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1.
Blood ; 138(24): 2485-2498, 2021 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-34359074

RESUMO

Proper regulation of p53 signaling is critical for the maintenance of hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs). The hematopoietic cell-specific mechanisms regulating p53 activity remain largely unknown. Here, we demonstrate that conditional deletion of acidic leucine-rich nuclear phosphoprotein 32B (ANP32B) in hematopoietic cells impairs repopulation capacity and postinjury regeneration of HSCs. Mechanistically, ANP32B forms a repressive complex with p53 and thus inhibits the transcriptional activity of p53 in hematopoietic cells, and p53 deletion rescues the functional defect in Anp32b-deficient HSCs. Of great interest, ANP32B is highly expressed in leukemic cells from patients with chronic myelogenous leukemia (CML). Anp32b deletion enhances p53 transcriptional activity to impair LSC function in a murine CML model and exhibits synergistic therapeutic effects with tyrosine kinase inhibitors in inhibiting CML propagation. In summary, our findings provide a novel strategy to enhance p53 activity in LSCs by inhibiting ANP32B and identify ANP32B as a potential therapeutic target in treating CML.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Células-Tronco Neoplásicas/patologia , Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Células Cultivadas , Regulação Leucêmica da Expressão Gênica , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Camundongos , Células-Tronco Neoplásicas/metabolismo , Proteínas do Tecido Nervoso/genética , Proteínas Nucleares/genética , Proteína Supressora de Tumor p53/genética
2.
EMBO Rep ; 16(11): 1563-80, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26415504

RESUMO

Apoptosis-inducing factor (AIF) exerts dual roles on cell death and survival, but its substrates as a putative oxidoreductase and roles in tumorigenesis remain elusive. Here, we report that AIF physically interacts with and inhibits the oxidation of phosphatase and tensin homolog on chromosome ten (PTEN), a tumor suppressor susceptible for oxidation-mediated inactivation. More intriguingly, we also identify PTEN as a mitochondrial protein and the ectopic expression of mitochondrial targeting sequence-carrying PTEN almost completely inhibits Akt phosphorylation in PTEN-deficient cells. AIF knockdown causes oxidation-mediated inactivation of the lipid phosphatase activity of PTEN, with ensuing activation of Akt kinase, phosphorylation of the Akt substrate GSK-3ß, and activation of ß-catenin signaling in cancer cells. Through its effect on ß-catenin signaling, AIF inhibits epithelial-mesenchymal transition (EMT) and metastasis of cancer cells in vitro and in orthotopically implanted xenografts. Accordingly, the expression of AIF is correlated with the survival of human patients with cancers of multiple origins. These results identify PTEN as the substrate of AIF oxidoreductase and reveal a novel function for AIF in controlling tumor metastasis.


Assuntos
Fator de Indução de Apoptose/metabolismo , Metástase Neoplásica/fisiopatologia , PTEN Fosfo-Hidrolase/metabolismo , Domínios e Motivos de Interação entre Proteínas , beta Catenina/metabolismo , Fator de Indução de Apoptose/genética , Transição Epitelial-Mesenquimal , Técnicas de Silenciamento de Genes , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Células HEK293 , Xenoenxertos , Humanos , Mitocôndrias/química , Oxirredução , Oxirredutases/metabolismo , PTEN Fosfo-Hidrolase/genética , Fosforilação
3.
Carcinogenesis ; 37(11): 1079-1088, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27543779

