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1.
Proc Natl Acad Sci U S A ; 116(19): 9433-9442, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-31000598

RESUMO

The RAS family of proto-oncogenes are among the most commonly mutated genes in human cancers and predict poor clinical outcome. Several mechanisms underlying oncogenic RAS transformation are well documented, including constitutive signaling through the RAF-MEK-ERK proproliferative pathway as well as the PI3K-AKT prosurvival pathway. Notably, control of redox balance has also been proposed to contribute to RAS transformation. However, how homeostasis between reactive oxygen species (ROS) and antioxidants, which have opposing effects in the cell, ultimately influence RAS-mediated transformation and tumor progression is still a matter of debate and the mechanisms involved have not been fully elucidated. Here, we show that oncogenic KRAS protects fibroblasts from oxidative stress by enhancing intracellular GSH levels. Using a whole transcriptome approach, we discovered that this is attributable to transcriptional up-regulation of xCT, the gene encoding the cystine/glutamate antiporter. This is in line with the function of xCT, which mediates the uptake of cystine, a precursor for GSH biosynthesis. Moreover, our results reveal that the ETS-1 transcription factor downstream of the RAS-RAF-MEK-ERK signaling cascade directly transactivates the xCT promoter in synergy with the ATF4 endoplasmic reticulum stress-associated transcription factor. Strikingly, xCT was found to be essential for oncogenic KRAS-mediated transformation in vitro and in vivo by mitigating oxidative stress, as knockdown of xCT strongly impaired growth of tumor xenografts established from KRAS-transformed cells. Overall, this study uncovers a mechanism by which oncogenic RAS preserves intracellular redox balance and identifies an unexpected role for xCT in supporting RAS-induced transformation and tumorigenicity.


Assuntos
Sistema y+ de Transporte de Aminoácidos/biossíntese , Transformação Celular Neoplásica/metabolismo , Sistema de Sinalização das MAP Quinases , Neoplasias Experimentais/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Sistema y+ de Transporte de Aminoácidos/genética , Animais , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Estresse do Retículo Endoplasmático , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Camundongos , Camundongos Knockout , Camundongos Nus , Células NIH 3T3 , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , Oxirredução , Estresse Oxidativo , Proteína Proto-Oncogênica c-ets-1/genética , Proteína Proto-Oncogênica c-ets-1/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética
2.
Cell Death Dis ; 15(7): 501, 2024 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-39003251

RESUMO

Eukaryotic elongation factor 2 (eEF2) kinase (eEF2K) is a stress-responsive hub that inhibits the translation elongation factor eEF2, and consequently mRNA translation elongation, in response to hypoxia and nutrient deprivation. EEF2K is also involved in the response to DNA damage but its role in response to DNA crosslinks, as induced by cisplatin, is not known. Here we found that eEF2K is critical to mediate the cellular response to cisplatin. We uncovered that eEF2K deficient cells are more resistant to cisplatin treatment. Mechanistically, eEF2K deficiency blunts the activation of the DNA damage response associated ATM and ATR pathways, in turn preventing p53 activation and therefore compromising induction of cisplatin-induced apoptosis. We also report that loss of eEF2K delays the resolution of DNA damage triggered by cisplatin, suggesting that eEF2K contributes to DNA damage repair in response to cisplatin. In support of this, our data shows that eEF2K promotes the expression of the DNA repair protein ERCC1, critical for the repair of cisplatin-caused DNA damage. Finally, using Caenorhabditis elegans as an in vivo model, we find that deletion of efk-1, the worm eEF2K ortholog, mitigates the induction of germ cell death in response to cisplatin. Together, our data highlight that eEF2K represents an evolutionary conserved mediator of the DNA damage response to cisplatin which promotes p53 activation to induce cell death, or alternatively facilitates DNA repair, depending on the extent of DNA damage.


