Tumor/genéticaRESUMO
BACKGROUND & AIMS: The liver is the main organ of ketogenesis, while ketones are mainly metabolized in peripheral tissues via the critical enzyme 3-oxoacid CoA-transferase 1 (OXCT1). We previously found that ketolysis is reactivated in hepatocellular carcinoma (HCC) cells through OXCT1 expression to promote tumor progression; however, whether OXCT1 regulates antitumor immunity remains unclear. METHODS: To investigate the expression pattern of OXCT1 in HCC in vivo, we conducted multiplex immunohistochemistry experiments on human HCC specimens. To explore the role of OXCT1 in mouse HCC tumor-associated macrophages (TAMs), we generated LysMcreOXCT1f/f (OXCT1 conditional knockout in macrophages) mice. RESULTS: Here, we found that inhibiting OXCT1 expression in tumor-associated macrophages reduced CD8+ T-cell exhaustion through the succinate-H3K4me3-Arg1 axis. Initially, we found that OXCT1 was highly expressed in liver macrophages under steady state and that OXCT expression was further increased in TAMs. OXCT1 deficiency in macrophages suppressed tumor growth by reprogramming TAMs toward an antitumor phenotype, reducing CD8+ T-cell exhaustion and increasing CD8+ T-cell cytotoxicity. Mechanistically, high OXCT1 expression induced the accumulation of succinate, a byproduct of ketolysis, in TAMs, which promoted Arg1 transcription by increasing the H3K4me3 level in the Arg1 promoter. In addition, pimozide, an inhibitor of OXCT1, suppressed Arg1 expression as well as TAM polarization toward the protumor phenotype, leading to decreased CD8+ T-cell exhaustion and slower tumor growth. Finally, high expression of OXCT1 in macrophages was positively associated with poor survival in patients with HCC. CONCLUSIONS: In conclusion, our results demonstrate that OXCT1 epigenetically suppresses antitumor immunity, suggesting that suppressing OXCT1 activity in TAMs could be an effective approach for treating liver cancer. IMPACT AND IMPLICATIONS: The intricate metabolism of liver macrophages plays a critical role in shaping hepatocellular carcinoma progression and immune modulation. Targeting macrophage metabolism to counteract immune suppression presents a promising avenue for hepatocellular carcinoma treatment. Herein, we found that the ketogenesis gene OXCT1 was highly expressed in tumor-associated macrophages (TAMs) and promoted tumor growth by reprogramming TAMs toward a protumor phenotype. Pharmacological targeting or genetic downregulation of OXCT1 in TAMs enhances antitumor immunity and slows tumor growth. Our results suggest that suppressing OXCT1 activity in TAMs could be an effective approach for treating liver cancer.
RESUMO
The MYC oncoprotein activates and represses gene expression in a transcription-dependent or transcription-independent manner. Modification of mRNA emerges as a key gene expression regulatory nexus. We sought to determine whether MYC alters mRNA modifications and report here that MYC promotes cancer progression by down-regulating N6-methyladenosine (m6 A) preferentially in transcripts of a subset of MYC-repressed genes (MRGs). We find that MYC activates the expression of ALKBH5 and reduces m6 A levels in the mRNA of the selected MRGs SPI1 and PHF12. We also show that MYC-regulated m6 A controls the translation of MRG mRNA via the specific m6 A reader YTHDF3. Finally, we find that inhibition of ALKBH5, or overexpression of SPI1 or PHF12, effectively suppresses the growth of MYC-deregulated B-cell lymphomas, both in vitro and in vivo. Our findings uncover a novel mechanism by which MYC suppresses gene expression by altering m6 A modifications in selected MRG transcripts promotes cancer progression.