RESUMO

Recently, we have reported that apoptosis-inducing factor (AIF) regulates the epithelial-mesenchymal transition (EMT) process of cancers, but the mechanisms underlying the regulation of AIF expression in cancers remain greatly unknown. Here, we report that hypoxia inversely correlates with the expression of AIF in tumor tissues from a cohort of colon cancer patients and inhibits AIF expression in multiple colon cancer cell lines. This inhibition is mediated by hypoxia-inducible factor-1 (HIF-1), which transcriptionally represses AIF through direct binding to the hypoxia-response element in AIF promoter as revealed by luciferase reporter and chromatin immunoprecipitation assays. We also show that downregulation of AIF contributes to hypoxia-induced EMT as overexpression or silencing of AIF partially reverses or potentiates the EMT program initiated by hypoxic treatment. Mechanistic study reveals that downregulation of AIF by hypoxia causes oxidative inactivation of the lipid phosphatase activity of phosphatase and tensin homolog on chromosome 10 (PTEN), with ensuing activation of Akt kinase, phosphorylation of the Akt substrate GSK-3ß and activation of WNT/ß-catenin signaling in colon cancer cells. These results identify AIF as a novel target gene of HIF-1 and reveal the role of AIF downregulation in hypoxia-induced EMT.


Assuntos
Fator de Indução de Apoptose/genética , Neoplasias do Colo/metabolismo , Transição Epitelial-Mesenquimal , Subunidade alfa do Fator 1 Induzível por Hipóxia/fisiologia , Animais , Fator de Indução de Apoptose/metabolismo , Sequência de Bases , Sítios de Ligação , Hipóxia Celular , Linhagem Celular Tumoral , Neoplasias do Colo/patologia , Regulação para Baixo , Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Oxirredução , PTEN Fosfo-Hidrolase/metabolismo , Regiões Promotoras Genéticas , Via de Sinalização Wnt
4.
BMC Cancer ; 15: 139, 2015 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-25885900

RESUMO

BACKGROUND: Annonaceous acetogenins are a family of natural products with antitumor activities. Annonaceous acetogenin mimic AA005 reportedly inhibits mammalian mitochondrial NADH-ubiquinone reductase (Complex I) and induces gastric cancer cell death. However, the mechanisms underlying its cell-death-inducing activity are unclear. METHODS: We used SW620 colorectal adenocarcinoma cells to study AA005 cytotoxic activity. Cell deaths were determined by Trypan blue assay and flow cytometry, and related proteins were characterized by western blot. Immunofluorescence and subcellular fractionation were used to evaluate AIF nuclear translocation. Reactive oxygen species were assessed by using redox-sensitive dye DCFDA. RESULTS: AA005 induces a unique type of cell death in colorectal adenocarcinoma cells, characterized by lack of caspase-3 activation or apoptotic body formation, sensitivity to poly (ADP-ribose) polymerase inhibitor Olaparib (AZD2281) but not pan-caspase inhibitor Z-VAD.fmk, and dependence on apoptosis-inducing factor (AIF). AA005 treatment also reduced expression of mitochondrial Complex I components, and leads to accumulation of intracellular reactive oxygen species (ROS) at the early stage. Blocking ROS formation significantly suppresses AA005-induced cell death in SW620 cells. Moreover, blocking activation of RIP-1 by necroptosis inhibitor necrotatin-1 inhibits AIF translocation and partially suppresses AA005-induced cell death in SW620 cells demonstrating that RIP-1 protein may be essential for cell death. CONCLUSIONS: AA005 may trigger the cell death via mediated by AIF through caspase-3 independent pathway. Our work provided new mechanisms for AA005-induced cancer cell death and novel clues for cancer treatment via AIF dependent cell death.


Assuntos
Acetogeninas/farmacologia , Fator de Indução de Apoptose/biossíntese , Caspase 3 , Álcoois Graxos/farmacologia , Lactonas/farmacologia , Acetogeninas/química , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Relação Dose-Resposta a Droga , Álcoois Graxos/química , Humanos , Lactonas/química , Espécies Reativas de Oxigênio/metabolismo , Células U937
5.
Cell Death Dis ; 15(5): 335, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38744853