Assuntos
Caenorhabditis elegans , Cisplatino , Dano ao DNA , Quinase do Fator 2 de Elongação , Proteína Supressora de Tumor p53 , Cisplatino/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Quinase do Fator 2 de Elongação/metabolismo , Quinase do Fator 2 de Elongação/genética , Animais , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Humanos , Reparo do DNA/efeitos dos fármacos , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Apoptose/efeitos dos fármacos
3.
Nat Commun ; 15(1): 4083, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38744825

RESUMO

Energetic stress compels cells to evolve adaptive mechanisms to adjust their metabolism. Inhibition of mTOR kinase complex 1 (mTORC1) is essential for cell survival during glucose starvation. How mTORC1 controls cell viability during glucose starvation is not well understood. Here we show that the mTORC1 effectors eukaryotic initiation factor 4E binding proteins 1/2 (4EBP1/2) confer protection to mammalian cells and budding yeast under glucose starvation. Mechanistically, 4EBP1/2 promote NADPH homeostasis by preventing NADPH-consuming fatty acid synthesis via translational repression of Acetyl-CoA Carboxylase 1 (ACC1), thereby mitigating oxidative stress. This has important relevance for cancer, as oncogene-transformed cells and glioma cells exploit the 4EBP1/2 regulation of ACC1 expression and redox balance to combat energetic stress, thereby supporting transformation and tumorigenicity in vitro and in vivo. Clinically, high EIF4EBP1 expression is associated with poor outcomes in several cancer types. Our data reveal that the mTORC1-4EBP1/2 axis provokes a metabolic switch essential for survival during glucose starvation which is exploited by transformed and tumor cells.


Assuntos
Acetil-CoA Carboxilase , Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Ciclo Celular , Sobrevivência Celular , Ácidos Graxos , Glucose , Alvo Mecanístico do Complexo 1 de Rapamicina , Animais , Humanos , Camundongos , Acetil-CoA Carboxilase/metabolismo , Acetil-CoA Carboxilase/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Fatores de Iniciação em Eucariotos/metabolismo , Fatores de Iniciação em Eucariotos/genética , Ácidos Graxos/metabolismo , Glucose/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , NADP/metabolismo , Estresse Oxidativo , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , Biossíntese de Proteínas
4.
Cell Death Differ ; 30(2): 442-456, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36443441

RESUMO

Oncogenic KRAS is the key driver oncogene for several of the most aggressive human cancers. One key feature of oncogenic KRAS expression is an early increase in cellular reactive oxygen species (ROS) which promotes cellular transformation if cells manage to escape cell death, mechanisms of which remain incompletely understood. Here, we identify that expression of oncogenic as compared to WT KRAS in isogenic cellular systems renders cells more resistant to ferroptosis, a recently described type of regulated necrosis. Mechanistically, we find that cells with mutant KRAS show a specific lack of ferroptosis-induced lipid peroxidation. Interestingly, KRAS-mutant cells upregulate expression of ferroptosis suppressor protein 1 (FSP1). Indeed, elevated levels of FSP1 in KRAS-mutant cells are responsible for mediating ferroptosis resistance and FSP1 is upregulated as a consequence of MAPK and NRF2 pathway activation downstream of KRAS. Strikingly, FSP1 activity promotes cellular transformation in soft agar and its overexpression is sufficient to promote spheroid growth in 3D in KRAS WT cells. Moreover, FSP1 expression and its activity in ferroptosis inhibition accelerates tumor onset of KRAS WT cells in the absence of oncogenic KRAS in vivo. Consequently, we find that pharmacological induction of ferroptosis in pancreatic organoids derived from the LsL-KRASG12D expressing mouse model is only effective in combination with FSP1 inhibition. Lastly, FSP1 is upregulated in non-small cell lung cancer (NSCLC), colorectal cancer (CRC) and pancreatic ductal adenocarcinoma (PDAC) as compared to the respective normal tissue of origin and correlates with NRF2 expression in PDAC patient datasets. Based on these data, we propose that KRAS-mutant cells must navigate a ferroptosis checkpoint by upregulating FSP1 during tumor establishment. Consequently, ferroptosis-inducing therapy should be combined with FSP1 inhibitors for efficient therapy of KRAS-mutant cancers.