Assuntos
Homólogo AlkB 5 da RNA Desmetilase , Neoplasias , Adenosina , Homólogo AlkB 5 da RNA Desmetilase/genética , Homólogo AlkB 5 da RNA Desmetilase/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Neoplasias/genética , RNA Mensageiro/genéticaRESUMO
Lin28 plays an important role in promoting tumor development, whereas its exact functions and underlying mechanisms are largely unknown. Here, we show that both human homologs of Lin28 accelerate de novo fatty acid synthesis and promote the conversion from saturated to unsaturated fatty acids via the regulation of SREBP-1. By directly binding to the mRNAs of both SREBP-1 and SCAP, Lin28A/B enhance the translation and maturation of SREBP-1, and protect cancer cells from lipotoxicity. Lin28A/B-stimulated tumor growth is abrogated by SREBP-1 inhibition and by the impairment of the RNA binding properties of Lin28A/B, respectively. Collectively, our findings uncover that post-transcriptional regulation by Lin28A/B enhances de novo fatty acid synthesis and metabolic conversion of saturated and unsaturated fatty acids via SREBP-1, which is critical for cancer progression.
Assuntos
Progressão da Doença , Ácidos Graxos/biossíntese , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Proteínas de Ligação a RNA/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Citoproteção , Estresse do Retículo Endoplasmático , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Modelos Biológicos , Ligação Proteica , Biossíntese de Proteínas , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
Cancer progression depends on cellular metabolic reprogramming as both direct and indirect consequence of oncogenic lesions; however, the underlying mechanisms are still poorly understood. Here, we report that CUEDC2 (CUE domain-containing protein 2) plays a vital role in facilitating aerobic glycolysis, or Warburg effect, in cancer cells. Mechanistically, we show that CUEDC2 upregulates the two key glycolytic proteins GLUT3 and LDHA via interacting with the glucocorticoid receptor (GR) or 14-3-3ζ, respectively. We further demonstrate that enhanced aerobic glycolysis is essential for the role of CUEDC2 to drive cancer progression. Moreover, using tissue microarray analysis, we show a correlation between the aberrant expression of CUEDC2, and GLUT3 and LDHA in clinical HCC samples, further demonstrating a link between CUEDC2 and the Warburg effect during cancer development. Taken together, our findings reveal a previously unappreciated function of CUEDC2 in cancer cell metabolism and tumorigenesis, illustrating how close oncogenic lesions are intertwined with metabolic alterations promoting cancer progression.
Assuntos
Carcinogênese , Proteínas de Transporte/metabolismo , Glicólise , Proteínas de Membrana/metabolismo , Proteínas 14-3-3/metabolismo , Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Transporte/genética , Linhagem Celular Tumoral , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Transportador de Glucose Tipo 3/genética , Transportador de Glucose Tipo 3/metabolismo , Células HeLa , Humanos , Isoenzimas/genética , Isoenzimas/metabolismo , L-Lactato Desidrogenase/genética , L-Lactato Desidrogenase/metabolismo , Lactato Desidrogenase 5 , Proteínas de Membrana/genética , Receptores de Glucocorticoides/metabolismo , Análise Serial de Tecidos , Ativação Transcricional , Regulação para CimaRESUMO
Since the description of the Warburg effect 90 years ago, metabolic reprogramming has been gradually recognized as a major hallmark of cancer cells. Mounting evidence now indicates that cancer is a kind of metabolic disease, quite distinct from conventional perception. While metabolic alterations in cancer cells have been extensively observed in glucose, lipid, and amino acid metabolisms, its underlying regulatory mechanisms are still poorly understood. Noncoding RNA, also known as the "dark matter in life," functions through various mechanisms at RNA level regulating different biological pathways. The last two decades have witnessed the booming of noncoding RNA study on microRNA (miRNA), long noncoding RNA (lncRNA), circular RNA (circRNA), PIWI-interacting RNA (piRNA), etc. In this chapter, we will discuss the regulatory roles of noncoding RNAs on cancer metabolism.