RESUMO

PTENα/ß, two variants of PTEN, play a key role in promoting tumor growth by interacting with WDR5 through their N-terminal extensions (NTEs). This interaction facilitates the recruitment of the SET1/MLL methyltransferase complex, resulting in histone H3K4 trimethylation and upregulation of oncogenes such as NOTCH3, which in turn promotes tumor growth. However, the molecular mechanism underlying this interaction has remained elusive. In this study, we determined the first crystal structure of PTENα-NTE in complex with WDR5, which reveals that PTENα utilizes a unique binding motif of a sequence SSSRRSS found in the NTE domain of PTENα/ß to specifically bind to the WIN site of WDR5. Disruption of this interaction significantly impedes cell proliferation and tumor growth, highlighting the potential of the WIN site inhibitors of WDR5 as a way of therapeutic intervention of the PTENα/ß associated cancers. These findings not only shed light on the important role of the PTENα/ß-WDR5 interaction in carcinogenesis, but also present a promising avenue for developing cancer treatments that target this pathway.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular , PTEN Fosfo-Hidrolase , Animais , Humanos , Camundongos , Motivos de Aminoácidos , Linhagem Celular Tumoral , Proliferação de Células/genética , Progressão da Doença , Histona-Lisina N-Metiltransferase/metabolismo , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/química , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/química , Camundongos Nus , Neoplasias/genética , Neoplasias/patologia , Neoplasias/metabolismo , Ligação Proteica , Domínios Proteicos , PTEN Fosfo-Hidrolase/metabolismo , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/química
6.
Dev Cell ; 2024 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-39197453

RESUMO

Loss of phosphatase and tensin homolog (PTEN) has been linked to an immunosuppressive tumor microenvironment, but its underlying mechanisms remain largely enigmatic. Here, we report that PTEN can be secreted by the transmembrane emp24 domain-containing protein 10 (TMED10)-channeled protein secretion pathway. Inhibiting PTEN secretion from tumor cells contributes to immunosuppression and impairs the tumor-suppressive role of PTEN, while intratumoral injection of PTEN protein promotes antitumor immunity and suppresses tumor growth in mice. Mechanistically, extracellular PTEN binds to the plexin domain-containing protein 2 (PLXDC2) on macrophages, triggering subsequent activation of JAK2-STAT1 signaling, which switches tumor-associated macrophages (TAMs) from the immunosuppressive to inflammatory phenotype, leading to enhanced activation of CD8+ T and natural killer cells. Importantly, PTEN treatment also enhances the therapeutic efficacy of anti-PD-1 treatment in mice and reverses the immune-suppressive phenotype of patient-derived primary TAMs. These data identify a cytokine-like role of PTEN in immune activation and tumor suppression and demonstrate the therapeutic potential for extracellular administration of PTEN in cancer immunotherapy.

7.
J Proteome Res ; 12(10): 4280-301, 2013 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-23879269

RESUMO

The proteolytic activation of protein kinase Cδ (PKCδ) generates a catalytic fragment called PKCδ-CF, which induces cell death. However, the mechanisms underlying PKCδ-CF-mediated cell death are largely unknown. On the basis of an engineering leukemic cell line with inducible expression of PKCδ-CF, here we employ SILAC-based quantitative phosphoproteomics to systematically and dynamically investigate the overall phosphorylation events during cell death triggered by PKCδ-CF expression. Totally, 3000 phosphorylation sites were analyzed. Considering the fact that early responses to PKCδ-CF expression initiate cell death, we sought to identify pathways possibly related directly with PKCδ by further analyzing the data set of phosphorylation events that occur in the initiation stage of cell death. Interacting analysis of this data set indicates that PKCδ-CF triggers complicated networks to initiate cell death, and motif analysis and biochemistry verification reveal that several kinases in the downstream of PKCδ conduct these networks. By analysis of the specific sequence motif of kinase-substrate, we also find 59 candidate substrates of PKCδ from the up-regulated phosphopeptides, of which 12 were randomly selected for in vitro kinase assay and 9 were consequently verified as substrates of PKCδ. To our greatest understanding, this study provides the most systematic analysis of phosphorylation events initiated by the cleaved activated PKCδ, which would vastly extend the profound understanding of PKCδ-directed signal pathways in cell death. The MS data have been deposited to the ProteomeXchange with identifier PXD000225.