Assuntos
Proteínas Reguladoras de Apoptose , Carcinogênese , Ferroptose , Animais , Humanos , Camundongos , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Ductal Pancreático/patologia , Transformação Celular Neoplásica , Neoplasias Pulmonares/genética , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Neoplasias Pancreáticas
5.
Cell Death Dis ; 12(10): 885, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34584066

RESUMO

Glioblastoma is the most common malignant primary brain tumor. To date, clinically relevant biomarkers are restricted to isocitrate dehydrogenase (IDH) gene 1 or 2 mutations and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation. Long non-coding RNAs (lncRNAs) have been shown to contribute to glioblastoma pathogenesis and could potentially serve as novel biomarkers. The clinical significance of HOXA Transcript Antisense RNA, Myeloid-Specific 1 (HOTAIRM1) was determined by analyzing HOTAIRM1 in multiple glioblastoma gene expression data sets for associations with prognosis, as well as, IDH mutation and MGMT promoter methylation status. Finally, the role of HOTAIRM1 in glioblastoma biology and radiotherapy resistance was characterized in vitro and in vivo. We identified HOTAIRM1 as a candidate lncRNA whose up-regulation is significantly associated with shorter survival of glioblastoma patients, independent from IDH mutation and MGMT promoter methylation. Glioblastoma cell line models uniformly showed reduced cell viability, decreased invasive growth and diminished colony formation capacity upon HOTAIRM1 down-regulation. Integrated proteogenomic analyses revealed impaired mitochondrial function and determination of reactive oxygen species (ROS) levels confirmed increased ROS levels upon HOTAIRM1 knock-down. HOTAIRM1 knock-down decreased expression of transglutaminase 2 (TGM2), a candidate protein implicated in mitochondrial function, and knock-down of TGM2 mimicked the phenotype of HOTAIRM1 down-regulation in glioblastoma cells. Moreover, HOTAIRM1 modulates radiosensitivity of glioblastoma cells both in vitro and in vivo. Our data support a role for HOTAIRM1 as a driver of biological aggressiveness, radioresistance and poor outcome in glioblastoma. Targeting HOTAIRM1 may be a promising new therapeutic approach.


Assuntos
Glioblastoma/genética , Glioblastoma/radioterapia , MicroRNAs/metabolismo , Tolerância a Radiação/genética , Animais , Carcinogênese/genética , Carcinogênese/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Células Clonais , Regulação para Baixo/genética , Regulação Neoplásica da Expressão Gênica , Glioblastoma/patologia , Humanos , Camundongos Nus , MicroRNAs/genética , Mitocôndrias/metabolismo , Invasividade Neoplásica , Fenótipo , Prognóstico , Proteína 2 Glutamina gama-Glutamiltransferase/metabolismo , Proteogenômica , RNA Interferente Pequeno/metabolismo , Espécies Reativas de Oxigênio/metabolismo
6.
Cancer Discov ; 11(11): 2884-2903, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34021002

RESUMO

Cancer cells must overcome anoikis (detachment-induced death) to successfully metastasize. Using proteomic screens, we found that distinct oncoproteins upregulate IL1 receptor accessory protein (IL1RAP) to suppress anoikis. IL1RAP is directly induced by oncogenic fusions of Ewing sarcoma, a highly metastatic childhood sarcoma. IL1RAP inactivation triggers anoikis and impedes metastatic dissemination of Ewing sarcoma cells. Mechanistically, IL1RAP binds the cell-surface system Xc - transporter to enhance exogenous cystine uptake, thereby replenishing cysteine and the glutathione antioxidant. Under cystine depletion, IL1RAP induces cystathionine gamma lyase (CTH) to activate the transsulfuration pathway for de novo cysteine synthesis. Therefore, IL1RAP maintains cyst(e)ine and glutathione pools, which are vital for redox homeostasis and anoikis resistance. IL1RAP is minimally expressed in pediatric and adult normal tissues, and human anti-IL1RAP antibodies induce potent antibody-dependent cellular cytotoxicity of Ewing sarcoma cells. Therefore, we define IL1RAP as a new cell-surface target in Ewing sarcoma, which is potentially exploitable for immunotherapy. SIGNIFICANCE: Here, we identify cell-surface protein IL1RAP as a key driver of metastasis in Ewing sarcoma, a highly aggressive childhood sarcoma. Minimal expression in pediatric and adult normal tissues nominates IL1RAP as a promising target for immunotherapy.See related commentary by Yoon and DeNicola, p. 2679.This article is highlighted in the In This Issue feature, p. 2659.