Assuntos
Reprogramação Celular/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias/genética , RNA Longo não Codificante/genética , Humanos , MicroRNAs/biossíntese , MicroRNAs/genética , MicroRNAs/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , RNA/genética , RNA/metabolismo , RNA Circular , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismoRESUMO
Itaconate is a well-known immunomodulatory metabolite; however, its role in hepatocellular carcinoma (HCC) remains unclear. Here, we find that macrophage-derived itaconate promotes HCC by epigenetic induction of Eomesodermin (EOMES)-mediated CD8+ T-cell exhaustion. Our results show that the knockout of immune-responsive gene 1 (IRG1), responsible for itaconate production, suppresses HCC progression. Irg1 knockout leads to a decreased proportion of PD-1+ and TIM-3+ CD8+ T cells. Deletion or adoptive transfer of CD8+ T cells shows that IRG1-promoted tumorigenesis depends on CD8+ T-cell exhaustion. Mechanistically, itaconate upregulates PD-1 and TIM-3 expression levels by promoting succinate-dependent H3K4me3 of the Eomes promoter. Finally, ibuprofen is found to inhibit HCC progression by targeting IRG1/itaconate-dependent tumor immunoevasion, and high IRG1 expression in macrophages predicts poor prognosis in HCC patients. Taken together, our results uncover an epigenetic link between itaconate and HCC and suggest that targeting IRG1 or itaconate might be a promising strategy for HCC treatment.
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Neoplasias Hepáticas/metabolismo , Receptor Celular 2 do Vírus da Hepatite A/genética , Receptor de Morte Celular Programada 1/metabolismo , Exaustão das Células T , Succinatos/farmacologia , Succinatos/metabolismo , Epigênese GenéticaRESUMO
Hepatocytes function largely through the secretion of proteins that regulate cell proliferation, metabolism, and intercellular communications. During the progression of hepatocellular carcinoma (HCC), the hepatocyte secretome changes dynamically as both a consequence and a causative factor in tumorigenesis, although the full scope of secreted protein function in this process remains unclear. Here, we show that the secreted pseudo serine protease PRSS35 functions as a tumor suppressor in HCC. Mechanistically, we demonstrate that active PRSS35 is processed via cleavage by proprotein convertases. Active PRSS35 then suppresses protein levels of CXCL2 through targeted cleavage of tandem lysine (KK) recognition motif. Consequently, CXCL2 degradation attenuates neutrophil recruitment to tumors and formation of neutrophil extracellular traps, ultimately suppressing HCC progression. These findings expand our understanding of the hepatocyte secretome's role in cancer development while providing a basis for the clinical translation of PRRS35 as a therapeutic target or diagnostic biomarker.
Assuntos
Carcinoma Hepatocelular , Armadilhas Extracelulares , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Armadilhas Extracelulares/metabolismo , Peptídeo Hidrolases/metabolismo , Hepatócitos/metabolismo , Linhagem Celular Tumoral , Quimiocina CXCL2/metabolismoRESUMO
Metabolic rewiring and epigenetic remodeling, which are closely linked and reciprocally regulate each other, are among the well-known cancer hallmarks. Recent evidence suggests that many metabolites serve as substrates or cofactors of chromatin-modifying enzymes as a consequence of the translocation or spatial regionalization of enzymes or metabolites. Various metabolic alterations and epigenetic modifications also reportedly drive immune escape or impede immunosurveillance within certain contexts, playing important roles in tumor progression. In this review, we focus on how metabolic reprogramming of tumor cells and immune cells reshapes epigenetic alterations, in particular the acetylation and methylation of histone proteins and DNA. We also discuss other eminent metabolic modifications such as, succinylation, hydroxybutyrylation, and lactylation, and update the current advances in metabolism- and epigenetic modification-based therapeutic prospects in cancer.