Assuntos
Apoptose , Fosfoproteínas/metabolismo , Proteína Quinase C-delta/metabolismo , Processamento de Proteína Pós-Traducional , Proteoma/metabolismo , Sequência de Aminoácidos , Linhagem Celular Tumoral , Sequência Consenso , Proteínas Culina/metabolismo , Ontologia Genética , Células HEK293 , Humanos , Dados de Sequência Molecular , Fosfoproteínas/genética , Fosforilação , Mapas de Interação de Proteínas , Proteoma/genética , Proteômica , Transdução de Sinais
8.
Biochem Biophys Res Commun ; 435(1): 46-51, 2013 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-23611775

RESUMO

Hypoxia-inducible factor 1α (HIF-1α) is an oxygen-sensitive subunit of HIF-1, the master transcription factor for cellular response to hypoxia. Down-regulation of the mitochondrial enzyme superoxide dismutase 2 (SOD2) contributes to the stabilization of HIF-1α under hypoxia due to the decreased dismutation of superoxide radical. Here we report that HIF-1α could also regulate the expression of SOD2. We found that both stabilization of HIF-1α expression under nomoxia caused by pVHL deficiency and hypoxia treatment significantly reduced SOD2 expression, and shRNAs specifically against HIF-1α restored SOD2 expression in both circumstances. Further analyses with luciferase reporter assay and chromatin immunoprecipitation assay revealed that HIF-1α inhibited and directly bound to the hypoxia-responsive element in SOD2 promoter. These findings indicated the existence of a positive feedback between HIF-1α and SOD2 and provided new clues for understanding the molecular mechanisms of hypoxia adaptation.


Assuntos
Regulação para Baixo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Superóxido Dismutase/metabolismo , Proteína Supressora de Tumor Von Hippel-Lindau/metabolismo , Sequência de Bases , Western Blotting , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/metabolismo , Carcinoma de Células Renais/patologia , Hipóxia Celular , Linhagem Celular Tumoral , Eletroforese em Gel Bidimensional , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Imuno-Histoquímica , Neoplasias Renais/genética , Neoplasias Renais/metabolismo , Neoplasias Renais/patologia , Regiões Promotoras Genéticas/genética , Ligação Proteica , Interferência de RNA , Elementos de Resposta/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Superóxido Dismutase/genética , Proteína Supressora de Tumor Von Hippel-Lindau/genética
9.
Biochem Biophys Res Commun ; 433(2): 220-5, 2013 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-23473759

RESUMO

Our previous study has shown that PKCδ stimulates proteasome-dependent degradation of C/EBPα, which partially contributes to PKCδ-mediated apoptosis. However, the molecular interrelationship between these two important proteins is still unknown. In this study, we reported that C/EBPα was phosphorylated by activated PKCδ on three serines, two of which were reported for the first time. Phosphorylated C/EBPα underwent cytoplasmic translocation, which led to the inactivation of its transcriptional activity. Inactive cytoplasmic C/EBPα was finally subjected to proteasome degradation. This work reveals the exquisite molecular events linking activated PKCδ and C/EBPα degradation during cell apoptosis.


Assuntos
Proteína alfa Estimuladora de Ligação a CCAAT/metabolismo , Citoplasma/metabolismo , Proteína Quinase C-delta/metabolismo , Apoptose/fisiologia , Proteína alfa Estimuladora de Ligação a CCAAT/genética , Linhagem Celular , Humanos , Fosforilação , Proteína Quinase C-delta/genética , Transporte Proteico , Serina/metabolismo
10.
Cell Metab ; 35(12): 2216-2230.e8, 2023 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-37979583