Assuntos
Anoikis , Proteína Acessória do Receptor de Interleucina-1 , Sarcoma de Ewing , Adulto , Linhagem Celular Tumoral , Criança , Humanos , Proteômica , Receptores de Interleucina-1 , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologia
7.
Mol Cell Oncol ; 7(1): 1654814, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31993493

RESUMO

In our recent study, we demonstrated that oncogenic RAS (rat sarcoma)-mediated transformation and tumorigenesis are supported by transcriptional induction of a crucial antioxidant component, SLC7A11 (solute carrier family 7 member 11), otherwise known as XCT, a gene encoding the cystine/glutamate transporter. Our data highlight that this promotes the biosynthesis of glutathione, in turn allowing RAS transformed cells to mitigate tumorigenesis-linked oxidative stress.

8.
Cell Death Dis ; 10(12): 955, 2019 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-31852884

RESUMO

The RAS family of proto-oncogenes comprises HRAS, KRAS, and NRAS, which are among the most mutated genes in human cancers. The RAS family genes encode small GTPases that coordinate key signaling pathways in response to growth factors. Mutations in RAS result in a constitutively active form of the protein that supports cellular transformation and tumorigenesis. The mechanisms of oncogenic RAS-mediated transformation encompass uncontrolled proliferation and inhibition of cell death through overactivation of the RAF-MEK-ERK and the PI3K-AKT pathways, respectively. In addition, the control of redox balance by RAS has also been proposed to play a role in its oncogenic properties. However, the exact role of redox balance in mediating mutant RAS transformation is still under debate. Here, we present, on one hand, the involvement of pro-oxidant components in oncogenic RAS transformation, such as NADPH oxidases and mitochondrial reactive oxygen species, and how these promote transformation. On the other hand, we describe the contribution of antioxidant components to mutant RAS transformation, including Nrf2, glutathione biosynthesis and xCT, as well as the mechanisms by which antioxidant programs drive transformation. Finally, we aim to reconcile the seemingly opposite effects of oncogenic RAS on redox balance and discuss a model for the complementary role of both pro-oxidant and antioxidant pathways in mutant RAS-driven tumor progression.


Assuntos
Transformação Celular Neoplásica/genética , Neoplasias/genética , Oncogenes/genética , Proteínas ras/genética , Animais , Transformação Celular Neoplásica/patologia , Humanos , Mutação/genética , Neoplasias/patologia , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/genética
9.
Cell Death Differ ; 24(9): 1564-1576, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28574509

RESUMO

MYC family proteins are implicated in many human cancers, but their therapeutic targeting has proven challenging. MYCN amplification in childhood neuroblastoma (NB) is associated with aggressive disease and high mortality. Novel and effective therapeutic strategies are therefore urgently needed for these tumors. MYC-driven oncogenic transformation impairs cell survival under nutrient deprivation (ND), a characteristic stress condition within the tumor microenvironment. We recently identified eukaryotic Elongation Factor 2 Kinase (eEF2K) as a pivotal mediator of the adaptive response of tumor cells to ND. We therefore hypothesized that eEF2K facilitates the adaptation of MYCN amplified NB to ND, and that inhibiting this pathway can impair MYCN-driven NB progression. To test our hypothesis, we first analyzed publicly available genomic databases and tissue microarrays for eEF2K expression in NB, and for links between eEF2K, MYCN, and clinical outcome in NB. Effects of eEF2K inhibition were evaluated on survival of MYCN amplified versus non-amplified NB cell lines under ND. Finally, NB xenograft mouse models were used to confirm in vitro observations. Our results indicate that high eEF2K expression and activity are strongly predictive of poor outcome in NB, and correlates significantly with MYCN amplification. Inhibition of eEF2K markedly decreases survival of MYCN amplified NB cell lines in vitro under ND. Growth of MYCN amplified NB xenografts is markedly impaired by eEF2K knockdown, particularly under caloric restriction. In summary, eEF2K protects MYCN overexpressing NB cells from ND in vitro and in vivo, highlighting this kinase as a critical mediator of the adaptive response of MYCN amplified NB cells to metabolic stress.


Assuntos
Quinase do Fator 2 de Elongação/metabolismo , Proteína Proto-Oncogênica N-Myc/metabolismo , Neuroblastoma/metabolismo , RNA Mensageiro/metabolismo , Animais , Western Blotting , Linhagem Celular , Quinase do Fator 2 de Elongação/genética , Feminino , Citometria de Fluxo , Células HEK293 , Humanos , Imuno-Histoquímica , Camundongos , Camundongos SCID , Proteína Proto-Oncogênica N-Myc/genética , Neuroblastoma/genética , Análise Serial de Tecidos
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