Assuntos
Epigênese Genética , Neoplasias , Cromatina , Metilação de DNA , Epigenômica , Histonas/genética , Histonas/metabolismo , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/terapiaRESUMO
Staphylococcal nuclease domain-containing protein 1 (SND1) is an evolutionarily conserved multifunctional protein that functions mainly in the nucleus and cytoplasm. However, whether SND1 regulates cellular activity through mitochondrial-related functions remains unclear. Herein, we demonstrate that SND1 is localized to mitochondria to promote phosphoglycerate mutase 5 (PGAM5)-mediated mitophagy. We find that SND1 is present in mitochondria based on mass spectrometry data and verified this phenomenon in different liver cancer cell types by performing organelle subcellular isolation. Specifically, The N-terminal amino acids 1-63 of SND1 serve as a mitochondrial targeting sequence (MTS), and the translocase of outer membrane 70 (TOM 70) promotes the import of SND1 into mitochondria. By immunoprecipitation-mass spectrometry (IP-MS), we find that SND1 interacts with PGAM5 in mitochondria and is crucial for the binding of PGAM5 to dynamin-related protein 1 (DRP1). Importantly, we demonstrate that PGAM5 and SND1-MTS are required for SND1-mediated mitophagy under FCCP and glucose deprivation treatment as well as for SND1-mediated cell proliferation and tumor growth both in vitro and in vivo. Aberrant expression of SND1 and PGAM5 predicts poor outcomes in hepatocellular carcinoma (HCC) patients. Taken together, these findings establish a previously unappreciated role of SND1 and the association of mitochondrion-localized SND1 with PGAM5 in mitophagy and tumor progression.
RESUMO
α-Enolase 1 (ENO1) is a critical glycolytic enzyme whose aberrant expression drives the pathogenesis of various cancers. ENO1 has been indicated as having additional roles beyond its conventional metabolic activity, but the underlying mechanisms and biological consequences remain elusive. Here, we show that ENO1 suppresses iron regulatory protein 1 (IRP1) expression to regulate iron homeostasis and survival of hepatocellular carcinoma (HCC) cells. Mechanistically, we demonstrate that ENO1, as an RNA-binding protein, recruits CNOT6 to accelerate the messenger RNA decay of IRP1 in cancer cells, leading to inhibition of mitoferrin-1 (Mfrn1) expression and subsequent repression of mitochondrial iron-induced ferroptosis. Moreover, through in vitro and in vivo experiments and clinical sample analysis, we identified IRP1 and Mfrn1 as tumor suppressors by inducing ferroptosis in HCC cells. Taken together, this study establishes an important role for the ENO1-IRP1-Mfrn1 pathway in the pathogenesis of HCC and reveals a previously unknown connection between this pathway and ferroptosis, suggesting a potential innovative cancer therapy.
Assuntos
Carcinoma Hepatocelular , Ferroptose , Proteína 1 Reguladora do Ferro/metabolismo , Neoplasias Hepáticas , Biomarcadores Tumorais , Carcinoma Hepatocelular/genética , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/genética , Ferroptose/genética , Humanos , Ferro/metabolismo , Proteína 1 Reguladora do Ferro/genética , Neoplasias Hepáticas/genética , Fosfopiruvato Hidratase/genética , RNA Mensageiro/genética , Proteínas Supressoras de Tumor/metabolismoRESUMO
Metformin, the first-line drug for type II diabetes, has recently been considered an anticancer agent. However, the molecular target and underlying mechanism of metformin's anti-cancer effects remain largely unclear. Herein, we report that metformin treatment increases the sensitivity of hepatocarcinoma cells to methotrexate (MTX) by suppressing the expression of the one-carbon metabolism enzyme DHFR. We show that the combination of metformin and MTX blocks nucleotide metabolism and thus effectively inhibits cell cycle progression and tumorigenesis. Mechanistically, metformin not only transcriptionally represses DHFR via E2F4 but also promotes lysosomal degradation of the DHFR protein. Notably, metformin dramatically increases the response of patient-derived hepatocarcinoma organoids to MTX without obvious toxicity to organoids derived from normal liver tissue. Taken together, our findings identify an important role for DHFR in the suppressive effects of metformin on therapeutic resistance, thus revealing a therapeutically targetable potential vulnerability in hepatocarcinoma.