RESUMO

Mammalian target of rapamycin complex 1 (mTORC1) monitors cellular amino acid changes for function, but the molecular mediators of this process remain to be fully defined. Here, we report that depletion of cellular amino acids, either alone or in combination, leads to the ubiquitination of mTOR, which inhibits mTORC1 kinase activity by preventing substrate recruitment. Mechanistically, amino acid depletion causes accumulation of uncharged tRNAs, thereby stimulating GCN2 to phosphorylate FBXO22, which in turn accrues in the cytoplasm and ubiquitinates mTOR at Lys2066 in a K27-linked manner. Accordingly, mutation of mTOR Lys2066 abolished mTOR ubiquitination in response to amino acid depletion, rendering mTOR insensitive to amino acid starvation both in vitro and in vivo. Collectively, these data reveal a novel mechanism of amino acid sensing by mTORC1 via a previously unknown GCN2-FBXO22-mTOR pathway that is uniquely controlled by uncharged tRNAs.


Assuntos
Proteínas Serina-Treonina Quinases , Serina-Treonina Quinases TOR , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Aminoácidos/metabolismo , RNA de Transferência/genética , RNA de Transferência/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo
11.
Biochem Biophys Res Commun ; 423(4): 721-5, 2012 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-22705300

RESUMO

The acidic leucine-rich nuclear phosphoprotein 32B (ANP32B) is a member of a conserved superfamily of nuclear proteins whose functions are largely unknown. In our previous work, ANP32B was identified as a novel direct substrate for caspase-3 and acted as a negative regulator for leukemic cell apoptosis. In this work, we provided the first demonstration that ANP32B expression was down-regulated during differentiation induction of leukemic cells by all-trans retinoic acid (ATRA). Knockdown of ANP32B expression by specific shRNA enhanced ATRA-induced leukemic cell differentiation, while ectopic expression of ANP32B attenuated it, indicating an inhibitory role of ANP32B against leukemic cell differentiation. Furthermore, luciferase reporter assay revealed that ANP32B might exert this role through inhibiting the ATRA dependent transcriptional activity of retinoic acid receptor (RARα). These data will shed new insights into understanding the biological functions of ANP32B protein.


Assuntos
Leucemia Mieloide Aguda/patologia , Proteínas Nucleares/fisiologia , Receptores do Ácido Retinoico/metabolismo , Apoptose , Linhagem Celular Tumoral , Regulação para Baixo , Técnicas de Silenciamento de Genes , Humanos , Leucemia Mieloide Aguda/induzido quimicamente , Proteínas Nucleares/genética , RNA Interferente Pequeno/genética , Receptores do Ácido Retinoico/antagonistas & inibidores , Transdução de Sinais , Tretinoína/farmacologia
12.
Cell Death Dis ; 13(6): 532, 2022 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-35668069

RESUMO

PTENα and PTENß (PTENα/ß), two long translational variants of phosphatase and tensin homolog on chromosome 10 (PTEN), exert distinct roles from canonical PTEN, including promoting carcinogenesis and accelerating immune-resistant cancer progression. However, their roles in carcinogenesis remain greatly unknown. Herein, we report that, after secreting into the extracellular space, PTENα/ß proteins are efficiently cleaved into a short N-terminal and a long C-terminal fragment by the proprotein convertase Furin at a polyarginine stretch in their N-terminal extensions. Although secreted PTENα/ß and their cleaved fragment cannot enter cells, treatment of the purified C-terminal fragment but not cleavage-resistant mutants of PTENα exerts a tumor-suppressive role in vivo. As a result, overexpression of cleavage-resistant PTENα mutants manifest a tumor-promoting role more profound than that of wild-type PTENα. In line with these, the C-terminal fragment is significantly downregulated in liver cancer tissues compared to paired normal tissues, which is consistent with the downregulated expression of Furin. Collectively, we show that extracellular PTENα/ß present opposite effects on carcinogenesis from intracellular PTENα/ß, and propose that the tumor-suppressive C-terminal fragment of PTENα/ß might be used as exogenous agent to treat cancer.


Assuntos
Furina , Neoplasias Hepáticas , Carcinogênese , Furina/genética , Humanos , Pró-Proteína Convertases
13.
Cell Death Differ ; 29(8): 1569-1581, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35140358

RESUMO

Linker histone H1 proteins contain many variants in mammalian and can stabilize the condensed state of chromatin by binding to nucleosomes and promoting a more inaccessible structure of DNA. However, it is poorly understood how the binding of histone H1s to chromatin DNA is regulated. Screened as one of a collection of epithelial cells-enriched long non-coding RNAs (lncRNAs), here we found that small nucleolar RNA host gene 8 (SNHG8) is a chromatin-localized lncRNA and presents strong interaction and phase separation with histone H1 variants. Moreover, SNHG8 presents stronger ability to bind H1s than linker DNA, and outcompetes linker DNA for H1 binding. Consequently, loss of SNHG8 increases the amount of H1s that bind to chromatin, promotes chromatin condensation, and induces an epithelial differentiation-associated gene expression pattern. Collectively, our results propose that the highly abundant SNHG8 in epithelial cells keeps histone H1 variants out of nucleosome and its loss contributes to epithelial cell differentiation.


Assuntos
Histonas , RNA Longo não Codificante , Animais , Cromatina , DNA/metabolismo , Células Epiteliais/metabolismo , Histonas/genética , Histonas/metabolismo , Mamíferos/metabolismo , Nucleossomos , RNA Longo não Codificante/genética
14.
Sci China Life Sci ; 64(11): 1858-1867, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33754289

RESUMO

Long non-coding RNAs (lncRNAs) are widely involved in a variety of biological processes, including epithelial-mesenchymal transition (EMT). In the current study, we found that lncRNA small nucleolar RNA host gene 8 (SNHG8) was tightly correlated with EMT-associated gene signatures, and was down-regulated by Zinc finger E-box-binding homeobox 1 (ZEB1) during EMT progress. Functionally, knockdown of SNHG8 induced EMT in epithelial cells, through destabilizing the CDH1 mRNA dependent on a 17-nucleotide sequence shared by SNHG8 and CDH1. In addition, analysis with public database showed that SNHG8 tended to be down-regulated in different cancer types and the lower expression of SNHG8 predicted poorer prognosis. Taken together, our study reports a ZEB1-repressed lncRNA SNHG8 which is important for stabilizing CDH1 mRNA, thereby maintaining the epithelial status of epithelial cells.


Assuntos
Antígenos CD/genética , Caderinas/genética , Transição Epitelial-Mesenquimal/genética , RNA Longo não Codificante/genética , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genética , Linhagem Celular Tumoral , Regulação para Baixo , Regulação Neoplásica da Expressão Gênica , Humanos
15.
Carcinogenesis ; 31(3): 419-26, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20015864

RESUMO

The acidic leucine-rich nuclear phosphoprotein 32 (ANP32)B has been reported to regulate gene expression by acting as a histone chaperone or modulate messenger RNA trafficking by serving as a HuR ligand. However, its exact cellular functions are poorly understood. By utilizing a proteomics-based approach, in this work, we identify that the human ANP32B protein is cleaved during apoptosis induction by NSC606985, a novel camptothecin analog. Further investigation shows that various apoptosis inducers cause a decrease of full-length ANP32B in multiple cell lines with a concomitant increase of an approximately 17 kDa fragment. The proteolytic cleavage of ANP32B is inhibited by a specific caspase-3 inhibitor Z-DEVD-fmk, and it cannot be seen in NSC606985-induced death of caspase-3-deficient MCF-7 cells. In vitro caspase cleavage assay and mutagenesis experiment reveal that ANP32B is a direct substrate of caspase-3 and it is primarily cleaved at the sequence of Ala-Glu-Val-Asp, after Asp-163. Additionally, the reduced expression of endogenous ANP32B by specific small interfering RNA enhances caspase-3 activation and apoptosis induction by NSC606985 and etoposide. These results suggest that ANP32B is a novel substrate for caspase-3 and acts as a negative regulator for apoptosis, the mechanism of which remains to be explored.