Assuntos
Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/patologia , Metformina/farmacologia , Metotrexato/farmacologia , Tetra-Hidrofolato Desidrogenase/metabolismo , Animais , Contagem de Células , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Fator de Transcrição E2F4/metabolismo , Antagonistas do Ácido Fólico/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células Hep G2 , Humanos , Neoplasias Hepáticas/genética , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Biológicos , Organoides/efeitos dos fármacos , Organoides/patologia , Proteólise/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Tetra-Hidrofolato Desidrogenase/genética , Transcrição Gênica/efeitos dos fármacosRESUMO
BACKGROUND: Histone deacetylases (HDACs) engage in the regulation of various cellular processes by controlling global gene expression. The dysregulation of HDACs leads to carcinogenesis, making HDACs ideal targets for cancer therapy. However, the use of HDAC inhibitors (HDACi) as single agents has been shown to have limited success in treating solid tumors in clinical studies. This study aimed to identify a novel downstream effector of HDACs to provide a potential target for combination therapy. METHODS: Transcriptome sequencing and bioinformatics analysis were performed to screen for genes responsive to HDACi in breast cancer cells. The effects of HDACi on cell viability were detected using the MTT assay. The mRNA and protein levels of genes were determined by quantitative reverse transcription-PCR (qRT-PCR) and Western blotting. Cell cycle distribution and apoptosis were analyzed by flow cytometry. The binding of CREB1 (cAMP-response element binding protein 1) to the promoter of the KDELR (The KDEL (Lys-Asp-Glu-Leu) receptor) gene was validated by the ChIP (chromatin immunoprecipitation assay). The association between KDELR2 and protein of centriole 5 (POC5) was detected by immunoprecipitation. A breast cancer-bearing mouse model was employed to analyze the effect of the HDAC3-KDELR2 axis on tumor growth. RESULTS: KDELR2 was identified as a novel target of HDAC3, and its aberrant expression indicated the poor prognosis of breast cancer patients. We found a strong correlation between the protein expression patterns of HADC3 and KDELR2 in tumor tissues from breast cancer patients. The results of the ChIP assay and qRT-PCR analysis validated that HDAC3 transactivated KDELR2 via CREB1. The HDAC3-KDELR2 axis accelerated the cell cycle progression of cancer cells by protecting the centrosomal protein POC5 from proteasomal degradation. Moreover, the HDAC3-KDELR2 axis promoted breast cancer cell proliferation and tumorigenesis in vitro and in vivo. CONCLUSION: Our results uncovered a previously unappreciated function of KDELR2 in tumorigenesis, linking a critical Golgi-the endoplasmic reticulum traffic transport protein to HDAC-controlled cell cycle progression on the path of cancer development and thus revealing a potential therapeutical target for breast cancer.
Assuntos
Neoplasias da Mama , Animais , Neoplasias da Mama/genética , Proteínas de Transporte , Ciclo Celular/genética , Proliferação de Células/genética , Feminino , Inibidores de Histona Desacetilases , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Camundongos , Proteínas de Transporte Vesicular/metabolismoRESUMO
Metastasis is responsible for the majority of breast cancer-related deaths, however, the mechanisms underlying metastasis in this disease remain largely elusive. Here we report that under hypoxic conditions, alternative splicing of MBD2 is suppressed, favoring the production of MBD2a, which facilitates breast cancer metastasis. Specifically, MBD2a promoted, whereas its lesser known short form MBD2c suppressed metastasis. Activation of HIF1 under hypoxia facilitated MBD2a production via repression of SRSF2-mediated alternative splicing. As a result, elevated MBD2a outcompeted MBD2c for binding to promoter CpG islands to activate expression of FZD1, thereby promoting epithelial-to-mesenchymal transition and metastasis. Strikingly, clinical data reveal significantly correlated expression of MBD2a and MBD2c with the invasiveness of malignancy, indicating opposing roles for MBD2 splicing variants in regulating human breast cancer metastasis. Collectively, our findings establish a novel link between MBD2 switching and tumor metastasis and provide a promising therapeutic strategy and predictive biomarkers for hypoxia-driven breast cancer metastasis. SIGNIFICANCE: This study defines the opposing roles and clinical relevance of MBD2a and MBD2c, two MBD2 alternative splicing products, in hypoxia-driven breast cancer metastasis. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/5/1265/F1.large.jpg.