Assuntos
Apoptose/fisiologia , Carcinoma/patologia , Caspase 3/metabolismo , Leucemia Mieloide/patologia , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Acetofenonas/farmacologia , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Benzopiranos/farmacologia , Camptotecina/análogos & derivados , Camptotecina/farmacologia , Carcinoma/metabolismo , Linhagem Celular Tumoral/efeitos dos fármacos , Linhagem Celular Tumoral/metabolismo , Inibidores de Cisteína Proteinase/farmacologia , Regulação para Baixo , Ativação Enzimática , Feminino , Humanos , Leucemia Mieloide/metabolismo , Masculino , Proteínas de Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/genética , Interferência de RNA , RNA Interferente Pequeno/farmacologia , Proteínas Recombinantes de Fusão/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Especificidade por Substrato
16.
Int J Cancer ; 127(8): 1795-803, 2010 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-20099282

RESUMO

Diabetes is now generally accepted as a crucial event in the process of pancreatic cancer (PaC). However, molecular mechanisms underlying the relationship between diabetes and PaC are not fully understood. Regenerating gene (REG) Ialpha is a growth factor affecting pancreatic islet beta cells, and it has been shown to be involved in the carcinogenesis in gastrointestinal tract. It is rational to speculate that REG Ialpha plays a potential role in the pathogenesis of PaC with diabetes. The aim of this study was to evaluate the REG Ialpha protein expression profile in PaC with and without diabetes, and define the contribution of REG Ialpha on PaC development. We found that REG Ialpha protein preferentially expressed in cancerous tissues of PaC patients with diabetes by Western blot. REG Ialpha positive cancer cells in PaC with diabetes (n = 38) was significantly higher than that in subjects without diabetes (n = 42, p < 0.05) by immunohistochemical analysis. Furthermore, we found that overexpression of REG Ialpha protein in PaC cell lines resulted in accelerated cell proliferation and consequently tumor growth, both in vitro and in vivo. The findings suggest that REG Ialpha may act as one of the tumor promoter and contribute to the aggressive nature of PaC, especially in the subpopulation with diabetes. This study would shed new insights for understanding the molecular mechanisms underlying the link between diabetes and PaC.


Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Litostatina/metabolismo , Neoplasias Pancreáticas/metabolismo , Adulto , Idoso , Animais , Western Blotting , Proliferação de Células , Ensaio de Unidades Formadoras de Colônias , Meios de Cultivo Condicionados/farmacologia , Diabetes Mellitus Tipo 2/patologia , Feminino , Humanos , Técnicas Imunoenzimáticas , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Pessoa de Meia-Idade , Neoplasias Pancreáticas/patologia , Células Tumorais Cultivadas , Regulação para Cima
17.
Nat Commun ; 11(1): 1720, 2020 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-32249768

RESUMO

Nuclear localization of PTEN is essential for its tumor suppressive role, and loss of nuclear PTEN is more prominent than cytoplasmic PTEN in many kinds of cancers. However, nuclear PTEN-specific regulatory mechanisms were rarely reported. Based on the finding that nuclear PTEN is more unstable than cytoplasmic PTEN, here we identify that F-box only protein 22 (FBXO22) induces ubiquitylation of nuclear but not cytoplasmic PTEN at lysine 221, which is responsible for the degradation of nuclear PTEN. FBXO22 plays a tumor-promoting role by ubiquitylating and degrading nuclear PTEN. In accordance, FBXO22 is overexpressed in various cancer types, and contributes to nuclear PTEN downregulation in colorectal cancer tissues. Cumulatively, our study reports the mechanism to specifically regulate the stability of nuclear PTEN, which would provide the opportunity for developing therapeutic strategies aiming to achieve complete reactivation of PTEN as a tumor suppressor.