Assuntos
Processamento Alternativo , Neoplasias da Mama/patologia , Proteínas de Ligação a DNA/genética , Receptores Frizzled/genética , Animais , Neoplasias da Mama/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Ilhas de CpG , Transição Epitelial-Mesenquimal/genética , Feminino , Receptores Frizzled/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos Nus , MicroRNAs/genética , Regiões Promotoras Genéticas , Fatores de Processamento de Serina-Arginina/genética , Hipóxia Tumoral/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
HIF-1 serves as an important regulator in cell response to hypoxia. Due to its key role in promoting tumor survival and progression under hypoxia, HIF-1 has become a promising target of cancer therapy. Thus far, several HIF-1 inhibitors have been identified, most of which are from synthesized chemical compounds. Here, we report that ALM (ActinoLactoMycin), a compound extracted from metabolites of Streptomyces flavoretus, exhibits inhibitory effect on HIF-1α. Mechanistically, we found that ALM inhibited the translation of HIF-1α protein by suppressing mTOR signaling activity. Treatment with ALM induced cell apoptosis and growth inhibition of cancer cells both in vitro and in vivo in a HIF-1 dependent manner. More interestingly, low dose of ALM treatment enhanced the anti-tumor effect of Everolimus, an inhibitor of mTOR, suggesting its potential use in combination therapy of tumors, especially solid tumor patients. Thus, we identified a novel HIF-1α inhibitor from the metabolites of Streptomyces flavoretus, which shows promising anti-cancer potential.
Assuntos
Antibióticos Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Ácidos Graxos/farmacologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/antagonistas & inibidores , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Lactonas/farmacologia , Neoplasias/tratamento farmacológico , Animais , Antibióticos Antineoplásicos/uso terapêutico , Everolimo/farmacologia , Everolimo/uso terapêutico , Ácidos Graxos/uso terapêutico , Humanos , Lactonas/uso terapêutico , Camundongos Endogâmicos BALB C , Camundongos Nus , Processos Neoplásicos , Células PC-3 , Transdução de Sinais/efeitos dos fármacos , Streptomyces/metabolismo , Serina-Treonina Quinases TOR/metabolismoRESUMO
DIS3-like 3'-5' exoribonuclease 2 (DIS3L2) degrades aberrant RNAs, however, its function in tumorigenesis remains largely unexplored. Here, aberrant DIS3L2 expression promoted human hepatocellular carcinoma (HCC) progression via heterogeneous nuclear ribonucleoproteins (hnRNP) U-mediated alternative splicing. DIS3L2 directly interacted with hnRNP U through its cold-shock domains and promoted inclusion of exon 3b during splicing of pre-Rac1 independent of its exonuclease activity, yielding an oncogenic splicing variant, Rac1b, which is known to stimulate cellular transformation and tumorigenesis. DIS3L2 regulated alternative splicing by recruiting hnRNP U to pre-Rac1. Rac1b was critical for DIS3L2 promotion of liver cancer development both in vitro and in vivo. Importantly, DIS3L2 and Rac1b expression highly correlated with HCC progression and patient survival. Taken together, our findings uncover an oncogenic role of DIS3L2, in which it promotes liver cancer progression through a previously unappreciated mechanism of regulating hnRNP U-mediated alterative splicing. SIGNIFICANCE: These findings establish the role and mechanism of the 3'-5' exoribonuclease DIS3L2 in hepatocellular carcinoma carcinogenesis.