Assuntos
Carcinogênese/genética , Núcleo Celular/metabolismo , Transformação Celular Neoplásica/genética , Neoplasias Colorretais/metabolismo , Proteínas F-Box/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Animais , Linhagem Celular Tumoral , Cromatografia Líquida , Neoplasias Colorretais/genética , Citoplasma/metabolismo , Proteínas F-Box/genética , Feminino , Humanos , Camundongos , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , PTEN Fosfo-Hidrolase/química , PTEN Fosfo-Hidrolase/genética , RNA Interferente Pequeno , Receptores Citoplasmáticos e Nucleares/genética , Transdução de Sinais/genética , Espectrometria de Massas em Tandem , Análise Serial de Tecidos , Transplante Heterólogo , Ubiquitinação
18.
Nat Cell Biol ; 22(1): 135, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31730051

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

19.
Am J Physiol Lung Cell Mol Physiol ; 297(4): L631-40, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19592460

RESUMO

Angiotensin-converting enzyme (ACE) enhances the proliferation and migration of pulmonary artery smooth muscle cells (PASMCs), which contribute to the pathogenesis of hypoxic pulmonary hypertension (HPH). Previous reports have demonstrated that hypoxia upregulates ACE expression, but the underlying mechanism is unknown. Here, we found that ACE is persistently upregulated in PASMCs on the transcriptional level during hypoxia. Hypoxia-inducible factor 1alpha (HIF-1alpha), a key transcription factor activated during hypoxia, was able to upregulate ACE protein expression under normoxia, whereas knockdown of HIF-1alpha expression in PASMCs inhibited hypoxia-induced ACE upregulation. Furthermore, HIF-1alpha can bind and transactivate the ACE promoter directly. Therefore, we report that ACE is a novel target of HIF-1alpha. Recently, a homolog of ACE, ACE2, was reported to counterbalance the function of ACE. In contrast to ACE, we found that ACE2 mRNA and protein levels increased during the early stages of hypoxia and decreased to near-baseline levels at the later stages after HIF-1alpha accumulation. Thus HIF-1alpha inhibited ACE2 expression, and the accumulated ANG II catalyzed by ACE is a key mediator in the downregulation of ACE2 by HIF-1alpha. Moreover, a reduction of ACE2 expression in PASMCs by RNA interference was accompanied by significantly enhanced proliferation and migration during hypoxia. We conclude that ACE is directly regulated by HIF-1alpha, whereas ACE2 is regulated in a bidirectional way during hypoxia and may play a protective role during the development of HPH. In sum, these findings contribute to the understanding of the pathogenesis of HPH.


Assuntos
Hipertensão Pulmonar/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/fisiologia , Hipóxia/metabolismo , Miócitos de Músculo Liso/metabolismo , Peptidil Dipeptidase A/metabolismo , Artéria Pulmonar/metabolismo , Angiotensina II/metabolismo , Enzima de Conversão de Angiotensina 2 , Western Blotting , Movimento Celular , Proliferação de Células , Células Cultivadas , Imunoprecipitação da Cromatina , Imunofluorescência , Humanos , Músculo Liso Vascular/citologia , Músculo Liso Vascular/metabolismo , Peptidil Dipeptidase A/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/farmacologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica
20.
Natl Sci Rev ; 6(6): 1111-1127, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34691990

RESUMO

Chemical biology has been attracting a lot of attention because of the key roles of chemical methods and techniques in helping to decipher and manipulate biological systems. Although chemical biology encompasses a broad field, this review will focus on chemical biology aimed at using exogenous chemical probes to interrogate, modify and manipulate biological processes, at the cellular and organismal levels, in a highly controlled and dynamic manner. In this area, many advances have been achieved for cancer biology and therapeutics, from target identification and validation based on active anticancer compounds (forward approaches) to discoveries of anticancer molecules based on some important targets including protein-protein interaction (reverse approaches). Herein we attempt to summarize some recent progresses mainly from China through applying chemical biology approaches to explore molecular mechanisms of carcinogenesis. Additionally, we also outline several new strategies for chemistry to probe cellular activities such as proximity-dependent labeling methods for identifying protein-protein interactions, genetically encoded sensors, and light activating or repressing gene expression system.

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